Experimental investigation of supercritical CO2 film cooling under supersonic mainstream conditions

In response to the pressing need for advanced cooling technologies in the thermal protection of hypersonic vehicles, this study presents a systematic experimental investigation of supercritical CO 2 film cooling under supersonic mainstream conditions. An integrated experimental system combining synchronized schlieren and infrared thermography was developed, alongside a correction method based on calibration experiments and schlieren data to mitigate infrared interference caused by CO 2 . Through comprehensive experimentation, flow field images and wall temperature distributions of the jet were obtained under varying supply pressures (7.5–8.5 MPa), temperatures (32–44℃), mainstream Mach numbers (1.4–3.0), and hole geometries. For the first time, the flow and cooling characteristics of supercritical CO 2 film under supersonic conditions were elucidated. The findings revealed that the jet exhibited a highly underexpanded morphology with a characteristic Mach disk structure. At elevated blowing ratios, the jet induced a detached shock wave in the mainstream. Solid-phase particles formed by throttling-induced desublimation accumulated on the windward side of the jet. The cooling effectiveness was enhanced with increased supply pressure and decreased temperature. This study offers a robust experimental foundation for supersonic thermal protection.