CFD AND EXPERIMENT INVESTIGATION OF THE MIXING CHARACTERISTICS OF NON-NEWTONIAN FLUIDS IN A STIRRED VESSEL

The mixing performance of a novel design propeller fixed at a position with the angle of -10 degrees combine the inference of the variety of rotation speed and rheology properties were investigated using an ultrasonic Doppler anemometer(UDA) and CFD simulation to investigate the flow patterns and the power consumption in a mixing vessel. The fluids of interest in this research are CMC fluids, which is a type of Walocel CRT 40,000PA powder was added into water to prepare the solutions with the mass concentration which performed shear thinning non-Newtonian fluid properties. As the viscosity of the non Newtonian fluids varies from the shear rate, rather than a constant value. Therefore, a non-Newtonian power-law model has been selected to describe the properties of the non Newtonian fluids, and combine with six turbulence models(the standard k-co model, RNG k-e, standard k-E, Realizable k-e, SST k-co and Reynolds stress model(RSM))for mechanical agitation of non-Newtonian fluids. Through comparing experiment results, the SST k-co and Reynolds stress model(RSM) are found more physical than other turbulence models at the design operating point. Furthermore, the CFD simulation results from Reynolds stress model(RSM) and the SST models were validated with the experimental results over the range of rotation speed (small, design, and large rotation speeds), and show that the simulated propeller torque and flow patterns agreed very well with experimental measurements. The velocity field distribution with different operating conditions within selected planes also have been compared with each other and found that for different rheology concentrations and operating conditions, the turbulence model should be properly chosen. The model for simulating non-Newtonian fluid in a stirred vessel in this study can lay a foundation for further optimum research.