Experimental and Numerical Study of Jets from Elliptic Nozzles with Conic Plug

摘要

University of Cincinnati, Cincinnati, Ohio 45221;University of Cincinnati, Cincinnati, Ohio 45221;University of Cincinnati, Cincinnati, Ohio 45221;%The study presents results concerning jets exhausting from elliptic nozzles with conic centerbody plugs. A nozzle with 3:1 ratio of exit heights is surveyed experimentally using particle image velocimetry for jet Mach numbers from 0.24 to 1.0, heated and unheated. At the exit, the nozzle inner surface has a slope of zero in the major axis plane, while in the minor axis plane the slope is steeper than that for a corresponding round nozzle. The conic plug causes splitting of the initial elliptic jet into two jets with their centerlines in the major-axis plane of the elliptic nozzle. Increasing M_j or total temperature causes the bifurcated potential cores of the individual jets to be slightly smaller and to diverge from one to another at a slightly greater angle from the nozzle centerline. Large eddy simulations of the experimental nozzle and two alternate nozzles are analyzed to find how the flow features are influenced by not forcing the jet towards the conic plug in the minor axis plane and by changing the ratio of exit heights to 2:1. Changing nozzle shape caused reduction in the spreading rate in the major axis and increase in spreading in the minor axis. Bifurcation occurs for all nozzles studied.