Method and arrangement for de-icing a structural element
TECHNICAL FIELD
The present invention relates to an arrangement and method for de-icing a
structure. In particular the invention relates to an arrangement and method
for de-icing a whole polymeric (fiber reinforced) or metallic wing or propeller.
The invention also relates to a computer programme and a computer
programme product. The invention also relates to a platform carrying the
arrangement.
BACKGROUND ART
Aircrafts are continuously exposed to varying climatic condition and among
the extremes situation is ice accretion one of the most threatening events. Ice
accretion is known to cause serious perturbation to the flying conditions due
to ice formations in aerodynamic surfaces of aircraft.
Ice accretion on aircrafts is a very complex physical process. The selection of
an adequate ice rejection technique is thus a difficult task. The technique to
be selected must be made compatible with a number of constrains
comprising materials properties, fatigue, dynamic deformation while in flight,
birds collision withstanding ability, repairing and servicing constrains,
durability, etc. just to name a few. Therefore, any method to be considered
has to be carefully analyzed in its total context to end up with technical
conclusions of value.
One of the issues now upcoming is to be found on the growing need of fuel
consumption reductions which in turn impose requirements of weight
reduction and exceptional aerodynamic constrains, especially laminar air
flow. This has been leading to the development of the Smart Fix-wings
Aircraft concept where the wings are thought to be made of light weight fiber
reinforced epoxy. The removal of ice can be accomplished either by
providing melting heat or mechanical stresses to the skin just to surpass
adhesion forces of the accreted ice layer. Heat however is known to demand
too much power, and in the case of epoxy based material, high temperature
is an ageing factor that should be avoided. Mechanical stresses on the other
hand should be impulsive to minimize the energy consumption and to
accomplish ice cracking while destroying the ice surface adhesion. The
accreted ice wil then be removed mainly due to the drag forces of the air.
Therefore, actuators able to accomplish wing skin surface displacements
through the action of impulsive forces are highly interesting.
US 5584450 depicts an electro-expulsive de-icing system for attachment to
an airfoil which is comprised of a plurality of electro-expulsive elements
separated by a dielectric filler regions all of which are disposed between a
top dielectric layer and a bottom dielectric layer. A contiguous top skin layer
covers the entire de-icing apparatus.
US 5129598 depicts an attachable electro-impulse de-icer for de-icing an
aircraft structural member including an inductor coi disposed in proximity
with the outer surface of the structural member. The coil is supported by a
flexible ice-accumulating support member that permits the coil to move
relative to the structural member. The coi! and the support member may be
formed in an integral construction that can be attached to the leading edge of
the structural member. The coil and the support member are rapidly
displaced away from the structural member upon passing a short-duration,
high current pulse through the coil.
Known ice rejection methods are mostly conceived for metallic skin materials
and are mostly inductive or thermal (heating). There are even methods that
accomplish deicing through total deformation (inflatable layers, etc.).
Known drawbacks of some of the methods are related to the fact that those
ice rejection devices introduce significant local perturbation to air flow. Since
laminar flow, particularly at wing surfaces, is a much wanted feature from the
view point of aerodynamic considerations, any protrusion to the surfaces is
not acceptable.
Another drawback of known deicing methods is to be found in the melting of
the interlayer of ice and wings which may lead to a gliding effect of the
accreted ice pushing it back of simply generating water that flows back and
risk to be frozen at the ailerons of aircraft wings.
SUMMARY OF THE INVENTION
There is an object of the invention to provide an improved method and
arrangement for de-icing a structural element, such as a wing of an aircraft or
a propeller b!ade of a wind power installation.
There is another object to provide a robust method and arrangement for deicing
a structural element, such as a wing of an aircraft or a propeller blade of
a wind power installation.
There is also an object of the invention to provide an alternative method and
arrangement for de-icing a structural element, such as a wing of an aircraft or
a propeller blade of a wind power installation.
Yet another object of the invention is to provide a method and arrangement
for improving performance of a platform exposed to harsh weather conditions
giving rise to ice accretion.
Still yet another object of the invention is to provide a method and
arrangement for reducing a risk of unwanted air turbulence at a platform,
which air turbulence results in impaired performance thereof.
These objects are achieved by a de-icing arrangement according to claim .
According to an aspect of the invention there is provided a de-icing
arrangement for de-icing a structural element, comprising:
a power source being electrically connected to an electrode configuration,
said power source is arranged to, when applicable, electrically charge said
electrode configuration, wherein said electrode configuration is arranged to
generate an impulsive force for removal of ice adhered on said structural
element.
Said electrode configuration may comprise a first electrode and a second
electrode being mutually displaceable, wherein one of said first and second
electrode being closest to the ice to be removed. The other one of said first
and second electrode being fixed to said structural element.
Said power source may be arranged to, when applicable, electrically charge
said electrode configuration to a predetermined state.
Said electrode configuration is arranged to generate an impulsive force for
removal of ice adhered on said structural element when charging to and d is
charging from said predetermined state. Said charging and dis-charging of
said electrode configuration is performed pulse like, i.e. with a short duration,
such as 1-5 milliseconds. This pulse is creating an impulsive force which is
acting on said structural element so as to remove said adhered ice.
By providing a voltage pulse to said electrode arrangement an electrical field
is quickly bui!t up between the first electrode and the second electrode.
During discharge of said electrode arrangement energy associated with said
electrical field is at least party transformed to an impulsive force which
impacts said structural element, resulting in an impulse like deformation of a
skin of said structural element. Hereby ice adhered to said structural element
may be removed.
A cracking effect on accreted ice is aimed to reduce the size of ice blocks
removed from front wings of an aircraft to avoid flying ice pieces that could
damage other parts of the aircraft while flying backwards.
Said predetermined state of said electrode configuration may be an arbitrary
suitable state, where said electrical field between said first electrode and
second electrode is large enough to remove a detected and measured ice
layer on said structural element. This means that said predetermined state
may be determined on the basis of a thickness and configuration measured
by an ice detecting/measuring system as depicted below.
The basic advantages of the invention are to be found in the simplicity of the
concept. The arrangement is simple to implement in existing platforms. t also
provides a low level of intrusion in the structural element of e.g. a whole
composite wing for aircraft.
There is however a wide spectrum of potential applications for the de-icing
concept hereby submitted, both military and civilian.
The mayor advantage of the de-icing concept is to be found in the fact that
the technique can equally be implemented in whole polymeric or metallic
wings, although the solution should be adapted carefully to each case to
ensure functionality and correct use of electricity.
