潜入式喷管对固体火箭发动机工作稳定性影响

Effects of Submerged Nozzle on Stability of

关键词:  固体火箭发动机  燃烧不稳定性  潜入式喷管  涡声耦合  喷管阻尼

Key words:  Solid rocket motor  Combustion instability  Submerged nozzle  Vortex-acoustic coupling  Nozzle damping

摘要:

为了揭示潜入式喷管对固体火箭发动机工作稳定性的影响，基于VKI (Von Karman Institute for Fluid Dynamics) 模型发动机，利用大涡模拟数值方法与脉冲衰减法，计算分析了潜入式喷管对涡声耦合特性及喷管阻尼的影响。结果表明:在存在障碍物旋涡脱落的条件下，潜入式空腔能够加剧涡声耦合强度，继而诱发明显的压力振荡，含有潜入式空腔模型内的压力振幅是不含潜入式空腔模型下的4倍左右；潜入式喷管削弱了发动机的阻尼特性，无潜入式空腔的喷管阻尼比含潜入式空腔的喷管阻尼提高了8.6%左右，而且喷管阻尼随着潜入式空腔体积的增大基本呈线性减小趋势。潜入式喷管一般而言不利于发动机工作稳定性。

Abstract:

In order to reveal the effects of submerged nozzle on the working stability of solid rocket motor，the vortex-acoustic phenomenon and nozzle damping characteristics are numerically studied via large eddy simulation (LES) and pulsed decay method based on VKI (Von Karman Institute for Fluid Dynamics) motor. Results indicate that the submerged cavity can enhance the vortex-acoustic coupling intensity under the condition of obstacle vortex shedding，which results in obvious pressure oscillations. The normalized pressure magnitude in the motor with submerged cavity is three times higher than that without submerged cavity. The submerged cavity can reduce the nozzle damping. The damping rate of no-submerged nozzle is 8.6% higher than that of submerged nozzle. Besides，the nozzle damping rate is inversely linear with the submerged nozzle cavity volume. The larger submerged nozzle cavity volume has，the smaller damping rate is. The submerged nozzle is usually harmful to the stability of solid rocket motors.