Numerical Simulation Of Scramjet Combustor Based On The Orthogonal Experimental Design

The scramjet is the core component of the hypersonic aircraft, and the design ofscramjet combustor is the pivotal technology, thus making its research significant. Thescramjet combustor was took as the research object in this dissertation, and theoptimization was proceeded on the geometric parameters of multiply combustorconfigurations by using numerical simulation method based on orthogonalexperimental design, in which the intuitive analysis method, the comprehensiveequilibrium analysis method, and the analytical method were together applied.First of all, the significance of the research was introduced, and both of the domesticand foreign research situations about the scramjet combustor were discussed, then theresearch contents of this dissertation was put forward.Secondly, the control equation in the process research was elaborated, including thebasic control of viscous fluid equations, turbulence model, turbulent combustion model,chemical reaction dynamic model. The grid generation and numerical calculationmethod were then introduced, including numerical format, combustion boundaryconditions, convergence criteria. The three-dimensional model was transformed intotwo-dimensional model with area equivalent treatment method, and then the feasibilityof the two-dimensional model and the reliability of the numerical method werevalidated.Thirdly, based on the investigation of domestic and foreign research about thescramjet combustor, combustion efficiency, total pressure recovery coefficient, thrustgain coefficient, are drawn forth the performance indexes, the configuration factorsaffecting the combustor performance were analyzed and13configuration fac torsaffecting the combustor performance was obtained, then the geometric parameters’ranges of13configuration factors were determined under the constraint that thecombust inlet height is at100mm, the combustor length is less then2080mm.Fourthly, the orthogonal experimental design method was introduced, later threefigures of equal difference were took precedence from the geometric parameter rangesfor the levels in order to design the orthogonal table.27new combustors configurationparameters were obtained with the orthogonal array L27(313). Parametric modeling andnumerical simulations were flowed to evaluate the performance of all new combustors.The numerical values were disposed by the intuitive analysis method, and then thetrend chart of the factor affecting the performance was drawn. By analyzing the trendchart, the reason that how the factors affected the performance was studied, and threecombustor configurations were acquired via the optimization on three performanceindexes (combustion efficiency, total pressure recovery coefficient, thrust gaincoefficient) respectively.Finally, the primary and secondary order of the factors affecting the performancewas achieved by means of the comprehensive equilibrium analysis method, and theoptimal combustor configuration was achieved via the optimization on threeperformance indexes together. Numerical results shows that the combustion efficiency, total pressure recovery coefficient, thrust gain coefficient of the optimal combustor are0.915,0.496,0.603respectively, which are33.4%、25%、43.8%higher than thebaseline combustor. And the performance indexes almost reach the maximums of27combustors form the orthogonal array, with combustion efficiency higher at0.8%, totalpressure coefficient lower at6.7%, thrust gain coefficient lower at1.7%, whichvalidates the best performance of the optimal combustor configuration. Combined withthe reason how configuration factors affect the combustor performance, the flow fieldin the optimal combustor and the baseline combustor were analyzed.