Parametric investigation of the effect of various phenomena on the performance of a scramjet nozzle

Abstract

Houshang B. €brahimi** Sverdrup Technology, Inc., A EDC Group Arnold Engineering Development Center Arnold Air Forece Base, TN, 37389-9010 A parametric study has been undertaken to determine the effects of combustor exit flow nonuniformities on scramjet nozzle performance. Previous investigations documented the effect on combustor and nozzle performance for 40 distinct cases in which the initial pressure, density, and velocity distributions were varied in addition to the fuel-to-air ratio. In that effort, phenomena affecting the prediction of inlet, scramjet combustor, and nozzle performance were identified. Some of the numerical data obtained from those analyses were utilized in this study, which emphasized the effects of viscosity, kinetic chemistry, wall temperature, and nonuniform initial radial property profiles on the nozzle performance. In addition, twoand three-dimensional calculations have been completed and are com-pared to conventional one-dimensional results. A Parabolized Navier-Stokes (PNS) solver with finite-rate chemical kinetics was used to generate the solutions for a generic scramjet nozzle design. Test cases were chosen that simulated a scramjet hypersonic aircraft operating at four flight conditions involving Mach number values of 6.0, 10.0, 16.0, and 22.0. Results indicate that the nozzle performance is sensitive to boundary-layer thickness, wall temperature, and static pressure nonuniformity at the start plane. Finite-rate chemistry calculations indicate improved performance esti-mates for the nozzle, compared to the frozen chemistry assumption.