Study Of Thermo-chemical Models For Nonequilibrium Flow In High-temperature Conditions

This thesis is about study on the models of nonequilibrium in high-temperatureconditions. Based on the Park’s two-temperature model, multi-vibratioanal-temperaturemodel and state to state chemical kinetic model are investigated and numericalcalculations are carried out to compare the characteristics of each other, which providesa better understanding of the nonequilibrium phenomenon and the applicability ofdifferent models.The essence of the study in multi-vibratioanal-temperature model is to definedifferent vibrational temperatures for different species, instead of using the average one.Numerical calculations are applied in this model using shape of ball column and theresults are compared with that in two-temperature model. Though this approach is morereasonable in theory, the accuracy of results doesn’t improve much for using thephenomenological method, so that more advanced model is needed.The state to state chemical kinetic model focuses on the transition of particlesbetween energy levels, which accomplishes the couple of thermodynamics andchemistry by simulating microcosmic collision processes. The thesis firstly introducesthe basic theory of the model, and then makes use of it in zero-dimension problemwhich doesn’t couple any flow and in one-dimension problem. In the zero-dimensionproblem, properties and mutual influence of single transition processes in N2(v)/Nsystem are studied and so are the nonequilibrium phenomenon inrecombination/dissociation regime. In the one-dimension problem, flow behind thenormal shock wave and that in nozzle are numerically calculated, using space marchingtechnique and time marching method respectively, to investigate the distribution ofmacroscopical physics quantities and vibrational energy levels, aiming at analyzing thedifferent trend of nonequilibrium phenomenon.The state to state method proves that vibrational energy levels don’t satisfyBoltzmann distribution, even if vibrational temperature that represents thenonequilibrium enegy is used. In different conditions, the dominant reaction is variedwhich leads to different distributions and that is the reason why two-temperature modelworks discriminatively in recombination and dissociation regime, which also stressesthe predominance of the state to state model.Finally, considering that it’s the first time to involve in state to state method, thisthesis discusses some problems in numerical calculations that will be helpful in futurestudy.