GB2347745A

GB2347745A - Matrix board fluid flow measuring device

Info

Publication number: GB2347745A
Application number: GB9905549A
Authority: GB
Inventors: David Kenneth Churches
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-03-11
Filing date: 1999-03-11
Publication date: 2000-09-13
Also published as: GB9905549D0

Abstract

The matrix board fluid flow measuring Device is used for the study, measurement, and detection of, one-phase fluid flows [e.g., Newtonian fluids], two-phase fluid flows including particulates in disperse suspension within a fluid medium [e.g., Smoke Plumes], and poly-phase fluid flows [e.g., Non-Newtonian fluids]. The matrix board G (Figs 2-4) is constructed from a sheet or flat plate of rigid or semi-rigid material perforated with a regular or non-regular array of apertures usually with a capillary diameter, or where the apertures are at a diameter < 0.25 of the fluid flow diameter. The matrix board fluid flow measuring device is mounted directly in a fluid flow H, and can be oriented perpendicular or at any angle between perpendicular and parallel to the direction of the fluid flow. It can be used in conjunction with an incident time varying electromagnetic wave or soundwave to improve the detection efficiency of the device. The device can be configured as an ultrasound double matrix board system, which has a tuned sensitivity to suit particular fluid densities and to suit the particular mean diameter of particulates suspended in a fluid medium. The tuned sensitivity can be set to a narrow selective bandwidth for a particular fluid type, or alternately set up with a wider bandwidth to include fluids from a wider range of types.

Description

Matrix Board Fluid Flow Measuring Device Section 1-Introduction The Matrix Board Fluid Flow Measuring Device is used for the study, measurement, and detection of, one-phase fluid flows [e. g., Newtonian fluids], two-phase fluid flows including particulates in disperse suspension within a fluid medium [e. g., Smoke Plumes], and poly-phase fluid flows [e. g., Non-Newtonian fluids].

The Matrix Board as its name implies, is a thin sheet of rigid or semi-rigid material perforated with a regular or non-regular array of apertures [holes] with a capillary diameter [e. g., lmm +], or where the apertures are at a diameter < 0.25 of the bulk fluid flow diameter. The Matrix Board is mounted directly in a fluid flow, oriented perpendicular or at any angle between perpendicular and parallel to the direction of the bulk flow.

The total number of apertures [holes] in the matrix may vary from application to application, but in general each matrix board usually has several hundred or even thousands apertures, but in special circumstances for particular types of flows the number might be less than ten.

The Matrix Board Fluid Flow Measuring Device may be arranged in single, double, or multilayers, and each successive layer is arranged parallel or near parallel to the other. The dimensions of each Matrix Board layer may be equal or non-equal to the adjacent layer. The dimensions of the interstitial cavity separating each successive Matrix Board layer may be arranged to be equal to some function of the aperture diameter and/or the length of the aperture, in one or other of the Matrix Boards.

The Matrix Board (s) facilitates a perturbated flow pattern in a transitory fluid flow at laminar flow velocities, even when the fluid system has low Reynolds Number (Re) and the apertures in one or other of the Matrix Boards have a capillary diameter.

The way in which the transitory fluid flow exits the Matrix Board and begins to reform a parallel or near parallel fluid flow, can be used to study, measure, and detect the properties, qualities and nature of the fluid flow.

The Matrix Board Fluid Flow Measuring Device tends to be more efficient when is it arranged in a double layer that is orientated perpendicular to the fluid flow direction, and this is known as the "Double Layer Matrix Board System".

The efficiency of the Matrix Board Fluid Flow Measuring Device may be improved by the addition of an incident time varying Electromagnetic wave or Soundwave emanating through the Matrix Board (s) in the general direction of the transitory fluid flow. The signal transmitter and/or the signal detector may be positioned either in the upstream or downstream position of the Matrix Board (s), so that the general direction of the incident time varying waveform may be parallel or anti-parallel to the direction to the transitory fluid flow.

