Measurement and analysis of flow behaviour in complex geometries using the Ultrasonic Velocity Profiling (UVP) technique

摘要

In this project a non-Newtonian CMC model fluid was tested in two different complex geometries using Ultrasonic Velocity Profiling (UVP). Velocity profiles were measured at three different positions at the center (contraction) of a specially manufactured 50% open diaphragm valve. The complex geometry coordinates and velocity magnitudes were analysed and compared to the bulk flow rate measured using an electromagnetic flow meter. The difference between the calculated and measured flow rates varied from 15% to 25%. A complete flow map in the axial direction from developed to contracting flow was also measured by scanning the transducer along a hyperbolic contraction using a high precision robotic arm set-up. Experimental results obtained using UVP showed good agreement (10%) with theoretical predictions. Results showed that it was possible, for the first time, to measure quantitative velocity data for non-Newtonian flow in a complex geometry, such as a diaphragm valve. It was found that the most important problem in order to increase measurement accuracy is the estimation of wall interface positions, which is due to the ultrasonic transducer's near field. This problem can be eliminated by the introduction of a next generation transducer, which is currently under development.