非定常空气流场中污染气体的对流与粘性扩散

基于离散涡方法求得的非定常、不稳定空气流场，数值求解了污染气体在空气中的对流湍流扩散方程．两者在每一个时间步耦合，以求非定常对流项．考虑速度脉动，改进了扩散模式．用SF6作为示踪气体，进行了现场测量实验．测得了各测点的SF6浓度随时间的变化．实验结果与数值仿真进行了对比，两者吻合．

CONVECTION AND TURBULENCE DIFFUSION OF POLLUTED GAS IN UNSTEADY AND UNSTABLE AIR FLOW FIELD

The present research on the convection and turbulence diffusion of polluted gas in unsteady and unstable air flow field was carried out numerically and experimentally. In thesolution procedure for numerical simulation, the unsteady and unstable air flow field is evaluated by using the Vortex Method; Based on the obtained unsteady air flow field, the Convection and Turbulence Diffusion Equation for gas is then solved. These two solution phasesare coupled at each time step, such that the effect of unsteady air flow on the convectionand diffusion of gas is effectively included in the simulation. The experiment was performedon the spot with the SF6 gas which was selected to be the tracer. A SF6 tank was locatedat somewhere as the pollution source. It had been released suddenly, then the variation ofthe densities of SF6 with time at the observation points were recorded simultaneously. Theobtained plot for the densities of SF6 versus time shows that the numerical results are ingood agreement with the experimental data. The method for numerical simulation proposedin this paper is also applicable to other relevant engineering problems.