Numerical Simulation of Mixed Compression Intake Buzz

Abstract

Numerical analysis has been conducted to simulate and capture Buzz phenomenon in a supersonic mixed compression air intake. Buzz is an unsteady self-sustained phenomenon occurred in supersonic intakes, especially when operating its subcritical condition, during which the system of compression and shock waves oscillate and move upstream and downstream along the intake. An axisymmetric and unsteady numerical simulation was used to solve Navier-Stokes equations in combination with URANS SST k-ω turbulence model The simulations were performed at M = 2.0 and at a specific subcritical point of the intake operation where buzz was detected experimentally. Results are compared with experimental pressure data. Buzz is captured numerically, and the results show that the buzz oscillation in this intake is periodic, during which the intake duct is loaded and unloaded. The results show that the large separation region on the compression ramp blocks the duct entry and causes the conical and lambda shocks located on the compression ramp to move upstream cause the self-sustained oscillation. The calculated buzz frequency is in agreement with the experimental one, and the difference is less than 0.2%. Further, the peak and trough of both total and static pressure fluctuations, and as a result, the amplitude of buzz are all accurately predicted.