DESC:RELATED PATENT APPLICATION:

This application claims the priority to and benefit of Indian Provisional Patent Application No. 202141013672 filed on March 27, 2021; the disclosure of which are incorporated herein by reference.

FIELD OF THE INVENTION:

This invention relates to a test system and method to measure velocity of jet in the field of missile, rocket, and the like. Particularly, the invention relates to a test system for precursor jet velocity measurement and method for measuring the precursor jet velocity. More particularly, the invention relates to test system for precursor jet velocity measurement wherein the velocity measured by indirect method.

BACKGROUND OF THE INVENTION:

A warhead comprises a hollow front section of the rocket or missile which is used to projectile the target. The hollow portion of the warhead is fitted with a variety of jet for propulsion. The jet warhead usually consists of a large number of explosive or chemical charge. Once the rocket or missile gets initiated the front portion of the rocket i.e., warhead, the jet starts travel towards the outward direction. The explosion creates a shock wave on the missile or rocket.

To know the projectile velocity or speed of the precursor warhead jet, a variety of methods and systems are used, however an accurate, simple, and cost-effective measurement is not achieved. In many of the existing technology, the test systems measure jet velocity by the direct method. Since the direct method comprises instruments like transducer etc. which are directly connected with the warhead. Once the explosion is involved in jet propulsion, the surrounding area gets damaged due to shock wave or vibration produced in it, so that the instruments used for the velocity measurement is destroyed by the vibration and explosion. It also affects the test system which may be gets damaged. Further, the velocity measured by this method is not accurate because of the vibration produced in it; the instrument is moved from the originated place and cannot be repeatable in nature due to damage of the equipment.

During activation of precursor warhead for propulsion of jet, explosion occurs as stated above and a large amount of shock waves or vibration is generated. Since explosion is involved in jet formation the total test and/or measurement system involved gets completely damaged. Any test and/or measuring instrumentation involved in measuring velocity of jet will be shattered due to shock wave generated by the explosion in the warhead. Thus, in such a situation, test/measuring devices or instruments do not able to accurately and properly measure the velocity of jet. Many efforts have been made in the prior arts to detect the velocity of the jet; some are as follows:

US Patent publication no. US8433460B1 discloses onboard sensor suite for determining projectile velocity which includes two main components: a proximity sensor suite for measuring the projectile muzzle velocity; and a pressure sensor suite for measuring the projectile airspeed. The flight velocity of the projectile can then be estimated with a high degree of accuracy using either the muzzle velocity by itself or the airspeed by itself, or, in a preferred embodiment, by using both the muzzle velocity and the airspeed. The proximity sensor suite includes proximity sensors that are mounted along a projectile body; a wire harness; and an onboard computer or CPU. The pressure sensor suite includes a Pitot pressure transducer and two static pressure transducers that are mounted within the projectile body; a wire harness; and a CPU. However, muzzle velocity requires a continuous airspeed measurement over a large portion of the trajectory, in that some projectiles do not rely on velocity measurements for navigation, which projectiles might not benefit totally from the airspeed measurement; cannot use GPS, or requires a redundant system to improve performance when jammed.

JP Patent publication no. JP2004069494A discloses jet flow speed measurement device wherein the jet flow speed meter is composed of a camera taking a picture of particles in liquid jetted from a nozzle, a laser light source radiating laser beams to the liquid, and a computer computing a particle physical state distribution on the basis of the image taken by the camera. The physical state distribution is composed of a speed distribution and a particle size distribution. The computer is composed of a speed distribution computing machine part computing the speed distribution and a particle size computing machine part computing the particle size distribution. When the particle size distribution is measured, a correlation between the particle size, a particle position, and light emission quantity of particles can be clarified, and particle flow vector can be more strictly extracted for computing. However, in such device it is difficult to determine the measurement accuracy of the adjustment of the exposure and the focus which differs for each measurer.

Therefore, there is a need to design and provide a test/measurement system, device and method thereof wherein accessories involved in test/measurement of jet velocity be in indirect form i.e., no transducers, instruments etc. are used.

Further, there is a need to design and provide a test/measurement system, device and method thereof wherein the measurement is efficient, simple, cost effective, accurate, reliable and repeatable in nature as unit under test (UUT) is single shot device.

Accordingly, present invention designs and provides a test system for precursor jet velocity measurement and method thereof. Design, System and Method of test system for precursor jet velocity measurement are provided by an indirect method which are efficient, simple, cost effective, accurate, reliable and repeatable.

OBJECTS OF THE INVENTION:

The principal object of present invention is to design and provide a test system for precursor jet velocity measurement and method thereof.

Another object of the invention is to design and provide a test system and a measurement device for precursor jet velocity wherein indirect way of measurement is involved.

