正置同轴旋转圆台环隙流场动力特性

Annular flow dynamics characteristics of two regular coaxial rotational cones

实施色流显示试验和粒子图像测速(PIV)流场测速试验对环隙流场动力特性进行定性及定量分析,揭示内圆台转速和环隙宽度对环隙流动特性的影响.通过解析速度场获取环隙径向速度及涡量分布、时均流场、雷诺应力等关键流场信息,在泰勒涡演变周期性规律的定性认知基础上研究泰勒涡动力机制.试验结果表明:当环隙宽度不变时,随着内圆台转速增大泰勒涡演变周期缩短;当转速为9.38 r/min时,涡B1出现先分裂后又融合的特征,体现为环隙流场稳定性减弱;当转速为9.38~20.68 r/min时,静压力主导流动状态形成弧形向内流动趋势;当转速≥24.44 r/min时,环隙内形成弧形外向流动趋势,说明离心力主导当前流态;雷诺应力随转速增大而增大,且雷诺径向正应力>雷诺轴向正应力>雷诺切应力.当内圆台转速不变时,随着环隙宽度增大泰勒涡稳定性先增后减;各工况下环隙流态主要呈现弧形内向流动趋势,说明环隙流场中的静压力总是大于离心力.

Dye liquid visualization and PIV(particle image velocimetry) experiments were conducted to investigate the influence of the inner cone rotate speed and the annulus width on the annular flow dynamics characteristics of two coaxial cones.The key flow information,such as the vorticity and velocity distributions,time-averaged flow field,and Reynolds stresses,were obtained by processing the velocity field.The Taylor vortex dynamics mechanism was studied based on the quantitative evaluation of the periodic vortex transformations.The experimental results show that when the annulus width is constant,the period time of Taylor vortex transformations decreases with the increase of inner cone rotate speed;the vortex B1 splits into 2 vortices and then merge again at9.38 r/min,indicating the weakened annular flow stability;the static pressure dominates and forms the inward flow pattern with the rotate speed in the range of 9.38~20.68 r/min;the outward flow pattern is observed at the rotate speed of 24.44 r/min or above,showing that the centrifugal force dominates;the Reynolds stress increases with the increase of the rotate speed,and the magnitudes of the stresses are in the following order:radial normal stress>axial normal stress>shear stress.When the inner cone rotate speed is constant,the annular flow stability increases and then decreases with the increase of the annulus width;there is always inward flow pattern under all experimental conditions,exhibiting that the static pressure is always greater than the centrifugal force.