Fluid flow measurement using electrical and optical fibre strain gauges

R Philip-Chandry
2017
The design, development and calibration of three flow sensors to measure the speed and direction of fluid flow is presented in this thesis. The force exerted by the fluid flow on the sensors are measured using strain gauges. Multidirectional fluid flow measurement has been made possible by vectorial addition of the orthogonal flow components. The fluid speed and direction are generated irrespective of each other. Electrical resistance strain gauges are used as the force measuring device for the
more » ... first version of the flow meter. These strain gauges are bonded to the four longitudinal surfaces of a square-sectioned, elastic, rubber cantilever having a drag element attached to its free end. An attempt has been made to oPtimise the shape and dimensions of the elastic beam to obtain a constant drag co-efficient over a wide flow range. Calibration of the electrical strain gauge flow sensor has been performed in a wind tunnel to measure air flow. The sensor has a repeatability of 0.02%, linearity within 2% and a resolution of 0.43 m/s. The most noteworthy feature of the flow sensor is its quick response time of 50 milliseconds. The sensor is able to generate a measurement of flow direction in two dimensions with a resolution of 3.6". Preliminary measurements in a water tank enabled the speed of water to be measured with a resolution of 0.02 m/s over a range from 0 to 0.4 m/s.
doi:10.24377/ljmu.t.00005565 fatcat:w63zpyld3jeqto3p3x4ztthkdm