The greatest efficiency observed in the"Double Layer Matrix Board System", was when a soundwave transmitter was in the upstream position and the soundwave detector was in the downstream position. The efficacy of the"Double Layer Matrix Board System"was further enhanced when the diameter of the apertures within the matrix are near equal to l/2 wavelength of an incident time varying soundwave frequency.

This limits the frequency of the incident time varying soundwave to the upper audible and ultrasonic regions of the audio spectrum, when the apertures in"Double Layer Matrix Board System"are at capillary or near capillary size.

The Matrix Board Fluid Flow Measuring Device is designed to study, measure, and detect the properties, qualities and nature of a fluid flow on or about a single point or position, and all the major component parts are generally [but not exclusively] spaced within 1 linear metre. The Matrix Board Fluid Flow Measuring Device may be used in open stream fluid flows or enclosed fluid flows.

One example of the Matrix Board Fluid Flow Measuring Device, is the"Double Layer Matrix Board System"and is further described in Section 2 below.

Section 2-Double Layer Matrix Board System-Description The"Double Layer Matrix Board System"is primarily configured as a device for the study, measurement, and detection of the properties, qualities and nature of smoke particulates in air suspension as contained in smoke plumes located in the post combustion zone of a fire.

However, it may equally be used for other fluid flow types.

As described earlier in Section 1, the"Double Layer Matrix Board System"is equipped with a soundwave transmitter in the upstream position of the matrix board and a soundwave detector was in the downstream position. It uses a time varying waveform with a sinusoidal excitation in the ultrasonic region at 160 kHz.

An illustration of the"Double Layer Matrix Board System"is shown in Figure 1 and the main features of the device are as follows.

Figure 1-Legend A Smoke Ejector. E Lower Matrix Board B 150-mm diameter circular tube. F Upper Matrix Board C Piezo Ultrasound transmitter. G End Seal for matrix boards D Piezo Ultrasound detector receiver. H Flow Direction.

2.1 Measurement Principles-Double Layer Matrix Board System The Double Layer Matrix Board System has essentially two measurement principles operating in tandem, and their synergy not only enhances their mutual sensitivity, but also facilitates the possibility of detection at a selectable or tuned frequency to suit particular smoke densities or various smoke types emanating from dissimilar fire types.

(a) Double Layer Matrix Board The"Orifice Plate"has long been used as a measurement device for the study of Fluid Flow Dynamics. By contrast the"Double Matrix Board"is usually equipped with several hundred or more capillary sized apertures and differs very greatly from the"Orifice Plate"which usually has only a single aperture.

The"Double Matrix Board"and the"Orifice Plate"also have very different operating principles. The"Orifice Plate"restricts the flow diameter and induces a flow velocity change in a single stream that can be measured by observing the velocity pressure and the residual pressure.

The"Double Matrix Board"on the other hand splits a fluid flow single stream into several hundred capillary sized streamlets (induced pseudo-turbulence), and measurement is achieved by observing the speed and the nature of the reformation of the single stream after it exits the matrix board.

(b) Ultrasound Flow Measurement Ultrasound has also been used for some time in the study of Fluid Flow Dynamics and uses a variation of the Doppler Effect to measure moving fluid flows. Like the Double Layer Matrix Board System it also uses an Ultrasound transmitter and detector, but unlike the Double Layer Matrix Board System, conventional Ultrasound Flow Measurement devices cannot easily detect a change in the density or nature of the fluid medium and assumes it to be a constant for measuring purposes.

(c) Combination Device The Double Layer Matrix Board System is a combined fluid flow measuring device that uses both the Double Layer Matrix Board and Ultrasound for measurement purposes. The combination facilitates the measurement of a change in the density or nature of the fluid medium itself, and a change in its local velocity, by observing the speed and the nature of the reformation of the single stream.

By selecting the appropriate aperture size in the matrix board and the frequency of the ultrasound waveform, a tuned response can be induced that facilitates increased sensitivity and selectablity for particular fluid flows.

