Abstract:
A high survivability fluid flow sensor includes a sensor housing defining an interior space. A sensor probe has a first end disposed within the interior space. The sensor probe also includes a second end opposite the first end outside the interior space. At least one load cell is disposed within the interior space and is operatively engaged with the first end of the sensor probe. The load cell is configured to detect loading on the sensor probe as a result of fluid flow impinging on the sensor probe adjacent to the second end. The sensor is operable to capture fluid flow data history through an over pressure event via the sensor probe, which exerts pressure upon the piezoelectric load cell(s), thereby enabling analysis of the wave fluid dynamics.

Description:
STATEMENT OF GOVERNMENT INTEREST 
       [0001]    The sensor disclosed herein was in part made with U.S. government support under contracts HDTRA1-08-P-0027 and HDTRA2-10-C-0001 awarded by the Defense Threat Reduction Agency (DTRA). The U.S. government has certain rights in the invention. 
     
    
     FIELD 
       [0002]    A sensor is provided that is operable to measure and record fluid, including but not limited to gas, flow direction and velocity resulting from an over-pressure event, including but not limited to a detonation. In particular, a fluid flow sensor is provided which is operable to capture fluid flow data history through an over-pressure event. 
       BACKGROUND 
       [0003]    In some circumstances it is desired to capture flow direction and velocity data in the hostile flow field produced from the dynamic pressure within the rapid expansion of gas products. Such an environment is commonly produced by explosive detonations. The environment experienced during a detonation inside of a multi-room structure comprises not only the shock and blast loading characterized by a very rapid release of energy, but also the fragmentation from the bomb casing material and the associated fragmentation of the internal structure and its associated contents. As the expanding gas flow moves from regions of confined high pressures to lower pressures, an energy wavefront from the detonation, as well as physical debris in the flow field, makes it difficult to use traditional “clean flow” instrumentation, such as hot-wire anemometry, pitot-tube or other conventional flow measurement methods. Thus, there has been a need to provide a sensor capable of operating in the hostile environment of detonation events. 
         [0004]    The flow conditions inherent during an internal structure weapon detonation event are far from ideal for existing sensor technologies. The rapid expansion of gas products cause high velocity gas movement within the multi-room structure that is driven by the high-to-low pressure mechanism referred to as dynamic pressure. As the event unfolds, the detonation shock wavefront propagates through the structure in the form of a high temperature gas flow carrying the remnants of the explosive case, debris within the structure, and test specific artifacts (desks, chairs, containers, shelves, etc.) at high speeds. Testing has demonstrated that this flow field is far from clean and contains massive amounts of high temperature gas/particulates and debris. Further, the hostile environment destroys sensors and produces zero visibility. It is in this extreme condition that existing traditional sensors experience shortcomings. 
         [0005]    Dynamic pressure sensors currently in use at DTRA test facilities typically use Wheatstone bridge type circuitry to measure pressure conditions using pitot-static probes such as the DTRA XCW-8WN-200 probe. This type of sensor measures along a streamline and produces unidirectional dynamic pressure for subsonic single-phase flow conditions. The nature of the sensing ports makes it susceptible to contamination from particulate matter and physical damage from debris impact. To provide any level of directionality to this type of measurement system requires many such probes to be oriented in the flow with a substantial investment in calibration of the probes. Multi-hole pressure probes can provide up to a 70° receptivity flow angle, but require 5-7 pressure transducers to achieve that cone of flow directionality. They too suffer from the contamination and debris issues mentioned for the current pitot-static tube systems, and have the requirement for dry and non-reactive gases. 
         [0006]    Another suite of existing sensor technologies that initially appears attractive but suffer from the hostile environment and the zero visibility are those that use laser array attenuation, particle image velocimetry or other visible tracking techniques. In addition to the technical difficulties in deploying systems of this type, cost considerations necessarily preclude these solutions from being cost-effective approaches. 
