Numerical Investigation of Pressure Loss in a Rectangular Channel with a Sharp 180-Degree Turn: Influence of Design Variables and Geometric Shapes

Gas turbine blade cooling typically uses a cooling air passage with a sharp 180° turn in the midchord area of the airfoil. Its geometric shape and dimensions are strictly constrained within the airfoil to ensure both aerodynamic and cooling performance. These characteristics imply the importance of understanding the relationships between the geometric dimensions and the cooling channel performance. In this study, we validated a numerical method using the commercial software, Ansys Fluent 2021 R2, by predicting a total pressure loss coefficient with less than 6% deviation from the experimental results of Metzger et al. for four different Reynolds numbers. Through parameter studies, the divider tip-to-wall clearance was found to be the most significant parameter influencing the pressure loss. Parameter correlations and predictive models between the design variables and the pressure loss were derived by regression analysis using the R language; the regression model predicted the pressure loss to within 2.29% of the numerical method. As the geometries changed, the response surface and the adjoint solver improved the pressure loss by approximately 20.87% and 25.96%, respectively, at the representative Reynolds number of 24,230; this showed that the adjoint solver was a relatively simple and effective method with minimal geometric changes.