Flow Characteristics of a Two-Stage EHD Gas Pump in a Circular Pipe

Flow characteristics of a two-stage electrohydrodynamic (EHD) gas pump in a circular tube have been experimentally investigated for two different sizes (61.8 and 127.8 mm in diameter). Each stage uses eight emitting electrodes flush mounted on the tube wall. Two electrode configurations, aligned and offset, with fixed spacing between electrodes have been considered in this study. The main objective of the study is to verify whether or not a two-stage EHD pump can sustain or even increase the volume flow rate produced by a single-stage pump over a greater tube length. To this end, electrodes at both stages are charged at the same voltages in positive polarity from 18 to 22 kV. Velocities are measured at three cross sections along the tube length and then integrated to obtain the volume flow rate. The velocity profile and volume flow rate delivered by the single top stage of the pump are compared with those produced by the two stages combined to give additional insight to the problem. The results obtained have important implications for practical applications of EHD gas pump.