Utilizing the combined experimental and computational method

the aerodynamic performance and internal flow pattern of a submerged inlet on the plane surface under ground running are obtained in this paper.Results indicate that:(1) The secondary flow at the cross sections behaves as two counter-rotating vortices which are originated by the side edge of the entrance.The ongoing vortex pair interacts with the separated flow near the aft lip of the inlet and results in the low total pressure region at the bottom surface of the exit.(2)With the ascent of Mach number at the exit

both the total pressure loss and distortion index increases.In spite of a remarkable shift of the distortion index under ground running

compared with high speed wind tunnel tests

the synthesis distortion index is kept below 10.0% at the maximum RPM which does not threaten the stable operation of the engine.(3) The CFD results agree well with the experiment and the relative errors of the total pressure coefficient is less than 1.2% though the distortion index by CFD is a bit higher.