Flow Characteristics and Windage Loss of CO₂ in Shaft-type Rotor-stator Gap

The windage loss and flow characteristics of CO₂ in the shaft-type gap were investigated by numerical methods. The effects of rotor speed, CO₂ condition and geometrical dimensions on windage loss and flow characteristics were analyzed, and the windage loss model was improved based on the Bilgen model. The study results show that the maximum deviation between the numerical results and results of Bilgen loss model is 14.65%, and results of Vrancik and Yamada loss models are 219.37%, -57.11%, respectively. With the rotation speed increasing, the diameter of Taylor vortex becomes larger, the flow in the gap is more instable, and the windage loss increases. With the pressure increasing in the gap, the Reynolds number becomes larger, the effect of viscous on flow characteristics decreases, the flow instability enhances, and the windage loss is also larger. With the width of the gap increasing, the flow stability will enhance and the flow loss will reduce. The improved windage loss model can improve the predicting precision. The numerical results show that the relative deviation of 57.14% is reduced to 10.30%, compared to the loss model of Bilgen.