COMBINED UNSTEADY EFFECTS OF HOT STREAK AND TRAILING EDGE COOLANT EJECTION IN A TURBINE STAGE

This paper presents a 3D unsteady flow and heat transfer analysis on the first stage turbine of a heavy duty gas turbine. Attention is focused on the combined unsteady effects and the unsteady interaction mechanism of hot streak and vane trailing edge coolant ejection. The turbine stage inlet hot streak has a temperature ratio of 1.23 and six clocking position variations. Three kinds of vane trailing edge configurations are computed and compared. The first is without slot, the second is a center-line slot, and the third is a cut-back slot. The both slots are spanwise clean ones. The temperature ratio of trailing edge coolant to inlet main flow is 0.57. The mass flow ratio of trailing edge coolant to inlet main flow is 3%. The two kinds of trailing edge slots have the same inflow boundary conditions. Results show that the combination of hot streak and trailing edge coolant ejection slightly enlarges the fluctuation range of the transient averaged heat load on blade pressure surface. And the trailing edge coolant ejection significantly decreases the transient averaged heat load on blade suction surface compared with the cases without trailing edge slot. However, the trailing edge coolant ejection enhances the local heat load on blade suction surface by complex flow interaction, especially trailing edge coolant ejection combining with the hot streak impinging the vane leading edge. In addition, trailing edge coolant ejection enlarges the fluctuation range of blade force greatly compared with the case without trailing edge slot. Also, the different hot streak clocking positions combining with the trailing edge coolant ejection have different behaviors and interaction mechanism. The influences of centerline slot combining with hot streak on both the transient fluctuation of heat load and blade force are greater than that of cut-back slot.