多喷管燃气降噪方案可行性数值研究

Numerical research on jet noise reducing with multi-nozzle geometry

根据燃气射流噪声的发声机理及辐射特性,提出了采用多喷管代替单喷管进行降噪的方案。以四喷管为例,构建相应的物理及计算模型,综合运用三维大涡模拟得到的近场瞬态流场数据与FW-H面积分相结合的计算气动声学方法,对射流流场及声学特性进行数值研究。通过与单喷管对比,得出多喷管结构在保证发动机质量流率及推力性能的前提下,降低了整个观测区域的噪声,尤其是射流下游,并且还改变了噪声辐射的指向性,起到了明显的降噪效果,验证了该方案的可行性。

Based on the generation mechanism and radiation characteristics of jet noise,a kind of method that substitute multi-nozzle for single nozzle for noise reducing was proposed.In order to verify the feasibility of this method,the physical and computational model of four nozzles jet were established,and far-field sound was predicted by Computational Aeroacoustics（CAA） methodology which coupled the near field unsteady flow filed data by three-dimensional Large Eddy Simulation（LES） and Ffowcs Williams-Hawkings（FW-H） integral acoustic formulation to get the characteristics of supersonic jet noise.The results show that,under the premise of motor performance a ssurance,the Overall Sound Pressure Level（OASPL） is reduced in the whole observation region especially in the downstream,comparing with the result of single nozzle,and the directivity of noise radiation is also changed.The feasibility of noise reducing method is validated.