Effect of fillet radius of receiver hole on the performance of gas turbine pre-swirl system

Since the main flow blades of gas turbines are in high temperature and high pressure condition, their life span depends on the performance of the cooling system. A pre-swirl system is a device that minimizes the flow loss that occurs when the cooling air is introduced into the rotating part from the stationary part by imposing the rotation component in advance. System performance depends on the shape of the pre-swirl nozzle and receiver hole. In this study, the performance trend according to the shape change of a direct injection type pre-swirl system was numerically investigated. First, the performance was examined by varying the system inlet/outlet pressure ratio, from which the optimum flow rate of the system was determined. When a study was conducted by changing the fillet radius of the receiver hole inlet, the larger radius results in greater discharge coefficient, but there was no significant difference for radius ratio greater than 0.13. Rather interestingly, the outlet of the receiver hole without a fillet that does not spread the cooling air produced a high value of temperature drop efficiency.