Abstract: Characteristics and influence factors of total pressure distortion are studied based on tests conducted on a disturbed board installed in the nacelle inlet. Values are obtained about the total pressure distortion at several inlet exit Mach numbers, and the relationships are discussed between the inlet exit total pressure distribution and distortion indexes and the flight Mach number, the disturbed board blockage ratio and the inlet exit Mach number. The test results show that the total pressure recovery of the corresponding points at the inlet exit increases with the decrease of the blockage ratio and inlet exit Mach number, but that it hardly changes with the flight Mach number. High pressure regions exist in local areas of the inlet exit, which are influenced by the disturbed board, the side slip flight angle and the rotation direction of the engine low pressure rotor.The size and position of high pressure regions vary with the flight Mach number, blockage ratio and inlet exit Mach number, and distortion indexes increase with the increase of the blockage ratio and inlet exit Mach number, but the flight Mach number has nearly no effect on distortion indexes. Moreover, characteristics and steady distortion indexes are calculated based on numerical simulation, and the results are consistent with the test results. The work indicates the reliability of the test and the validity of numerical simulation in distortion study. The research in this article may provide the necessary basis for further surge tests in the air.

Key words: disturbed board, inlet exit, total pressure distortion, testbeds, blockage ratio, Mach number