锚式搅拌槽中高粘弹性流体的流速分布及其功率消耗

用照相法测定了锚式搅拌槽中高粘弹性流体的流型和流速分布,另测定了搅拌功率消耗,结果发现:1.与牛顿流体相比,在低Re数下,粘弹性流体的切向速度较大,而径向速度则较小.2.转速相同时,在高剪切率区域,粘弹性流体的剪切率大于牛顿流体.由CEF方程导出功率计算式N_pRe_af_s~(1-n)=k_pf_vf_s~21+F_1avf_s~(m-n-3)Wi/K_s~2]用实验数据确定f_(?)和F_(1av),得到可适用于牛顿流体、假塑性流体和粘弹性流体的普适功率计算式,计算结果与实验值比较接近.

Velocity Distributions and Power Consumption for the Flow of Highly Viscoelastic Fluid in Agitated Vessel with Anchor Impeller

The flow patterns and velocity distribution for the flow of highly viscoe-lastic fluid in an agitated vessel with an anchor impeller were obtained from streak photographs by using selective illumination of the vessel and polystyrene pearl as tracer particles. At the same time, the power consumption were measured. The conclusions are follows: ( 1 ) In the low Re*number regime, the magnitude of the tangential velocity for the viscoelastic fluid is greater and that of the radial velocity is smaller in comparison with Newtonian fluid, the radial position of the peak in velocity distribution for the viscoelastic fluid is nearer to wall than for Newtonian fluid. ( 2 ) The shear rate distribution is similar for these two fluids, but the magnitude of shear rate viscoelastic fluid is greater in the highly shear area for the same rotational speed of the impeller. The power consumption correlation for agitating Newtonian, pseudoplastic and viscoelastic fluids was developed by means of a CEF rheological model. The parameters fv, fs and F*1av were determined experimentally. The predicted results agree with experimental data.