Another object of the invention is to provide a precursor jet velocity measurement system and method, where measurement happens in microseconds.

Another object of the invention is to provide a precursor jet velocity measurement system, wherein capturing of data is efficient having high sampling rate and resolution in Nano seconds.

Yet another object of the invention is to provide a velocity measuring test system and method which is cost effective.

SUMMARY OF THE INVENTION:

Accordingly, the present invention provides and discloses a test system for measuring precursor jet velocity and method thereof. More particularly, the invention relates to an indirect method to determine the precursor velocity wherein a twisted copper wire and a contact foil are used to determine the velocity. The velocity is determined by a basic formula Velocity= Distance/Time, using the time calculated by the system and method of the present invention which is a novel method for measuring the jet velocity.

The present invention provides a velocity measurement device having high accuracy, cost effective, accurate, reliable and repeatable in nature as UUT is single shot device.

The present invention discloses a novel system and a novel method for measuring the precursor jet velocity.

In one aspect, the present invention provides a test system for precursor jet velocity measurement by indirect method, wherein the system (1) comprises:
- a precharge (2);
- a contact foil (3);
- a wooden block (4);
- a thermocol V block (5);
- an insulated twisted metal wire (6);
- igniter wires (7);
- an igniter (8);
- a PVC Block (9);
- a thermocol spacer (10);
- plurality of plates (11)
- contact foil wires (12); and
- a test panel (13);
wherein the contact foil (3) is placed at a predetermined distance from the precharge (2);
wherein the insulated twisted copper wire (6) are connected to the precharge (2) for generating a START pulse at the instant when the igniter (8) ignites the precharge (2);
wherein the contact foil wires (12) are connected to the contact foil (3) to generate the STOP pulse when the coupling plate of the contact foil (3) comes in contact with each other due to penetration of precharge (2) and produce a shock wave thus generating the STOP pulse;
wherein the plurality of plates (11) and the thermocol spacer (10) are configured to fix the contact foil (3) at a predetermined distance from the precharge (2);
wherein the thermocol V block (5) and wooden block (4) are configured to fix precharge (2);
wherein the igniter wires (7) are connected with the igniter (8) for producing high voltage to trigger the precharge (2) and a key operable SAFETY switch is mounted on the test panel (13) to provide a SHORT across the igniter;
wherein the velocity calculated by said test system (1) employs a high sampling rate and high resolution and reliability of acquired data.

The contact foil (3) is placed at a predetermined distance of 240mm from the precharge (2).

The twisted metal wire (6) is made up of copper and the contact foil (3) is a coupling plate and made up of a thin material.

The system (1) measures velocity in the range of 6 km/sec to 8 km/sec at 100 nano sampled signal and 240mm distance.

More particularly, the system (1) measures velocity 6.5 km/sec at 100 nano sampled signal and 240mm distance.

In another aspect of the present invention, a method for precursor jet velocity measurement by indirect method is disclosed. The said method comprising steps of:
a) supplying 50V DC output through channel A to a twisted copper wire (6) connected to the precharge (2);
b) at the same instant of step (a), supplying 50V DC output through channel B to a contact coil wires (12) connected to the contact foil (3);
c) switching the safety switch on the test panel (13) to ON position;
d) pressing a FIRE button present on the test panel to produce a high voltage by igniter firing circuit;
e) providing an ignition pulse to the precharge (2) by means of discharging a fully charged capacitor through the igniter by a bounce free solid state switching circuit;
f) initiating the precharge (2) resulting in melting of the twisted copper wire (6) and creating a short and generating a START pulse ;
g) traveling of the precharge (2) towards the contact foil (3) assembly and penetrating the contact foil (3);
h) creating a short in contact foil (3) and generating a STOP pulse ;
i) calculating the time between START and STOP pulse and displaying it on the test panel (13);
j) calculating the velocity by employing the calculated time of step (i) and predetermined distance based on the formula Velocity= Distance/Time;
wherein the velocity calculated by said test method employs a high sampling rate and high resolution and reliability of acquired data.

The velocity measured using the said method is in the range of 6 km/sec to 8 km/sec at 100 nano sampled signal and 240mm distance.

More particularly, the velocity is 6.5 km/sec. at 100 nano seconds sampled signal and 240mm distance.

The time required by the precharge (2) to travel is in the range of 30µs to 40µs.

More particular the time required by the precharge (2) to travel is 35 µs.

The aim of the present invention is to develop a novel kind of system and method for measuring the precursor jet velocity having cost effective, very high sampling rate and resolution and reliability of acquired data.

The above description merely is an outline of the technical solution of the present disclosure; in order to know the technical means of the present disclosure more clearly so that implementation may be carried out according to contents of the specification, and in order to make the above and other objectives, characteristics and advantages of the present disclosure more clear and easy to understand, specific embodiments of the present invention will be described in detail below.

