冲压发动机进气道堵盖碎块运动仿真研究

Numerical Simulation of the Movement of Inlet Port Cover's Fragments in Ramjet

整体式冲压发动机进气道出口堵盖大多为可抛易碎式,助推器工作结束后,堵盖会分裂成小碎块随气流进入燃烧室内。碎块在运动过程中,可能与燃烧室壁面发生碰撞,当碰撞严重时,会对热防护结构造成破坏。在非定常流场数值仿真结果的基础上,经过适当地简化,模拟了冲压发动机可抛易碎式堵盖碎块在燃烧室内的运动过程。仿真研究表明,堵盖破碎后大部分碎块会在燃烧室中后部与壁面发生碰撞;离燃烧室头部较近的堵盖破碎后,朝壁面运动的趋势更明显,危害性更大;碎块的运动过程与相对气流的速度密切相关,而与自身受到的重力关系不大;增大气流沿燃烧室轴线方向的速度分量有利于减小碎块对壁面的撞击力;堵盖所用材料的密度及碎块的尺寸对其运动轨迹影响不明显。

Fragile port cover is generally used in the integral ramjet. After the boost phase, the port covers will split into several small fragments, and be blown into the combustion chamber. In this process, the cover fragments may collide to the combustor wall, which can cause damage to the thermal protection structures. Based on transient flow field simulation and proper simplification, the movement of the cover fragments is simulated in this paper. Re- suits show that most of the cover fragments will impact in the middle and back zone of the combustion chamber. The ones close to the dome have larger possibility of collision, so they are more dangerous to the structure. The movement is closely related to the velocity of flow, but has much less relationship with the gravity of the fragments. Increase of the axial velocity component can be useful to reduce the impact force. The density of the cover and the size of the fragments have little impact on the moving track.