Research Of Slit Structure Parameters Effect On The Turbulent Taylor-couette Vortex Flow And Heat Transfer Characteristics

This study was supported by the National Natural Science Foundations of China(No.51676086)and the Natural Resources Foundation of Jiangsu Province(BK20161351).The effect of slit structure parameters on the flow distribution and heat transfer characteristics in the turbulent Taylor-Couette flow regime was researched.It is beneficial to carry out research on this kind of flow phenomenon for the optimization and design of the related machinery.In this paper,the flow field distribution of the experimental model under different working conditions was measured by Particle Image Velocimetry method.The numerical simulation results were compared with the experimental results to obtain the suitable partially-averaged Navier-Stokes method which was applied to simulate the turbulent flow in the annulus accurately.The investigation on the flow distribution and heat transfer characteristics of the turbulent Taylor-Couette flow under isothermal conditions and non-isothermal conditions was carried out.The influence of the slit structure on the flow field and heat transfer performance in the annular gap was obtained.The main contributions of this paper included:1.PIV method was applied to measure the flow field distribution in the annulus to study the flow field characteristics of the turbulent Taylor-Couette flow.The mesh construction was ensured by the mesh independency validation.Comparing the experimental results with the numerical simulation results to achieve a reliable numerical simulation method.2.Under isothermal condition,Taylor vortices existence was caused by the rotating inner cylinder.The near-wall fluid transmitted the kinetic energy to the flow field in the annulus through the jet-like flow.The turbulent Taylor vortices affected the distribution of physical quantities in the annulus: the shear stress,turbulent intensity and radial velocity presented periodic fluctuations.What is more,with the increasing Reynolds number,the differences between different periods increased.The smaller scale vortices which existed in the slit region promoted the energy exchange of the fluid between the annulus and the slit region.As the number of slits and the width of the slits increased,the convection strength between the inner and outer walls also increased.3.Under non-isothermal condition,the heat transfer way of the fluid in the model was the thermal convection coexists with the heat conduction and the heat convection dominated.The parameters of the slit structure had a significant influence on the distribution of the flow field and the heat transfer performance in the model: When the width and number of the slits increased,the radial velocity in the middle of the annular gap became larger and the heat transfer performance of the model became stronger.The increasing width of the slits can enhance the heat transfer characteristics of the model because the influence of the fluid in the annular gap became larger and the impact point became shallower;the increasing number of slits can enhance the heat transfer characteristics of the model due to the shallower impact point and the smaller loss caused by fluid viscosity as well as friction force.The effect of the slit width was more pronounced than the number of slits.4.The response surface methodology was applied to optimize the parameters of the structure structure.The regression equation of the objective function is obtained.The results show that within the scope of the study,the number of slits,dimensionless slit width,rotating Reynolds number and fluid Prandtl number affected the averaged Nusselt number of the inner cylinder.What is more,the influence of Reynolds number was the most obvious.The influence of the dimensionless slit width was smaller,the number of slits and the Prandtl number of fluid had the smallest influence.The heat transfer performance of the optimized model was 27% larger than that in the original model.