Numerical investigation for a rotating cavity with axial throughflow with asymmetric heating in different flow patterns in a compressor

This paper investigates the flow and heat transfer mechanisms of the disk cavities with axial throughflow with asymmetric heating in different patterns by numerical simulation. At present, much progress has been made in the study of the disk cavities with axial throughflow with symmetric heating. However, the asymmetric heating has become a non-negligible factor as the pressure ratio of the compressor has increased. According to the two patterns of the symmetric heating disk cavity (shear-induced and buoyancy-induced), the flow in the asymmetric heating disk cavity is divided into four different patterns with different buoyancy parameters. Pattern I is the fusion of two shear-induced flow structures. Pattern II is the fusion of a shear-induced flow structure and a buoyancy-induced flow structure. Pattern III is the fusion of two buoyancy-induced flow structures. In addition, the shroud average temperature of the Pattern II_a is lower than critical value and that of the Pattern II_b is higher than critical value. Large eddy simulation was used for the calculation to study the flow and heat transfer in each pattern, and the numerical simulation was compared with the Bath test results, indicating that the numerical results have reliable engineering accuracy. For each asymmetric heating disk cavity, a comparative analysis was performed with three corresponding symmetric heating disc cavities.

The results of the numerical simulation show that in pattern I, the radial temperature difference is small and the additional effect of the axial temperature difference is obvious. The heat transfer of the shroud is significantly greater under asymmetric heating conditions. In pattern III, radial heating dominates under asymmetric heating, but the presence of axial heating changes the velocity distribution of the left, middle, and right planes inside the disk cavity. Pattern II_a and patterns II_b are intermediate transition states. Compared with pattern I, the radial velocity in the disk cavity in pattern II_a increases significantly. Therefore, the heat transfer of the downstream disk and the right side of the shroud is higher in pattern II_a. Compared with pattern III, the tangential velocity in the disk cavity in patterns II_b has not evolved completely. Therefore, the heat transfer of the upstream disk and the left side of the shroud is lower in pattern II_b. In engineering calculations, considering the flow and heat transfer mechanisms of each pattern can help to evaluate the compressor rotor temperature field and tip clearance more accurately.