Description:F O R M 2

THE PATENTS ACT, 1970
(39 of 1970)

COMPLETE SPECIFICATION
(See section 10 and rule 13)

TITLE
SYSTEM AND METHOD FOR DETERMINING MULTIPLE PARAMETERS OF FLUIDS
INVENTORS:
RAJA, Nishanth
Dr. BALASUBRAMANIAN, Krishnan
RADHAKRISHNAN, Raveen
IITM RESEARCH PARK, B4-01, 4th Floor, B Block, Kanagam, Tharamani, Chennai, Tamil Nadu 600113, India
APPLICANT
XYMA ANALYTICS PRIVATE LIMITED
IITM RESEARCH PARK, B4-01, 4th Floor, B Block, Kanagam, Tharamani, Chennai, Tamil Nadu 600113, India

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED:

 
SYSTEM AND METHOD FOR DETERMINING MULTIPLE PARAMETERS OF FLUIDS
CROSS-REFERENCES TO RELATED APPLICATION
None.
FIELD OF INVENTION
The present disclosure relates to system of measuring fluid properties and in particular to system and method for measuring fluid properties with ultrasound sensing.
DESCRIPTION OF THE RELATED ART
A major problem faced by industries during the measurement of rheology parameters of fluids at higher temperatures such as above 1000℃ is damage to the equipment used for measuring the parameters of the fluids. The sensors present on the equipment are unable to without very high temperature and inevitably sustain considerable damage. Another problem encountered during the measurement of fluids is the portability of the sensor and the durability/efficiency of the sensor in corrosive environments while measuring the rheology parameters of any corrosive fluid. The sensors experience extreme wear and tear which reduces the durability as well as its efficiency considerably. Further any damage to the sensors in the equipment would require replacement of the equipment which is costly particularly when the equipment gets damaged frequently.
Various publications have tried to address the problems associated with equipment used for measuring parameters of fluid in extreme environments. US publication11226281B1 discloses techniques for non-invasive diagnosis and/or monitoring of corrosion in high temperature systems using specialized sensors that produce multi-mode acoustic signals in situ for accurate determination of wall loss and/or physical property changes for a vessel in contact with a high temperature, highly corrosive substance. PCT publication 2020100157A1 discloses methods for simultaneously measuring various properties of a fluid using a waveguide. Various non-patent literature also discusses the usage of equipment for measuring fluid parameters. Huanget. al., “Simultaneous Measurements of Temperature and Viscosity for Viscous Fluids Using an Ultrasonic Waveguide” (2021) discusses the simultaneously determine the temperature and viscosity of a fluid based on the changes in the velocity and attenuation of the elastic shear waves in the waveguide. An ultrasonic waveguide sensor for liquid level measurements using three guided wave modes Longitudinal L(0,1), Torsional T(0,1) and Flexural(1,1) simultaneously is discussed in Raja et.al., “Ultrasonic Waveguide Based Level Measurement Using Fundamental Guided Wave Mode L(0,1) T(0,1) And F(1,1) Simultaneously” (2019).
Presently, there are no systems for measuring rheological parameters of fluids accurately without causing damage to the equipment used for measurement. Therefore, there is a need for asystem for measuring the parameters of fluids precisely while ensuring durability of the equipment and the components present in the equipment.
SUMMARY OF THE INVENTION
The present subject matter relates to a robot for navigating elongated profiles or structures.
An embodiments of the present disclosure may include a system for measuring multiple properties of a fluid, including viscosity, density and temperature in real-time, the system including a transducer adapted to generate ultrasonic waves within the fluid and receive the reflected waves, a first cylindrical waveguide and a second cylindrical waveguide, the waveguides made of materials having differing elastic properties, and coupled to the transducer to transmit the ultrasonic waves into the fluid wherein one end of the waveguides may be acoustically coupled to the transducer and the second end may be immersed in the fluid, the waveguides having one or more sensing surfaces configured to generate reflected ultrasonic waves. The system may also include a pulser-receiver unit adapted to receive the reflected waves as amplitude-time signals from the sensing surface, a digital converter unit adapted to convert the amplitude-time signals received at the pulser-receiver unit from analog to digital form and a computing unit with display and input devices.The computing unit adapted to receive the digital amplitude-time signals from the converter unit and the computing unit configured to filter the reflected wave signals received from the sensing surfaces to remove noise, combine the plurality of signals in an A-scan, determine at least one of time of flight and amplitude ratio corresponding to peaks and valleys of the reflected waves and compute viscosity, density and temperature of the fluid based on the determined time of flight or amplitude ratio of the reflected waves corresponding to selected peaks and valleys wherein the selection may be based on the property being computed.
