抄録
For our earlier study, we added metal powder to microcrystalline wax, a solid fuel, to improve the fuel regression rate. Results of those earlier combustion experiments revealed that aluminum (Al) powder increases the combustion flame temperature in the combustion chamber of a hybrid rocket engine, and that Al powder addition improves the solid fuel performance. Nevertheless, details of Al powder ignition in the combustion chamber remain unconfirmed. Therefore, numerical analysis of combustion in a hybrid rocket engine was conducted using software (ANSYS 2020 R2; Fluent Inc.). In general, solid fuels for hybrid rocket engines are made of polymeric thermosets (e.g., hydroxyl-terminated polybutadiene (HTPB)) or hydrocarbon compounds (e.g., paraffin). To use materials and methods similar to those used for earlier studies, we decided to use gaseous oxygen as the oxidizer and kerosene as the melted solid fuel for analyses. Through this numerical analysis, we reproduced the actual combustion experiment conducted at our laboratory. Based on the temperature distribution in the combustion chamber, the residence time, and the temperature distribution of the Al powder obtained from the analysis, we confirmed locations in the combustion chamber at which the Al powder melting and ignition might occur. Results of numerical analyses demonstrated that boundary layer combustion occurs in the combustion chamber and that the temperature rises sufficiently for Al powder melting and ignition. Additionally, results confirmed that the Al powder residence time is the period during which the Al powder can reach its melting point and confirmed that ignition and combustion can occur in the combustion chamber.
