Numerical investigations on acoustic environment of multi-nozzle launch vehicle at lift-off

Abstract The acoustic environment significantly influences the safety and reliability of the launch vehicle at lift-off. Aeroacoustic has always been the focus of attention in the field of aerospace. In the paper, the flow field and acoustic environment caused by multiple jets of the launch vehicle at lift-off are numerically simulated using the three-dimensional compressible Navier-Stokes equation, second-order Roe scheme, scale-adaptive simulation (SAS) and acoustic analogy method (FW-H). The jet noise of single-nozzle launch vehicle are numerically simulated for the verification of numerical methods solving the acoustic, and the relative error in between the numerical results and the experimental data is less than 1.6%. Then the influence of the position of the tower, the vehicle's altitude and the configuration of the deflector on the acoustic environment of the vehicle is studied. The results show that the overall sound pressure level (OASPL) reaching the vehicle with the one-sided jet deflector is larger than that of the vehicle with the two-sided jet deflector. Compared with the initial lift-off altitude, the vehicle's altitude at 12 times of the nozzle-exit's diameter can increase the acoustic load around the vehicle. However, the position of the tower has little effect on the OASPL reaching the vehicle with the one-sided jet deflector. The analysis method provides reference for noise prediction and acoustic environment control of the launch vehicle.