In some embodiments, the sensing surfaces may include one or more of a through-hole, a notch with a reduced diameter, or a change in section from round to flat.
In some embodiments, the elastic property may be one of Shear Modulus in the range 20 GPa to 90 GPa, or Poisson’s ratio, in the range 0.13 – 0.4.
In some embodiments, the first waveguide may be made of aluminium and the second waveguide may be made of stainless steel.
Embodiments of the present disclosure may also include a method for simultaneously measuring multiple properties of a fluid, including viscosity, density andtemperature in real time, the method including providing a first cylindrical waveguide and a second cylindrical waveguide, the waveguides made of materials having differing elastic properties, the waveguides having a first end and a second endwherein one end of the waveguides may be acoustically coupled to an ultrasonic transducer. The method may also include immersing the second end of the waveguides in the fluid to be measured, transmitting ultrasonic shear waves into the fluid via the two waveguides, receiving a plurality of amplitude-time signals including reflected waves from one or more sensing surfaces of the two waveguides, the sensing surfaces including one or more of a through-hole, a notch with a reduced diameter, or a change in section from round to flat. The method also includes combining the signals in an A-scan, determining at least one of time of flight (ToF) and amplitude ratio (AR) corresponding to peaks and valleys of the reflected waves in the combined signal, include computing a property of the fluid based on the determined ToF or AR of selected peaks and valleys of the combined signal, the selection depending on whether the property being measured may be viscosity, density and temperature.
Embodiments may also include combining the signals in an A-scan may include digitizing analog amplitude-time signals to digital signals, filtering the plurality of signals to remove noise, detecting peaks and valleys in the signals and selecting appropriate peaks and valleys in the signals depending on the required measurement.
In some embodiments, the fluid viscosity may be measured by attenuation of amplitude ratio obtained from sensing surfaces located at different depths within the fluid.
In some embodiments, the temperature of the fluid may be measured by computing difference in time of flight from two different sensing surfaces of the cylindrical portion of the first or the second waveguide.
In some embodiments, the density of the fluid may be measured by computing difference in time of flight across the flat portion of the waveguide.
In some embodiments, the ultrasonic wave transmitted by the transducer may be a shear wave or a torsional wave.
This and other aspects are described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention has other advantages and features, which will be more readily apparent from the following detailed description of the invention and the appended claims, when taken in conjunction with the accompanying drawings, in which:
FIG. 1A illustratesa system for simultaneously measuring multiple properties of a fluid.
FIG. 1Bshows a waveguide assembly, according to some embodiments of the present disclosure.
FIG. 2illustrates a method for simultaneously measuring multiple properties of a fluid, according to embodiments of the present disclosure.
FIG. 3A illustratesan exemplary waveguide assembly and FIG. 3B representsA-scanprofile generated by the waveguides.
FIG. 4A and 4B illustrates data filtering using Savitzky-Golay filter and Gaussian filter respectively.
FIGS. 5A, 5B and 5C illustrate graphs representing amplitude ratio and time of flights extracted from A-scan generated by waveguides, according to some embodiments of the present disclosure.
FIG. 6 illustrates the graph representing the difference in amplitude ratio of used and unused lubricating fluid, according to some embodiments of the present disclosure.
Referring to the figures, like numbers indicate like parts throughout the various views.
 
