The numerical study of the relation between supersonic impinging shock structures and temperature fluctuation on the stagnation region

Abstract

The numerical study of the relation between supersonic impinging shock structures and temperature fluctuation on the stagnation region Impinging jets are widely used for cooling and heating due to their high convective heat transfer performance. Depending on the nozzle pressure ratio (NPR), jet flows are classified as subsonic or supersonic(under-expanded), with the latter showing complex shock structures. This study conducted RANS-based simulations referencing Kim and Lee [13], who experimentally investigated temperature fluctuations in N₂ supersonic impinging jets at different NPRs and nozzle-to-plate distances. Simulations were performed for NPR = 4.03 and = 4.95, focusing on how variations in distance affect surface heat transfer via shock structure changes. Results showed temperature fluctuations within similar ranges in both experiments and simulations, though with opposite trends. Temperature rise and oscillations appeared mainly between the expansion fan and oblique shock. Radial profiles near stagnation revealed that axial jet velocity governs heat transfer performance. Higher surface temperatures were associated with lower Nusselt numbers near stagnation. Findings suggest that temperature fluctuations at the jet center result from average axial velocity at expansion fan above stand-off shock structure.