BRIEF DESCRIPTION OF DRAWINGS:

The accompanying drawings which are incorporated herein constitute a portion of this specification and illustrate exemplary practices according to the invention which, together with the general description above and the detailed description set forth below will serve to explain the principals of the invention wherein:

Figure 1: is a perspective schematic view of the test setup of the test system (1) of the preferred embodiment of the present invention.

Figure 2: is a schematic view of the contact foil (3) of the present invention.

Figure 3: is a block diagram of precursor jet velocity test panel (13) of the present invention.

Figure 4: is a perspective schematic front view of the test panel (13) of the present invention.

Figure 5: is a perspective schematic back view of the test panel (13) of the present invention.

DESCRIPTION OF THE INVENTION:

Accordingly, the present invention provides a test system for precursor jet velocity measurement and method thereof. More particularly, the invention discloses a test system for precursor jet velocity measurement which uses an indirect way, i.e. without using any transducer, sensor or other instruments to measure the velocity of the precursor jet. The invention provides design of Test System to measure velocity of Jet when Precursor warhead is initiated.

As mentioned above, during activation of precursor warhead for propulsion of jet, explosion occurs and a large amount of shock waves or vibration is generated. Since explosion is involved in jet formation, the total test and/or measurement system involved gets completely damaged. Any test and/or measuring instrumentation involved in measuring velocity of jet will be shattered due to shock wave generated by the explosion in the warhead. Thus, in such a situation, test/measuring devices or instruments do not able to accurately and properly measure the velocity of jet. Therefore, the present invention to over the said problem provides an indirect method for measuring the jet velocity.

The performance and the effectiveness of precursor warhead depends on the produced jet velocity. The test system of the present invention measures the jet generated when warhead is initiated. The Unit under test (UUT) when initiated generates a high-speed jet along with high-energy shock wave. The acceptance and performance of Precursor can be evaluated only by measuring the velocity of jet which is typically more than 6100 m/sec.

The test system for precursor jet velocity measurement of the present invention mainly calculate the time duration used by the precharge to hit the contact foil and displays the result on the LCD display of the test panel used in the present invention. Further, the distance between the precharge and the contact foil is predetermined and fixed at one particular value and already known. Thus, the velocity can be measured using the basic formula:
Velocity = Distance/Time

The time measured by the test panel is very less time, which is of the order of few microseconds in explosive environment.

Further, for capturing such low duration events the test system should have very high sampling rate and high resolution and reliability of acquired data. The test system and method of the present invention meet the above requirements and need and provides accurate result in very less time, efficiently.

In one aspect of the present invention, the present invention provides a test system for measuring the precursor jet velocity wherein the system involves a totally non-destructive approach to calculate the velocity i.e. indirect way of measurement is involved.

The test system of velocity measurement of present invention mainly includes a precharge which is a small warhead made up of very thin material; a contact foil which is a coupling plate placed at particular predetermined distance from the precharge; a twisted metal wire is placed on the precharge and a contact foil wire is placed in the contact foil.

The velocity measurement system further includes a test panel which consists of two channels and other input output ports. One channel A is connected with the twisted metal wire of the system, to measure the START event when the precharge is initiated and the other channel B which is connected with the contact foil wire of the system to measure the STOP event when the precharge hits the contact foil wherein each channel has an open circuited power supply.

The said system also comprises of a time interval measurement COUNTER which is used to measure the time difference between two trigger inputs of channel A and channel B.

The velocity measurement system further includes an igniter firing circuit which can produce high voltage. The ignition pulse is to be provided by means of discharging a fully charged capacitor through the igniter using a bounce free solid-state switching circuit on pressing a FIRE button present on the test panel.

A key operable SAFETY switch is provided on the test panel that always provides a SHORT across the igniter. To fire the ignitor, the SAFETY switch is put in ON position and a FIRE button is pressed. An earth-referenced terminal is to be provided to monitor the Ignition pulse on external instrument.

TEST-SETUP/SYSTEM (1)

Fig. 1 shows the perspective schematic view of test system (1) of a preferred embodiment of the present invention. The test system (1) comprises of a precharge (2), a contact foil (3), a wooden block (4), a thermocol (V) block (5), a twisted copper wire (6), igniter wires (7), an igniter (8), a PVC Block (9), a thermocol spacer (10), a plurality of plates (11), contact foil wires (12) and a test panel (13) comprising of Channel A and Channel B.

The thermocol block (4) is located above the wooden block (3) and the precharge (2) which is a small warhead and made up of a thin material as used to measure the velocity is located above the wooden block (4) and a thermocol V block (5). An insulated twisted copper wire (6) is connected to the precharge (2) to generate START pulse of jet when the igniter (8) ignites the precharge and it starts to travel toward the contact foil (3).

