Investigation on the Combustion Characteristics of Hydrogen-Oxygen Internal Combustion Engine Under Direct Injection Mode on Orbit
Based on the CONVERGE simulation platform,the optical hydrogen engine simulation model of Argonne National Laboratory in the United States was improved to study the combustion characteristics of hydrogen-oxygen internal combustion engines in two models,direct injection of hydrogen(DI-H2)and direct injection of oxygen(DI-O2).Firstly,aiming at DI-H2 mode,by controlling the mass flow rate of hydrogen injection,the in-cylinder mixing degree,combustion controllability and output work under different oxygen equivalent ratios(Φ)of 0.33,0.10 and 0.08 were studied.Then,the combustion characteristics in the cylinder were compared with those in the rich combustion environment with oxygen equivalent ratio(Φ)of 8.00 in DI-O2 mode.The uniformity of hydrogen and oxygen mixing,the controllability of combustion and the output power of internal combustion engine were compared.The results show that when Φ is 0.33 in DI-H2 mode,the combustion in cylinder is uncontrollable and the explosion pressure in cylinder exceeds 10.0 MPa.When Φ is 0.08,although the combustion is controllable,due to too thin combustion,the mixing degree of the fuel in the cylinder is low and the output power does not meet the 2 kW requirement of the integrated vehicle fluids(IVF)system.When Φ=0.10,it can not only meet the needs of good mixing degree in the engine cylinder and controlled combustion,but also meet the power output requirements of the IVF system for the internal combustion engine.In addition,considering the bearing limit of the temperature and pressure in the cylinder,it is considered that the oxygen equivalent ratio suitable for the engine condition should be about 0.10.In the DI-O2 mode,the combustion in the cylinder is controllable due to the rich combustion in the cylinder,and the mixing degree Φ=8.00 is the same as that in the DI-H2 mode when Φ=0.33,the explosion pressure is lower than 5.0 MPa,the maximum temperature is lower than 1 500 K,and the output power of 2.26 kW is also greater than 2 kW,which meets the design requirements.Therefore,the model has great potential and is one of the optional combustion modes for in-orbit hydrogen-oxygen combustion engines in the future.
on orbitH2-O2 combustioninternal combustion enginedirect injectioncombustion control
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