The exact constructional features (see Figure 2) of the Double Matrix Board are critical to maintain the"Tuned Cavitational and Interstitial Response"of the device. This includes the selection of materials and their dimensions, as well as their spatial arrangement and orientation.

In operation the frequency and the amplitude of the incident waveform are adjusted until a "sweet spot"or"ideal tuned response"in the device occurs.

The definition of a"sweet spot"in the above context is when comparative maximum amplitude is received at the point detector, and is accompanied by the maximum sensitivity of the apparatus to detect the presence of smoke particulates in air suspension.

A sectional illustration of through the"Double Layer Matrix Board"is shown in Figure 2 and the main features of the device are as follows.

Figure 2-Legend A Lower Matrix Board C Upper Matrix Board B Typical Smoke Travel 2.2 Acoustic Synergetic Tuned Resonance Another aspect of the"Double Layer Matrix Board System"is"Acoustic Synergetic Tuned Resonance"and the device uses this as one of the detection tools. This is not a particularly new idea since"Synergetic Tuning"is commonly used in a number of everyday devices. A common example is the technique in Audio Hi-Fi equipment to mechanically"tune"the spatial cavity in a loudspeaker cabinet to enhance the sensitivity or performance of the electromagnetic speaker unit.

The Double Layer Matrix Board Device shown in Figure 1 also uses"Acoustic Synergetic Tuned Resonance"to enhance its sensitivity and performance. It uses a combination of the resonant frequency of the Piezoelectric Transducers [transmitter and the detector], together with the [mechanical] resonant frequency of the Double Matrix Board and the internal spatial cavity of the device itself. There are essentially two synergetic resonances of interest in the Double Layer Matrix Board Device, and they are as follows.

(a) Maximum Power Transfer The maximum power transfer Acoustic Synergetic Resonant Frequency, when the amplitude at the detector is at a maximum and the attenuation within the apparatus is at a minimum.

(b) Minimum Power Transfer The minimum power transfer Acoustic Synergetic Resonant Frequency, when the amplitude at the detector is at a minimum and the attenuation within the apparatus is at a maximum.

When the Double Layer Matrix Board Device is tuned to the maximum power transfer Acoustic Synergetic Resonant Frequency, it has a delicate fine tuned balance that can be perturbated by the introduction of smoke particulates into the device. This gives the Double Layer Matrix Board Device a"tuned sensitivity"and performance due to the Acoustic Synergetic Resonance.

The"tuned sensitivity"can be theoretically set to suit a particular smoke density and particular mean particulate diameter. In other words, the Acoustic Synergetic Tuned Resonance point could be set to a narrow selective bandwidth for a smoke from a particular fire type, or alternately set up with a wider bandwidth to include smoke from a wider range of fire types.

The frequency was selected on the basis of attaining the maximum power transfer Acoustic Synergetic Resonance. Several synergetic resonant frequencies are observed over a range of frequencies, but the highest amplitude occurred when the frequency of interest [160 kHz] compared to the diameter of the apertures [i. e., 1mm] in the Double Matrix Board, was equal to the half wavelength (V2X) of the incident frequency [i. e., ~2mm].

The appropriate amplitude selection is also very important to the functionality of the method. A relatively high amplitude is needed to enable the apparatus to be sensitive at the synergetic resonant frequency point, to provide adequate detection of smoke particulates.

Conversely, a relatively low amplitude is needed to prevent the onset of rapid mutual coalescence of the smoke particulates, which can be brought on by high amplitude soundwaves. The selected amplitude of 98 dBA was the median that satisfied both the above conditions with a vertical air velocity through the apparatus at 0.01 to 0.02 m/sec.

2.3 Aim of the Double Layer Matrix Board Device The main aim of the Double Layer Matrix Board Device is to facilitate the detection of a media density change, such as detecting the presence of fine smoke particulates in air suspension at low plume velocities [typically 0.10 to 0.02 m/sec]. The Double Matrix Board in conjunction with an incident time varying waveform passing through the detector apparatus, induces two circumstances which aid the detection of the media density change, which are"Spatial Resonance"and"Pseudo Turbulence". These are characterised as follows.

