CAJ | 학술논문

为了降低缝翼噪声，提出了一种基于前缘平行射流的缝翼噪声控制技术，利用数值计算验证了该方法的有效性，并分析了其噪声控制机理。采用 FREQUENZ 两段翼型，利用 DDES 混合方法进行二维非定常数值计算，获取声源分布，采用 FW-H 积分获得远场噪声特性。计算结果表明平行射流基本不影响翼型的气动力特性，同时缝翼的中低频噪声得到有效的抑制，宽频噪声强度也有所减弱。通过对时均流场和瞬态流场的分析，初步阐述了两种降噪机理：（1）平行射流与缝翼尖端分离流相互作用，改变了剪切层中的大尺度拟序结构，展向涡的尺度及其不稳定性均得到有效抑制，从而减弱了剪切层与缝翼压力面撞击而产生的压力脉动，达到降低声源强度的目的；（2）射流减小了回流速度，削弱了声反馈机制。
위료강저봉익조성，제출료일충기우전연평행사류적봉익조성공제기술，이용수치계산험증료해방법적유효성，병분석료기조성공제궤리。채용 FREQUENZ 량단익형，이용 DDES 혼합방법진행이유비정상수치계산，획취성원분포，채용 FW-H 적분획득원장조성특성。계산결과표명평행사류기본불영향익형적기동력특성，동시봉익적중저빈조성득도유효적억제，관빈조성강도야유소감약。통과대시균류장화순태류장적분석，초보천술료량충강조궤리：（1）평행사류여봉익첨단분리류상호작용，개변료전절층중적대척도의서결구，전향와적척도급기불은정성균득도유효억제，종이감약료전절층여봉익압력면당격이산생적압력맥동，체도강저성원강도적목적；（2）사류감소료회류속도，삭약료성반궤궤제。
A numerical investigation into the suppression of slat noise has been conducted with upstream parallel mass injection near the slat cusp.The efficiency and mechanism of noise attenuation with upstream parallel mass injection is studied in a hybrid approach.Delayed Detached Eddy Simulation is performed to describe the noise sources of a two component high-lift model,FREQUENZ;Ffowcs-Williams and Hawking’s integration is employed to obtain the far-field aeroacoustic signatures.Results show that with injection, aerodynamic capability of the high-lift devices is sustained,and both broad band and tonal noise attenuation are observed.With detailed analysis of the time-averaged and the instantaneous flow fields,two mechanisms are identified as the reasons accounting for the noise attenuation:(1 )the interaction of upstream parallel mass injection and the detached flow at the cusp alters the characteristics of the free shear layer,leading to the breakup of the large coherent structures and creation of smaller vortical structures,these reduced-scale vortical structures are well confined in a narrow space,thus reduces the shear layer flapping and leades to a smaller impingement between free shear layer and slat pressure surface,and then eventually reduces the fluc-tuating pressure levels;(2)upstream parallel mass injection reduces the velocity of the back-flow,which alleviates the feed-back loop.