Research On Transpiration Cooling Of Liquid Rocket Thrust Chamber And Blunt Nose Cone

Platelet transpiration cooling has been applied in some special situations,however platelet machining is still very expensive and there is still insufficient theoretical and applied research on sintered porous media transpiration cooling. In this study, the SST k-ωturbulence model was used to simulate the coupled whole field for the transpiration cooling of a thruster in a liquid O2/H2 propellant rocket engine. The model includes the influences of porosity , varible properties , supersonic compressibility, slip flow and the thermal dispersion in the micro-porous media and of the mass transfer between various components. The whole field solution includes the coupled low Reynolds flow in the micro-porous media and the supersonic flow in the nozzle. The influences of porosity on the local blowing ratio, wall temperature and boundary layer thickness were compared with the effects with regenerative cooling. The simulation results agree well with both the experimental results and a one dimension aerodynamics formula.For sintered porous media transpiration cooling of a rocket nozzle, a strong pressure gradient develops where the cooling flow enters the main channel causing the blowing ratio to vary greatly along the chamber wall and which waste coolant. This thesis presents a design that reduce the coolant usage with a subsection porous wall structure using an impermeable gas proof material partition wall, the partition principles and the coolant inlet pressure distribution method. Numerical simulations of the transpiration cooling thruster with a four-section porous wall show that the design reduces of the required coolant flow by half. The subsection porous wall design is an effective way to optimize the coolant flow in a transpiration cooled thruster.The flow around a curved blunt porous body was also studied experimentally to analyze the influences of main flow temperature, blowing ratio and Reynolds number on the wall temperature and the cooling efficiency. Simulations of the influence of Klinkenberg effects on the flow resistance in the micro-porous flow agreed well with the flow experimental data. The experiment investigation and simulation discovered the rules of the influences of the pressure gradient along the curved surface, the blowing ratio, the sintered material properties, the coolant properties, porosity, permeability, microscale flow and the wake flow on transpiration cooling. In addition the effectiveness of the upstream transpiration cooing on the downstream wall temperature was also studied. Then the model was used to analyze transpiration cooling of a supersonic missile nosecone. The high resolution bow shock before the nosecone was snapped accurately by dynamic grid adaption. The interactions between the transpiration flow, the boundary layer and the bow shock were studied. The comparison with theoretical aerothermodynamics equations showed that the key parameters before and after the bow shock and on the stagnation point were well predicted by the simulations. Even with strong supersonic aeroheating, because the transpiration flow expands the shock layer and thickens boundary layer,the transpiration cooling effectively protects not only the porous nosecone and the porous forebody of the missile, but also the downstream non-transpiration cooled window.