Unsteady pressure fluctuations in the boattail region of a heat shield

Unsteady, turbulent, compressible, axisymmetric, Reynolds-averaged Navier-S tokes equations are served for the flow past a bulbous payload shroud for a freestream Mach number of 0.95 and Reynolds number of 16.40 x 10(6). A tim e-dependent numerical simulation is carried out using a finite-volume discr etization technique in conjunction with a multistage Runge-Kutta time-stepp ing scheme. The closure of the system of equations is achieved using the Ba ldwin-Lomax turbulence model. Comparisons have been made with experimental results such as the schlieren picture and surface pressure distribution. A good agreement is found between them. A separated flow zone on the boattail region is observed and is found to be highly unsteady. Standard deviation, higher-order moments, histograms, and spectrum of surface pressure levels are analysed in the separated region of the boattail. (C) 2000 Editions sci entifiques et medicales Elsevier SAS.