The energy amount expected to be demanded by the operation of de-icing
arrangement is very low as it will be intermittent in pulses and proportional to
V2, where V is a voltage of over the first electrode and the second electrode,
before dis-charge. Furthermore, it must be mentioned that the impulsive
forces, e.g. tabulated in the section "Principles of the invention" below, will be
much more enhanced than those given in the second force column if a typical
polyester film is used. Actually the impulsive forces may increase by a factor
about 40-50, or higher, depending upon dielectric properties. A gap between
the first electrode and the second electrode not greater that 0.5 mm will be
needed, which can be an advantage in many aerodynamic aspects. It should
be evident that the gap, its length and the thickness of the skin of the
structural element as well as the maximum attainable impulsive forces should
be coordinated to be within the limits of de-lamination of the chosen
composite. The impulsive forces have to be decided on the basis of what is
needed to accomplished, while still coordinated with material properties and
withstanding ability. In practice, there is needed a design involving a
compromise between material properties of the arrangement and how the
chosen materia! will work during a long life time.
An advantage relating to mechanical stresses is to be found in the fact that
the concept according to an aspect of the invention is very compact and
therefore will not be particularly affected by impacts with e.g. birds or other
potential objects in the air which may impact on the wings (debris, stones
etc.).
For aircrafts, an ice thickness above about 3-4 mm will create a too
significant deterioration of aerodynamic behavior and therefore ice rejection
should in general not be allowed for too much ice accretion. A too thin layer
of ice, say below 1 mm is too much elastic and will therefore follow the
induced oscillations (provided by repeated generation of impulsive forces) in
a skin of the structural element too easily. On the other side, a too heavy ice
accumulation means a large thickness of accreted ice and therefore the
forces needed to accomplish mechanical deformation of the skin of the
structural element will grow to limits closer to those that might cause damage
to the say composite skin of the wings. Therefore it is very much needed to
carefully evaluate the optimal range of operation of such a device to ensure
performance and no-risk of operation against the possibility of structural
damages to composites or metallic skins. This is however a possible to
accomplish through a careful experimental work and design of the power
system to activate de-icing.
A too low accreted ice layer thickness, say beiow 0.5-0.7 mm is a very elastic
layer of ice whereby the deformation induced in the skin by impulsive forces
is in general not able to accomplish ice-rejection. On the other side, a too
thick layer of ice will increase the mass of the skin in such a way that the
impulsive forces may not able to accomplish a displacement of the skin with
a deformation level enough to cracks the accreted ice and thereby induce
rejection. Careful thickness measurement of accreted thicknesses is thus
mandatory for correct implementation of ice rejection strategies.
Advantageously the arrangement can be installed in carbon or glass fiber
reinforced polymers (structural element). Cables for communication between
devices within the de-icing arrangement, power cables as well as the
electrode configuration may be integrated in a whole plastic structural device.
In a case of whole metallic wings, there are methods of implementing a
secure solution with advanced methods of coordinated insulation.
Said electrode configuration may comprise a first electrode and a second
electrode being provided in a close proximity of each other.
Said electrode configuration may comprise a first electrode and a second
electrode being mutually displaceable, wherein one of said first and second
electrode is closest to the ice to be removed, and wherein the other one of
said first and second electrode is fixed to said structural element.
Said electrode configuration may comprise a sandwiched dielectric element.
Said dielectric element may be very thin. According to one example said
dielectric element is about 250 micrometer thick. Hereby a larger impulsive
force may be generated for a given voltage.
Said electrode configuration may comprise a plate capacitor. A plate
capacitor is in genera! a rather cheap device. The arrangement therefore
provides for a cost effective solution of the above stated problems.
Said first and second electrodes may be strip like. The ice rejection method
hereby proposed is intrinsically flat and not protruding, has very low thickness
and thereby does not affect neither the aerodynamics of a surface of the
structural element nor the structural intrusion on composites wings or metallic
wings of a platform. Those are otherwise common drawbacks of known deicing
methods.
Said first electrode may comprise a plurality of separated first electrodes, and
wherein said second electrode is functionally provided at each of said
plurality of separated first electrodes. By providing generation of said
impulsive forces at predetermined distinct locations along said second
electrode, such as at locations where ice accretion is a known problem, less
material for manufacturing the first electrode is required. A cheaper de-icing
arrangement is thus provided, without delimiting performance of said
arrangement. Naturally, according to another embodiment, said second
electrode may comprise a plurality of separated second electrodes, and said
first electrode may be functionally provided at each of said plurality of
separated second electrodes.
It should be noted that in the electrode configuration hereby suggested,
according to an example, one of the electrodes should be an integral part of
a movable skin, while the other electrode is attached to wing structural
beams so as to accomplish a fix part relative to the movable one.
One possible advantage of this concept in a whole polymeric wing is to be
found in the fact that one of the electrodes, e.g. the one attached to the wing
structural beams, could be made continuous over the whole extension of the
structural element and dimensioned to allow for high current densities,
whereby its functionality couid be extended using it as a lightning diverting
path, wherein this electrode should be earthed.
Said generated impulsive force may have an amplitude sufficient for removal
of an adhered layer of ice having a thickness of about 1-3 millimeter (10 3m).
Said generated impulsive force may alternatively have an amplitude sufficient
for removal of an adhered layer of ice having a thickness of about 1-10
millimeter (10 m). The applied voltage to the electrode configuration, as well
as dimensions and characteristics of said first electrode, second electrode
and said dielectric element should be chosen so as to achieve a suitable
impulsive force for removing ice adhered to said structural element.
Said arrangement is arranged to generate a number of successive impulsive
forces for removal of ice adhered on said structural element. Hereby an
effective de-icing arrangement is provided. According to one embodiment
there is generated a predetermined number of chock pulses for removing the
ice on the structural element. According to one example 3-5 successive
chock pulses are generated by means of said electrode configuration.
According to another example more than 5 successive chock pulses are
generated.
A technical implementation of high voltage pulses generation could be seen
as a similar solution as the one encountered in spark generation for
automobiles, where voltage pulses of 10 - 15 kV are commonly used. The
number of pulses and their shape could be adjusted electronically at the
primary side of a HV coil by a microprocessor controlled device. The phase
shift of a coil transformer has to be considered if positive or negative pulses
are wanted. The key issue here is that the noise band of the pulses can be
controlled and, for the specific application a noise band below or at most 1
MHz is expected for pulses with rice and fall in the range of milliseconds.
Each pulse may have an arbitrarily suitable duration. According to one
example a pulse has a duration of 1 millisecond. The impulsive force for
removing ice on the structural element is operating substantially during the
generated voltage power pulse.
According to one aspect of the invention there is determined a need to
generate an impulsive force for removing ice on the structural element before
said impulsive force is generated. A need to generate an impulsive force for
removing ice on the structural element may be determined by a means to
determine ice thickness on said structural element. This means to determine
ice thickness on said structural element may be provided adjacent to said deicing
arrangement.
The de-icing arrangement may comprise at least two electrode
configurations. The at least two electrode configurations may be powered by
one single power source, such as a battery or a main power source aboard
an aircraft. Alternatively, the at least two electrode configurations may be
powered by different power sources, such as a main power source and an
auxiliary power source aboard an aircraft, respectively t should also be
noted that the at least two electrode configurations may be operationally
driven by means of one or more control units for controlling generation of
said impulsive forces and, when applicable, de-ice said structural element
according to an aspect of the invention.
Said two electrode configurations may be generating said impulsive forces in
an alternating way. Said electrode configurations do not need to be
synchronized to generate oscillation in a skin of the structural element to
achieve ice rejection. According to another example, said two electrode
configurations may be generating said impulsive forces substantially
simultaneously.
Said voltage power source may create an electric field between said first
electrode and said second electrode, which field has an arbitrarily suitable
magnitude, such as 1kV, 5 kV or 10 kV. Alternatively, the electric field may
have an amplitude which is lower than 1 kV or more than 10 kV.
Said structural element may be made of a non-metallic material, such as a
full-plastic material, comprising e.g. carbon-fibre and/or glass-fibre. Said
structural element may be made of a metallic material, such as Alumina, or
light weight metallic alloys. According to one example, said structural element
may be made of a metallic material and whole plastic material.
Said structural element may be part of any other application demanding
controlled ice accretion on its surface with periodical ice rejection as it can be
accomplished with a tailored application of this ice ejection concept.
Said structural element may be a wing of an aircraft. Said structural element
may be a skin of a wing of an aircraft. Said structural element may be a
propeller blade of a wind power installation.
The de-icing arrangement has a very low volume, compared to a prior art
solution using coils for removing ice on said structural element. The de-icing
arrangement may advantageously also preserve a smooth surface of the
structural element, which is highly desirable seen from an air turbulence point
of view.
According to an aspect of the invention there is provided a platform
comprising the de-icing arrangement depicted herein.
Said platform may be a stationary facility.
Said platform may be a stationary wind power installation or an off shore
wind power installation. The concept according to the invention could easily
be implemented in the blades of a wind power generator at high latitudes. For
instance, in a wind power market perspective the proposed de-icing invention
will significantly increase the profitability of wind energy in icing climates. The
invention will facilitate the wind power expansion in arctic areas. At present,
the absence of effective deicing methods reduces the energy production
causing significant economic losses. Furthermore, a huge potential area
suitable for generation of electricity as due to their excellent wind conditions
in arctic areas is avoided as no adequate de-icing technology is available.
Similar arguments could be provided for many other potential application of
efficient and compatible deicing technology.
The platform may be an aircraft and said structural element may be an
aircraft wing or aircraft rudder. The technology depicted herein may be of
easy adaptation to many other civilian and military applications. A person
skilled in the art realizes that the technique depicted herein, according to the
invention, is applicable to any other application where there exists a basic
need of ice rejection of a structural element.
According to an aspect of the invention there is provided a method for deicing
a structural element, comprising the step of:
- when applicable, electrically charging an electrode configuration by means
of a power source, which is electrically connected to said electrode
configuration, and the step of:
- generating an impulsive force for removal of ice adhered on said structural
element.
According to an aspect of the invention there is provided a rapid change in
voltage delivered to the electrode configuration.
In case of an aircraft platform, the de-icing method may be performed before
take-off, during take-off, in flight, and/or during landing, i.e. in any case where
ice has been detected on one or more wings of the aircraft.
The method may further comprise the step of:
- activating said electrically charging of said electrode configuration on the
basis of a signal indicating presence of a current ice state on said structural
element.
The method may further comprise the step of:
- determining whether said electricaily charging of said electrode
configuration has set said electrode configuration in said predetermined
state.
The method may further comprise the step of:
- determining a state of ice built up on said structural element, and generating
said impulsive force on the basis on said determined state.
BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the present invention and further
objects and advantages thereof, reference is now made to the examples
shown in the accompanying drawings, wherein like reference characters refer
to like parts throughout the several views, and in which:
Figure 1a schematically illustrates a platform in the form of an aircraft,
according to an aspect of the present invention;
Figure 1b schematically illustrates platform in the form of a wind power
installation, according to an aspect of the present invention;
Figure 2 schematically illustrates a de-icing arrangement, according to an
aspect of the present invention;
Figure 3a schematically illustrates a wing of an aircraft being provided with a
plurality of de-icing arrangements, according to an aspect of the present
invention;
Figure 3b schematically illustrates a cross sectional view of a wing of an
aircraft being provided with a pair of de-icing arrangements, according to an
aspect of the present invention;
Figure 4a schematically illustrates a method for de-icing a structural element,
according to an aspect of the present invention;
Figure 4b schematically illustrates a method for de-icing a structural element,
depicted in greater detail, according to an aspect of the present invention;
and
Figure 5 schematically illustrates a control unit, according to an aspect of the
present invention.
DETAILED DESCRIPTION
With reference to Figure 1 there is depicted a platform 00 according to an
aspect of the invention. According to Figure 1a the platform 100 is
exemplified by an aircraft. The aircraft may be a fighter, bomber, surveillance
aircraft, or a combination thereof. The aircraft may be a commercial civilian
aircraft, such as an airliner, or utility aircraft. The aircraft may be engine
powered or a glider. The aircraft may be manned or unmanned, e.g. an UAV
(Unmanned Aerial Vehicle). The aircraft may be fixed-wing, ornithopter,
rotary wing or a combination thereof. The platform 00 may alternatively be a
satellite, space-shuttle, rocket or missile.
According to other examples where the arrangement may be implemented,
the platform may be a watercraft, such as a ship, boat or ferry. The
arrangement may be installed on an oil rig, or other floating platform. In
particular the arrangement is suitable for installation on a floating wind power
installation.
With reference to Figure there is schematically depicted a platform, which
is suitable for an arrangement for de-icing a structure, according to an aspect
of the invention.