DETAILED DESCRIPTION OF THE EMBODIMENTS
While the invention has been disclosed with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt to a particular situation or material to the teachings of the invention without departing from its scope.
Throughout the specification and claims, the following terms take the meanings explicitly associated herein unless the context clearly dictates otherwise. The meaning of “a”, “an”, and “the” include plural references. The meaning of “in” includes “in” and “on.” Referring to the drawings, like numbers indicate like parts throughout the views. Additionally, a reference to the singular includes a reference to the plural unless otherwise stated or inconsistent with the disclosure herein.
The present subject matter describesasystem and method for measuring multiple properties of a fluid. It facilitates the measurement of fluids that have extreme environments such have high temperature or are highly corrosive without causing any damage of to the components of the system.
A system 100for measuring multiple parameters of a fluid is illustrated in FIG. 1A and 1B, according to embodiments of the present disclosure. The system 100is utilized for simultaneously measuring multiple properties of fluids, including viscosity, density and temperature of fluids in real-time. The system includes a waveguide unit 150 having a transducer 102 that is adapted to generate ultrasonic waves within the fluid and receive the reflected waves. In various embodiments, the ultrasonic wave transmitted by the transducer 102 is either a shear wave or a torsional wave.Afirst cylindrical waveguide 110 and a second cylindrical waveguide 130are coupled to the transducer 102to transmit the ultrasonic waves in the fluid. The waveguides 110, 130may be made of materials having different elastic properties such that the signals when superimposed in an A-scan, do not overlap. The materials may have Shear Modulus in the range 20 GPa to 90 GPa, or Poisson’s ratio, in the range 0.13 – 0.4.In some embodiments, the difference in Shear Modulus of the material of the two waveguides may be at least 10GPA. The waveguides 110, 130are acoustically coupled to the transducer 102at one end and immersed in the fluid at the second end.
The waveguide unit 150in various embodiments is illustrated in detail in FIG. 1B. As shown in FIG. 1B, the waveguides 110, 130may have a plurality of sensing surfaces for generating reflected ultrasonic waves. As observed in FIG. 1B, the waveguides 110 and 130 are illustrative of the kind of sensing surfaces that may be employed for various measurements. Waveguide 110 in FIG. 1B is thus shown having a through-hole121, and notches with a reduced diameter122 or 123.The notch 122 may be positioned at length l1 along the waveguide 110 from the transducer 102, while notch 123 and back wall of the waveguide 119 may be positioned at lengths l2and l3 from the notch 122 and 123, respectively. of the or a change in section from round to flat141, or a back wall of the waveguide119 or 139, as illustrated in FIG. 1B. Further, the first cylindrical waveguide 110 includes a first cylindrical portion 111 of length l1, a second cylindrical portion 112 of length l2and a third cylindrical portion 113of length l3. As shown in FIG. 1B, the second cylindrical waveguide 130 includes a cylindrical portion 131 of length m1and a flat section 132 of length m2.
The system 100 further includes a pulser-receiver unit 104 adapted to receive the reflected waves as amplitude-time signals from the sensing surfaces and a digital converter unit 106 adapted to convert the amplitude-time signals received at the pulser-receiver unit 104from analog to digital form.
The system 100also includes a computing unit 108 having display and input devices.The computing unit 108 is adapted to receive the digital amplitude-time signals from the converter unit 106.The computing unit 120may be configured tofilter the reflected wave signals received from the sensing surfaces to remove noise, and to combine the plurality of signals in an A-scan. Thereafter, the combined A-scan may be used to determine a number of parameters relating to the reflected signals. The parameters may in various embodiments be time of flight oramplitude ratio corresponding to peaks and valleys of the reflected waves, which may be used to compute viscosity, density and temperature of the fluid. The computation may be based on the determined time of flight or amplitude ratio of the reflected waves corresponding to selected peaks and valleys.The selection of peaks may bebased on the property being computed.In one embodiment, the fluid viscosity may bemeasured by attenuation of amplitude ratio obtained from sensing surfaces located at different depths within the fluid.In one embodiment, the temperature of the fluid may bemeasured by computing difference in time of flight from two different sensing surfaces of the cylindrical portion of the first or the second waveguide.In various embodiments, thedensity of the fluid may bemeasured by computing difference in time of flight across the flat portion of the waveguide.
