大长径比的固体火箭发动机在燃烧室易出现声不稳定燃烧导致发动机工作异常，为了对声不稳定燃烧有更为清晰的认识和有效的抑制，从系统阻尼的角度出发，通过使用OSCILOS求解器，基于声阻尼理论、紧致性假设和喷管声边界条件，开展了对不同空腔参数和工况进行阻尼数值仿真，对比分析了阻尼随燃面退移的变化，空腔不同位置和头部空腔大小对发动机阻尼系数的影响规律，研究了对声不稳定性的影响。研究发现，将尾部装药改为头部装药，在燃烧室长度和声腔固有频率不变的前提下，使用头部空腔可明显增大结构阻尼，在点火初始时刻增加约2倍；适当增加头部空腔大小可明显增大点火初始时刻的结构阻尼。结果表明，在固体火箭发动机上合理采用头部空腔并根据实际情况适当增大头部空腔大小，可有效抑制燃烧不稳定现象。

Solid rocket motors with a large aspect ratio are prone to acoustic instability combustion in the combustion chamber, leading to abnormal engine operation. To gain a clearer understanding and effective suppression of acoustic instability combustion, from the perspective of system damping, damping numerical simulations were conducted using the OSCILOS solver. These simulations were based on acoustic damping theory, compactness assumptions, and nozzle acoustic boundary conditions, considering different cavity parameters and operating conditions. The variation of damping with the regression of the combustion surface, the influence of different cavity positions and head cavity siz-es on the engine damping coefficient, and the impact on acoustic instability were comparatively analyzed. The study found that changing the tail charge to a head charge can significantly increase structural damping at the initial ignition moment by approximately 2 times, provided that the combustion chamber length and acoustic cavity natural frequency remain unchanged. Properly increasing the size of the head cavity can significantly enhance structural damping at the initial ignition moment. The results indicate that reasonably adopting a head cavity in solid rocket motors and appro-priately increasing the size of the head cavity according to actual conditions can effectively suppress combustion in-stability phenomena.