GB2117517A - Flowmeters - Google Patents

Abstract

A fast response flowmeter for high speed transient flow measurement in water has a threaded body (13) in a threaded hole (11) in a cylinder (10) confining the flow. The body carries a blade (14) extending into the flow and disposed so that a face of the blade is presented to the flow. The blade carries a strain gauge (16) and flow is measured in terms of strain. An apparatus for calibrating the flowmeter is also described. <IMAGE>

Description

SPECIFICATION Flowmeters This invention relates to flowmeters and is concerned with the problem of providing a fast response flowmeterforthe measurement of a high speed transient flow in a fluid such as may occur by the detonation of an explosive. In the context of the present invention a typical high speed transient flow is one lasting for five milli-seconds at a velocity of fifty metres per second. Such transients can arise during experiments relating to the containment of nuclear structures.

The flowmeter according to the present invention comprises a means holding a nominally rigid mem berprojecting into the flow from a mounting, said member being provided with at least one strain gauge so that flow can be measured as strain in the member.

Preferably the nominally rigid member is a blade projecting into the duct so as to present the face of the blade against the flow with the strain gauge mounted on a face of the blade.

The invention will now be described further with reference to the accompanying drawings in which: Figure lisa longitudinal section through a cylinder equipped with a flowmeter according to the invention; Figure 2 is a view in the direction of the arrow II of Figure 1; and Figure 3 is a diagrammatic longitudinal section of a calibration apparatus for the flowmeter of Figure 1.

Figure 1 shows a cylinder 10 past which water flows which can be subject to high speed transients.

The cylinder has a threaded hole 11 into which is fitted a flowmeter 12.

The flowmeter comprises a body part 13 through which a blade 14 and two insulating tubes 15 extend.

The blade 14 extends downwardly (as seen in Figure 1) beyond the body part 13 and reaches into the fluid with the plane of the blade perpendicular to the direction of flow in the pipe. The blade 14 also extends upwardly.

The downward extension of blade 14 carries a strain gauge 16 and the upward extension carries a terminal block 17. Wires 18 are taken from the gauge 16, through the tubes 15 to the block 17.

High speed transient flow past the cylinder 10 causes a response at the strain gauge 16 which can be measured.

The meter requires calibration and this is achieved with apparatus as shown in Figure 3.

This apparatus comprises a length of pipe 20 into which a flowmeter 12 is inserted. Two pistons 21, 22 are movable in the bore of the pipe, one on each side of the flowmeter 12, and the pipe is water filled between the pistons. The piston 21 can be driven by being connected through a rod 23 to a piston 24 in a shock tube 25 having a buffer 26. The piston 22 has a connecting rod 27 to a fast response deflection transducer 28.

When the shock tube 25 is fired a pressure wave acts on the piston 21 which forces the water existing between the pistons 21, 22 past the blade 14 of the flowmeter 12 and moves the piston 22 and rod 27.

The velocity of the water can be obtained from the transducer record and this is used to calibrate the output of the flowmeter.

1. A flowmeter comprising a body for holding a nominally rigid member projecting into the flow from a mounting, said member being provided with at least one strain gauge so that flow can be measured as strain in the member.

2. A flowmeter as claimed in ciaim 1 in which said member is a blade, the blade presents a face to the flow and the strain gauge is mounted on said face.

3. A flowmeter as claimed in claim 2 in which the blade extends through the body and carries a terminal block for connecting wires to the strain gauge.

4. A flowmeter substantially as hereinbefore de scribedwith reference to Figures 1 and 2 of the drawings.

5. Aflowmeter set to measure high speed transient flow in a fluid in a cylinder (10), the meter comprising a threaded body (13) in a threaded hole (11) in the cylinder and a blade (14) extending from the body into the fluid so that a face of the blade is presented to the flow and a strain gauge (16) is mounted on said face so that flow can be measured as strain on the blade.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Flowmeters This invention relates to flowmeters and is concerned with the problem of providing a fast response flowmeterforthe measurement of a high speed transient flow in a fluid such as may occur by the detonation of an explosive. In the context of the present invention a typical high speed transient flow is one lasting for five milli-seconds at a velocity of fifty metres per second. Such transients can arise during experiments relating to the containment of nuclear structures. The flowmeter according to the present invention comprises a means holding a nominally rigid mem berprojecting into the flow from a mounting, said member being provided with at least one strain gauge so that flow can be measured as strain in the member. Preferably the nominally rigid member is a blade projecting into the duct so as to present the face of the blade against the flow with the strain gauge mounted on a face of the blade. The invention will now be described further with reference to the accompanying drawings in which: Figure lisa longitudinal section through a cylinder equipped with a flowmeter according to the invention; Figure 2 is a view in the direction of the arrow II of Figure 1; and Figure 3 is a diagrammatic longitudinal section of a calibration apparatus for the flowmeter of Figure 1. Figure 1 shows a cylinder 10 past which water flows which can be subject to high speed transients. The cylinder has a threaded hole 11 into which is fitted a flowmeter 12. The flowmeter comprises a body part 13 through which a blade 14 and two insulating tubes 15 extend. The blade 14 extends downwardly (as seen in Figure 1) beyond the body part 13 and reaches into the fluid with the plane of the blade perpendicular to the direction of flow in the pipe. The blade 14 also extends upwardly. The downward extension of blade 14 carries a strain gauge 16 and the upward extension carries a terminal block 17. Wires 18 are taken from the gauge 16, through the tubes 15 to the block 17. High speed transient flow past the cylinder 10 causes a response at the strain gauge 16 which can be measured. The meter requires calibration and this is achieved with apparatus as shown in Figure 3. This apparatus comprises a length of pipe 20 into which a flowmeter 12 is inserted. Two pistons 21, 22 are movable in the bore of the pipe, one on each side of the flowmeter 12, and the pipe is water filled between the pistons. The piston 21 can be driven by being connected through a rod 23 to a piston 24 in a shock tube 25 having a buffer 26. The piston 22 has a connecting rod 27 to a fast response deflection transducer 28. When the shock tube 25 is fired a pressure wave acts on the piston 21 which forces the water existing between the pistons 21, 22 past the blade 14 of the flowmeter 12 and moves the piston 22 and rod 27. The velocity of the water can be obtained from the transducer record and this is used to calibrate the output of the flowmeter. CLAIMS

1. A flowmeter comprising a body for holding a nominally rigid member projecting into the flow from a mounting, said member being provided with at least one strain gauge so that flow can be measured as strain in the member.

2. A flowmeter as claimed in ciaim 1 in which said member is a blade, the blade presents a face to the flow and the strain gauge is mounted on said face.

3. A flowmeter as claimed in claim 2 in which the blade extends through the body and carries a terminal block for connecting wires to the strain gauge.

4. A flowmeter substantially as hereinbefore de scribedwith reference to Figures 1 and 2 of the drawings.

5. Aflowmeter set to measure high speed transient flow in a fluid in a cylinder (10), the meter comprising a threaded body (13) in a threaded hole (11) in the cylinder and a blade (14) extending from the body into the fluid so that a face of the blade is presented to the flow and a strain gauge (16) is mounted on said face so that flow can be measured as strain on the blade.