The suitability of a prototype flowmeter for the measurement of transient flows in high pressure hydraulic systems is examined. The flowmeter uses hot film anemometry and is capable of measuring both steady-state and dynamic flow velocities. The flowmeter has been subjected to an extensive series of calibration trials under steady-state flow conditions over a wide range of hydraulic fluid temperature and pressures. Dynamic calibration has also been obtained for the meter response when subjected to sinusoidal and step changes in flow. An investigation into the generation of pressure and flow transients in a simple pump-pipeline-termination hydraulic system is also undertaken using the prototype flowmeter. Employment of suitable analytical techniques enables the harmonic content of the complex pressure and flow waveforms to be determined over ten harmonics of pump piston frequency. A digital computer model of the hydraulic system has been developed based on the Impedance concepts, and the results compared with those obtained experimentally. The accuracy of the simulation for pressure and flow ratios at positions on the pipeline is considered to be good throughout the frequency range. Methods have been developed to determine the source impedance spectra of the pump from experimental data. Inclusion of the predicted source impedance values in the model gave good agreement between theoretical and experimental pressure and flow waveforms. Having obtained the source impedance enabled the pump flow spectra and instantaneous flow to be established using the theoretical model and the experimental flow harmonics measured at a point on the pipeline. This latter part of the work gives a method of remote measurement of pump discharges which would be extremely valuable for test and development work. Further slight modification would allow it to be used for test and development of valve characteristics.
|Date of Award||1976|