According to Figure b the platform 100 is a stationary facility. According to a
preferred embodiment the stationary facility is a wind power installation for
generating electrical power in a conventional manner. According to this
example the wind power installation comprises a base structure 50, a hub
160 and three propeller blades 170. Other features, such as generator, gear
box and control units are not shown in Figure 1b, for reasons of clarity. A
rotor diameter of said wind power installation may be up to 120 meters,
however any suitable rotor diameter may be used, such as 50 meters or 75
meters. The wind power installation may be adapted for low, medium or high
wind. According to one example the wind power installation is provided with
three propeller biades, however, any suitable number of propeller blades may
be suitable.
Wind power installations may suffer from ice accretion on e.g. the propeller
blades 170. Ice accreted on the propeller blades, in general, has a negative
impact on the performance of the wind power installation 10. Generated
electrical power may be reduced by as much as 40%, or even more in
extreme icing conditions, as compared to operation during more favourable
weather conditions, i.e. conditions implying acceptable or zero ice accreted
on the propeller blades 170.
In a situation where adhered ice is covering at least a part of one propeller
blade, shear forces at the hub 160 of the propeller blades causes impaired
operation and an increased risk for shut down or, in severe cases, a
breakdown of the wind power installation 110.
An arrangement depicted with reference to Figure 2 is according to an
embodiment of the invention integrated in at least one propeller blade,
preferably all propeller blades of the wind power installation.
Alternatively, a suitable stationary facility (platform) may be any chosen from
a group comprising: wireless communication installations, such as antennas
carrying radio base stations for cell phone communication, parabolas
arranged on support structures, radar stations, any civi and/or military device
or systems where ice accretion on its surface impairs a desired functionality,
thereof, etc.
With reference to Figure 2 there is schematically illustrated an example
configuration of an arrangement for de-icing a structural element, according
to an aspect of the invention.
The de-icing arrangement comprises an electrode configuration 200. In more
detail, the de-icing arrangement comprises a first electrode 210 and a second
electrode 220. A dielectric element 230 is interposed between said first
electrode 210 and said second electrode 220.
One of the electrodes (electrode 210) of the electrode configuration is fixed
while the other electrode (electrode 220) is made movable with the skin of
the system. Mechanical design precautions have to be undertaken so as to
allow the de-icing arrangement to accomplish oscillations in the range of
about 1 mm in amplitude without damaging to the skin (for instance delamination,
fatigue, etc.). Furthermore, the bouncing back of the electrode
once rejected must also be considered and damped to avoid mechanical
damages.
According to one example, the de-icing arrangement comprises a plate
capacitor. In more detail the de-icing arrangement comprises a first capacitor
plate 2 0 and a second capacitor plate 220. The plate capacitor is according
to one aspect of the invention a parallel plate capacitor.
The first electrode 2 10 may be made of any suitable material, which is a
material being compatible with the structural element, second electrode 220
and the dielectric element 230, where the de-icing arrangement employed.
The first electrode 210 may be made of any suitable metal or alloy. Also, the
first electrode 2 0 may have any suitable dimensions. However, according to
a preferred embodiment the first electrode 210 is substantially twodimensional,
i.e. in a shape of a sheet, e.g. having a rectangular shape.
According to one example the first electrode 210 is strip like. The first
electrode 210 may be integrated in the structural element.
The second electrode 220 may be made of any suitable material, which is a
material being compatible with the structural element, first electrode 2 0 and
the dielectric element 230, where the de-icing arrangement employed. The
second electrode 220 may be made of any suitable metal or alloy. Also, the
second electrode 220 may have any suitable dimensions. However,
according to a preferred embodiment the second electrode 220 is
substantially two-dimensional, i.e. in a shape of a sheet, e.g. having a
rectangular shape. According to one example the second electrode 220 is
strip like. The second electrode 220 may be integrated in the structural
element.
A width of the first electrode is in one example in the range of 3 - 8 cm or
more. The width of the second electrode is in one example in the range of 1 -
4 cm. The length of the movable electrode (electrode 220) would according
to an example be in the case of aircraft applications of a suitable fraction
length of a slat, i.e. roughly in the range of 20 - 60 cm. The fixed electrode
(electrode 210) may however be of the whole length of a slat. Several
movable electrodes could use different fractions of the fixed electrode. A key
issue is to select lengths of the movable electrode that will generate a
suitable and optimized pattern of oscillations of the skin of the wings
(structural element) as needed to accomplish ice rejection.
There is a gap provided between the first electrode 210 and the second
electrode 220. In the gap there is provided the dielectric element 230. The
gap may have any suitable dimension. The dielectric eiement 230 closely fit
in the gap, and thus substantially fills the gap between the first electrode 2 0
and the second electrode 220.
The dielectric element 230 may be made of any suitable material, which is a
material being compatible with the structural element, first electrode 2 0 and
the second electrode 220, where the de-icing arrangement employed. The
dielectric element 230 may be made of any suitable material, which is a
material having suitable mechanical provisions for allowing a desired
oscillation pattern of the electrode configuration. According to one example
the dielectric eiement has a inherit characteristic giving the dielectric element
a relative permittivity of about 3-4, or higher. It should also have a breakdown
withstanding ability higher than the highest dimensioned voltage of applied
pulses and, where applicable, a margin of safety e.g. within an interval 30-
50%. However any suitable material having a suitable relative permittivity
may be used. Also, the dielectric element 230 may have any suitable
dimensions. However, according to a preferred embodiment the dielectric
element 230 is substantially two-dimensional, i.e. in a shape of a sheet, e.g.
having a rectangular shape. According to one example the dielectric element
230 is strip like. The second electrode 2 1 may be integrated in the structural
element closely fitted between the first electrode 210 and the second
electrode 220.
The dielectric element 230 may have any shape providing that its surface
extension is extended in all directions of the surface between electrodes. The
dielectric element 230 must cover and extend above the largest one of the
first and second electrodes i.e., say the larger electrode has a surface of
5x60 cm; then a suitable surface of the dielectric element should have a
dimension of about 10x70 cm. The construction demands that the foil should
be in place through the working life time of the device.
According to this example, the second electrode 220 is integrated in a
movable skin of the structural element 270 where ice accretion results in
adhered ice 201 . The second electrode 220 is connected to the high voltage
pulse source 250 via a cable 251 and is significant smaller in dimension
(width), as compared to the fixed, non movable electrode 210, which is
earthed and significantly wider than the movable electrode 220. According to
one example, the second electrode 220 is 1/3 of the width of the first
electrode 210, while the dielectric element 230 is about twice the width of the
fixed electrode 2 0 extending equally both sides symmetrically.