The contact foil wire (12) are attached to the contact foil (3) and the contact foil (3) is placed at a predetermined distance from the pre charge (2) which is used to measure the end of a jet. The contact foil (3) is a coupling plate wherein the coupling plate shorts when precharge (2) penetrate to the contact foil (3).

When the precharge (2) in initiated, at this time the it starts travelling towards the contact foil (3) and penetrate to the contact foil (3), the coupling plate of the contact foil (3) comes in contact and produce a shock wave thus generating the STOP pulse.

Further, plurality of plates (11) are used in the test setup (1) to keep the contact foil (3) at a fixed position. In one embodiment, the plurality of plates can have different dimension. In another embodiment, the plurality of plates can have same dimension. The primary purpose of the plurality of plates (11) as used in the present system (1) is to support the contact foil (3) and keep the contact foil (3) in a fixed position as the contact foil (3) is made up of very thin material and movement of the contact foil (3) can damage the contact foil (3). Further, a thermocol spacer (10) is also used to fix the contact foil (3) at a particular position.

In one embodiment, the plates having dimension of 3 mm, 5 mm and two 80 mm are used to fix the contact foil (3) along with the thermocol spacer (10) having dimension 120 mm is used to fix the contact foil (3).

Further, the system includes the plurality of igniter wires (7). The said wires (7) are connected with the igniter (8) which can produce high voltage to trigger the precharge (2). The ignition pulse is to be provided by means of discharging a fully charged 1 micro-Farad ± 5% capacitor through the igniter (8) using a bounce free solid state switching circuit on pressing a FIRE button present on the test panel (13).

A key operable SAFETY switch is also provided on the test panel (13) that always provides a SHORT across the igniter. To fire the ignitor, the SAFETY switch is put in ON position and a FIRE button is pressed. An earth-referenced terminal is to be provided to monitor the Ignition pulse on external instrument. Details regarding the test panel (13) will be explained later here below.

To make the system work, a 50V DC output power is supplied through channel A and Channel B to open circuited lines of the twisted copper wire (6) and contact foil wires (12). The 50VC voltages is supplied through channel A to the insulated twisted copper wire (6) and through channel B to contact foil wire (12). When the precharge (2) is initiated, the twisted copper wire melts and creates a short for a fraction of microseconds. This initiates the Start pulse. The jet then travels the predetermined distance and penetrates the contact foil (3) which shortens the contact foil (3) for fraction of mili seconds. The Channel B senses this second short and STOP pulse is generated.

Since, the shorting period at twisted copper wire and contact foil is order of microseconds; therefore, to capture the events of such short duration, the copper material used should be 99.9 % pure oxygen free for twisted copper wire and contact foil.

The data captured in the measurement is accurate as the event lasts for around 30 microseconds.

Figure 2 shows the schematic view of the contact foil (3) as used in the system of the present invention. The contact foil (3) is made up of very thin material. The contact foil (3) is a coupling plate wherein the one plate is coupled with another plate and at the time of measuring the velocity of the precharge (2), the precharge (2) is penetrated to this coupling plate and shock wave is generated. The contact foil (3) is used for measuring the STOP pulse. In one embodiment, the contact foil (3) is placed at a predetermined distance of 240mm from the precharge (2).

Thus, the above said system (1) for measuring the precursor velocity measurement can be summarized as:

The said system (1) for measuring the precursor jet velocity, the system measures the precursor jet velocity by indirect method, the system (1) comprises:
- a precharge (2);
- a contact foil (3);
- a wooden block (4);
- a thermocol V block (5);
- an insulated twisted metal wire (6);
- igniter wires (7);
- an igniter (8);
- a PVC Block (9);
- a thermocol spacer (10);
- plurality of plates (11)
- contact foil wires (12); and
- a test panel (13);
wherein the contact foil (3) is placed at a predetermined distance from the precharge (2);
wherein the insulated twisted copper wire (6) are connected to the precharge (2) for generating a START pulse at the instant when the igniter (8) ignites the precharge (2);
wherein the contact foil wires (12) are connected to the contact foil (3) to generate the STOP pulse when the coupling plate of the contact foil (3) comes in contact with each other due to penetration of precharge (2) and produce a shock wave thus generating the STOP pulse;
wherein the plurality of plates (11) and the thermocol spacer (10) are configured to fix the contact foil (3) at a predetermined distance from the precharge (2);
wherein the thermocol V block (5) and wooden block (4) are configured to fix precharge (2);
wherein the igniter wires (7) are connected with the igniter (8) for producing high voltage to trigger the precharge (2) and a key operable SAFETY switch mounted on the test panel (13) to provide a SHORT across the igniter;
wherein the velocity calculated by said test system (1) employs a high sampling rate and high resolution and reliability of acquired data.

