<p class="MsoNormal" style="text-indent: 24.65pt">The turbine blade squealer tip is a key area in gas turbine for both aerodynamic performance and heat transfer characteristics, which should be carefully designed. However, harsh operating conditions near the blade squealer tip can cause the geometry of the squealer tip to degrade, and manufacturing inaccuracies can also cause the squealer tip geometry to deviate from the ideal design. In addition, the operating conditions of the squealer tip itself are also characterized by uncertainty. In this work, an uncertainty quantification (UQ) method is proposed by non-intrusive &nbsp;polynomial chaos expansion method and Smolyak sparse grids. Then coupled with three dimensional (3D) Reynolds-Averaged Navier-Stokes (RANS) solutions, an uncertainty quantification procedure is carried out for heat transfer performance of GE-E3 rotor blade squealer tip. A parameter sensitivity analysis using Sobol Indice method is carried out to identify the key parameters to aerothermal performance of the squealer tip. Wherein, the total temperature of the mainstream inlet and the blowing ratio are considered as flow condition uncertainty parameters. As geometrical uncertainty parameters, tip clearance is considered.</p><p class="MsoNormal" style="text-indent: 24.65pt">The uncertainty analysis result show that under the influence of the uncertainty of geometry and operating conditions, the statistical mean value of the squealer tip film cooling effectiveness is reduced by 29.52% compared to the design value, and the probability of 10% deviation from the design value is as high as 91.83%. Heat flux of squealer tip basically conforms to the normal distribution and the statistical mean value of the heat flux of squealer tip increased by 13.56% relative to the designed value and the probability of 10% deviation from the designed value is as high as 65.68%. The result of sensitivity analysis shows that the uncertainty of the aerodynamic characteristics of the squealer tip is almost entirely caused by the change of the tip clearance for the ratio of tip clearance deviation to the variance of the discharge flow rate , tip total pressure loss coefficient and the downstream total pressure loss coefficient reached 88.02% ,86.44% and 85.13%, respectively. In terms of the uncertainty of the heat transfer characteristics of the squealer tip, all of the three variables studied in this paper have non-negligible contribution to the uncertainty of film cooling effectiveness. At the leading edge of the blade tip, the change in tip clearance is the biggest source of film cooling effectiveness uncertainty. The blowing ratio contributes most of the uncertainty in the effectiveness of film cooling in the middle region. The uncertainty of the h film cooling effectiveness of the trailing edge is most affected by the total mainstream inlet temperature. What is worth noting is that he mainstream inlet total temperature also is the dominant variable in the uncertainty of the heat flux of squealer tip for its contribution to the uncertainty of heat flux of squealer tip and Heat flux of blade is 93.87% and 98.32%. Compared with the main effect of the tip clearance, mainstream inlet total temperature and bowing ratio , the influence of the second-order interaction effect between the variables on the squealer tip aerothermal performance is almost negligible.</p>

Investigations on the Aerothermal Performance Uncertainty Quantification of the Turbine Blade Squealer Tip

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2021/volume/84898

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