(a) Disassociated Flow Pattern Induces a disassociated flow pattern (pseudo-turbulence) in the smoke plume as it enters the lower matrix layer (strainer effect) and then into the Interstitial Cavity, at laminar velocities when the detector system has a low Reynolds Number (Re).

Subsequently, when the smoke plume exits the upper matrix layer, a rapid reassociation is induced within the plume and quickly forms a cohesive and structured laminar bulk flow pattern.

(b) Spatial Resonance A spatial resonance is formed when the combination of the critical dimensions of the Double Layer Matrix Array are similar to a function of the half-wave (1/2) of a time varying Ultrasound wave emanating through the device.

The rate of the onset of pseudo-turbulence [disassociated flow patterns in the Double Layer Matrix Board Device, and the speed of the subsequent reassociation of the cohesive laminar bulk flow, differs for dissimilar smoke types and varying optical smoke densities. The media density change is the transition from"air-only no-smoke"condition, to the "smoke and air"mix condition. In other words a change from a"single phase fluid" (air, i. e., NO2) to a"two-phase fluid" (smoke particulates in air suspension).

The perturbated flow patterns of a variety of dissimilar smoke types are observed to have another affect within the Double Layer Matrix Board. When the frequency of the incident Ultrasound wave was tuned to the natural [mechanical] spatial and cavitational resonant frequency, it was particularly sensitive to a media density change within the Double Matrix Interstitial Cavity.

2.4 Constructional Features-Double Layer Matrix Board Device The constructional features described below are as a sample only for demonstration purposes and are not indicative of all matrix board configurations. The Double Layer Matrix Board as its name implies, is two separate layers of regular array of apertures of capillary diameter [lmm +].

The double layer board has a 4.5-mm parallel interstice (see Figure 2) separating each layer and the whole unit is mounted directly in a moving smoke plume, oriented perpendicular to the direction of the flow.

(a) Mutual Total Surface Area The Mutual Total Surface Area of each of the Matrix Boards is 7600mm2 (80mm x 95mm). The Mutual Surface Area is defined as the mutual overlap area of the Matrix Boards in contact with a smoke plume traversing through the device.

(b) Matrix Size The regular array of apertures on each Matrix Board in the Mutual Total Surface Area is 32 x 38 holes (total of 1216 apertures). The pitch or matrix of the apertures or capillaries on each Matrix Board is 2.54mm x 2.54mm.

(c) Capillary Apertures Each of the apertures or capillaries within the array has a diameter of lmm (3.141mm2), with a length of 1.6 mm. The total volume contained within each capillary is 5.026 mm3.

(d) Interstitial Cavity The cavity or interstice (see Figure 3) between the upper and lower Matrix Board is 4.5mm in height and with a total area of 7600mu, and a corresponding total volume of 34200 mm3.

(e) End Seal The Interstitial Cavity is laterally sealed on all sides (see Figure 4), and only has a vertical entrance and exit via the apertures in the Matrix Board.

2.5 Doppler Effect The conventional method of detecting the difference between two dissimilar media sequentially passing through an Ultrasound wave is to measure the Doppler Shift Frequency. The popular description of the Doppler Effect is when either a sound source or the observer of the sound source moves in relation to the medium in which the sound waves travel, and as a result the observer measures a different frequency to that when no motion occurs. This is the common description for the Doppler Effect, i. e., when the "observer"or the"sound source"moves.

Let vo = the velocity of either the sound source or the observer moving in the opposite direction to the wave travel, subscript 1 = stationary observer, and subscript 2 = moving observer, o is the angular velocity of the wave, and c is the local speed of sound, we can describe the Doppler Shift thus,

Equation 2.5 (I) From Equation 2.5 (1) we find that the observer measures a higher frequency when moving in the opposite direction to the sound source, and a lower frequency when moving in the same direction as the wave travel, which is given by,

Equation 2.5 (2) There are other less popular cases that also generate an apparent Doppler Effect or Shift.