Figures 3 shows the block diagram representation of test panel (13) system to measure precursor jet velocity. The details of each block used in the test panel is as given below:

280 V AC, 50Hz power supply (101): the supply is given to the circuit of test setup (1) wherein voltage and current can be regulated and a particular range of voltage and current is given to the device setup. The supply is given to the test system for precursor jet velocity measurement via direct plug-in method.

Step down transformer (102): Step-down transformer (102) is used to covert the high voltage and low current from the primary side of the transformer to the low voltage (LV) and high current value on the secondary side of the transformer. The step-down transformer (102) covert the AC supply voltage 280 V to the multiple range of AC output voltage which is smaller than the 280 V.

Internal power supply (103): The output of the step-down transformer which is low voltage value is given to the threshold voltage module wherein the AC voltage converts into DC power supply at a particular voltage range i.e. 50 V DC power supply.

50V SMPS (104, 105): A switch mode power supply (SMPS) is a power converter that utilizes switching devices that continuously turn on and off at high frequency. The SMPS is also an energy storage device such as the capacitors and inductors to supply power during the non-conduction state of the switching device. The 280 VAC, 50Hz supply is provided to the 50V SMPS.

Threshold voltage module (106): The threshold module (106) provides DC power output at a particular voltage range i.e. 50 V. The output of both the 50V SMPS is provided to the threshold voltage module (106) along with the internal power supply (103). The output of the threshold voltage module is then given to the front panel as a DC output voltage V1 and V2.

Microcontroller PCB (107): The microcontroller printed circuit board is designed to provide all of the circuitry necessary like I/O circuit, counter circuit, display circuit etc.

Jumbo LCD (108): The Jumbo LCD display is used for displaying the time between the start pulse and stop pulse, which is calculated in the time interval measurement COUNTER and displayed in the Jumbo LCD.

Current source (109): A current rating through a current source (109) is given to the Front panel controls/ interlocks (110) and front panel Ignitor points (111) wherein the current rating can be regulated via the regulator as shown in fig. 4. In one embodiment, 2 Ampere current rating is given to the ignitor wires (7), copper wire (6) and contact foil wire (12). The current supply is also given to the microcontroller PCB (107).

Front panel controls/interlocks (110): The Front panel of the test system comprises a current adjustment and a time adjustment, wherein the current and time can be adjusted as per the requirement of the circuit. The current provides from 0A to 50A, and a pulse/time provides 5ms to 50ms. Further, the front panel controls also include a threshold adjustment.

Front panel ignitor points (111): The front panel of the test system comprises igniter points wherein an ON/OFF switch, a FIRE switch and an ignitor supply port. The ignitor supply port is connected with the ignitor wires.

Front panel V1 & V2 outputs (112): The front panel output power includes two-output DC power, one is V1, 50V DC power given to the insulated copper wire (6), and another is V2, 50V DC power given to the contact foil wires (12).

Further, Figure 4 and Figure 5 respectively show the perspective schematic view of front and backside view of the test panel of embodiment of the present invention.

Figure 4 shows the front view of the test panel wherein it comprises following points:

A threshold point: the threshold point comprises adjustment/regulator for voltage V1 and voltage V2, which can be used for regulating the supply at a particular range of voltage. The output of the step-down transformer is given to the threshold point wherein it provides DC power output at a particular voltage range i.e. 0-50 V. In one embodiment, the supply voltage is 50V. The output of the threshold voltage is given the V1 points and V2 points (shown in figure) wherein the V1 point is connected with the insulated copper wire (6) and V2 point is connected with the contact foil wires (12).

Current and time adjustment/regulator: The current and time regulator point is used for the adjustment of current and time at a particular fixed value. 0A-5A current adjustment and 5ms-50ms time adjustment are used.

In one embodiment of the present invention, the current rating is fixed at a 2 Ampere.

Ignitor points: The ignitor points comprise a FIRE button, ON/OFF switch and ignitor connection points. The ignitor circuit provides a pulse of 90-100V. The ignition pulse is to be provided by means of discharging a fully charged 1-microfarad ± 5% capacitor through the igniter using a bounce free solid-state switching circuit on pressing a FIRE button.

A key operable SAFETY switch i.e. ON/OFF switch is to be provided that always provides a SHORT across the igniter. To fire the ignitor, the SAFETY switch is put in ON position and a FIRE button is pressed. An earth-referenced terminal is to be provided to monitor the Ignition pulse on external instrument.

Display: The display is a jumbo display which is configured to display the time duration between two short pulses i.e. START pulse and STOP pulse which is calculated in the time internal COUNTER and displayed in the jumbo display.

Fig. 5 shows a back view of the test system wherein it comprises V1 and V2 supply port, a reset button, ON/OFF switch and power supply port.

