Evaluation Of Mixing Characteristics Of Supersonic Jet

Abstract

The objective of this work is to estimate the mixing promotion newlineand screech frequency of circular and elliptical throat supersonic jet newlinewith and without passive control. Flow field characteristics elliptical newlinethroat and circular throat ratio jet with various aspect ratio is examined newlineat over expanded, under expanded, and correctly expanded conditions. newlineFurther, the tabs are placed at nozzle lip exit along the major and newlineminor axis and the potential core length had been estimated. In this newlinestudy, three cases of CD nozzle configuration is analyzed in and it is newlinestudied for various NPR ratios of 2, 3, 4 and 6. In addition, the newlineacoustic characteristic of the jet flow is also measured for respective newlineNPRs. Measurements of acoustic data are done using microphones newlineplaced at 30, 60 and 90 degrees to imprison the effects of screech tone. newlineAt NPR 2, 3 and 4, the jet with elliptical throat witnesses superior newlinemixing and shorter core length compared to the circular throat. The newlineresults show that the mixing done by the minor axis is superior to the newlinetabs along major axis. At all pressure ratios, the content of jet noise newlineand the frequency are high for the tabs along the major axis due to newlineincrease in amplitude of screech frequency. Introduction of the newlineelliptical throat on circular modifies the structure of shock cell which newlinesignificantly changes the magnitude of screech tone due to the newlineweakening of shock waves. Further the tabs along minor axis show a newlinedominance of large scale vertical structures. In under expanded newlineconditions the shock cell shows the rapid change due to the presence newlineof tabs. The tabs along minor axis are making the shock weaker, hence newlineno evidence of axis switching. To achieve the greater performance of newlineix newlinejet, we need to reduce the potential core length of the issuing jet. This newlinecan be achieved by implementation different types of tabs at the exit newlineof the nozzle.