大涵道比风扇/增压级单自由度声衬优化设计及应用

Design Optimization and Application of a Single Degree of Freedom Acoustic Liner for High Bypass Ratio Fan/Booster

为了发展大涵道比发动机噪声传播途径控制的降噪技术,基于数值仿真与优化算法,以某型大涵道比风扇/增压级试验件为应用对象,开展进口单自由度声衬设计。在声衬设计过程中,采用非线性谐波法对省略内涵增压级的简化结构进行模拟,并在光壁及声阻为0~5、声抗为-5~5条件下,以此作为声源开展基于有限元方法的声传播模拟。在固定声衬穿孔板厚度及穿孔直径的情况下,采用Guess声阻抗模型,将声阻抗-降噪量关系映射到声衬几何参数-降噪量关系,获得声衬几何参数-降噪量图谱,筛选出最佳声衬几何(参数),同时采用模拟退火优化算法获得最大降噪效果的声衬几何参数,并与遍历算法结果进行对比,开展不同状态条件下的降噪效果评估。结果表明:该声衬在风扇0.8转速状态及起飞状态下对1BPF的风扇噪声具有良好的降噪效果。

In order to develop the noise reduction technology based on noise propagation control of high bypass ratio engine,numerical simulation and optimization algorithm were applied to the design of the inlet single degree of freedom acoustic liner for a high bypass ratio fan/booster test vehicle. During the design process of the liner,the non-linear harmonic method was used to simulate the simplified structure without the booster,and the acoustic propagation simulation based on the finite element method was carried out as the acoustic source under the conditions of rigid wall and acoustic resistance of 0 to 5 and acoustic reactance of-5 to 5. By fixing the thickness and diameter of the perforated plate of the liner,the GUESS acoustic impedance model was used to map the relationship between the acoustic impedance and the amount of noise reduction to the relationship between the geometric parameters of the liner and the amount of noise reduction. The contour plots of liner geometric parameters and the amount of noise reduction was obtained,and the optimum geometry(parameters)were screened out. Meanwhile,the simulated annealing optimization algorithm was used to derive the optimum geometric parameters of the liner for maximum noise reduction effect,and the results were compared with the traversal algorithm. Finally,the noise reduction effectiveness was evaluated under different fan operating conditions. The results showed that the liner performs well on the fan noise of 1BPF(Blade Passing Frequency)at 0.8 fan speed and takeoff condition.