The test system consists of two DC power supplies of 50 Volt, 2 Amp current rating and a time interval counter, configured to measure the time period. The test system of embodiment of present invention consists of two channels:
- one is to measure the START event and
- the other one is to measure the STOP event.

Both the channels A and B having an input threshold voltage adjustable/regulator from 0 to 50V DC.

Both the channel outputs are sampled at 1 nano second resolution to detect for any short in channels.

The output of Channel A and Channel B are sampled at 1 nano second resolution to detect the pulse for a very short period in channels. The counter measures the time differences between two trigger inputs. Channel A and Channel B are sampled of maximum 0.1 Nano seconds, with an accuracy of 0.1 microseconds.

Each channel comprises an open circuit power supply. When the event is triggered short is detected in each channel A and B.

The time duration between two short pulses is calculated in the internal counter times and is displayed it on the jumbo display of the test system.

The counter comprises a START measurement, when a falling edge is detected at the Channel A and STOP measurement, when a falling edge is detected at Channel B input. The time interval between START and STOP events is to be measured with an accuracy of ± 0.1 microseconds.

A temperature stabilized crystal oscillator is to be used accurately measure the time interval. A HI level PULSE output is to be provided to monitor the pulse width on a standard instrument.

Since the jet travels in order of 6.5 km/sec and travel time is very less of the order of 35 microseconds, the signals should be sampled in the order of 100 nano seconds.

Specifications for front charge test rack/ test panel (13):

In one embodiment of the present invention, as an example the following is the specification of the test panel used in the test system for precursor velocity measurement set at a particular value:

Supply Voltage : 230V AC ± 10%, 50Hz
Operating Temp Range : 20-50° C
Power Supply Voltage outputs : 2
Power supply ratings : 50V, 2A
Counter measurement Range : 1-100 microseconds
Counter Accuracy : 1% of Full scale
Counter Resolution : 100 nano seconds
Counter LCD display : Jumbo type LCD
Input trigger threshold : 0-50 V adjustable
Ignition firing circuit : 0-50 Amps
Firing Pulse duration : 5-50 msec in steps of 5 msecs

METHOD:

In another aspect of the present invention, the present invention provides a method for measuring the precursor jet velocity using the test system (1) of Figure 1.

The test system for precursor jet velocity measurement of figure 1 mainly calculate the time duration used by the precharge to hit the contact foil and displays the result on the LCD display of the test panel. Further, the distance between the precharge and the contact foil is predetermined and fixed at one particular value and already known. Thus, the velocity can be measured using the basic formula:
Velocity = Distance/Time

The time measured by the test panel is very less time, which is of the order of few microseconds in explosive environment.

As mentioned above, the precharge (2) and contact foil (3) are placed at a particular distance. A twisted metal wire is placed on the precharge and a contact foil wire is placed in the contact foil. The test panel which consists of two channels, one channel A which is connected with the twisted metal wire of the system, to measure the START event when the precharge is initiated and the other channel B which is connected with the contact foil wire of the system to measure the STOP event when the precharge hits the contact foil wherein each channel has an open circuited power supply.

The test system consists of two DC power supplies of 50V at 2A current rating and a time interval measurement COUNTER. The counter measures time difference between two trigger inputs, Channel A and Channel B of maximum 0.1 Nano seconds, with an accuracy of 0.1 microseconds.

The counter should START measurement when a falling edge is detected at the Channel A input and STOP measurement when a falling edge is detected at Channel B input.

The time interval between START and STOP events is to be measured with an accuracy of ? 0.1 microseconds.

The method starts with 50V DC output power of threshold voltage is supplied through Channels A and B to open circuited lines. Channel A is supplied on twisted copper wire which is placed on pre-charge. Channel B is supplied on the contact foil wire (12) which is connected with the contact foil. The igniter firing circuit produces a high voltage and the ignition pulse is provided by means of discharging a fully charged capacitor through the igniter using a bounce free solid-state switching circuit on pressing a FIRE button present on the test panel. To fire the ignitor, the SAFETY switch is put in ON position and a FIRE button is pressed. An earth-referenced terminal is to be provided to monitor the Ignition pulse on external instrument.

When the precharge (2) is initiated, the twisted copper wire starts to melt and creates a short for a fraction of microseconds. The channel A senses the first short and initiates the START pulse. The jet then travels and penetrate to the contact foil (3) wherein the contact foil (3) shortens for fraction of mili seconds. The Channel B senses the second short and STOP pulse is generated.

The time between the START and STOP pulses is calculated in the time interval measurement COUNTER and displayed on the LCD display of the test panel of the system.

Since the distance is predetermined, velocity is calculated by the formula velocity = distance / time, gives the jet velocity in meters per second.

