Simulation of truncated ideal contour nozzle separation considering external stream interactions

摘要

The multi-block computational approach is used to study the physics of shock and turbulent flow separation in the truncated ideal contour nozzle, considering the jet and external stream interactions. The code employs a fully implicit finite volume, lower–upper symmetric successive overreaction scheme with van Leer flux vector splitting using monotone upstream-centred schemes for conservation law technique to get a higher-order spatial accuracy for the total variation diminishing property. Several combustion-chamber-to-ambient pressure ratios at surrounding Mach range from 0.5 to 1.2 for both cold and hot gases are investigated to study their effects on the wall pressure, the separation point, and the thrust force. It is observed that although the flight Mach number and ambient pressure decrements delay the separation and raise the specific impulse, the combustion chamber temperature has a reverse effect on the separation point. Crisscrossing (or diamond-shaped) shock waves in the supersonic exit jet enforce the compressible flow properties to oscillate because of the external jet and ambient flow interactions. These oscillations are damped effectively by viscous and turbulent dissipations as one goes farther from the jet centreline and/or moves downstream. The position of separation point, oblique shock, and lambda shock structure angles are compared rigorously with experimental data of a two-dimensional convergent–divergent nozzle, and reasonable agreements are achieved.