FIG. 2A illustrates the method for simultaneously measuring multiple parameters in a fluid such as viscosity, density and temperature, according to some embodiments of the present disclosure. The method 200includesproviding a first cylindrical waveguide 110and a second cylindrical waveguide130, the waveguides made of materials having differing elastic properties, the waveguides having a first end and a second end, wherein one end of the waveguides 110, 130is acoustically coupled to an ultrasonic transducer102as provided in 201. At 202, the method includesimmersing the second end of the waveguides in the fluid to be measured. At 203, the method includestransmitting ultrasonic shear waves into the fluid via the two waveguides110, 130. In some embodiments, at 204, the method includes receiving a plurality of amplitude-time signals including reflected waves from plurality of sensing surfaces for generating reflected ultrasonic waves.
At 205, the method includesdigitizing analog amplitude-time signals to digital signals. At 206, the method includes filtering the plurality of signals from the reflecting surfaces to remove noise. The method further includes combining the plurality of signals into an A-scan,detecting the peaks and valleys in the combined A-scan signal and selecting the appropriate peaks and values as provided in 207. At 208, the method includes determining at least one of time of flight (ToF) and amplitude ratio (AR) corresponding to peaks and valleys of the reflected waves in the combined A-scan signal. The method includes computing the viscosity, density and temperature of the fluid based on the determined Time of Flight or Amplitude Ratio of selected peaks and valleys of the combined A-scan signal as provided in 209.
In various embodiments, in step 206, filters may be used on the data obtained from the waveguides to enhance the computation and improve the accuracy of detection of peaks. Savitzky–Golayand Gaussian filters may be applied on A-scans for de-noising as shown in FIG. 2B.
A Savitzky–Golay (SG) filter is a digital filter that can be applied to a set of digital data points for the purpose of smoothing the data based on a mathematical model of local least-squares polynomial approximation. The least-square smoothing reduces noise while maintaining the shape and height of waveform peaks that is, to increase the precision of the raw signal for further analysis of waveform & computation of results without distorting the signal tendency.
In various embodiments, the following methodmay be used for the Savitzky-Golay filtering, wherein,
the x – coordinate data is filtered using:
scipy.signal.savgol_filter(x, window_length, polyorder), ……….(1)
and the y – coordinate data may be filtered using the algorithm:
y = savgol_filter(x, 61, 3)………………………………………………..(2)
where, window_lengthis the length of the filter window (i.e., the number of coefficients), and polyorderis the order of the polynomial used to fit the samples.
In various embodiments of the method, a Gaussian filter may be used for the detection of peaks of the Ultrasound Signal. Index of peaks are identified and Gaussian fit is applied to further increase the resolution of the peak detection andenhance the computation process. The Gaussian fit used in one embodimentmay be
a * np.exp(- (x - x0)**2 / (2 * sigma**2 )) + b * np.exp(-(x - x1 )**2 / (2 * sigma1**2)) + c * np.exp(-(x - x2)**2 / (2 * sigma2**2)) ……………………(3).
FIG. 2C shows the comparison between normal A-scan and Gaussian filtered A-scan indicating the magnified view of one peak with better resolution.
The advantages of the invention include measurement of multiple parameters of the fluid simultaneously, while minimizing errors in measurement. The claimed device and method is capable of multi point multi parameter measurements using multiple sensors in the same waveguide. This technology assures repeatability, reproducibility and accuracy as the ultrasonic wave emitted from the transducer doesn’t change over time.
EXAMPLES
Example 1 –A first configuration of two waveguides
In a first configuration of the two waveguides, the first cylindrical waveguide 110is aluminium and the second cylindrical waveguide 130 was stainless steel.as shown in FIG. 3A. The first cylindrical waveguide 110 had 2 symmetric notches with notch length of 45mm and 50mm respectively with a total length of 380mm. The second cylindrical waveguide 130hadone flat section of length 40mm with total length of 295mmwith aspect ratio as 1.6. Both the waveguides had a uniform cross-section dimension of 3.2mm by 2mm. The following table indicates the properties of the two waveguides:
TABLE 1: Properties of Waveguide Materials

