Cooling Performance of Impingement–Effusion Double-Wall Configurations Under Atmospheric and Elevated Pressures

The combustor liner of the modern aero-engine operates under extreme thermal loads with limited coolant supply, necessarily making efficient cooling approaches important. Impingement–effusion double-wall cooling integrates impingement, convection, and film cooling, but most studies testing this approach have been conducted at atmospheric pressure, limiting the application of the technology in real engines. This work experimentally and numerically evaluates the cooling performance of baseline and optimized configurations, focusing on the effects of pressure drop, initial cooling filmand operating pressure under atmospheric and elevated pressures up to 0.3 MPa. The results show that increasing the pressure drop enhances cooling effectiveness, which can be attributed to enhanced jet momentum and cooling film coverage, though benefits diminish when the pressure drop further increases to over 4%. Introducing initial film cooling extends upstream protection, improves downstream uniformity, and stabilizes overall effectiveness across varying pressure drops. Elevated operating pressure further enhances the cooling effectiveness of impingement–effusion cooling, as higher coolant density promotes stronger impingement and more coherent cooling film formation. The simulations confirm that pressure-induced density effects dominate the cooling process, whereas blowing-ratio-based similarity fails to capture these dependencies. The results highlight the limitations of atmospheric evaluations and provide physical insights for designing efficient combustor liners under realistic pressure conditions.