Numerical simulation and noise reduction design of outlet valve pipe cavity

For aircraft, a cavity is a common structure. Under the action of high-speed airflow, the cavity will produce strong noise and vibration, which will affect the passengers' riding comfort and even flight safety. In this paper, the numerical simulation of the cavity formed by the outlet valve and the installation pipeline is carried out, including two configurations of valve opening and closing. When the outlet valve is closed, the installation pipeline and the outlet valve form a curved cylindrical cavity. When the outlet valve is opened, a cavity containing the bottom jet is formed between the installation pipeline, the outlet valve and the body. The numerical simulation results are compared with the experimental results. It shows that the fundamental frequency of the cavity noise is basically not affected regardless of the status of the valve and good agreement with experimental results. Four kinds of noise reduction measures are designed, and the simulation analysis shows that all of them can reduce the fundamental frequency noise of the cavity. Among them, the grille design can almost completely eliminate the fundamental frequency noise of the cavity.