关键词: 固体微推力器；局部点火模型；逆压梯度；回流；热反馈

Abstract: In order to investigate the local ignition process of a solid propellant microthruster with restricted ignition device heating surface，by numerical simulation，a local ignition model based on solid-fluid coupled heat transfer model and local remeshing technique was proposed，and the solid propellant microthruster ignition process under normal pressure was studied. The flow and heat transfer property of gas inside the microthruster was analyzed. Based on the thrust-time curve，the proposed model was compared with the whole surface ignition model，as well as the local ignition model proposed by Jongkwang Lee. Simulation results clearly show that the burning surface expands due to the heat feedback of the gas to unburned propellant surface.The gas velocity is under local sound speed at the nozzle throat，which generates adverse pressure gradient in the divergent nozzle，hence causes boundary layer split. As the adverse pressure gradient at the backward of the divergent nozzle increases，the backflow becomes more significant，and enhances heat transfer and kinetic energy dissipation of the gas. The thrust increasing tendency agrees better with experimental results.

Key words: Solid propellant microthruster；Local ignition model；Adverse pressure gradient；Backflow；Heat feedback