         [0007]    Measuring wind speeds through the use of piezoelectric load sensors has been accomplished in the past. For example, U.S. Pat. No. 4,615,214, issued Oct. 7, 1986, entitled, Piezoelectric Wind Sensor, provides an array of piezoelectric sensors mounted around the circumference of a vertical shaft, as disclosed in FIGS. 1 and 2 of the patent. The shaft is forced against the sensors by the wind, and by observing the direction of greatest force magnitude, the direction of the wind can be determined. The speed of the wind is also determined through the force readings by inserting the largest force reading into a look up table that is calibrated to read velocity. 
         [0008]    However, many piezoelectric crystals are needed to realize a velocity vector in the &#39;214 design, and the piezoelectric components are exposed to the elements, which make its use in detonation environments problematic. 
         [0009]    In U.S. Pat. No. 4,366,718, issued Jan. 4, 1983, entitled “Bi Directional Flow Transducer”, fluid flows through a restriction core mounted in the center of cylindrical packaging. Flow impacts the restriction core and causes it to slide along the centerline of the outer casing in the direction of fluid flow. The flow restricting core deflects relative to the spring constant of the two movement restricting springs mounted on either side of it. The restriction core is attached to a probe that deflects axially along with the core. A linear differential voltage transducer (LVDT) senses the probe&#39;s deflection and produces an electrical profiling of the spring&#39;s contraction. However, LVDTs are too large to use in sensors used to measure 2D flow fields, as desired herein. In fact, two units would be needed, and the size of the casing would be directly proportional to how accurate the LVDTs were. 
         [0010]    In U.S. Pat. No. 4,332,157, issued Jun. 1, 1982, entitled “Pyroelectric Anemometer Concept”, two pyroelectric sensors sandwich a heating element. In no wind conditions, the heating element affects both sensors the same, and each are a fluctuating median temperature. In windy conditions, the upstream sensor is cooled, while downstream sensor is heated due to the wind forcing more convective heat transfer from the heating element to the downstream sensor than in the no wind condition. This type of design is not applicable in sensing detonation events, as heating is not an optimal means by which to gather data on explosive wind events due to their quick duration and the necessity of equilibrium. Differential temperatures between the sensors would still exist no matter how hot the explosive event, but with extremely high wind temperatures, the ability to measure differential temperatures diminishes and would be costly. Further, this type of sensor has no ability to resolve direction. 
         [0011]    U.S. Pat. No. 4,905,513, issued Mar. 6, 1990, entitled “Wind Speed Measuring Device”, the temperature difference between the heated coil and the casing of the sensor is measured with the difference being the change in temperature due to the wind. This differential temperature is processed to compute wind speed, while wind direction is realized by processing the signals of each wire around the periphery of the cylinder and computing the direction of the largest gradient. With such a design, extreme wind conditions could have adverse effect on small wires, and certain processing must be dedicated to accounting for changes in ambient temperature. Accordingly, fatigue and embrittlement may cause inaccurate readings over time. 
         [0012]    In U.S. Pat. No. 3,408,855, issued on Nov. 5, 1968, entitled “Apparatus for determining detonation velocity of explosives”, a sensor is provided wherein the pressure of a detonation event collapses the conductive outer shell over a length of resistive coiled wires. The change in resistance of the wires is used to mathematically derive the velocity of air hitting the sensor. This sensor, however, is solely based on pressure, and the effect of temperature on the resistivity of wire is not accounted for. Further, the outer casing permanently collapses upon each detonation, and is therefore not reusable. 
         [0013]    A current commercial one dimensional air blast sensor being used to measure detonations is the LC33 Canadian piezoelectric instrument (DTIC ADA302543), which is a pencil model which has a sensitive element consisting of a short cylinder of lead zirconate titanate with a sensitivity of 120 pc/psi. Testing of this sensor has shown it to be problematic, possibly due to stressing in sensitive elements. It displayed unsatisfactory performance in detonation tests conducted under the Monograph Air Blast Instrumentation (MABS) project. 
