Numerical Investigations on the Film Cooling Characteristics of Gas Turbine Blade With Squealer Tip

摘要

The steady and unsteady film cooling characteristics of the gas turbine blade with squealer tip was numerically investigated in this paper.The availability of the utilized three-dimensional Reynolds-Averaged Navier-Stokes(RANS)with standard k-ω turbulence model for analyzing the heat transfer performance of blade tip was demonstrated by comparisons of numerical results with four kind of turbulent model and experimental data.The numerical result with k-ω turbulence model is well agreement with the experimental data for the turbine blade with flat tip.The accuracy of the utilized numerical approach is demonstrated.The blade in this paper has a tip gap of 1％of the blade span.The blade tip has 8 film cooling holes with same diameter located at the camber line on the squealer cavity bottom.Effect of the different blow ratios and relative motion between the blade and casing on the film cooling performance was studied.The best film cooling effectiveness with blow ratio 1.0 is obtained among three blow ratios.The relative motion between the blade and casing can improve the film cooling performance of blade tip near the leading edge.The centrifugal and Coriolis forces can slightly improve the film cooling effectiveness.The unsteady computations show that the unsteadiness film cooling effectiveness is significantly influenced by the upstream stator vane wake.The maximum fluctuation of the flow field near the leading edge of the rotor blade arises at the first order blade passing frequency.The averaged film cooling effectiveness of the blade tip surface obtained by steady calculation is higher 3.2％than that of the unsteady time-averaged result.