One example is when neither the sound source nor the observer has any relative motion to each other, but instead the medium through which the soundwaves travel begins to move.

This also generates an apparent Doppler Shift from the observer's prospective, we witness this phenomenon quite often without realising it when the pitch of normal everyday sounds we hear in the open air, suddenly appears to change in high winds.

Another example is when a sudden change in the in the nature or density of the medium may also cause a corresponding variation in the local speed of sound (c), such as the introduction of smoke particulates into an air column. This also tends to generate an apparent Doppler Shift. The Double Layer Matrix Board Device as shown in Figure 1 has the sound source [piezo transmitter unit] and the observer [single point piezo detector] at fixed points. Lets imagine that the piezo detector initially receives a stable Ultrasound signal when only clean air is present in the device, when smoke is introduced the medium then undergoes a change to a smoke/air mix [aerosol]. The change in the medium then generates an apparent Doppler Shift at the piezo detector If we consider the value for cl in Equation 2.5 (1) and Equation 2.5 (2), its shown to be a constant when the media through which the Ultrasound travels is also a constant. If we have a media change then the value for c will change to c2 (i. e., change in the local speed of sound). So if we subtract the initial value for c from the new value (i. e., cl-c2), then we get c,, [change in the speed of sound due to a density change in the medium], which is analogous to a pseudo-velocity since its value is measured over distance with time. If we substitute cm for vo in Equation 2.5 (1) and Equation 2. 5 (2) we get,

Equation 2. 5 (3) Equation 2.5 (4) We can see from Equation 2.5 (3) and Equation 2.5 (4) that a sudden media change can cause a Doppler Shift, and depending on the nature of the media change will either be positive or negative (e. g., decrease or increase in the media density). The positive or negative value for cm is analogous to an observer either moving towards or away from the sound source. The media change Doppler Shift is one of the essential elements of the Double Layer Matrix Board Device for detecting the presence of smoke particulates.

2.6 Composite Signal Since the Double Layer Matrix Board Device as in Figure 1 uses a Single Point Piezo Detector mounted just above the Double Layer Matrix Board, it receives the Ultrasound signal from each aperture across the whole area of the matrix board at different time intervals. Therefore, the composite signal received at the Single Point Piezo Detector is the algebraic sum of all the Ultrasound signals from each aperture. When a density change occurs in the media within the device such as the introduction of smoke particulates, it was observed that the frequency bandwidth ["Phase Shift" (ip)] and the amplitude ["Group Frequency Shift" (Tg)] correspondingly changed in the composite signal.

The increase in the media density from"air-only"to the"smoke/air mix"brings about an increase in the local speed of sound for an incident Ultrasound waveform. This may be a single transient single event in the case of a stable density change, or where the density varies then an undulation of"Group Frequency Shift" (rg) will predominate. This can be described thus, ) Equation 2. 6 (1) rg-=-" The second area of frequency shift is the"Phase Shift" (ip) where the individual signals from each aperture in the matrix board will be phase shifted in the algebraic sum of the composite signal arriving at the point detector. This is due to the increase in the local speed of sound in the case of an Ultrasound waveform for a media density change. It is characterized by the following, 7-p (oi) =-0 (0))/co Equation 2. (2) The"Phase Shift" (Tp) will be similarly affected as for the"Group Frequency Shift" (-cg) above, and will modulate for a changing media density. So in conclusion both the"Phase Shift" (#p) and"Group Frequency Shift" (Tt, may be characterized as relatively stable constants at a constant incident frequency and density, and can be expressed in the following Taylor series expansion, #(#)#-##p(#0)-#p(#0)[#-#0] Equation 2.6(3) We can see from the above there will be a modulation of the composite soundwave, caused by the interaction between the Group Shift (#g) and the Phase Shift (#p) frequencies, at the ultrasonic detector. In other words there will be wave interference under all density conditions. There will be a sound reinforcement (constructive) and sound attenuation (destructive) regions. Where the path difference dsin# is an integral number of whole wavelengths (X), constructive interference occurs. Where the path difference dsin# is an integral number half wavelengths (##), destructive interference occurs, i. e., dsin # = mX (m = 0, 1, 2,....) Equation 2.6 (4) dsin#=(# + m)# (m = 0, ~1, ~2,....) In terms of the amplitude the constructive and destructive conditions become, Dm =Dm0 cos# t Equarion 2. (5) Dama,, = Dmo cos (t +Q) Using the identity I + coso = 2cos2(#), the phasor of the magnitude (Dmp) is,

