Effect of Heat Source Power on the Structure of a High-Velocity Flow and Heat Transfer with Channel Walls

This paper presents the results of numerical simulation of supersonic turbulent air flow in a planar channel with a backward-facing step in the presence of a volumetric heat source of specified power, which models heat release from chemical reactions. The calculations account for conjugate heat transfer between the high-velocity flow and copper plates (sensing elements of heat flux sensors) embedded into the channel walls. It is shown that the presence of the heat source leads to a decrease in the flow velocity within the channel and an upstream shift of the wave structure of the supersonic flow. Amplifying the source power increases the transverse size of the subsonic zone due to flow separation in the region where the shock wave impinges. A localized subsonic zone forms in the flow core, separated by a narrow supersonic jet from the near-wall subsonic zone. In this regime, the thermal wake of the source is located within the flow core. It is revealed that an abrupt change in the flow structure occurs when the local separation zone merges with the recirculation zone behind the step, causing gas heated by the source to enter the extensive separated region. This results in a narrowing of the effective cross-sectional area, leading to the formation of a compression wave at the step corner instead of a rarefaction wave. Consequently, the temperature in the flow core decreases, while the heat fluxes on the walls increase significantly.