Effect of Streamwise Micro-Rib Film Cooling Arrangements on Heat Transfer and Cooling Performance of Cavity Turbine Blade Tips

ObjectivesTo enhance the heat transfer and cooling performance of blade tips and explore how curved micro-ribs induce cooling air flow and affect heat transfer performance, this study uses a numerical solution of three-dimensional Reynolds averaged Navier-Stokes (RANS) equation and standard k-ω turbulence models. The effects of streamwise micro-rib film cooling arrangements on heat transfer and cooling performance of cavity turbine blade tips are analyzed.MethodsBased on the cavity blade tip of the first stage in GE-E3 high-pressure turbine, and following previous experience, a film cooling arrangement (case 1) is designed with large-diameter film holes at the leading and trailing edges, and two small-diameter film holes near the pressure side at the mid-chord region. Then, two additional small-diameter film holes are added near suction side at the mid-chord region where cooling air is scarce, and four mid-chord film holes are arranged at three positions to investigate the effect of hole position. For these three cooling arrangements, a curved micro-rib with 30% arc length is added to explore the effect of rib structure.ResultsCompared to case 1, placing the micro-rib at the leading edge of the cavity reduces blade tip leakage flow by 0.9% and total pressure loss at the outlet cross-section of flow passage by 0.5%. Positioning the micro-rib near the trailing edge results in an 8% reduction in blade tip heat transfer coefficient, and a 16% reduction when the micro-rib surface is excluded. Additionally, the streamwise micro-rib film cooling arrangement at this position achieves a film cooling effectiveness of 0.43 and optimal cooling uniformity.ConclusionsThe research findings can provide valuable references for the coupled design of high-performance blade tip structures in gas turbines; Reynolds averaged Navier-Stokes equation