AP/HTPB复合推进剂低压燃烧特性数值研究

Numerical Study on Combustion Characteristics of AP/HTPB Composite Propellant at Low Pressure

关键词:  复合推进剂  低压燃烧特性  数值仿真  燃面退移  三明治模型

Key words:  Composite propellant  Low pressure combustion characteristics  Numerical simulation  Surface regression  Sandwich model

摘要:

为研究AP/HTPB复合推进剂低压燃烧特性，使用二维三明治模型进行了数值仿真研究。该模型使用简化的四步总包反应机理，考虑燃烧过程中的燃面退移，计算时大粒径AP取平均粒径，小粒径AP采用“均质黏合剂假设”，认为其与HTPB组成“均质黏合剂”。在0.02～0.08MPa的压强下进行了仿真，并与高压（5MPa）下的燃烧仿真进行对比。结果表明，低压下固相AP对黏合剂的传热导致了交界面处燃面的下陷，下陷程度随压强减小而增大；随着燃烧的进行，燃面各点燃速趋于一致，燃面形状不再改变。低压下气相反应表现为预混燃烧，初焰为主导反应。低压下燃速仿真与实验值基本一致，压强指数小于高压下的压强指数。

Abstract:

In order to study the combustion characteristics of AP/HTPB composite propellant at low pressure， a two-dimensional sandwich model was used for numerical simulation. A four-step kinetic mechanism was implemented into this model. This model assumed a homogeneous binder to represent the fine AP and HTPB， and took the average size of coarse AP as the size of pure AP. The unsteady non-planar regressing surface is considered. The simulation was carried out under the pressure of 0.02～0.08MPa， and compared with the simulation under high pressure（5MPa）. The results show that under low pressure， the heat transfer from AP to binder leads to the subsidence of the burning surface at AP/Binder interface， with the decrease of pressure， the subsidence degree increase. As the combustion progresses， the burning rates at various location of the burning surface tend to be the same and the shape of the burning surface does not change. The gas phase reaction under low pressure is premixed combustion， and the primary flame is the dominant reaction. The simulation results of burning rate at low pressure are similar to the experimental data， the pressure index is smaller than that at high pressure.