The thickness of the first and second electrodes according to an example
does not need to be larger than a fraction of a mm. The dielectric element
330, could be typically of about 250 - 300 m h . The width of the first and
second electrode could typically be in the range 1-4 mm. The length of said
first and second electrode would according to an example be of at least the
central 1/3 of a slat of an aircraft wing, i.e. roughly about 40 - 60 cm.
A voltage power source 250 is electrically connected to the movable second
electrode 220 via a cable 251 . The voltage power source 250 may be a high
voltage power source, arranged to provide voltages in a range 10-30 kV (10
kilo Volts-30 kilo Volts). The arrangement 200 as in Fig. 2 is also referred to
as transducer and will be supplied with voltage pulses. The voltage power
source 250 may be a voltage pulse source. The voltage power source 250 s
arranged to charge the electrode configuration 200. The voltage power
source 250 is arranged to charge the electrode configuration 200, when
suitable, i.e. in a case where there is decided that ice adhered to the
structural element should be removed.
According to the example arrangement shown in Figure 2, the first electrode
is provided at ground (zero, 0) voltage. The second electrode 220 is in a
charged state at a voltage V, determined by a control unit 500 connected to
the voltage power source 250 via a link L250. The control unit 500 is depicted
in greater detail with reference to Figure 5 below. The control unit 500 is also
referred to as computer. The voltage V may be of a positive or negative sign,
e.g. +10000V, or -10000V.
An ice detecting/measuring system 280 is arranged for communication with
the control unit 500 via a communication link L280. The ice
detecting/measuring system 280 is arranged to detect if there is any ice
adhered to the structural element. The ice detecting/measuring system 280 is
also arranged to measure a thickness of detected ice. The ice
detecting/measuring system 280 is also arranged to, when suitable, send a
signal comprising relevant information to said control unit. The signal may
comprise information about that ce has been detected and also a value
representing a thickness of said detected ice on the structural element.
The control unit 500 is arranged to receive signals from the
detection/measuring system 280. The control unit 500 is arranged to control
operation of said electrode configuration on basis of said received signals
and/or stored programme routines. In other words, the control unit 500 is
arranged to control a de-icing procedure using said voltage power source
250 so as to generate impulsive forces Fn of the first electrode 210 and/or
the second electrode 220.
It should be noted that an operator or said platform, e.g. aircraft (pilot) or
wind power installation (maintenance staff) may manually activate a de-icing
procedure according to an aspect of the invention. This could be done by use
of actuating means, such as a key board or push button, being signaling
connected to said control unit 500.
Possible problems with the arrangement 200, concerning e.g. use of high
voltage and the implicit risk of corona inception, partial discharges, ageing
and alike, can be prevented with intelligent solutions, proper design and
correct materials selection. The design of the first electrode 210 and second
electrode 220 depicted above is such an example.
As depicted herein an the energy W stored in the electric field E generated
between the first eiectrode 210 and the second electrode 220 is supporting
the generation of an impulsive force Fn (a force being orientated norma! to
the surface of the electrodes) so as to create a shock pulse for cracking and
thereby removing ice 201 adhered on the structural element.
The force Fn is schematically illustrated in Figure 2 and, when generated,
affects a skin 270 of the structural element. Fn has a direction normal to a
plane of the first electrode 210. Fn has a direction normal to a plane of the
second electrode 220.
The first electrode 210 is fixed to the bulk of the structural element, while the
second electrode 220 is integrated in the movable skin. The dielectric
element 230 may be integrated in either the first electrode 210 or the second
electrode 220 so as to allow impulsive movement of one eiectrode with
respect to the other.
The voltage power source may naturally be connected to both the first
eiectrode 210 and the second electrode 220, thereby ailowing generation of
an electric fieid as a source to said impulsive forces for de-icing
Figure 3a schematically illustrates a wing of an aircraft being provided with a
plurality of de-icing arrangements, according to an aspect of the present
invention;
There is shown a wing 370 of an aircraft 100. The wing 370 is provided with
seven slats, namely a first slat 310, a second slat 320, a third slat 330, a
fourth slat 340, a fifth slat 350, a sixth s at 360 and a seventh slat 370,
separated, distributed and controlled in a conventional manner.
According to an aspect of the invention at ieast one de-icing arrangement is
provided for at Ieast one of the siats 3 10-370. According to one example one
electrode configuration 200 is integrated in each of said seven slats 310-370.
The voltage power source 250 is arranged to be controlled by the control unit
500 according to what is depicted with reference to Figure 2. According to
this example, the voltage power source 250 is arranged to power an
electrode configuration 200 located in each of said seven slats 310-370.
According to this example the control unit 500 is arranged for communication
with a detection/measuring system 280 in each of said slats 310-370 of said
wing 370 via a communication link L300.
Each slat may be de-iced mutually independent according to an aspect of the
invention.
Figure 3b schematically illustrates a cross sectional view of a wing of an
aircraft being provided with a pair of the electrode configurations 200,
according to a aspect of the present invention. A dotted head line is
indicated by the letter HL.
The electrode configurations 200 may be arranged in each slat 310-370 in
this advantageous manner. Ice 201 is built up on the wing 370 approximately
as shown in Figure 3b. Thus, by arranging two electrode configurations
where ice is known to be built up during flight with the aircraft 100 an
effective means for rejecting said ice is provided.
Under certain conditions, say in the absence of slats or in the case of wind
mill propeller blades, one of the electrodes of the electrode configuration (the
fixed one) could be dimensioned to be able to carry current intensities
occurring in lightning conditions, whereby it can be used as a lightning
diverter conductor assuming the other electrode protected for induced
transients backwards to electronics.
It should be noted that said electrode configurations may be installed in any
of slats 310-370 of aircraft 100, and may also be used in a rest position as
well as in a protruded position, as schematically indicated in Figure 3b.
Power lines for supplying a voltage to the electrode arrangement 200 may be
operating in both the rest position and the protruded position.
As it can be realized, the very small thicknesses of all the components (first
electrode 210, second electrode 220 and dielectric element 230) involved in
the concept make it of very iow intrusion level, low weight and volume.
The total cost of the concept is rather low in terms of material and
components. The total architecture of a technical solution with it could
comprise a microprocessor based core and a sensor encompassing the
possibility of alarms, activations, events register data base, etc.
It should be noticed that with the suggested dimensions the total weight
addition to the whole composite nose profile of a wing will not be significant at
all.
