Accession Number : ADA325675

Title :   Linear and Nonlinear Evolution of Disturbances in Supersonic Streamwise Vortices.

Descriptive Note : Final rept. 1 Dec 94-31 Jan 97,

Corporate Author : HIGH TECHNOLOGY CORP HAMPTON VA

Personal Author(s) : Khorrami, Mehdi ; Chang, Chau-lyan

PDF Url : ADA325675

Report Date : MAR 1997

Pagination or Media Count : 87

Abstract : Evolution of disturbances in a supersonic vortex is studied by using quasi-cylindrical linear stability analysis and parabolized stability equations (PSE) formulation. Appropriate mean flow profiles suitable for stability analysis were identified and modeled successfully. Using the quasi-cylindrical linear stability code, the stability characteristics of cylinder axisymmetric vortices were mapped thoroughly and discussed in detail. Important trends such as viscous and compressibility effects were obtained and analyzed. The results indicate that viscosity has very little effect while increasing Mach number significantly stabilizes the disturbance. The streamwise evolution of the constructed base flow was obtained by solving quasi-cylindrical steady-state equations using finite-difference techniques and the resulting mean flow was analyzed by using PSE. Linear PSE analysis shows that the effect of streamwise mean flow variation (non-parallelism) is small for the case considered here. Nonlinear evolution of helical modes as well as modal interaction is also studied by using PSE. It is found that the growth of the disturbances results in the appearance of coherent large scale motion and significant mean flow distortion in the axial velocity and temperature fields. In the end, nonlinear effects tend to stabilize the vortex.

Descriptors :   *VORTICES, *SUPERSONIC CHARACTERISTICS, *VISCOSITY, *BASE FLOW, AERODYNAMIC STABILITY, FINITE DIFFERENCE THEORY, AXISYMMETRIC, NONLINEAR ANALYSIS, MACH NUMBER, DISTORTION, COMPRESSIVE PROPERTIES.

Subject Categories : Acoustics
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE