Influence of Wall Temperature on Shock Train in a Unilateral Expansion Isolator

This study investigates the influence of wall surface temperature on the flow characteristics of the shock train in an isolator of scramjet engine. The numerical simulations were performed using a Reynolds-Averaged Navier-Stokes framework with the k-ω shear stress transport turbulence model, implemented through a pressure-based steady-state implicit solver. Performance study was conducted by systematically varying wall thermal conditions (21 discrete configurations spanning 120–1100 K) and back pressure ratios (2, 3, 4, 5, 5.1, and 5.2), while maintaining constant inlet conditions: Mach number 2, total pressure 0.37 MPa, and static pressure 47,314 Pa. The effect of wall temperature on the flow characteristics of the shock train under high back pressure ratios is significantly different from that under low back pressure ratios. The leading edge of the shock train exhibits an upstream displacement ranging from 5.8% to 90.0% as wall temperatures increase from 120 K to 1100 K under low back pressure ratios, whereas it shifts downstream by 5.87% under high back pressure ratios. The study demonstrates a coupling relationship between wall temperature and back pressure ratios, highlighting distinct influence patterns on shock train characteristics at low and high back pressure ratios, providing essential insights for the optimal design of isolators in hypersonic vehicles.