The performance of electrogasdynamic expanders with slightly conducting walls

Abstract

In electrogasdynamic (EGD) devices the radial movement of charge carriers to insulating duct walls can produce high parasitic electric fields and greatly degrade the overall performance. In principle these parasitic fields may be reduced by constructing the EGD ducts from slightly conducting materials, but there is then a power loss due to current flow through the wall. This paper examines the effect of particle deposition velocity, wall resistivity, load resistance and aspect ratio, as well as fluid friction and gas density, on this resistive wall power loss and on the overall performance of EGD devices. Given suitable and realistic values of the relevant parameters, isentropic efficiencies in excess of 85 per cent are predicted at pressures of the order 10–40 atmospheres.