With reference to Figure 4a there is illustrated a method for de-icing a
structural element, according to an aspect of the invention. The method
comprises a first step 401 . The method step s401 comprises the step of,
when applicable, electrically charging an electrode configuration by means of
a power source, which is electrically connected to said electrode
configuration. The method step s401 also comprises the step of: generating
an impulsive force for removal of ice adhered on said structural element.
After the method step s401 the method ends.
With reference to Figure 4b there is illustrated a flowchart of the inventive deicing
method depicted in greater detail, according to an aspect of the
invention.
The method comprises a first method step s 0. In the method step s410
there is detected if a structural element is at least partly covered with
adhered ice. This may be performed in various ways, e.g. by means of the
detecting/measuring system 280. n the method step s410 there is also
measured a thickness of the detected ice. The thickness may be an average
thickness, or a minimum or maximum thickness of said ice. The thickness of
the detected ce may be a thickness associated with a predetermined area of
said structural element. After the method step s410 a subsequent method
step s420 is performed.
The method step s420 comprises the step of determining if a predetermined
ice criterion is fulfilled. The predetermined ice criterion may be fulfilled if the
detected ice has a thickness that exceeds a predetermined thickness, e.g.
1 mm. The predetermined ice criterion may be fulfilled if the detected ice has
a thickness which falls within a predetermined ice thickness interval, e.g. 1-3
mm. Any suitable ice thickness interval may be used to determine whether
the predetermined ice criterion is fulfilled.
The predetermined ice criterion may not be fulfilled if the detected ice has a
thickness that is lower than a predetermined ice thickness value, e.g. 1 mm.
The predetermined ice criterion may not be fulfilled if the detected ice has a
thickness that is larger than a predetermined ice thickness value, e.g. 3 mm.
If the predetermined ice criterion is fulfilled (Yes), a subsequent method step
s430 is performed. If the predetermined ice criterion is not fulfilled (No), the
method step s4 0 is performed again.
The method step s430 comprises the step of charging the electrode
configuration 200 to a predetermined electric state. This electric state may be
defined by an electric field E and a voltage V between the first electrode 210
and the second electrode 220 of said electrode configuration 200. Said
electric state involves a stored electrical energy which, when transformed to
an impulsive force, is large enough to remove at least a part of said adhered
ice on said structural element. Basically, it is the sudden change in the
energy stored in the electrodes arrangement that will lead to a force which is
normal (perpendicular) to the surface of the electrodes and therefore, if one
is fixed, the other will be repelled. A variation in the stored energy will be
proportional to a variation of the separation of the electrodes times a force.
After the method step s430 a subsequent method step s440 is performed.
The method step s440 comprises the step of determining if the
predetermined electric state is achieved. If the predetermined electric state
has been achieved (Yes) due the charging of said electrode configuration
200 a subsequent method step s450 is performed. If the predetermined
electric state has not yet been achieved (No), the method step s430 is
performed again (charging continues).
The method step s450 comprises the step of generating an impulsive force
Fn, based upon said charging and a discharging of said electrode
configuration 200. Thus, charging and discharging to and from said electric
state is performed in a controlled way, for successful removal of at least a
part of said ice adhered on said structural member. Preferably all adhered ice
on said structural element. After the method step s450 a subsequent method
step s460 is performed.
The method step s460 comprises the step of determining if the ice adhered
to the structural element has been removed to a desired extent. This step
may also be performed by means of said detection/measure system 280. If
the ice adhered to the structural element has removed to a desired extent
(Yes), the method ends if the ice adhered to the structural element has not
been removed to a desired extent (No), the method step s430 is performed
again.
With reference to Figure 5, a diagram of one embodiment of the electronic
data processing unit 500 is shown. The data processing unit 500 is also
illustrated with reference to Figure 2 and 3a. The electronic data processing
unit 500 is also referred to as control unit 500. The control unit 500 may be a
de-icing control unit aboard an aircraft 100. The control unit 500 may be a deicing
control unit of a wind power installation 110. The control unit 500
comprises a non-volatile memory 520, a data processing device 510 and a
read/write memory 550. Non-volatile memory 520 has a first memory portion
530 wherein a computer program, such as an operating system, is stored for
controlling the function of the control unit. Further, the control unit 500
comprises a bus controller, a serial communication port, l/O-means, an A/Dconverter,
a time date entry and transmission unit, an event counter and an
interrupt controller (not shown). Non-volatile memory 520 also has a second
memory portion 540.
The control unit 500 may be arranged for communication with a main mission
computer of an aircraft or a central monitoring system computer of e.g. a
wind power installation.
A computer program P comprising routines for de-icing a structural element,
may be stored in an executable manner or in a compressed state in a
separate memory 560 and/or in read/write memory 550. The memory 560 is
a non-volatile memory, such as a flash memory, an EPROM, an EEPROM or
a ROM. The memory 560 is a computer program product. The memory 550
is a computer program product.
When it is stated that the data processing device 510 performs a certain
function it should be understood that the data processing device 510
performs a certain part of the program which is stored in the separate
memory 560, or a certain part of the program which is stored in the read/write
memory 550.
The data processing device 510 may communicate with a data
communications port 599 by means of a data bus 515. The non-volatile
memory 520 is adapted for communication with the data processing device
510 via a data bus 512. The separate memory 560 is adapted for
communication with the data processing device 510 via a data bus 5 1 . The
read/write memory 550 is adapted for communication with the data
processing device 510 via a data bus 514.
Signals may received from the detection/measuring system 280 and be
stored in the memory 550 or 560.
When data, such as ice detection/ice thickness data, is received on the data
port 599 from the detection/measuring system 280 it is temporarily stored in
the second memory portion 540. When the received input data has been
temporarily stored, the data processing device 5 10 is set up to perform
execution of code in a manner described herein. The processing device 510
is arranged to perform routines so as to de-ice the structurai element
according to an aspect of the invention.
Parts of the methods described herein can be performed by the apparatus by
means of the data processing device 510 running the program stored in the
separate memory 560 or the read/write memory 550. When the apparatus
runs the program, parts of the methods described herein are executed.
An aspect of the invention relates to a computer programme P comprising a
programme code for de-icing a structural element, such as an aircraft wing,
comprising the step of:
- when applicable, electrically charging an electrode configuration by means
of a power source which is electrically connected to said electrode
configuration, and the step of:
- generating an impulsive force for removal of ice adhered on said structural
element, when said computer programme is run on a computer.
An aspect of the invention relates to a computer programme product
comprising a program code stored on a, by a computer readable, media for
de-icing a structural element, comprising the steps of:
- when applicable, electrically charging an electrode configuration by means
of a power source which is electrically connected to said electrode
configuration, and the step of:
- generating an impulsive force for removal of ice adhered on said structural
member, when said computer programme is run on a computer.
