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为研究点火元器件加热区域受限下固体微推力器的局部点火过程,通过数值模拟手段,基于流固耦合传热模型和局部网格重构技术建立了推力器局部点火模型,研究了常压环境下的固体微推力器点火过程,分析了点火过程中推力器内燃气的流动和传热特性,并结合仿真所得推力-时间曲线与全表面点火模型和Jongkwang Lee提出的局部点火模型进行了对比。仿真结果表明,随着推进剂产生燃气往未燃推进剂表面的热反馈,推进剂燃面逐渐扩大。点火过程中喷喉燃气流速未达到声速,外界反压使微喷管内产生逆压梯度,导致喷管扩张段内出现边界层分离。由于喷管扩张段后部逆压梯度随时间增大,喷管扩张段后部回流相应加剧,从而增强了壁面表面的对流换热和燃气主流的动能耗散。模型的推力上升趋势与实际情况更加吻合。
In order to study the local ignition process of the solid micro thrusters with limited heated area of the ignition components, a local ignition model of the thrusters was established based on the fluid-solid coupling heat transfer model and the local mesh reconstruction technique by means of numerical simulation. Environment, and analyzed the flow and heat transfer characteristics of the gas in the thruster during the ignition process. The thrust-time curve was compared with the full surface ignition model and the local ignition model proposed by Jongkwang Lee . The simulation results show that as the propellant produces thermal feedback to the surface of the unburned propellant, the combustion surface of the propellant gradually expands. During the ignition, the gas velocity of the throat gas did not reach the speed of sound, and the external back pressure led to the reverse pressure gradient in the nozzle, resulting in the separation of the boundary layer in the nozzle expansion section. Due to the increase of the back pressure gradient at the rear of the nozzle expansion section with time, the backflow in the nozzle expansion section is correspondingly intensified, which enhances the convective heat transfer on the wall surface and the kinetic energy dissipation of the gas mainstream. The upward thrust of the model is more in line with the actual situation.