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颗粒运动轨迹上流体的温度统计特性对于理解非等温/反应气粒两相湍流的机理,特别是对于检验非等温气粒两相湍流Lagrangian模型是十分重要的.对带有平均标量梯度的气固两相各向同性湍流中颗粒及颗粒所见流体温度的统计行为进行了直接数值模拟研究,讨论了颗粒惯性对于颗粒温度以及颗粒所见流体温度的Lagrangian统计特性的影响.结果显示,对于τp/τk<1的颗粒,颗粒所见流体温度的脉动强度随τp/τk的增大而减小;而对于τp/τk>1的颗粒,其趋势相反.小颗粒(τp/τk<5)温度的Lagrangian自相关系数RpT也随颗粒惯性(τp/τk)的增大而减小,对于大颗粒这一趋势也相反.颗粒运动轨迹上流体温度的自相关系数RpTf都随颗粒惯性的增加而减弱,而且随颗粒惯性的增加,颗粒运动轨迹上流体温度的自相关比颗粒温度的自关联下降得快.平均温度梯度的存在使得在沿平均温度梯度的方向上颗粒速度和温度有很强的关联性.当τp/τk<1时,其关联系数随颗粒惯性的增加而增大;当τp/τk>1时,这一系数的值与颗粒惯性无关.
The statistical properties of the temperature of the particles on the trajectories of the particles are very important for the understanding of the non-isothermal / reactive gas-particle two-phase turbulence, especially for testing the non-isothermal gas-particle two-phase turbulent Lagrangian model. The direct numerical simulation of the fluid behavior of particles and particles in two-phase isotropic turbulence was conducted and the effects of particle inertia on the particle temperature and the Lagrangian statistic of the fluid temperature seen in the particles were discussed. The results show that for τp / τk <1, the pulsating intensity of the fluid temperature seen by the particles decreases with the increase of τp / τk, whereas the tendency of the particles with τp / τk> 1 is opposite. The Lagrangian autocorrelation coefficient RpT also decreases with the increase of particle inertia (τp / τk), which is contrary to the tendency of larger particles. The autocorrelation coefficient RpTf of fluid temperature on particle trajectory decreases with the increase of particle inertia, Moreover, as the inertia of particles increases, the autocorrelation of the fluid temperature on the particle trajectory decreases faster than the self-correlation of the particle temperature.The existence of the average temperature gradient makes it possible to measure the temperature in the direction along the average temperature gradient When τp / τk <1, the correlation coefficient increases with the increase of particle inertia; when τp / τk> 1, the value of this coefficient has nothing to do with the particle inertia.