Waveguide First Waveguide Second waveguide
Material Aluminum 5356 Stainless steel 316
Density 2700 Kg/m3 8000 Kg/m3
Shear modulus 26 GPa 74 GPa
Poisson's ratio 0.33 0.27
Dimensions Diameter = 3.2mm Diameter = 3.2mm
Frequency 500 kHz 500 kHz
For determining the viscosity, density and temperature of a fluid using the two waveguides,overlapped signals were obtained from the A-scan generated having the combined signals from the two waveguides 110, 130 is shown in FIG. 3B. Three signals were obtained from the first waveguide 110 located at the distance of 285mm, 330mm and 380mm while two signals are obtained from the second waveguide 130 located at the distance of 255mm and 295mm. The torsional velocity of the first waveguide 110 was3101 m/s while the torsional velocity of second waveguide was2898 m/s
Time taken for the signal to reach back to transducer = (2*Distance)/Velocityofwave
Second waveguide:
At 255mm, t1 = (2*0.255 )/2898 = 175.98 µs
At 295mm, t2 = (2*0.295 )/2898 = 203.58 µs
First waveguide:
At 285mm. t3 = (2*0.285 )/3103 = 183.69 µs
At 330mm, t4 = (2*330 )/3103 = 212.69 µs
Hence from aforementioned time values, signalswerereceived in the order of time t1-t3-t2-t4 which is in accordance with the A-scan as shown in FIG. 3B.
For determining the viscosity, density and temperature of a fluid, amplitude ratio of the signal obtained from two notches wasused to find the shear impedance of the fluid while time of flight (ToF) between two notches in the second waveguide wasused to find the temperature of the fluid.
Dt =ū*Þ+ώ*SI
Dt = Difference in ToF from backwall and change in cross-section in the second waveguide for a particular temperature between fluid and air
ū ((s*cc)/g), ώ((s^1.5*〖(cc*cm)〗^0.5)/g)
SI = Shear Impedance , Þ = Density
ū and ώ of the above equation wereobtained by using actual density and Shear Impedance of the fluid at those temperatures. The density wasobtained by using the aforementioned equation with the experimental values of shear impedance and Dt. Using the values of both density and shear impedance the value of viscosity wasdetermined.
Signals wereobtained from notches, backwall and change in cross section of the waveguides. Viscosity depends on the amplitude of the reflection from the notch of the waveguide. So, amplitude ratio is used to calculate viscosity of the fluid.
Amplitude ratio = (A1-V1)/(A2-V2)
Time of flight is the difference in time duration of two reflections of the notches. The time duration values of peak of the reflections is used to find the difference in the duration.
Time of flight = ToF2 – ToF1
ToF1 – Time duration of the reflection from 1st notch
ToF2 – Time duration of the reflection from 2nd notch
The temperature depends on time of flight of the signal from the first waveguide. So, temperature wascalculated by correlating time of flight with temperature.Time of flight from second waveguide between change in cross section and backwall wasutilized to obtain density. The difference in time of flight ofsecond waveguide between air and fluid was taken to negate the temperature’s effect on the waveguide.
The A-scan generated by the two waveguides was filtered to remove noise, the peaks and valleys present were detected. The data was successively filtered using Savitzky-Golay filter as shown in FIG. 4A, and Gaussian filter (FIG. 4B). Based on the requirement, peaks and valleys were selected and their (x, y) co-ordinates recorded. The Time-of-Flight was determined by the difference in x co-ordinates of selectedpeaks and valleys while the amplitude ratiowas obtained from the y co-ordinate ratio of two peak-valley length. The Time of Flight and amplitude ratios were used with thecalibration equation to obtain required parameters. For each of the A-scans generated the aforementioned actions were performed.
Example 3: Implementation of the waveguides in a fluid with rising temperature
The system having two waveguides of steel and aluminium was used for calibration used in a fluid whose temperature is raised from 35℃ to 100℃.The fluid was maintained at various temperatures using a constant temperature bath as shown in Table 2. The properties of the fluid measured at each temperature are further listed in Table 2. In Table 2, the first column represents temperature of the constant temperature bath, while measured temperature using the device and method of the invention are given in column 2. The amplitude ratio and time of flights is extracted from the A-scan generated by the waveguides as illustrated in FIGS. 5A, 5B and 5C. After calibration, the dynamic viscosity, density and temperaturewere measured for the fluid. The three parameters obtained from Viscometer, Density meter and RTD were compared while the temperature was varied from 30℃ to 100℃. The Table 2 indicates the comparison of the parameters, the third column being viscometer reading vs. 4th column representing measured viscosity. The sixth and seventh columns represent the density meter reading vs. measured value, respectively:

TABLE 2: Comparison of Parameters of a Fluid after Calibration and Measurement
Temp
(℃) Temp obtained (℃) Kinematic Viscosity (cSt) K Viscosity Obtained (cSt) Dynamic Viscosity (cP) Density
(g/cc) Density obtained (g/cc) Shear Impedance

30 31.2 382.58 375.3 79.20 878.6 882.76 8.34

40 41.32 208.2 212.9 49.79 871.6 875.74 6.58

50 50.67 122.41 126.6 33.08 864.6 868.725 5.35

60 60.6 76.82 71.16 23.04 857.6 861.77 4.44

70 71.2 50.93 45.04 16.68 850.6 858.08 3.77

80 81.34 35.38 35.5 12.49 843.5 855.3 3.25

90 90.81 25.58 28.124 9.63 836.4 852.61 2.84

100 101.3 19.13 16.64 7.60 829.3 849.4 2.51

wherein, shear impedanceis √(█(Dynamic Viscosity(cP)@*Density(g/cc))))
The viscosity, density and the temperature of a fluid whose properties are being measured maybe viewed in a dashboard in real-time. The location of waveguides used for measuring the fluid are also displayed for a user’s convenience. The live and previous measurements can be viewed and stored. The live measurements can be viewed and analyzed by selecting Live graph option. The previous measurements can be viewed and stored. This can be done using two ways: By selecting values and by time options.Value represents the sample points of measurements and time means the time at which measurement was done.

Example 4: Identification of contamination or crystallization in fluids
The waveguides allow identification of contamination or crystallization in fluids using the ultrasonic signals. A measure of 180ml of fresh and used lubricant fluid was utilized for testing. A stand with test tube fixture is used for the experimentation with thesensor attached to the stand. Test tubes with different samples are collected and are used for testing. Fresh and used lubricant fluids were used for checking the sensor activity to contamination. 75W80 fresh, 75W80 used (30k km), 80W110 fresh, 80W110 used (30k km) and 80WAMG were used for testing.Amplitude ratio was measured from the signal received from the waveguide, which can be used to find viscosity of the fluid. As the lubricant fluids keeps circulating around the engine, it becomes contaminated due to inclusion of wear particles and mixing of other elements which increases the viscosity of the fluid. The difference in amplitude ratio of used and unused fluid is shown in FIG. 6.The change in amplitude ratio with varying fluid indicates the sensor’s capability to distinguish between different fluids and between fresh and used fluid. The used lubricating fluid shows higher attenuation compared to the fresh oil, due to contamination.
Although the detailed description contains many specifics, these should not be construed as limiting the scope of the invention but merely as illustrating different examples and aspects of the invention. It should be appreciated that the scope of the invention includes other embodiments not discussed herein. Various other modifications, changes and variations which will be apparent to those skilled in the art may be made in the arrangement, operation and details of the system and method of the present invention disclosed herein without departing from the scope of the invention, which should be as delineated in the claims appended hereto.
 
, Claims:WE CLAIM:
1. A system (100) for simultaneously measuring multiple properties of a fluid, including viscosity, density and temperature in real-time, the system comprising:
a transducer (102) adapted to generate ultrasonic waves within the fluidusing waveguides and receive the reflected waves;
a first cylindrical waveguide (110) and a second cylindrical waveguide (130), the waveguides (110, 130) made of materials having differing elastic properties, and coupled to the transducer (102) to transmit the ultrasonic waves into the fluid, wherein the one end of the waveguides (110, 130) are acoustically coupled to the transducer (102) and the second end is immersed in the fluid, the waveguides (110, 130) having one or more sensing surfaces configured to generate reflected ultrasonic waves;
a pulser-receiver unit (104) adapted to receive the reflected waves as amplitude-time signals from the sensing surfaces;
a digital converter unit (106) adapted to convert the amplitude-time signals received at the pulser-receiver unit (104) from analog to digital form; and
a computing unit (108) with display and input devices, the computing unit (108) adapted to receive the digital amplitude-time signals from the converter unit (106), the computing unit (108) configured to:
filter the reflected wave signals received from the sensing surfaces to remove noise;
combine the plurality of signals in an A-scan;
determine at least one of: time of flight and amplitude ratio corresponding to peaks and valleys of the reflected waves;
and
compute viscosity, density or temperature of the fluid based on the determined time of flight or amplitude ratio of the reflected waves corresponding to selected peaks and valleys, wherein the selection is based on the property being computed.

2. The system (100) as claimed in claim 1, wherein the sensing surfaces comprise one or more of: a through-hole, a notch with a reduced diameter, or a change in section from round to flat.

3. The system (100) as claimed in claim 1, wherein the elastic property is one of Shear Modulus in the range 20 GPa to 90 GPa, or Poisson’s ratio, in the range 0.13 – 0.4.

4. The system (100) as claimed in claim 1, wherein the first waveguide (110) is made of aluminium and the second waveguide (130) is made of stainless steel.

5. A method (200) for simultaneously measuring multiple properties of a fluid, including viscosity, density and temperature in real time, the method (200) comprising:
providing (201) a first cylindrical waveguide (110) and a second cylindrical waveguide (130), the waveguides (110, 130) made of materials having differing elastic properties, the waveguides (110, 130) having a first end and a second end, wherein one end of the waveguides (110, 130) is acoustically coupled to an ultrasonic transducer (102);
immersing (202) the second end of the waveguides (110, 130) in the fluid to be measured;
transmitting (203) ultrasonic shear waves into the fluid via the two waveguides (110, 130);
receiving (204) a plurality of amplitude-time signals including reflected waves from one or more sensing surfaces of the two waveguides (110, 130), the sensing surfaces comprising one or more of: a through-hole, a notch with a reduced diameter, or a change in section from round to flat;
combining (207) the signals in an A-scan;
determining (208) at least one of: time of flight (ToF) and amplitude ratio (AR) corresponding to peaks and valleys of the reflected waves in the combined signal; and
computing (209) a property of the fluid based on the determined ToF or AR of selected peaks and valleys of the combined signal, the selection depending on whether the property being measured is viscosity, density and temperature.

6. The method (200) as claimed in claim 5, wherein combining the signals in an A-scan comprises:
digitizing (205) analog amplitude-time signals to digital signals;
filtering (206) the plurality of signals to remove noise;
detecting (207) peaks and valleys in the signals; and
selecting (207) appropriate peaks and valleys in the signals depending on the required measurement.

7. The method (200) as claimed in claim 5, wherein the ultrasonic wave transmitted by the transducer (102) is a shear wave or a torsional wave.

8. The method (200) as claimed in claim 6, wherein the fluid viscosity is measured by attenuation of amplitude ratio obtained from sensing surfaces located at different depths within the fluid.

9. The method (200) as claimed in claim 6, wherein the temperature of the fluid is measured by computing difference in time of flight from two different sensing surfaces of the cylindrical portion of the first (110) or the second (130) waveguide.

10. The method (200) as claimed in claim 6, wherein the density of the fluid is measured by computing difference in time of flight across the flat portion of the waveguide.

Sd.- Dr V. SHANKAR IN/PA-1733
For and on behalf of the Applicants