Study of slit wall aspect ratio effect on the flow stability and heat transfer in rotating concentric cylinders

The slit wall aspect ratio effect on the flow instability and heat transfer characteristics of taylor-couette flow was studied by numerical simulation method. the accuracy of the numerical simulation result was confirmed by piv experiment. four different models with aspect ratios of 0.5,0.75,1 and 1.25,respectively were investigated. it is found that the axial size of taylor vortex does not vary with the slit aspect ratio at isothermal condition,but increased with slit wall aspect ratio at non-isothermal condition. the slit aspect ratio also has significant influence on the distribution of radial velocity in the annular gap. the maximum radial velocity in the model with aspect ratio of 0.75 is larger than other models. comparing with the temperature distribution in different models,the temperature gradient of the fluid near the inner cylinder to the wall has the maximum value in the model with aspect ratio of 0.75. the average nusselt number also has the largest value in the same model. as the aspect ratio increases from 0.5 to 0.75,the heat transfer ability of the fluid is enhanced obviously. as the aspect ratio increases further,the heat transfer ability of the fluid is weaken slightly.