Enhanced thermal performance with high-amplitude intermittent impingement cooling

•Remarkable enhancement in cooling efficiency was confirmed by experimental and numerical data for high-amplitude intermittent impingement cooling.•The generation and interaction of vortex rings break the development of thermal boundary layer and enhance local turbulence of the wall jet region.•High amplitude intermittent impingement cooling technique potentially can save coolant consumption with solid materials with low thermal diffusivity.•There is an ample design space to optimize the time control of the unsteady conjugate heat transfer process. The advances of many future engineering applications rely on effective cooling techniques. Beyond the traditional thermal management solutions, the design potential of unsteady impingement cooling is still under-explored. As a combined experimental and numerical study, this paper reports new findings on high-amplitude intermittent impingement cooling with controlled unsteady patterns. Specifical attention was paid on the intermittent flow close time ratio. The experimental work involved unsteady cooling performance measurement with a small-scale water tunnel system. Unsteady Reynolds Averaged Navier-Stokes Simulation (URANS) was conducted to illustrate the unsteady flow physics, and to evaluate the cooling performance at a wider range of flow conditions (average Reynolds number 2800 < Rem