非球形混合颗粒的沉降特征长度

提出以Stokes径和Newton径作为计算非球形颗粒终端速度的特征长度,推导出联用双径计算终端速度的方程,并将混合颗粒的粒径分布计入双径值中.理论推导作了实验验证.

On Settling Characteristic Dimensions for Mixed Non-spherical Particles

Based on the analysis of some equivalent diameters of non-spherical particles, both the Stokes diameter and Newton diameter are recommended as the characteristic dimensions of non-spherical particles settling in the intermediate region. Through the use of Kaskas correlation on drag coefficient, a new equation for estimating the terminal falling velocity has been derived as following:The equation is applicabe to both Stokes Law region and Newtons law region.The characteristic dimensions were dependent upon the size distribution. The data from sieve analysis were processed with cubic spline function interpolation, and two equations for estimating the nominal diameter were derived for the particles settling in Stokes law region or Newtons law region respectively. The nominal diameter may be modified by shape coefficient to obtain the Stokes diameter and Newton diameter.A series of experiments carried out in a fluidized bed equipment showed that the calculated values fitted well the experimental data.