Flow Measurements in a Transparent Centrifugal Pump by Using 3-D PIV Technique

Abstract

With the development of laser measurement technique, LDV (Laser Doppler Velocimeter) and PIV (Particle Image Velocimetry) have been widely used to measure the flow fields. Comparison with LDV, PIV is a multiple point measurement technique and the flow fields can be measured convenient. Nowadays, 2-D (two Dimensional) PIV have been used to investigate the flow fields in the centrifugal pump, while 3-D (three Dimensional) PIV is seldom to be used. The reason is that the calibration for 3-D PIV in a small space of centrifugal pumps in very difficult. In this paper, a special water tank was used for 3-D PIV calibration in rotation impeller. The 3-D transient relative velocity in one impeller passage at three axial sections were obtained, when the pump run under the design flow rate. The radial component velocity Wr showed a concave distribution except R = 45 mm. With the increase of radius, the circumference location of minimum Wr moved from the pressure side to the suction side and the tangential component velocity Wθ on the suction side decreases, while on the pressure side increases gradually. The PIV measurement error was investigated based on the mass conservation equation. The maximum error of the PIV measurement was 3.14%, it showed that the test results have higher accuracy and the measured data was reliable.