关键词: 高超声速；风洞试验；进气道；转捩准则；边界层转捩

Abstract: As for an air-breathing hypersonic forebody/inlet model，the onset positions of Boundary Layer Transition (BLT) and their decisive parameters were studied based on the experiments of BLT from Φ600mm pulse combustion tunnel and Φ0.5m hypersonic tunnel，as well as the flow field data of Computational Fluid Dynamics (CFD). A transition criterion was devised through the regression analysis method. The transition criterion can be predicted by the onset position of the natural BLT and the forced BLT of diamond-shaped elements for conventional hypersonic wind tunnels and pulse combustion tunnels. The transition criterion considered the main decisive factors of BLT，including the Mach number at the edge of the boundary layer，the Reynolds number，the ratio between total temperature and wall temperature，the average molecular weight of the gas flow，and the height of roughness element. When the height of roughness element was declined to 0，the forced transition criterion was degraded into the natural transition criterion. The transition criterion was successfully generalized to the BLT predictions of X-43A inlet test in wind tunnel and the domestic flight test with the maximum prediction error of about 13% of the entire length of the inlet. The transition criterion can be applied to the BLT prediction of engineering project.

Key words: Hypersonic；Wind tunnel test；Inlet；Transition criterion；Boundary layer transition