         [0014]    The MQ10 British piezoelectric instrument, illustrated in  FIG. 1 , is another commercially available sensor. It is comprised of a quartz crystal with a hatched-shaped streamline baffle and sensitivity of 100 pc/psi from 1 to 70 psi. The MQ10 gage is ranged from 1 to 300 psi. It usually mounted in a concrete block, flush with ground surface. 
         [0015]    Although this gage gave the nearest approximation to true pressure-time variations in blast wave of all gage types deployed in the Monograph Air Blast Instrumentation (MABS) project, this device was not designed for multiaxial applications, and post processing is thus necessary to derive wind velocity. 
         [0016]    The commercially available KKQ American piezoelectric instrument, illustrated in  FIG. 2 , uses piezo-electric elements to measure dynamic pressures by observing the difference in stagnation and side on pressures. This gage showed promising results in the Monograph Air Blast Instrumentation (MABS) tests, and was the only gage presented that had the ability to directly determine wind speed. However, it does not resolve direction, and is in effect a piezo-electric, pitot-static probe. 
         [0017]    Other such devices have been patented with similar characteristics as those above. In the case of sensing wind speed from a detonation event, it would be impractical to use small wires for durability reasons unless properly shielded. The extremely brief test durations would limit the possibility of thermodynamic equilibrium occurring between resistive wires and the gas flow, therefore thermodynamic metal expansion is inapplicable. 
         [0018]    A probe based sensor system that has the fidelity to measure gas flow velocity and direction yet survive the hostile environment of a detonation event would be desirable. 
       SUMMARY 
       [0019]    A high survivability fluid flow sensor is described that is operable to measure and record fluid flow direction and velocity resulting from an over-pressure event. The over-pressure event can be produced by, but is not limited to, a detonation (i.e. explosion) or other events associated with a very rapid release of energy. The fluid flow sensor is particularly suited for use with flows of gas resulting from the over-pressure event. But the fluid flow sensor can be used with any fluids. 
         [0020]    In one embodiment, a dynamic pressure induced fluid flow sensor is provided that includes a sensor housing defining an interior space, and a sensor cap disposed on the sensor housing and closing the interior space, the sensor cap having a probe port formed therein. A sensor probe has a first end mounted to the sensor housing and is disposed within the interior space. The sensor probe also includes a second end opposite the first end and extending away from the sensor cap outside the interior space where it is exposed to the fluid flow environment. The sensor probe extends through the probe port in the sensor cap. At least one load cell is disposed within the interior space and is operatively engaged with the first end of the sensor probe. The load cell is configured to detect loading on the sensor probe as a result of fluid flow impinging on the exposed portion of the sensor probe adjacent to the second end. 
         [0021]    In another embodiment, a one-dimensional (1D) high survivability fluid flow sensor is provided having a somewhat similar construction. However, the 1D sensor constrains the fluid flow measurement along only one axis, and can contain as few as one load cell, and two load transfer blocks. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  illustrates a known prior art pressure transducer. 
           [0023]      FIG. 2  illustrates a known prior art piezoelectric pressure sensor. 
           [0024]      FIG. 3  is an exploded perspective view of a two-dimensional fluid flow sensor described herein, also referred to as a compact cartridge gage (“CCG”). 
           [0025]      FIG. 4  is a perspective view of the sensor housing element of the two-dimensional fluid flow sensor shown in  FIG. 3 . 
           [0026]      FIG. 5  is an exploded perspective view of another embodiment of a two-dimensional fluid flow sensor described herein. 
           [0027]      FIG. 6  is an exploded perspective view of still another embodiment of a two-dimensional fluid flow sensor described herein, also referred to as a symmetric cartridge gage (“SCG”). 
           [0028]      FIG. 6A  is a cross-sectional view of the sensor shown in  FIG. 6  in an assembled state. 
           [0029]      FIG. 7  is a partial perspective cross sectional view of the one-dimensional sensor described herein. The fluid flow direction is indicated by the arrows. 
           [0030]      FIG. 8  is an exploded perspective view of the one-dimensional sensor of  FIG. 7 . 
