FLUID FLOW MEASURING DEVICE, SYSTEM AND METHOD

Abstract

A sensing element is provided for use in a system for measuring fluid flow, such as, turbulent air flow. The sensing element comprises a sensor body and a first load cell arrangement connected to the sensor body. The sensor body has a three dimensional shape which is rotationally symmetric about a longitudinal axis passing through the first load cell arrangement and the sensor body. The first load cell arrangement is configured to measure the force exerted on the sensor body by fluid flow in at least an xy plane perpendicular to the longitudinal axis. A system for measuring fluid flow comprising the sensing element and a method for measuring fluid flow using the sensing element and the system are also provided.

Claims

1. A sensing element for use in a system for measuring fluid flow, the sensing element comprising a sensor body and a first load cell arrangement connected to the sensor body, wherein the sensor body has a three dimensional shape which is rotationally symmetric about a longitudinal axis passing through the first load cell arrangement and the sensor body and wherein the first load cell arrangement is configured to measure the force exerted on the sensor body by fluid flow in at least an xy plane perpendicular to the longitudinal axis.

2. A sensing element according to claim 1, wherein sensor body has n-order rotational symmetry about the longitudinal axis, where n>2.

3. A sensing element according to claim 1, wherein the shape of the sensor body is selected from a sphere, an ellipsoid, and a cylinder.

4. A sensing element according to claim 1 wherein the shape of the sensor body is selected from a polyhedron, a regular polyhedron and a regular prism.

5. A sensing element according to claim 1, wherein the sensor body comprises an outer surface and wherein the outer surface comprises a texture which is selected to control the coefficient of drag of the sensor body.

6. A sensing element according to claim 5, wherein the texture comprises a plurality of depressions.

7. A sensing element according to claim 1, wherein the sensor body comprises a polymeric material.

8. A sensing element according to claim 1, wherein the mass of the sensor body is selected to control the inertial response of the sensor body when subjected to fluid flow.

9. A sensing element according to claim 1, wherein the sensor body is hollow.

10. A sensing element according to claim 1, wherein the sensing element comprises a second load cell arrangement, and wherein the first load cell arrangement and the second load cell arrangement are arranged at opposing sides of the sensor body.

11. A sensing element according to claim 1, wherein at least one of the first load cell arrangement and the second load cell arrangement is further configured to measure the force exerted on the sensor by fluid flow along the longitudinal axis.

12. A sensing element according to claim 1, wherein the sensing element comprises one or more shrouds, and wherein said shrouds are arranged to enclose or partly enclose one or both or the first load cell arrangement and the second load cell arrangement.

13. A sensing element according to claim 1, wherein one or both of the first load cell arrangement and the second load cell arrangement comprises one or more strain gauges.

14. A system for measuring fluid flow comprising the sensing element of claim 1 and a support structure, wherein the sensing element is connected to the support structure.

15. A system according to claim 14, wherein the sensing element is connected to the support structure by means of one or more damping members,

16. A method for measuring the flow of a fluid, the method comprising: providing a sensing element according to claim 1; and measuring the response of the sensor body using the load cell arrangement.

17. The method of measuring fluid flow according to claim 16, comprising the step of deriving one or more of the speed, direction, velocity, static pressure or dynamic pressure of the fluid flow from the measured response.

18. The use of the sensing element according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The invention will now be described, purely by way of example, with reference to the accompanying drawings, in which;

[0068] FIG. 1 shows a side elevation illustration of a sensing element according to a first aspect the invention;

[0069] FIG. 2 shows a side elevation cross sectional illustration of a sensing element according to a first aspect of the invention;

[0070] FIG. 3 shows a top-down cross-sectional illustration of the interior of a sensor body of a sensing element according to a first aspect of the invention;

[0071] FIG. 4 shows a side elevation illustration of a system for measuring fluid flow according to the second aspect of the invention;

[0072] FIG. 5 shows a top-down illustration of a system for measuring fluid flow according to the second aspect of the invention when in use;

[0073] FIG. 6 shows a side elevation illustration of a system for measuring fluid flow according to the second aspect of the invention when in use; and

[0074] FIGS. 7a and 7b show a flow diagram illustrating a method according to a third aspect of the invention.

[0075] The drawings are for illustrative purposes only and are not to scale.

DETAILED DESCRIPTION

[0076] FIG. 1 shows a side elevation illustration of a sensing element 1 according to a first aspect the invention. FIG. 2 shows a side elevation cross sectional illustration of a sensing element 1 according to a first aspect of the invention. FIG. 3 shows a top-down cross-sectional illustration of the interior of a sensor body 2 of a sensing element 1 according to a first aspect of the invention. The sensing element 1 comprises a spherical sensor body 2 which is attached to both a first load cell arrangement 3 and a second load cell arrangement 4. The first load cell arrangement 3 and the second load cell arrangement 4 are positioned opposite one another at either side of the sensor body 2. The longitudinal axis, indicated by dashed line Z, passes through the first load cell arrangement 3, the second load cell arrangement 4 and the sensor body 2.

[0077] The load cell arrangements 3, 4 are attached to the sensor body 2 by means of protrusions 5, 6 which extend from the respective first and second load cell arrangements 3, 4 into openings 7, 8 within the sensor body 2. The protrusions 5, 6 are secured in place within the sensor body 2 using adhesive but other suitable fastening means may be used. The protrusions 5, 6 as shown are formed as an integral part of the load cell arrangements 3, 4 but could equally be arranged as an additional element attached to the load cell arrangements 3, 4.

