Experimental investigation of return currents in electrogasdynamic flows

An investigation is made of return electric currents in electrogasdynamic flows for laboratory sources of unipolar charged particles. These currents play an important role in the process of airplane electrification as a result of the work of jet engines. Models have been built, making it possible to study the behavior of return currents outside and inside an axisymmetric electrogasdynamic flow, in the absence (“single-contour” source) and the presence (“double contour” source) of an external annular neutral jet. It is shown that a rise in the return current J− outside an electrogasdynamic jet is accompanied by a decrease in the take-off current J °. A decrease in the relative distance L from the source to an external grounded surface and an increase in the ratiov of the velocity of the external neutral jet to the velocity of the electrogasdynamic flow lowers J− in both grounded and insulated models; in the latter case, where J ° J°≡0, there is an appreciable return current outside the jet. With an increase in the potential of the source from ϕ=0 to the floating potential, the current J− rises, attaining a maximum, and then decreases. This effect is observed also when J−=0 in both grounded and insulated models. For the case L−1,v=1, the theoretical and experimental dependences of J− on the potential of the source ϕ, retarding the charged particles of the flow under transitional conditions, are in satisfactory agreement.