Effect of periodic heat addition on the structure of supersonic turbulent flow in a channel with sudden expansion

The paper presents the results of numerical modeling on the effect of periodic volumetric heat release on a supersonic turbulent flow in a plane suddenly expanded channel, including conjugate heat transfer with sensitive elements of heat-flux sensors embedded in the walls. The simulations are based on the Favre-averaged Navier–Stokes equations closed by the two-equation k – ω SST turbulence model. The source power varies harmonically; the oscillation amplitude is varied at a fixed mean power. The flow settles into a periodic regime with a pronounced relaxation delay. At maximum heat input the wave structure shifts upstream and local subsonic zones form in the flow core. Periodic power variations also change local heat transfer. A sensor located in the expanding part of the channel heats more strongly in the periodic regime than under a constant source of the same mean power. The integrated heat flux depends non-monotonically on the oscillation amplitude. The peak thermal load on this sensor occurs at an intermediate, not the largest amplitude, owing to the dynamics of shock wave stabilization near the sensor.