In this paper we provide information for the design of a 3D external compression inlet system which is affected by the exhaust plume of a missile. The inlet 3D flow field has been simulated by 3D time dependent Euler equations and solved using the J. D. Denton scheme. The total temperature and total pressure distributions are obtained for a quasi–steady state and the temperature increment (DT) and its variation rate (RDT) are calculated. Two definitions of DT and RDT are given and a simple condition has been put forward for calculating the inlet flow field with serious upstream distortion. Finally, an attenuation law is presented which estimates the temperature distortion in the inlet duct from the inlet entrance to the exit for different conditions and different intervals.
Based upon the acoustic mode matches between the source modes and propagating modes, this paper applies the flexible tolerance optimization method to optimize the acoustic parameters (impedance), geometric structure parameters, such as open area ratio, cavity depth, and hole diameter, and operating condition parameters, such as blade passing frequency. The optimum values of the design variables are determined when the in-duct sound suppression approaches the maximum. It can be derived from the optimum results that the emphasis of the engineering optimization design of the perforated plate honeycomb structure should be placed on the optimum choice of the open area ratio and cavity depth. Some other referential criteria for the engineering design of the multi-linings are also provided. Thus, the theoretical prediction system for rotor–stator interaction noise generation and in-duct propagation and optimization of acoustic liners has been developed in this paper. By means of this prediction system, the acoustically multi-sectioned treatments can be theoretically designed for the suppression of rotor–stator interaction noise with discrete frequency, in advance of the beginning of the practical engineering design of acoustic liners.
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