The present work is to computationally analyze side loads in a thrust-optimized parabolic nozzle during high-altitude testing. The engine startup and shutdown processes of the Korean Space Launch Vehicle II third-stage rocket engine combustor are examined using three-dimensional time-accurate computations. The generation of side loads is closely related to the transition of the separation pattern due to the nozzle shape. However, the results also show that the side loads are significantly affected by the unique flow features of high-altitude testing, such as the flow entering through the gap between the nozzle and the diffuser, as well as the pressure waves produced by the impact of the diffuser flow breakdown. During the engine startup process, the interaction between the nozzle flow and the entrained flow produces unexpected side loads before the transition of the separation pattern. The first transition process generates two side-load peaks. The second transition does not produce any side loads owing to the smooth transition process, which is caused by the entrained flow acting like a nozzle extension. During the engine shutdown process, the initial pressure wave from the diffuser causes fluctuating side loads. The second pressure wave leads to the transition of the separation pattern, which temporarily increases the magnitude of the side loads.

目前的工作是在高海拔测试过程中以计算方式分析推力优化的抛物线形喷嘴中的侧向载荷。使用三维时间精确计算，检查了韩国航天运载火箭II第三级火箭发动机燃烧室的发动机启动和关闭过程。由于喷嘴的形状，侧向载荷的产生与分离模式的转变密切相关。但是，结果还表明，侧面载荷受高空测试独特的流动特性的显着影响，例如通过喷嘴和扩散器之间的间隙进入的流体，以及因冲击而产生的压力波。扩散器流量故障。在引擎启动过程中，喷嘴流和夹带流之间的相互作用会在分离模式转换之前产生意外的侧向载荷。第一次过渡过程会产生两个侧向负载峰值。由于平稳的过渡过程，第二过渡过程不会产生任何侧向载荷，这是由夹带的流动像喷嘴延伸一样引起的。在发动机关闭过程中，来自扩压器的初始压力波会引起波动的侧向载荷。第二压力波导致分离模式的转变，这暂时增加了侧向载荷的大小。这是由于夹带的流动像喷嘴延伸部分一样造成的。在发动机关闭过程中，来自扩压器的初始压力波会引起波动的侧向载荷。第二压力波导致分离模式的转变，这暂时增加了侧向载荷的大小。这是由于夹带的流动像喷嘴延伸部分一样造成的。在发动机关闭过程中，来自扩压器的初始压力波会引起波动的侧向载荷。第二压力波导致分离模式的转变，这暂时增加了侧向载荷的大小。