The above said method for measuring the precursor jet velocity can be summarized as:

In one embodiment, the present invention provides the method for measuring the precursor jet velocity, the precursor jet velocity is measured by indirect method, the method comprising steps of:
a) supplying 50V DC output through channel A to a twisted copper wire (6) connected to the precharge (2);
b) at the same instant of step (a), supplying 50V DC output through channel B to a contact coil wires (12) connected to the contact foil (3);
c) switching the safety switch on the test panel (13) to ON position;
d) pressing a FIRE button present on the test panel (13) to produce a high voltage by igniter firing circuit;
e) providing an ignition pulse to the precharge (2) by means of discharging a fully charged capacitor through the igniter by a bounce free solid state switching circuit;
f) initiating the precharge (2), resulting in melting of the twisted copper wire (6) and creating a short, START pulse ;
g) traveling of the precharge (2) towards the contact foil (3) assembly and penetrating the contact foil (3);
h) creating a short in contact foil (3) and generating the STOP pulse ;
i) calculating the time between START and STOP pulse and displaying in the test panel (13);
j) calculating the velocity by employing the calculated time of step (i) and predetermined distance based on the formula Velocity= Distance/Time;
wherein the velocity calculated by said test method employs a high sampling rate and high resolution and reliability of acquired data.

EXPERIMENT DETAILS:

The precursor velocity was measured by the above said test system for the jet velocity measurement which is shown in Fig. 1.

An experimental setup was established where the precharge having 40mm thickness was placed on wooden block and the thermocol V block which was used for measuring the velocity. A twisted copper wire was connected to the precharge, wherein the copper wire was used to determine the START pulse.

The contact foil (3) was placed at 240mm from the precharge (2). The contact foil (3) being formed of a very thin material and therefore was supported using a thermocol spacer of 120mm thickness and plurality of plates having 3mm, 5mm and two 80mm steel plates . A set of contact foil wire were connected to the contact foil and configured to determine the STOP pulse.

230V AC ± 10%, 50Hz supply voltage was stepped down with the help of step-down transformer and threshold voltage module where a 50V DC output power was generated which was given to the test system through channel A and channel B to the open-end circuit lines. 50V DC output power at 2A current rating was given through channel A to the insulated copper wire and channel B to the contact foil wire.

As the power was given, the precharge was initiated. Due to initialization and supply voltage the twisted copper wire starts getting melted and creates a short pulse for a fraction of microseconds which initiated/generated the START pulse. The jet then travelled and penetrated to the contact foil. The contact foil was shortened for fraction of mili seconds, the Channel B sensed the second short and STOP pulse was generated.

The time between the start and stop pulses was calculated and displayed on the LCD display of test rack/test panel. Since the distance was predetermined as 240mm, velocity was calculated by velocity = distance / time in meters per second.

The above said experiment with the mentioned specification was performed on various Lot and the results were obtained. The results of Lot No: 002 and Lot No: 007 for precursor velocity measurement are mentioned in below.

Experimental data 1:

The following are the proof firing results of precharge assembly Lot No: 002, Quantity: 1200 numbers manufactured by GOCL, Hyderabad.

Lot Numbers: 002
Lot Quantity: 1200 Nos
Lot Samples: 18 Nos
Net Quantity: 1182 Nos
Date of proof testing: 31-03-2016 & 01-04-2016

S. N. Sample Number Jet Velocity (m/sec)
1. 1082 7058
2. 1063 6629
3. 1074 6666
4. 1131 6557
5. 1140 6664
6. 1152 6741
7. 1186 6629
8. 1194 6703
9. 0956 6611
10. 0947 6760
11. 0939 7121
12. 0934 7164
13. 0901 Outlier
14. 0911 6722
15. 0802 6760
16. 0812 6504
17. 0820 6629
18. 0821 7079

Acceptance Index Qi = 3.20 (i = number of samples, Qi > 1.76)

Experimental data 2:

The following are the proof firing results of precharge assembly Lot No: 007, Quantity: 663 numbers manufactured by GOCL, Hyderabad.

Lot Numbers: 07 GOCL2017
Lot Quantity: 663 Nos
Lot Samples: 12 Nos
Net Quantity: 651 Nos
Date of proof testing: 14-07-2017 & 18-07-2017

S. N. Sample Number Jet Velocity (m/sec)
1. 5050 6818
2. 4999 6760
3. 4678 6611
4. 4636 6857
5. 4578 6703
6. 4949 6666
7. 5123 7667
8. 5191 6594
9. 5232 6611
10. 4789 6539
11. 4890 6703
12. 4597 6417

Acceptance Index Qi = 2.05 (i = number of samples, Qi > 1.59)

RESULTS:

Thus, from the obtained test results we can conclude that the velocity of precursor jet is obtained between 6 km/sec to 8 km/sec when the distance between the precharge and the contact foil is maintained as 240mm.

