Buzz evolution process investigation of a two-ramp inlet with translating cowl

In order to satisfy the requirement of high integration, the inlet equipped with translating cowl, which is able to adjust the geometries of combustor and inlet simultaneously, is proposed and studied. Numerical investigations are conducted to obtain hysteresis loop, stability boundary and buzz evolution process with various internal contraction ratios in wide range of flight Mach numbers. The dynamic mesh method is utilized to simulate the geometric adjustment. The results reveal that the buzz evolution process has obvious hysteretic characteristics under the change of translating direction. Meanwhile, the mechanism of inlet buzz mode transition is provided. Then, the effects that the translating velocities have on the oscillatory frequency, position of separation leading edge and dynamic drag are given. The higher velocity is able to restrain the intension of separation oscillation and enlarge the stable region, but has insignificant effect on the reduction of oscillatory frequency and dynamic drag. For specific velocities, there is no oscillation. Therefore, the appropriate velocity can be selected for the improvement of inlet stability. This research gives a full insight into the dynamic performance of a hypersonic variable-geometry inlet. (C) 2018 Elsevier Masson SAS. All rights reserved.