           [0031]      FIG. 9  is an exploded perspective view of another embodiment of a one-dimensional sensor. 
       
    
    
     DETAILED DESCRIPTION 
       [0032]      FIG. 3  illustrates a two-dimensional fluid flow sensor  10  that is operable to measure and record fluid flow direction and velocity resulting from an over-pressure event such as a detonation. Hereinafter, the fluid that is measured and recorded will be described as being gas, and the flow sensors described herein will be described as being gas flow sensors. However, it is to be realized that the sensor could be used to measure and record other fluids. 
         [0033]    The gas flow sensor  10 , which can also be referred to as a CCG, is generally comprised of a sensor probe  12  which rests in a sensor housing  14 , four piezoelectric load cells  16 , four load transfer blocks  18  which act to place the load cells  16  in communication with the sensor housing  14 , and a sensor cap  20  which protects the interior space  21  of the sensor housing  14  from debris. 
         [0034]    As shown in  FIG. 3 , in one embodiment, the outer surface of the sensor probe  12  adjacent to a first end  22  thereof is machined to have at least four flat surfaces  24 , thereby providing flat surfaces for interaction with the load cells  16 . The flat surfaces  24  are in contact, for example direct contact, with the load cells  16 . Cutting the flat surfaces as close as possible to parallel and perpendicular allows for a proper load transmission to the load cells  16  and gives the best performance. The sensor probe  12  can be formed of a high strength metallic compound, such as tungsten carbide, thus enabling it to withstand high pressure detonations and providing it with high survivability characteristics. Unlike previous designs, this new design allows the sensor probe  12  to be relatively short in length while still providing sufficient sensitivity. 
         [0035]    In one embodiment, a high-tolerance hole (not illustrated) is machined into the bottom of the sensor probe  12  adjacent to the first end  22  thereof to accept a boss  26  on the sensor housing  14  (see  FIG. 4 ). The boss  26  interface will support the probe  12  equally in all flow directions, preventing deflection that could cause improper loading of the load cells  16 . In the illustrated embodiment, the boss  26  is disposed on or adjacent to the vertical axis of the sensor housing  14 , for example by being machined into the center of the sensor housing  14 . 
         [0036]    The load cells  16  can be any piezoelectric type load cells. For example, Applicant has found that suitable load cells  16  can include, but are not limited to, Kistler 9132B load cells available from Kistler Group of Winterthur, Switzerland. The load cells  16  are disposed with the load blocks  18  within the interior space  21  of the housing  14 . The load cells  16  include cabling  23  that is routed through openings  25  formed at the base of the housing  14  (see  FIG. 4 ). 
         [0037]    With reference to  FIG. 3 , the sensor load blocks  18  are designed to both orient and preload the piezoelectric load cells  16 . A boss  28  is located on each of the sensor load blocks  18  that aligns with a hole  30  in the respective load cell  16 . The boss  28  prevents lateral movement of the load cells  16  during installation. The sensor load blocks  18  and the load cells  16  are preloaded using off-the-shelf flat end set screws  32  that are threaded into threaded openings  34  formed in the sensor housing  14 . The openings  34  are formed on flat surfaces  36  formed on an outer perimeter, illustrated as being generally circular, of the sensor housing  14 . Similar flat surfaces  37  are formed opposite the flat surface  36  on an inner perimeter, illustrated as being generally circular, of the sensor housing  14 . The ends of the set screws  32  engage with the sides of the load blocks  18  opposite the bosses  28  to apply a force to the load blocks, which in turn allows application of a preload to the load cells  16 . Optionally, the load blocks  18  can include recesses  31  for receiving ends of the set-screws  32 . 
