旋流数为1.0的强旋湍流两相流动的PDPA实验

EXPERIMENT ON STRONGLY SWIRLING TURBULENT GAS-PARTICLE FLOWS WITH SWIRL NUMBER OF 1.0

采用相位多普勒颗粒测速仪 (PDPA)对旋流数为 1 0的轴向和切向进风的圆柱形旋风筒内强旋湍流气粒两相流动进行了测量研究 ,并与旋流数为 0 47、 1 5和 2 0 8的实验结果进行了对比分析 ,指出了旋流数变化对两相流场及两相湍流特性的影响 .

Strongly swirling flows are frequently encountered in cyclone separators,cyclone combustors and hydrocyclones .Their flow behavior significantly affects the pressure drop,collection efficiency,flame stabilization,combustion efficiency and pollutant formation.Previously this kind of flow with swirl numbers of 0 47,1 5 and 2 08 was studied. To further clarify the effect of swirl number,strongly swirling turbulent gas particle flows in a cylindrical chamber with axial and tangential inlets and a swirl number of 1 0 were studied using a phase Doppler particle anemometer.The measurements give the gas phase and particle phase axial,tangential and radial mean velocities,turbulent fluctuation velocities and particle concentration.The results show the change of flow behavior with the increase of swirl number.As the swirl number increases,the reverse flow region in axial velocity profiles gradually dissappears and the particle axial velocity changes from exceeding the gas velocity in some regions to lagging behind the gas velocity everywhere.For all swirl numbers the tangential velocity profiles of two phases have Rankine vortex structure and the particle tangential velocity always lags behind the gas one.With the increase of swirl number,the relative size of the soild body rotation zone in tangential velocity profiles increases.The two phase turbulent fluctuation is anisotropic for all swirl numbers.With the increase of swirl number the axial fluctuation changes from exceeding the tangential one to lagging behind the tangential one.ne.Withthe