Experimental study of evolution for circular impinging microand macrojets
Yu.A. Litvinenko, M.A. Litvinenko, I.D. Zverkov
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: impinging micro- and macrojets, diffusive combustion, acoustic coherent structures
Abstract
The paper describes how the acoustic impact on an impinging jet induces a maldistribution in the radial velocity field within the nearwall zone of spreading jet. The r.m.s. velocity pulsation level in the nearwall jet is lower than in the natural jet. A higher length of the laminar flow zone in a microjet was noted. The development of sinusoid-type instability facilitates a higher combustion efficiency for a propane-butane fuel mixture in the impinging microjet; this reduces the soot emission. The tests demonstrated that the zero acoustic impact makes the flame spectrum more yellow (including the flame from the nearwall zone). This testifies about deficiency of oxidizer (air) and soot presence in the combustion products. The combustion efficiency for diffusive flame in the impinging jet depends on the nozzle diameter and nozzle-target distance.
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