         [0038]    The sensor housing  14  is the element of the CCG with the highest complexity. The housing  14  houses the sensor probe  12 , the load cells  16  and the sensor load blocks  18 , as well as providing support for the sensor probe. The housing  14  can be sized to fit inside a DTRA small gage port  38  in a low profile type installation to be flush with a test facility wall. As shown in  FIG. 3 , the sensor cap  20  is mounted to the sensor housing  14 , adjacent to the top surface thereof, using fasteners  40  such as screws that extend through openings formed through the housing  14  and thread into openings formed in a ledge (a similar ledge  124  is visible in  FIG. 5 ) within the gage port  38 . The sensor cap  20  also includes a probe port  42  formed therein through which a second end  44  of the sensor probe  12  extends to perform its sensing function in a manner similar to that discussed below for  FIGS. 7 and 8 . The sensor cap  20  also helps to protect the load cells  16  from debris. 
         [0039]    In use of the sensor  10 , a high pressure fluid is generated from a detonation or other over-pressure creating event that impacts the probe  12  and deflects the second end  44 . The probe  12 , by virtue of the high stiffness of its formed material, transfers the deflection to the force sensors  16 . As the fluid flows around the exposed end of the probe  12 , the force sensors  16  react the deflection through the sensor load blocks  18  into the housing  14 , resolving the direction and velocity of the fluid flow into two dimensions. Opposing force sensors  16  at the first end  24  of the probe  12  work in a near equal and opposite manner and are superimposed electrically to provide force data on each of two dimensions, or flow axes. The force data from opposing force sensors  16  constitute the data that can be added vectorally to produce a final flow vector, or in other words the fluid flow direction and velocity. 
         [0040]      FIG. 5  illustrates another embodiment of a fluid flow sensor  100  that is generally similar to the sensor  10  including a sensor probe  102 , a sensor housing  104 , four piezoelectric load cells  108 , four load transfer blocks  106 , and a sensor cap  110  which protects the interior space  112  of the sensor housing  104  from debris. The load transfer blocks  106  and the load cells  108  are preloaded using set screws  114  that are threaded into threaded openings formed in the sensor housing  104 . The housing  104  can be sized to fit inside a DTRA small gage port  118  in a low profile type installation to be flush with a test facility wall. The sensor cap  110  is mounted to the sensor housing  104 , adjacent to the top surface thereof, using fasteners  120  such as screws that extend through openings formed through the housing  104  and thread into openings  122  formed in a ledge  124  within the gage port  118 . 
         [0041]    One way in that the sensor  100  differs from the sensor  10  is that each of the load blocks  106  includes a boss  126  that fits within an opening  128  formed in the respective load cell  108 . The bosses  126  prevent lateral movement of the load cells  108  relative to the load transfer blocks  106 . 
         [0042]      FIG. 6  illustrates another embodiment of a fluid flow sensor  150 , also referred to as a SCG. In this embodiment, the sensor  150  includes a sensor probe  152 , a sensor housing  154 , four piezoelectric load cells  156 , four load transfer support blocks  158  which support the load cells  156  and help to place the load cells  156  in communication with the sensor housing  154 , and a sensor cap  160  which protects the interior space  162  of the sensor housing  154  that contains the load cells  156  and the like from debris. 
         [0043]    In this embodiment, the sensor  150  also includes a deflection ramp  164  that is secured to the top of the housing  154  by the cap  160  and the fasteners  166 . The deflection ramp  164  is configured to shield the interior space  162  and deflect debris during an over pressure event. In the illustrated example, the deflection ramp  164  has a frustoconical shape. However, the ramp  164  can have any shape that achieves the shielding and deflection functions. 
         [0044]    The sensor  150  also includes a collet sleeve  168  that in use is disposed within the housing  154 . When assembled, the collet sleeve  168  surrounds the sensor probe,  152 , the load cells  156 , and the support blocks  158  for applying a pre-load to the support blocks  158 . The pre-load is changed by increasing or decreasing the diameter of the collet. 
