Investigations on Uncertainty Quantification of Film Cooling Effectiveness and Aerodynamic Performance of Turbine Blade Squealer Tip

Combining the non-embedded polynomial chaotic expansion method, sparse grid, Sobol Indic technology and Reynolds-averaged Navier-Stokes (RANS) equation solving method, an uncertainty quantitative analysis method for the aerodynamic and heat transfer performance of the turbine blade squealer tip was proposed. Numerical simulations were consistent with experimental data, which verified the effectiveness of the numerical method for predicting the aerodynamic and heat transfer performance of the squealer tip. The aerodynamic and heat transfer performance of the GE-E3 rotor blade tip was quantified on the basis of the uncertainties of the tip clearance, the total temperature of the mainstream inlet and the blowing ratio. The influences of the uncertain inputs on the average film cooling effectiveness, gap leakage and downstream total pressure loss coefficient were analyzed in detail. The Sobol Indic method was used to quantify the contribution of each uncertain variable to the uncertainty of the tip aerothermal characteristics. The results of the uncertainty analysis show that the leakage in the leading edge area of the blade tip is not sensitive to the uncertain input, but the uncertain deviation of the leakage in the trailing edge area can reach 25%. The downstream total pressure loss coefficient is generally less affected by uncertain fluctuations. Under the influence of the uncertainty of geometry and working conditions, the statistical mean value of the blade tip film cooling effectiveness is reduced by 29.52% compared with the design value, and the probability of 10% deviation from the design value is as high as 91.83%. The sensitivity analysis results show that the tip clearance deviation is the dominant variable in the uncertainty of the tip aerodynamic performance. The variances of the tip clearance deviation to the leakage and the total downstream pressure loss coefficient account for 88. 02% and 85. 31%, respectively. Among the three variables studied in this paper, tip clearance has the greatest comprehensive influence on the aerodynamic performance and film cooling effectiveness of the blade squealer tip, so the machining accuracy of tip clearance should be strictly guaranteed in the process of blade machining and assembly. © 2021, Editorial Office of Journal of Xi'an Jiaotong University. All right reserved.