Abstract <p>The propagation of disturbances generated by a heat source in a supersonic boundary layer interacting with an oblique shock wave is studied by direct numerical simulation. Calculations are performed using the HyCFS-R hybrid code. The generation and evolution of unstable boundary-layer disturbances, the effect of the incident shock wave on the development of disturbances and the effect of disturbances on boundary-layer separation and flow development in the regions of separation and laminar-turbulent transition are investigated. The influence of heat pulse duration on the generation and development of unstable waves in the boundary layer and the interaction region is examined. The generation of disturbances by a pair of sources located some distance apart is considered. Decreasing the heat pulse duration is shown to lead to an increase in the amplitudes of the first and second harmonics of the fundamental unstable mode. As result, the spectrum of disturbances in the interaction region changes and the flow transition to turbulence speeds up, leading to a decrease in the size of the separation region.</p>