PRINCIPLES OF THE INVENTION
The invention relies on the following basic principle of electrodynamics:
Let us consider a plane parallel capacitor configuration, where the
capacitance can be expressed as follows:
Where W is the energy stored in the field of the capacitor, V is the voltage
across the plates (electrodes), and A is the area of the electrodes while h is
the distance of the separation gap between the electrodes.
Since the energy stored in the field can be expressed as force times a
displacement, the following can be derived:
d =- V dC - V d =-Kdn
2 2 h
Where the last term represent the work done on the system. This in turn can
be expressed as follows
w =--V ^dh =-Fndn
2 h
Where the differential has been evaluated at h=h, the initial separation of the
electrodes. It is therefore evident that
" 2 h
Which means that a force perpendicular to the surface of the electrodes in
the normal direction will be present being proportional to the square of the
applied voltage and inversely proportional to the gap of the electrodes for a
given area A of the electrodes. Furthermore, the force Fn is independent of
the electrodes materials properties. The gap h between the electrodes has
been considered as an air gap for sake of simplicity.
However, if the gap is to be filled with some dielectric medium, the relative
dieiectric constant of the medium should be added as a multiplying factor. If
the gap is filled with a dielectric material, it could be thin enough to avoid
electrical breakdown, especially at field enhancement points at electrodes
borders. Furthermore, this can be very much needed to avoid flexural
deformation of the skin of the wings as due to pressure at the aerodynamic
flying conditions.
The displacement is the interesting parameter in this case since, assuming
an impulsive voltage, it will result in impulsive force that in turn will induce
membrane oscillations modes in the skin needed to obtain ice rejection
through the mechanical action on it. it should be noticed that the sign of the
voltage will not change the rejection character of the acting force.
Let us assume, for the sake of exemplification in the last equation a fix area
of 0.40x0.60 m = 0.24 m2 and a separation of the electrodes of 0.001 . The
following forces will be acting upon the electrodes of the capacitor as a
function of voltage levels:
Voltage (Volts) Force (Newtons) Force (Newtons)
A 1 A2
2 000 4.25 0.27
3 000 9.56 0.60
4 000 17.0 1.06
5 000 26.56 1.66
6 000 38.25 2.39
7 000 52.06 3.25
8 000 68.06 4.25
9 000 86.06 5.38
10 000 106.25 6.64
Where:
A 1: 0.40x0.60=0.24 m2 ; and
A2: 0.04x0.60=0.02 m2
Which show that the forces attainable with this system are better or
comparable to the order of magnitude of those found in the prior art actuators
(electromagnetic coii actuators).
The first Force column had been calculated for an area of 0.24 m2 while the
second is for an area of 0.02 m2 (0.04x0.60 m) both at the same thickness of
0.001 m. The resulting maximum impulsive force density ranges from about
450 N/m2 to 350 N/m2 in the second column.
Force densities in these ranges are expected to be enough to accomplish ice
rejection from surfaces (skin) of wings of aircrafts. Force densities in these
ranges are expected to be enough to accomplish ice rejection from surfaces
(skin) of propeller blades of wind power installations.
In any case, it can be foresee that the total weight/volume ratio of the whole
concept is definitely highly suitable for the suggested integration in both
aircrafts and wind power installations.
It should be realized that a movable skin can be designed with a pattern of
strip electrodes while the fix, non movable electrode could be as wide as
needed. The activation of different electrodes at different times via electronic
means where the unit 250 even comprise a addressable multiplexer who
could activate different movable electrodes on the skin at different time
intervals whereby a variety of oscillations patterns can be accomplished, i.e.,
surface deformations of the skin such that ice rejection can effectively be
accomplished. The basic physical principle on which this ice accretion
detection and thickness measurements of accreted ice is founded is basically
related to the temperature dependence of the dielectric property tensor of
water and ice. The real part of the dielectric constant has shown a linear
behavior on temperature. Furthermore, at the liquid to solid state phase
transition point, i.e., at 0 °C, the dielectric constant exhibit a discontinuity that
could be used to detect the inception of ice formation, however the chosen
differential setup of the measuring lock-in amplifier based method will not
focus on just this feature. Accreted ice thickness however correlates very well
to the linear behavior of the dielectric properties on temperature.
Measurements and sensors should comply with a number of restrictions to
be applicable to constrains in the aeronautic environment. First, it must be
such that the sensor does not introduce any perturbation to the aerodynamic
demands of laminar flow at the wings and fuselage skin where sensors might
be needed.
Measurements needs to be performed in a rather fast manner as to
accomplish a reliable signal for process control, for instance the secure
activation of ice rejection devices as soon as the accumulated ice exceeds a
preselected thickness threshold value. Furthermore, noise rejection is
mandatory in such environments where spurious signals can jeopardize the
measuring process, therefore high quality of the measuring method is
mandatory.
Furthermore, the whole system can be adapted to many other applications,
aeronautical or not. A sensor of the detection/measuring system is such that
it can even be made compatible with for instance icephobic coatings or other
paintings providing that they are not affecting the guard or short-circuiting the
electrodes. Mobile or stationary applications are also fully compatible.
Furthermore, a whole miniaturization of the electronic and sensor system is
fully achievable and therefore complex applications like in each asp of a
wind-turbine could be considered.
However, it should be mentioned that differential measurements with a
reference encased in a canister or otherwise kept at constant conditions
could lead to the detection of spurious signals in some applications since the
sensor would be able to detect reactive responses of whatever is in the
surrounding. Such could be the rotor blade of an aircraft if the sensor is
installed just behind the area of the rotor in such a case the signal detected
would be moduiated by each blade of the propeller. Although such effects
could be filtered electronically, provisions have to be taken due to the very
high sensitivity of the sensor devices, spurious reactive signals could be
generated by any object that changes position or shape. This will not be the
case in aircraft for instance but could be a situation in other applications with
variable environmental where more massive objects are involved.
A possible design for integration in a composite structure aimed to offer highly
laminar flow smoothness of the surface while still integrated a de-icing
solution as the one here by suggested could, as an example, comprise the
following:
1. A basic electrode made of a metallic sheet connected to power wire,
otherwise electrically isolated in the matrix of polymeric structure of the
structure element. Contacts and wiring must be done quite carefully paying
particular attention to all field enhancement effects at borders, corners, sharp
edges, etc.