         [0045]    As shown in  FIGS. 6 and 6A , the collet sleeve  168  has an exterior tapered ramp surface  180  that is engageable with a tapered ramp surface  182  formed inside the housing  154 . By forcing the collet sleeve  168  in a longitudinal direction (i.e. axially) within the housing  154 , the ramp surface  180  engages with the ramp surface  182 . As the collet sleeve  168  is forced axially downward, the engagement between the ramp surfaces  180 ,  182  reduces the diameter of the collet sleeve thereby increasing the pre-load force. As the collet sleeve  168  is forced axially upward, the engagement between the ramp surfaces  180 ,  182  is reduced, allowing the diameter of the collet sleeve to increase thereby decreasing the pre-load force. 
         [0046]    The collet sleeve is forced to move axially within the housing  154  via a threaded pre-load nut  170  that is threaded onto the base of the collet sleeve  168 . Rotation of the pre-load nut  170  in one direction pulls the collet sleeve  168  down into the housing  154 , forcing the ramp surfaces  180 ,  182  into engagement and causing the collet to tighten uniformly on the four load transfer support blocks  158 , and subsequently tightening onto the probe  152  through the load cells  156 . Rotation of the pre-load nut  170  in the opposite direction, forces the collet sleeve  168  upward into the housing  154 , reducing the pinching force caused by the ramp surfaces and allowing the diameter of the collet sleeve to increase to reduce the clamping force on the load transfer support blocks  158 . 
         [0047]    The base end of the sensor probe  152  is supported in a probe support sleeve  172  which is retained by a lock nut  174 , providing a vertical support during assembly and a pivot point for the probe. The probe support sleeve  172  is notched to allow for routing of the load cell  156  cabling. 
         [0048]    With reference to  FIGS. 7 and 8 , an exemplary embodiment of a one-dimensional (1D) sensor  50  is illustrated. In the sensor  50 , the sensor probe is designed to only allow one axis of motion. In this embodiment, this was accomplished by a set of load transfer blocks that precluded the probe from moving laterally relative to the load sensor. However, this is inadequate for the sensor  10  because the sensor probe  12  needs to communicate a full 360 degrees of motion onto at least two (or perhaps more) load cells  16  which are required to resolve the wind velocity vector. 
         [0049]    In particular, this embodiment of the sensor  50  is illustrated as including a sensor housing  52  having an interior space  54 . The sensor housing  52  is generally rectangular with a rectangular outer perimeter and an inner perimeter defining the interior space. A sensor cap  56  is fixed to the top of the housing  52  by fasteners  58  such as screws to close the top of the housing. 
         [0050]    A sensor probe  60  extends through a probe port  62  formed in the sensor cap  56  and into the interior space  54 . The lower end of the probe  60  is pivotally secured within the interior space by a pin  64  extending through an opening at the base of the sensor probe  60 . The upper end of the probe  60  extends away from the housing  52  where it can be exposed to moving air  63  as shown in  FIG. 7 . 
         [0051]    In addition, disposed perpendicular to the axis of the pin  64  is a load transfer block  66  that is engaged with what can be termed as a pre-load side of the probe  60  to apply a pre-load force to the probe  60 . A set-screw  68  or other pre-load mechanism is used to force the block  66  into engagement with the probe  60  to permit application of the pre-load. The end of the load transfer block  66  engaged with the probe  60  is provided with a concavity  70  which permits better engagement between the block  66  and the probe  60  surface. 
         [0052]    Another load transfer block  72  is disposed opposite the load transfer block  66 . The block  72  is engaged with what can be termed as the sensor or reaction side of the probe  60 . Like the block  66 , the block  72  is provided with a concavity  74  which permits better engagement between the block  72  and the probe  60 . A force sensor  76  is disposed between the block  72  and a wall of the housing  52  to detect force caused by deflections of the end of the probe  60  that extends upwardly from the housing  52 . An example of a suitable sensor  76  is a Kistler 9101A sensor available from Kistler Group of Winterthur, Switzerland. A suitable mechanism  78 , for example a shoulder bolt, extends through the wall of housing  52 , through a hole  80  in the sensor  76 , an into engagement with the block  72 . The mechanism  78  keeps the block  72 , the sensor  76  and the wall of the housing  52  engaged with one another for accurate pressure readings. 
