A High Fidelity Quality Assessment of High Pressure Turbine Blades Using Surface Curvature and Gradient-Based Adjoint

Abstract

Gas turbine performance is highly dependent on the quality of the manufactured parts. Manufacturing variations in the parts can significantly alter the performance, especially efficiency and thus SFC. The legacy process is to accept variations within predefined profile tolerance limits and a few other qualitative parameters, mostly at a few, key two-dimensional aerofoil sections. With the widespread use of White light scans and other similar three-dimensional scans, this has improved to include the three-dimensional profile. The future however may lie with performance based quality assessment of manufactured parts, combined with quantitative surface quality assessment to implement an intelligent screening process for the parts. The adjoint method, typically used for shape optimization is adapted to provide a prediction of the impact on performance due to manufacturing variations. The work presented outlines a three stage quality assessment process for manufactured parts, involving three-dimensional profile tolerance based screening, followed by a surface curvature based screening and finally an Adjoint based performance prediction.

A review on aerodynamic optimization of turbomachinery using adjoint method

“…The effects of geometric variations have been studied using the adjoint method by different authors. 243–247 The discrete adjoint method available in the TRACE flow solver was used to investigate the impacts of geometric variations on a 2D leading-edge fan blade, resulting in an optimized leading edge with 0.5% higher maximum isentropic efficiency. 243 In another study, the HYDRA adjoint approach was utilized to enhance the manufacturability of turbine blades.…”

“…243 In another study, the HYDRA adjoint approach was utilized to enhance the manufacturability of turbine blades. 245 Mulloth et al 246 employed the adjoint method to evaluate the turbine blade production quality in terms of aerodynamic performance while restricting the range based on blade surface curvature. Using a continuous adjoint method 80 and Principal Component Analysis (PCA)-based MCS, the influence of geometric deviations due to manufacturing on mass flow rate and adiabatic efficiency of multistage turbomachinery (29 actual rotor blades) was assessed.…”