Equation 2.6 (6) Constructive interference occurs when, 0= 0, and Dmp = 2Dm. Destructive interference occurs when 0 rad, Dmp = 0. In other words, amplitude maximum occurs when,

Equation 2. 6 (7) 2.7 Sound Absorption The absorption of Ultrasound in Aerosols such as Smokes is said to arise from the scattering affect of the particulates in suspension, particularly when the mean particulate size is comparable wavelength (k) of the incident Ultrasound wave.

The incident Ultrasound wave used in Double Layer Matrix Board Device as in Figure 1, has a wavelength ( mean smoke particulate size, so that the attenuation of the incident Ultrasound wave by the scattering affect is not a major factor. The typical size range for most smoke particulates from a variety of fires lies somewhere between 10''and 3 microns (10-7 mm to 3 4 mu). The frequency of incident Ultrasound wave used in the apparatus is 160 kHz, and assuming the approximation for the local speed of sound (c) a sea level to be 331.4 m/sec, then the incident wavelength (x) is in the region of 2.07125mm.

Since the diameter of the apertures in the regular array of the Double Matrix Board is 1 mm , then it follows that most of the attenuation of the Ultrasound within the device will be due to the"Matrix Board Effect"rather than the"Scattering Affect"of the particulates themselves. Even allowing for normal expected Barometric and Hygroscopic changes within the detector device, the diameter of the apertures is still going to stay near equal to the half-wave ('/z2 ,) of the incident Ultrasound wave.

2.8 Acoustic/Mechanical Pumping It has long been known that gas molecules appear to take up a motion when placed in the path of a sound source. This is the phenomenon we observe when we place our hand in front of a Hi-Fi loudspeaker cabinet when playing loud music and we detect the sound pressure on our skin. When light solid particulates [such as smoke or finely divided dusts] are placed into the sound field of a gas, the particulates take up a motion depending on their inertia relative to the gas molecules.

This phenomenon is often described as"acoustic/mechanical pumping"and very small particulates tend to have a higher velocity in the gas sound field than particulates of a larger mass. Since smoke particulates are of a sufficiently small size they appear to be greatly affected by an intense sound field, and they will assimilate a motion that will be some function of wavelength of the incident Ultrasound wave. It is therefore apparent that under certain conditions the velocity of the smoke particulates entering the Double Layer Matrix Board Device is likely to increase due to this"acoustic/mechanical pumping" action. This velocity change is also a significant part of the operation of the Double Matrix Board System, and increases the sensitivity of the device when a change in the nature or the density of the media occurs.

Claims

Section 3-Claims

3.1 Fluid Flow Measurement The Matrix Board is a fluid flow measuring device used in the study, measurement, and detection of, one-phase fluid flows, two-phase fluid flows including particulates in disperse suspension within a fluid medium, and poly-phase fluid flows.

3.
2 Number of Layers The Matrix Board Fluid Flow Measuring Device may be arranged in single, double, or multi-layers.

3.3 Perturbated Flow Pattern The Matrix Board (s) facilitates a perturbated flow pattern in a transitory fluid flow at laminar flow velocities, even when the fluid system has low Reynolds Number (Re) and the apertures in one or other of the Matrix Boards have a capillary diameter

3.4 Electromagnetic Wave or Soundwave The Matrix Board Fluid Flow Measuring Device can be used with an incident time varying Electromagnetic wave or Soundwave emanating through the Matrix Board (s) to improve the detection efficiency of the device.

