Development of S3D and adjoint design methods for efficient aerodynamic design of three-dimensional high-speed compressor blades.

摘要

In this study, two CFD-based design methods were developed to overcome two of the biggest obstacles in designing high-speed compressor blades with three-dimensional (3D) Navier-Stokes flow physics: aerodynamic performance improvement per design cost and reliability of design results. In the first method, named sectional three-dimensional (S3D) design method, 3D design was performed with the S3D flow analysis concept, which simulates the 3D flow environment in sectional flow modeling. The S3D flow modeling performs two-dimensional-like flow analysis at a spanwise grid plane, where spanwise fluxes are fixed as obtained in a 3D flow analysis. The validation study shows that S3D flow solutions are as reliable as 3D solutions and much more reliable than quasi-three-dimensional (Q3D) flow solutions. The S3D design method enables efficient 3D design, producing reliable designs with Navier-Stokes physics at an affordable design cost, and its design results demonstrate that the method can successfully handle the strong 3D effects of compressor flows, compared with other available 3D design methods.; In the second part of the study, an adjoint design method was employed for compressor design to broaden the range of design capability, to facilitate 3D design applications, and to complement the S3D design method.{09}An adjoint design code was developed, based on a 3D compressor flow analysis code, using the discrete adjoint method for the Euler equations. Unlike external flows where any near-field disturbances are attenuated at far-field, internal flow problems create improper interactions of adjoint variables between boundaries because boundary surfaces are closely facing each other. A validation study on sensitivities reveals that, in internal flow problems, constraints should be imposed on internal boundaries to reflect proper physics of the adjoint system. The design results of the adjoint method indicate that the method enables highly efficient 3D designs by drastically reducing the computational cost of sensitivity analysis and that it can be combined with the S3D method to provide a practical and efficient 3D design tool for transonic compressor blades.