In order to obtain a further understanding of the cavity aeroacoustics and test the noise suppression effect using a saw tooth spoiler,aeroacoustics characteristic over an open cavity with a length to depth ratio of 5∶1 at Mach 0.85 are investigated in the present study.The CFD simulations are performed by delayed detached eddy simulation (DDES)based on Spalart-Allma-ras one equation turbulence model.The results obtained from clean cavity prediction are com-pared with experimental sound pressure level (SPL)data from QinetiQ,UK.It can be observed from the results that the tone amplitude of the 2 nd and 3 rd dominant modes are generally well pre-dicted (within 2 dB),whilst the 1 st and the 4 th tones are not so well resolved.In order to evaluate leading-edge spoiler which is widely used as a passive control method on cavity noise suppression, the main focuses are sound pressure level of cavity with a leading-edge saw tooth spoiler.Accord-ing to the comparison of computational SPL results between cavity with spoiler and clean cavity, the saw tooth spoiler reduce the 2 nd dominant tone amplitude over 10dB,and the over-all SPL a-bout 5dB,significant noise suppression effect for open cavity is validated.%为了进一步了解腔体流场的物理特性以及锯齿形扰流片这种被动控制方法对腔体噪声振荡的抑制效果，对马赫数0．85下、长深比为5∶1的矩形腔体进行了气动声学分析。分析过程采用了基于 Spalart-Allmaras 单方程模型的延迟分离涡模拟（DDES）的 CFD 方法。计算结果以声压级（SPL）形式与英国 QinetiQ 基地进行的实验研究结果进行比较。计算准确地预测出了第二阶和第三阶主导模态的声调噪声幅值，其误差均不超过2 dB。为了验证腔体前缘安装扰流片这种广泛应用的腔体噪声被动控制方法，计算重点分析了带有锯齿形扰流片的腔体结构噪声等级。计算分析结果与空腔结果对比分析后认为前缘锯齿形扰流片可以降低第二阶主导模态的峰值噪声等级10 dB以上，其它频率下的腔体噪声等级可降低接近5 dB，降噪效果较好。
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