Aero-acoustical Optimization of a High-Lift Device Based on Hybrid RANS-LES Method

The prediction and reduction of the high-lift device noise is becoming more and more important for civil transport aircraft design. The hybrid RANS-LES method is used to simulate unsteady flow filed of a wing-flap configuration and acoustic analogy (FW-H) method is used for noise propagation. Results show that accurate characteristics of the turbulence pulsation can be captured while high computational efficiency is maintained. With this method, the optimization process is established. Flap position and deflection angle are chosen as optimized variables. Sample points randomly distributed within the given range are generated by optimal Latin hypercube design. Simulation results of sample points are based on the hybrid RANS-LES method and FW-H method. Kriging model and the radial basis function are used to construct surrogate model modules. Modified particle swarm optimization with niche count is developed as optimization searching algorithm. The optimization results are verified by the hybrid RANS-LES method and FW-H method. The correlations between aerodynamic/aeroacoustic characteristics and position and deflection parameters of the benchmark configuration are revealed. Results show that a strong linear relationship exists between the lift-to-drag ratios and flap deflection angle within the range of the optimized variables given. Another trend that the overall sound pressure level of the far field is positively correlated with the flap deflection angle is also emerged. Comparing with the benchmark configuration, the overall sound pressure level of optimized configurations are respectively 2.03 dB and 1.51 dB lower than that of the benchmark configuration (71.99 dB) while the lift-to-drag ratios of the two optimized points increase − 0.4% and 4.3%. Noise reduction and aerodynamic performance of the optimized configuration show that the developed low-noise optimization process is effective.