流化床气固相间脉动能量作用分析

Analysis of the Gas-Solid Interphase Fluctuating Energy Interaction in Fluidized Bed

以气相大涡模拟–颗粒相二阶矩双流体模型为框架,类比Simonin气固相间脉动能量二阶作用模型,考虑气相亚格子湍动能与颗粒相速度脉动二阶矩之间的脉动能量传递,提出气固相间脉动能量二阶作用项,建立气固相间脉动能量二阶作用模型。比较了Koch模型与修正后的Simonin模型的模拟结果,研究了不同模型下气固相间脉动能量随颗粒浓度分布的变化规律。分析了气固相间脉动能量作用对颗粒浓度和速度等宏观物理量的影响,发现脉动能量作用对宏观物理量影响很小。分析了气固相间脉动能量作用对气相亚格子湍动能和颗粒相速度脉动二阶矩等微观物理量的影响,模拟结果表明,考虑脉动能量作用后亚格子湍动能与亚格子能量耗散的模拟值升高;颗粒速度脉动二阶矩的模拟值也升高。

Large-eddy simulation with subgrid-scale （SGS） turbulent kinetic energy model was used for simulated gas turbulence, and second-order moment model was used for simulated anisotropy characteristic of particles. Huilin- Gidaspow drag model was used for simulated gas-solid interphase force. The large-eddy simulation of gas-second- order moment of particles two-fluid model （LES-SOM model） was presented. Based on Simonin gas-solid interphase fluctuating energy second-order interaction model, considering the gas-solid fluctuating energy transfer between SGS turbulent kinetic energy of gas and SOM of particles, the gas-solid interphase fluctuating energy second-order interaction item was proposed, and revised Simonin gas-solid interphase fluctuating energy second-order interaction model is established for LES-SOM model. The simulations compared with Koch model and revised Simonin model were researched for the distributions of gas-solid interphase fluctuating energy with particles concentration. The effects of gas-solid interphase fluctuating energy on concentration and velocity of particles were analyzed, which showed that fluctuating energy had little effect on macro parameters. The effects of gas-solid interphase fluctuating energy on SGS turbulent kinetic energy of gas and SOM of particles were analyzed, which showed that fluctuating energy had significant effect on micro parameters. The simulation results showed that the value of SGS turbulent kinetic energy and SGS energy dissipation was larger with considering gas-solid interphase fluctuating energy second-order interaction item, and the value of SOM was also larger. Compared with the effect of fluctuating energy second-order interaction on SOM of particles, the simulations with revised Simonin model are lower than with Koch model at high particles concentration since revised Simonin model considers the effect of collision dissipation between particles, and higher at low particles concentration since revised Simonin model considers the effect of gas turbulent fluctuation energy to particles movement.