Numerical Simulation Of Aerodynamic Heat For Mars Entry Capsule

Human beings have started exploring Mars since 1960s. A human voyage to Mars is one of the most important goals of deep space exploration in the 21st century. Marian probes entering Mars atmosphere differs from capsules reentering Earth, but still has some similarities. The physicochemical changes of gas around the probe differ from Earth as the Marian atmosphere is full of CO2. It is difficult to simulate the process of entering Mars atmosphere by ground-based experiments, which restricts the development of aerodynamic configuration and thermal protection system.In order to obtain aerodynamic characteristics of Mars capsule entering the Mars atmosphere, numerical simulations of a Mars Pathfinder (MPF) like capsule are carried out by the CFD-FASTRAN software.Firstly, an axial symmetry mathematical model in hypersonic flow is developed. The aerodynamic heat of the Lobb sphere in the Earth atmosphere is simulated by CFD-FASTRAN software. The simulation results match those in references well.Secondly, the paper simulates the two-dimensional flow fields of four time conditions of MPF during the entrance process. Roe discrete format is adopted in the discretization of the convection term and backward Euler is used in discretization of the time term in this model. During the process, after entering the Mars atmosphere for 71s, the Mach number decreases and the chemical reactions weaken till none. The shock detachment distance becomes larger markedly. Heat flux decreases in stagnation point as velocity decreases. The flow field acceleration and pressure decaying effects are obvious after shoulder region. Temperature is a little higher than other regions after shoulder in tail region because of the subsonic flow. Chemical non-equilibrium effect is significant and components of gas change rapidly under a high Mach number.Last but not least, a three-dimensional mathematical model in hypersonic flow is developed. The influence of angle of attack (AOA=5°,10°,15° and 20°) is also under consideration. The flow fields of head region of a MPF like capsule under different angles of attack are simulated. It turns out that the angle of attack does not affect the peak values of temperature, pressure and heat flux much. Stagnation point, which is the most affected, is more close to the windward shoulder region as AOA becomes larger. Near the head and near the shoulder are two high heat flux regions in windward. Heat flux in leeside reduces significantly.