3.5 Electromagnetic Wave or Soundwave Transmitter and Detector Position The Electromagnetic Wave or Soundwave Transmitter and Detector may be positioned either in the upstream or downstream position of the Matrix Board (s), parallel or anti parallel to the general direction of the transitory fluid flow.

3.6 Induced Pseudo-Turbulence The Matrix Board Fluid Flow Measuring Device splits a single fluid bulk flow stream into several hundred capillary sized streamlets (induced pseudo-turbulence), and measurement is achieved by observing the speed and the nature of the reformation of the single stream after it exits the matrix board.

Section 3-Claims (cont.)

3.7 Double Layer Matrix Board System The"Double Layer Matrix Board System"is a combined fluid flow measuring device that uses both the Double Layer Matrix Board and Ultrasound for detection purposes, which measures a change in the density or nature of the fluid medium itself and a change in the local velocity, by observing the speed and the nature of the reformation of the single stream.

3.8 Tuned Response By selecting the appropriate aperture size in the"Double Layer Matrix Board System"and the frequency of the ultrasound waveform, a tuned response can be induced that facilitates increased sensitivity and selectablity for particular fluid flow types.

3.9 Acoustic Synergetic Tuned Resonance The Double Layer Matrix Board System uses"Acoustic Synergetic Tuned Resonance"to enhance its sensitivity and performance, and is a combination of the resonant frequency of the Piezoelectric Transducers [transmitter and the detector] together with the [mechanical] resonant frequency of the Double Matrix Board and the internal spatial cavity of the device itself.

3.10 Tuned Sensitivity The"tuned sensitivity"Double Layer Matrix Board System can be set to suit particular fluid densities and to suit the particular mean diameter of particulates suspended in a fluid medium.

3.11 Detection Bandwidth The Double Layer Matrix Board System can be set to a narrow selective bandwidth for a particular fluid type, or alternately set up with a wider bandwidth to include fluids from a wider range of types.

Section 3-Claims (cont.)

3.12 Media Change The Matrix Board Fluid Flow Measuring Device can detect a change in the nature of a fluid media by observing the Doppler Shift of an incident Electromagnetic Wave or Soundwave emanating through the device.

3.13 Group Frequency Shift and Phase Shift The Double Layer Matrix Board System can detect a density change in the fluid media within the device, by observing the Phase Shift [frequency bandwidth] and the Group Frequency Shift [amplitude] in the composite signal at the detector.

3. 14 Attenuation The diameter of the apertures in the regular array of the Double Layer Matrix Board System ensures that most of the attenuation of the Ultrasound within the device will be due to the"Matrix Board Effect"rather than the"Scattering Affect"of the particulates themselves.

3.15 Barometric and Hygroscopic Changes The efficiency of the Double Layer Matrix Board System is not seriously affected by everyday Barometric and Hygroscopic changes within the detector device, since the half wave (1/2 i) of the incident waveform under such conditions is still going to stay near equal to the diameter of the apertures in the matrix board.

3.16 Acoustic/Mechanical Pumping Action At high Ultrasound intensities the Double Layer Matrix Board System will induce an acoustic/mechanical pumping"action and a subsequent change in the local velocity of the fluid media.

3.17 Orientation The Matrix Board Fluid Flow Measuring Device is mounted directly in a fluid flow, and can be oriented perpendicular or at any angle between perpendicular and parallel to the direction of the fluid flow.

Section 3-Claims (cont.)
3.19 Matrix Board-Regular or Non-Regular Array The Matrix Board is constructed from a sheet or flat plate of rigid or semi-rigid material perforated with a regular or non-regular array of apertures usually with a capillary diameter, or where the apertures are at a diameter < 0.25 of the fluid flow diameter.

3.18 Number of Apertures The total number of apertures [holes] in the matrix array of the Matrix Board Fluid Flow Measuring Device can vary from application to application, but in general it operates with several hundreds or thousands of apertures, and in special circumstances the number of apertures can be less than ten.