고도모사용 2차목 초음속 디퓨져 시동특성에 영향을 미치는 파라미터에 관한 연구

Starting characteristics of the axi-symmetric supersonic exhaust diffuser (SED) with a second throat are numerically investigated. Main purpose of this study is to predict theoretical starting pressure of STED using 1-D normal shock theory and to present the range of optimum starting pressure through parametric study with essential design parameters of STED influencing on starting performance. Renolds-Average Navier-Stokes equations with a standard k -e turbulence model incorporated with standard wall function are solved to simulate the diffusing evolutions of the nozzle plume. Minimum(optimum) starting pressure difference of 20~25% between 1-D theory and experimental evidences validated from previous results[5] is also applied to predict those in this system. The analysis results indicate that dominant parameters for diffuser starting in this system is diffuser expansion ratio(A d /A t ), which has optimum value 120 and second throat area ratio(A d /A st ), which has optimum range 3.3~3.5.