Numerical investigation on heat transfer characteristics of twin-web turbine disk-cavity system

A twin-web turbine disk with two rotor-stator cavities and inner cavity system is developed to investigate the effect of nozzle geometrical parameters on both sides, including pre-swirl angle (theta(3)), radial position (R-d), and inlet flow ratio of of the rotor-stator cavity to inner cavity (P-1), on the heat transfer characteristics of the system using the RNG k-epsilon turbulence model. The maximum disk temperature (T-max), disk temperature uniformity and local Nu are adopted as evaluation indexes. Nine structures with different theta(3) and Rd are designed. The results show that the effect of theta(3) is greater than that of Rd. Model 3 with a high-radius nozzle (R-d = 0.8) and small preswirl (theta(3) = 30 degrees) shows the lowest T-max and the highest Nu. The axial temperature difference is affected less by 0 3 and R-d, i.e., approximately 11 K. The radial temperature uniformity improved with increasing R-d. The Nu on the disk wall increased along the direction of radial temperature gradient increasing. The inlet flow ratio is optimized based on model 3 with different P-1. It is revealed that T-max is the lowest and the radial temperature uniformity is the best when P-1 is 1. The axial temperature uniformity is appropriate when P-1 is 1 or 2. After optimizing P-1, T-max reduced by 7.1 K, whereas the average temperature of Clip1 and Clip2, T-C1 and T-C2, reduced by 0.2 and 1.6 K, respectively. The radial temperature uniformity improved slightly, but the axial temperature difference increased by 1.4 K.