         [0053]    In operation of the sensor  50 , a high pressure fluid  63  that is generated from a detonation or other over-pressure creating event impacts the probe  60  and deflects the probe. The probe  60 , by virtue of the high stiffness of its formed material, transfers the deflection to the force sensor  76 . 
         [0054]      FIG. 9  illustrates another embodiment of a one-dimensional (1D) sensor  200  that is configured and operates generally similar to the sensor  50 , but includes a pair of load cells. The sensor  200  includes a sensor housing  202  having an interior space  204 . The sensor housing  202  is generally rectangular with a rectangular outer perimeter and an inner perimeter defining the interior space. A sensor cap  206  is fixed to the top of the housing  202  by fasteners such as screws to close the top of the housing. The housing  202  can be fixed to a mount  207  via the fasteners extending through the cap  206  and the housing  202  and into suitable apertures in the mount  207 . 
         [0055]    A sensor probe  208  extends through a probe port  210  formed in the sensor cap  206  and into the interior space  204 . The lower end of the probe  208  is pivotally secured within the interior space by one or more conically tipped pins  212  that seat in recesses  214  at the base of the sensor probe  208 . The lower end of the probe  208  is secured from lateral motion by opposing set screws  216  The upper end of the probe  208  extends away from the housing  202  where it can be exposed to moving air  218  as shown in  FIG. 9 . 
         [0056]    In addition, disposed perpendicular to the axis of the pivot axis is a load transfer block  220  that is engaged with the side of the probe  208  to apply a pre-load force to the probe  208 . A pre-load mechanism  222 , for example a set screw, having a centering boss  224  is used to force the block  220  into engagement with the probe  208  to permit application of the pre-load. The end of the load transfer block  220  engaged with the probe  208  is provided with a flat surface  226  that engages one of the flat surfaces  228  (similar to the flat surfaces  24 ) on the probe  208 . A force sensor  230  is disposed between the block  220  and pre-load mechanism  222  and the wall of the housing  202  to detect force caused by deflections of the end of the probe  208  that extends upwardly from the housing. 
         [0057]    Another load transfer block  232  is disposed opposite the load transfer block  220 . The block  232  is engaged with the opposite side of the probe  208 . Like the block  220 , the block  232  is provided with a flat surface  234  that engages with the opposite flat surface  228 . A second force sensor  236  is disposed between the block  232  and a wall of the housing  202  to detect force caused by deflections of the end of the probe  208  that extends upwardly from the housing. An example of a suitable sensor  230 ,  236  is a Kistler 9101A sensor available from Kistler Group of Winterthur, Switzerland. A suitable mechanism  238 , for example a shoulder bolt, extends through the wall of housing  202 , through a hole  240  in the sensor  236 , an into engagement with the block  232 . The mechanism  238  keeps the block  232 , the sensor  236  and the wall of the housing  202  engaged with one another for accurate pressure readings. 
         [0058]    In this embodiment, a high pressure fluid  218  is generated from a detonation or other over-pressure creating event that impacts the probe  208  and deflects the flat surface  228 . The probe  208 , by virtue of the high stiffness of its formed material, transfers the deflection to the force sensors  230 ,  236 . As the fluid flows around the probe  208 , the force sensors  230 ,  236  react the deflection through the sensor load blocks  220 ,  232  into the housing  202 , measuring the direction and velocity of the fluid flow in one dimension. The opposing force sensors  230 ,  236  on the probe  208  work in a near equal and opposite manner and are superimposed electrically to provide force data in one dimension, or flow axis. The force data from the opposing force sensors  230 ,  236  constitute the data that can be added mathematically to produce the fluid flow direction and velocity. 
         [0059]    Although specific embodiments have been disclosed herein, those having ordinary skill in the art will understand that changes can be made to the specific disclosed embodiments without departing from the spirit and scope of the invention. Thus, the scope of the invention is not to be restricted to the specific disclosed embodiments. Furthermore, it is intended that the appended claims cover any and all such applications, modifications, and embodiments within the scope of the disclosure.