2. An insulating layer of the highest electric breakdown performance, for
instance Polyesters like Mylar, PTFE Teflon or alike {Typical values are 250
m thick, 15 kV breakdown level, e ~ 3.2, etc).
3. A thin electrode, eventually the highly anisotropic conductivity of carbon
fiber reinforced whole polymeric construction elements could serve as
electrode providing it exhibit an electrical conductivity that is suitable to have
it regarded as ground level connected to the rest of the aircraft.
4. The suggested geometrical dimensions of the electrodes at each slat of
aircraft 100 could be of the order of £40 mm x length (say 40 - 60 cm long).
The material could be stainless steel, aluminum or any other metallic
compatible foil of a thickness of less than 0.5 mm (Cu or Al may act as
catalytic agent for the onset of oxidative process in the epoxy bulk).
The structural element comprising the electrode configuration should be
carefully analyzed with respect to long term materials compatibility in view of
the particular application (aircraft, wind power installation or any other)
The foregoing description of the preferred embodiments of the present
invention has been provided for the purposes of illustration and description. It
is not intended to be exhaustive or to limit the invention to the precise forms
disclosed. Obviously, many modifications and variations will be apparent to
practitioners skilled in the art. The embodiments were chosen and described
in order to best explain the principles of the invention and its practical
applications, thereby enabling others skilled in the art to understand the
invention for various embodiments and with the various modifications as are
suited to the particular use contemplated.

PCT I SE 2010 J05 \ 0 41
:j,9 -07- 2012
CLAIMS
1. De-icing arrangement for de-icing a structural element (170; 270; 370).
comprislng:
5 a power source (250) being electrically connected to an electrode
configuration (200). said power source being arranged to, when applicable.
electrically charge saId electrode configuration (200),
a control unit (500) connected to said power source 250
characterized in that
10 said electrode configuration (200) is arranged to generate an impulsive force
(Fn) for removal of ice adhered on said structural element (170; 270; 370)
wherein said electrode configuration (200) comprises a plate capacitor.
2. De·icing arrangement according to claim 1, wherein said electrode
15 configuration (200) comprises a first electrode (210) and a second electrode
(220) being mutuafiy displaceable.
3. De-icing arrangement according to claim 2. wherein one of said first and
second electrode (210. 220) being ctosest to the ice to be removed.
20
4. De-icing arrangement according to claim 3. wherein the other one of said
first and second electrode (210. 220) being fixed to said structural element
(170; 270; 370).
25 5. De--icingarrangement according to any of previOUS claims, wherein said
electrode configuration (200) comprises the first electrode (210) and the
second electrode (220) being provided in a close proximity of each other.
6. De-icing arrangement according to any of previous claims, wherein said
30 electrode configuration (200) comprises a sandwiched dietectrie element
(230).
peT I SE 2010 I 05 f 0 4,
1 9 -01· 2012
7. De-icing arrangement according to any of prevtous claims, wherein said
first and second electrodes (210; 220) are strip like.
8. De-icing arrangement according to any of previous claims, wherein said
5 first electrode (210) comprises a plurality of separated first electrodes (210),
and wherein said second electrode (220) is functionally provided at each of
said plurality of saparatedflrst electrodes (210).
9. De-icing arrangement according to any of previous claims. wherein said
10 generated impulsive force (Fn) has an amplitude sufficient for removal of an
adhered layer of ice having a thickness of about 1-3 millimeter (10~m).
10. De-icing arrangement according to any of previous claims, wherein said
arrangement is arranged to generate a number of successive impulsive
15 forces (Fn) for removal of ice adhered on said structural element (170; 270;
370).
11. De-icing arrangement according to any of previous claims, comprising at
least two electrode configurations (200).
20
12. De-icing arrangement according to any of previous claims, wherein said
structural element (170; 270; 370) is made of a non-metallic material. such as
a fUll-plastic material. comprising e.g. carbon-fibre and/or glass-fibre.
25 13. Platform (100; 110) comprising the de-icing arrangement acCOrding to
any of claims 1-12.
14. Platform according claim 13. wherein said platform is a stationary facility.
30 15. Platform according to claim 13 or 14, wherein said platfonnisa stationary
wind power installation or an off shore wind power instaUation.
pct I SE 2010 I 05 10 ~ 1
t a -07- 2012 0;
16. Platform (100) according to claim 15. wherein the platform (100) is an
aircraft and said structural element is an aircraft wing or aircraft (udder.
17. Method for de-iCing a structural ele.ment (170; 270~ 370). comprising the
5 step of:
- when applicable, electrically charging (s430) an electrode configuration
(200) by means of a powerSOlJfce (250), which is electrically connected to
said electrode configuration (200) and controlled by a control unit (500),
characterUed by the step of:
10 • generating (S4oo) an ~puJsive force (Fn) for removal of ice adhered on
said structural element (110; 270; 310) wherein said electrode configuration
comprises a plate capacitor.
18. Method according to claim 17, further comprising the step at
15 - activating (5430) said electrically charging of said electrode configuration
(200) on the basis of a signal indicating presence of a current lee state on
said structural element (110; 270; 370).
19. Method according to Claim 17 or 18, further comprising the step of:
20 • determirnng (s420) whether said electrically charging of said electrode
configuration (200) has set said electrode configuration (200) in a
predetermined state.
20. Method according to any of claim 17-19. further comprising the step of:
25 • determining (5410) a state of ice built up on said structural element (170;
270;370). and generating said impulsive force on the basis on said
determined state.
21. Computer ,programme (P) comprising a programme code for de-icing a
30 strueturaleJement(170; 270; 3.70), comprising the step of:
PCT I Sf 2010 ,0 5 10 It 1
~1 S-07- 2012
- when applicable, electrically charging (s43O) ao electrode configuration
(200) by means of a power source (250), which is electrically coonected to
said electrod.e configuration (200).
characterized by the step of:
5 • generating (s450) an impulsive force (Fn) for removal of ice adhered on
said structural element (170; 270; 370), when said computer programme is
run on a computer (500) wherein said electrode configuration comprises a
plate capacitor.
10 22, Computer programme product comprising a programme code stored on
a, by a computer readable, media for de-icing a structural element,
comprising the steps of:
• when applicable, electrically charging (s430) an electrode configuration
(200) by means of a power SOUrce (250}wt\ich is electrically connected to
15 said etectrode configuration (200),
characterized by the step of:
- generating (8450) an impulsive force (Fn) for removal of ice adhered on
said structural member (170; 270; 370). when said computer programme is
run on a computer (500) wherein said electrode configuration comprises a
20 plate capacitor.