Intensification of mixing by small-size jets in ejectors with central nozzle

Abstract

An experimental investigation of the influence of mixing intensification by small-size jets on the startup and characteristics of a gas ejector with central nozzle and a convergent mixing chamber is carried out. It is shown that at high flow rates of the secondary gas, the critical regime is not settled because of the formation of a thick subsonic layer near the chamber wall. In these cases, a stepwise startup was done. The range of critical regimes is limited by the reloading point, at which the velocity near the chamber wall becomes sonic. The critical regime breakdown behind the reloading point occurs due to the upstream propagation of the back pressure through the subsonic layer. The mixing intensification ensures the equalization of the velocity profile and the extension of the range of critical regimes. Despite the improvement of characteristics the mixing in an ejector with the central nozzle remains incomplete. Experimental characteristics are compared with the computed ones. The mixing process is isobaric in the computation without the consideration of dissipative losses because of which the rise of the pressure of a mixture of primary and secondary gases occurs.