Shape optimization of axial compressor blades using adjoint method with emphasis on thickness distribution

Shape parameterization plays an important role in aerodynamic optimization design of axial compressor blades. Blade thickness is one of the most important parameters in blade design, which has strong influence on compressor aerodynamic performance. However, the previous adjoint-based optimization designs using the Hicks-Henne functions only parameterized the perturbations to the tangential coordinates of points on suction surface or meanline, and kept the tangential thickness of the blade constant during the optimization process. In previous development work of turbomachinery blade optimization using adjoint method and thin shear-layer N-S equations, a new shape parameterization is introduced, which uses Hicks-Henne functions to parameterize the perturbations to both the tangential coordinates of mesh points on suction blade surface and the tangential thickness of the blade. This new approach is applied to the redesign of NASA rotor 67 and the results obtained with and without the blade tangential thickness parameterization are discussed in detail. The results show the redesign with and without the blade tangential thickness parameterization can both improve the aerodynamic performance of the axial compressor. However, the redesign with the blade tangential thickness parameterization can produce a consistently better performance than that without it.