混合型气动CO_2激光器主喷管冻结效率研究

Freezing efficiency of donor nozzle of mixing gasdynamic CO_2 laser

采用两振型弛豫模型及严海星的弛豫速率数据,对混合型气动CO2激光器(简称MGDL)主喷管中的非平衡流动进行了计算。研究了N2(ν=1)分子质量分数沿喷管轴线的分布,总温、总压、CO2和H2O的摩尔分数、喷管构型对N2(ν=1)分子冻结效率的影响。计算结果表明:N2(ν=1)分子质量分数沿喷管轴线方向逐渐减少,在喉部附近降低幅度最大;随着总温的升高,N2(ν=1)分子冻结效率先降低后升高;随着总压、CO2和H2O摩尔分数的增大,N2(ν=1)分子冻结效率逐渐降低;随着喷管扩张段半锥角的增大或者喷管喉部直径的减小,N2(ν=1)分子冻结效率逐渐增大。

By using relaxation model of two vibrational modes and Yan Haixing＇s relaxation times data, the nonequilibrium flow in donor nozzle of mixing gasdynamic CO2 laser is calculated. Mass fraction distribution of N2 （v=1） molecules along nozzle axis, influences of total temperature, total pressure, mole fractions of CO2 and H2O and nozzle profile on freezing efficiency of N2 （ v = 1 ） molecules are studied. Calculation results indicate that mass fraction of N2 （ v = 1 ） molecules decreases gradually along nozzle axis and decreases at a large range around the throat. When total temperature rises, freezing efficiency of N2 （ v = 1 ） molecules decreases at first and then rises. When total pressure and mole fraction of CO2 and H2O rise, freezing efficiency of N2 （ v = 1 ） molecules decreases gradually. When half-an- gle of expansion section of nozzle rises or when throat diameter of nozzle decreases, freezing efficiency of N2 （ v = 1 ） molecules rises gradually.