用双流体—轨道模型模拟四角喷燃模型炉内三维湍流两相流动和煤粉燃烧

目前炉内两相流动和煤粉燃烧数值模拟中多半用颗粒随机轨道模型和单流体无滑移模型，这些模型都难以完整地给出三维空间内颗粒速度，浓度，湍流度分布的信息。主采用双流体－轨道模型（颗粒相连续介质－轨道模型）对一个四角喷燃模型炉内三维湍流两相流动及煤粉燃烧进行了模拟。此模型基于欧拉气相方程组、欧拉颗粒连续方程组和动量方程组以及拉氏颗粒能量方程和质量变化的方程，并使用k-ε-kp两相湍流模型，EBU－Arrhenius湍流燃烧模型，离散坐标辐射传热模型，煤粉颗粒的水分蒸发，热解挥发模型和焦炭燃烧的扩散－动力模型等。热态模拟中，为了减小为信散造成的影响，采用了扭转坐标法（将坐标扭转一定的角度使之与煤粉射流方程一致）。为了检验数值模拟，采用三维相位移普勒测速仪（PDPA）对于冷态模型炉内湍流两相流场进行了测量，得到了两相速度，湍流脉动及颗粒浓度的分布。分别对冷态模炉内两相流动和热态模型炉内三维两相流动和煤粉进行了模拟，冷态两相流动的计算与实验结果的对比表明预报的两相流场是合理的，热态模拟的结果给两相速度，气相温度、组分浓度及壁面热，显示出靠近出口处气相速度和温度分布不对称，造成一个局部高温区。

Simulation of 3-D gas-particle flows and coal combustion in a tangentially-fired furnace model using a two-fluid-trajectory model

Most of investig ators use Eulerian gas-phase model and particletrajectory model (Eulerian-Lag rangian) to simulate coal combustion in boiler furnaces. In this paper, a two-fluid-tra jectory (continuum-trajectory, CT) model (Eulerian-Eulerian-Lagrangian) is used for simulating turbulent reacting gas-particle flows and coal combustion in a tangentially fired furnace. It is based on Eulerian gas-phase equations, Eule rian particle-phase continuity and momentum equations and Lagrangian equations of particle temperature and mass change, with submodels of k-ε-kp two-ph ase turbulence model, EBU-Arrhenius turbulent combustion model, DO(discrete-ordina tes) radiation model, coal moisture evaporation,devolatilization and char combu stion models with simultaneous three reactions. To reduce the numerical diffusion caused by non-orthogonal crossing of the burner jets with the grid lines, acoordinate system rotated with an angle is adopted. To validate the two-phase fl ow models, an experimental study of the gas-particle flow field in a cold model of tangentially fired furnace was carried out using PDPA measurements, which gi ves the two-phase velocities, turbulence intensities and particle concentration .The comparison of cold two-phase flow predictions with measurements shows that the mean flow field is plausibly predicted. The 3-D coal combustion predictions give the hot-flow field, coal concentration distribution, the gas temperature, species concentration, and heat fluxes on the walls. The results show asymmet ric temperature distribution and a local high temperature zone near a sidewall at the furnace exit.