Active aerodynamic noise control research for supersonic aircraft cavity by nonlinear numerical simulation

Prediction of aerodynamic noise is the key technology for the internal weapon bay of supersonic aircraft. Nonlinear numerical simulation is proposed as a new method to analyze noise recently. The Non-Linear Acoustic Solver (NLAS) is employed to study the cavity noise in supersonic combined with Reynolds-averaged Navier-Stokes (RANS) equation. It is shown by the comparison between the calculated results and the WICS wind tunnel tests when the Mach number is 2, the sound pressure level of every monitoring point is in good agreement with experiments. It indicates that the NLAS method which is based on turbulence reconstruction could well simulate the cavity noise in supersonic and reduce mesh numbers. Based on this, the contribution to aerodynamic noise suppression made by active control measure such as adding jet screen at the leading edge of cavity is investigated. It is found that jet screen improves flow condition and increases cavity safety, therefore, it is suitable for suppression of aerodynamic noise under supersonic condition.

Nonlinear Numerical Simulation for Oscillating Pressure in Cavity and Passive Control Research

Prediction of oscillating pressure is a key technology for cavity research. Nonlinear Acoustic Solver (NLAS) is applied to analyze aeroacoustics recently. A nonlinear numerical solver is combined with the Reynolds-averaged Navier-Stokes (RANS) method. RANS is applied to solving the flow field around a cavity, and average solution of initial turbulent statistics is obtained which contains the basic characteristics of the average flow field and statistic description of turbulence fluctuation. The source of acoustic generation is reconstructed, and the spreading of oscillating pressure is simulated precisely. According to the comparison of the cavity noise calculation and experimental results under Mach numbers 0.6, 0.85, and 1.35, it indicates that NLAS is capable to predict oscillating pressure of cavity flow from subsonic to supersonic with acceptable deviation. On this basis, the contribution to oscillating pressure suppression made by passive control such as rectangular fence (RF) and square tooth spoiler (STS) is investigated. It is found that these two passive control methods can lessen the total noise.