双螺带桨Metzner常数的模拟计算

Using the multiple reference frames （MRF） impeller method, the three-dimensional non-Newtonian flow field generated by a double helical ribbon （DHR） impeller has been simulated. The velocity field calculated by the numerical simulation was similar to the previous studies and the power constant agreed well with the experimental data. Three computational fluid dynamic （CFD） methods, labeled Ⅰ, Ⅱ and Ⅲ, were used to compute the Metzuer constant k5. The results showed that the calculated value from the slop method （method Ⅰ） was consistent with the experimental data. Method Ⅱ, which took the maximal circumference-average shear rate around the impeller as the effective shear rate to compute ks, also showed good agreement with the experiment. However, both methods suffer from the complexity of calculation procedures. A new method （method Ⅲ） was devised in this paper to use the area-weighted average viscosity around the impeller as the effective viscosity for calculating k5. Method Ⅲ showed both good accuracy and ease of use.

Calculation of Metzner constant for double helical ribbon impeller by computational fluid dynamic method

Using the multiple reference frames(MRF)impeller method,the three-dimensional non-Newtonian flow field generated by a double helical ribbon(DHR)impeller has been simulated.The velocity field calculated by thc numerical simulation was similar to the previous studies and the power constant agreed well with the experi-mental data.Three computational fluid dynamic(CFD)methods,labeled Ⅰ,Ⅱ and Ⅲ,were used to compute the Metzner constant ks.The results showed that the calculated value from the slop method(method I)was consistent with the experimental data.Method Ⅱ.which took the maximal circumference-average shear rate around the impel-ler as the effective shear rate to compute ks,also showed good agreement with the experiment.However,both methods SUgcr from the complexity of calculation procedures.A new method(method III)was devised in this papcr to use the area.weighted average viscosity around the impeller as the effective viscosity for calculating ks.Method Ⅲ showed both good accuracy and ease of use.