[0078] The sensor body 2 is formed from a nylon polymer and is substantially spherical having an outer diameter of 50 mm. The sensor body 2 is substantially hollow and comprises a number of interior support members 9, 10, 11 which bisect the interior of the sensor body 2, thereby partitioning the interior into a plurality of hollow wedge-shaped segments 12, 13. The interior supports 9, 10, 11 are formed from the same nylon material as the sensor body 2 but could equally be formed from any other suitably rigid material.

[0079] The whole of the outer surface 14 of sensing element 2 comprises a textured region 15 formed from a plurality of concave depressions 36. The concave depressions 36 have a have a hemispherical profile with a diameter of approximately 10 mm and a maximum depth of approximately 0.5 mm.

[0080] Each of the first and second load cell arrangements 3, 4 comprises a first load cell 16, 17 for detecting load in the xy plane and a second load cell 18, 19 for detecting load along the longitudinal axis. The first load cells 16, 17 and second load cells 18, 19 are attached to an isolating member 20, 21. The isolating members 20, 21 are formed from plastic. The load cells 16, 17, 18, 19 are strain gauge load cells which comprise a wheatstone bridge configuration to convert mechanical energy into an electrical signal.

[0081] The device 1 further comprises shrouds 22, 23 which wholly enclose the first and second load cell arrangements 3, 4. The shrouds 12, 23 are substantially cylindrical in shape and reduce in cross sectional area at the end arranged closest to the sensor body 2.

[0082] FIG. 4 shows a side elevation illustration of a system for measuring fluid flow 24 according to second aspect of the invention. The system 24 comprises a support structure 25 arranged as a rectangular frame formed from support members 26, 27, 28, 29, 30. The support structure 25 comprises fixing means 32, 33 by which the support structure 25 is fixed onto surface 31. The fixing means 32, 33 are each formed from a supporting bracket and a bolt. The distance between the sensing element 1 and the surface 31 is 400 mm.

[0083] The system 24 further comprises a sensing element 1 which is mounted within the support structure 25. The sensing element 1 is connected to the support structure 35 by means of damping members 34, 35.

[0084] FIG. 5 shows a top-down illustration of a system for measuring fluid flow 24 according to the second aspect of the invention when in use. FIG. 6 shows a side elevation illustration of a system for measuring fluid flow 24 according to the second aspect of the invention when in use. Sensing element 1 is attached to surface 31 by means of support structure 25 which comprises fixing means 32.

[0085] In use, force is exerted upon the sensing body 2, of sensing element 1, by fluid flow contacting the surface of the sensing body 2. Fluid flow may strike the sensing body from any direction. As illustrated in FIG. 6, fluid flow may strike the sensor body from any direction in the xy plane, for example, between the angle indicated by the arc A-H. Fluid flow in the direction of arrow B causes the sensing body 2 to move relative to the first and second load cell arrangements 22, 23 which are held in position by the support structure 25. The response of the sensing body 2 to fluid flow in the direction of arrow B is measured, as a force, by the load cells within the first and second load cell arrangements 22, 23. A change in fluid flow from the direction indicated by arrow B to the direction indicated by arrow C causes a change in the direction of the relative motion between the sensing body 2 an the load cell arrangements 22, 23. The force exerted upon the sensor body 2 by fluid flow in the direction of arrow C is measured by the load cells within the load cell arrangements 22, 23.

[0086] In this example, as the direction of fluid flow changes from that indicated by arrow B to that indicated by arrow C the magnitude of the fluid flow remains constant. The sensor body 2, having circular rotational symmetry, therefore exhibits a substantially similar response to the fluid flow indicated by both arrows B and C. In particular, the sensor body 2 is deflected relative to the load cell arrangements 23 by the same amount, as a result of the constant magnitude of fluid flow, but in a direction corresponding to the direction of arrows B and C respectively.

[0087] As illustrated in FIG. 6, fluid flow may also strike the sensor body from any direction other than the xy plane, for example, in any direction between the angle indicated by the arc D-J. Fluid flow in the direction of arrow E causes the sensing body 2 to move relative to the first and second load cell arrangements 22, 23 which are held in position by the support structure 25. The force exerted on the sensing body 2 by the fluid flow in the direction of arrow E is measured by the load cells within the first and second load cell arrangements 22, 23. A change in fluid flow from the direction indicated by arrow E to the direction indicated by arrow F causes a change in the direction of the relative motion between the sensing body 2 an the load cell arrangements 22, 23. The force exerted upon the sensor body 2 by fluid flow in the direction of arrow F is measured by the load cells within the load cell arrangements 22, 23.

[0088] In this example, as the direction of fluid flow changes from that indicated by arrow E to that indicated by arrow F the magnitude of the fluid flow remains constant, said magnitude being equal in value to the fluid flow indicated by arrows B and C of FIG. 6. The sensor body 2, having circular rotational symmetry, therefore exhibits a substantially similar response to the fluid flow indicated by arrows B, C, E and F. In particular, the sensor body 2 is deflected relative to the load cell arrangements 23 by the same amount, as a result of the constant magnitude of fluid flow, but in a direction corresponding to the direction of arrows B, C, E and F respectively.

[0089] FIGS. 7a and 7b show a flow diagram illustrating a method according to a third aspect of the invention. A sensing element or system is provided 60 within a fluid flow environment of interest. The response of the sensing element to forces exerted by fluid flow are measured 61 by the load cell(s) within the load cell arrangement(s). Parameters including the speed, direction, velocity, static pressure and dynamic pressure of the fluid flow are then derived 62 from the measured response.