Further, with the above test system more than 16 batches of Precursor serial production was accepted with zero error in the system. This has resulted in integration of more than Qty: 10,000 precursor warheads in to main warhead of Milan 2T missile.

ADVANTAGES:

The following are the advantages of the embodiment of present invention:

1. The system can measure Jet velocity of any shape charged device warhead from any distance due to its versatility in operation. The distance for measurement is not a constrain unless the jet formed does not deviate its path.

2. The Test system is cost effective as the test accessories used are twisted copper wire and copper contact foil which are nominal in cost as they get destroyed during testing and also the unit under test is highly explosive in nature and usage of any transducers will destroy them instantly.

3. The test system is highly accurate of the order of 100 nano seconds.

4. Design of the test system is modular and compact and can be field portable and rugged in construction.

5. Other accessories are Thermocol V block and Wood height pieces. The test system is very cost effective for measurement of Jet Velocity.
,CLAIMS:1. A test system for precursor jet velocity measurement by indirect method, wherein the system (1) comprises:
- a precharge (2);
- a contact foil (3);
- a wooden block (4);
- a thermocol V block (5);
- an insulated twisted metal wire (6);
- igniter wires (7);
- an igniter (8);
- a PVC Block (9);
- a thermocol spacer (10);
- plurality of plates (11)
- contact foil wires (12); and
- a test panel (13);
wherein the contact foil (3) is placed at a predetermined distance from the precharge (2);
wherein the insulated twisted copper wire (6) are connected to the precharge (2) for generating a START pulse at the instant when the igniter (8) ignites the precharge (2);
wherein the contact foil wires (12) are connected to the contact foil (3) to generate the STOP pulse when the coupling plate of the contact foil (3) comes in contact with each other due to penetration of precharge (2) and produce a shock wave thus generating the STOP pulse;
wherein the plurality of plates (11) and the thermocol spacer (10) are configured to fix the contact foil (3) at a predetermined distance from the precharge (2);
wherein the thermocol V block (5) and wooden block (4) are configured to fix precharge (2);
wherein the igniter wires (7) are connected with the igniter (8) for producing high voltage to trigger the precharge (2) and a key operable SAFETY switch is mounted on the test panel (13) to provide a SHORT across the igniter;
wherein the velocity calculated by said test system (1) employs a high sampling rate and high resolution and reliability of acquired data.

2. The test system as claimed in claim 1, wherein the contact foil (3) is placed at a predetermined distance of 240mm from the precharge (2).

3. The test system as claimed in claim 1, wherein the twisted metal wire (6) is made up of copper and the contact foil (3) is a coupling plate and made up of a thin material.

4. The test system as claimed in claim 1, wherein the system (1) measures velocity in the range of 6 km/sec to 8 km/sec at 100 nano sampled signal and 240mm distance.

5. The test system as claimed in claim 4, wherein the system (1) measures velocity 6.5 km/sec. at 100 nano sampled signal and 240mm distance.

6. A method for precursor jet velocity measurement by indirect method, wherein the method comprising steps of:
a) supplying 50V DC output through channel A to a twisted copper wire (6) connected to the precharge (2);
b) at the same instant of step (a), supplying 50V DC output through channel B to a contact coil wires (12) connected to the contact foil (3);
c) switching the safety switch on the test panel (13) to ON position;
d) pressing a FIRE button present on the test panel to produce a high voltage by igniter firing circuit;
e) providing an ignition pulse to the precharge (2) by means of discharging a fully charged capacitor through the igniter by a bounce free solid state switching circuit;
f) initiating the precharge (2) resulting in melting of the twisted copper wire (6) and creating a short and generating a START pulse ;
g) traveling of the precharge (2) towards the contact foil (3) assembly and penetrating the contact foil (3);
h) creating a short in contact foil (3) and generating a STOP pulse ;
i) calculating the time between START and STOP pulse and displaying it on the test panel (13);
j) calculating the velocity by employing the calculated time of step (i) and predetermined distance based on the formula Velocity= Distance/Time;
wherein the velocity calculated by said test method employs a high sampling rate and high resolution and reliability of acquired data.

7. The method as claimed in claim 6, wherein the velocity measured is in the range of 6 km/sec to 8 km/sec at 100 nano sampled signal and 240mm distance.

8. The method as claimed in claim 7, wherein the velocity is 6.5 km/sec. at 100 nano seconds sampled signal and 240mm distance.

9. The method as claimed in claim 6, wherein the time required by the precharge (2) to travel is in the range of 30µs to 40µs.

10. The method as claimed in claim 9, wherein the time required by the precharge (2) to travel is 35 µs.