Optimal Shape Design of the S-Shaped Subsonic Intake using NURBS

Abstract

An optimal shape design approach is presented for a subsonic S-shaped intake using aerodynamic sensitivity analysis. Two-equation turbulence model is adopted to predict the strong counter vortices in the S-shaped duct more precisely. Sensitivity analysis is performed for the three-dimensional Navier-Stokes equations coupled with two-equation turbulence models using a discrete adjoint method. For code validation, the result of the flow solver is compared with experiment data and bench marking data of other computation researches. To study the influence of turbulence models and grid refinement in the duct flow analysis, the results using several turbulence models are compared with each other on various grid systems. The adjoint variable code is validated by comparison with the complex step derivative results. And to guarantee a sufficient design space, NURBS equations are applied as a geometric representation and a new grid modification technique, Least Square NURBS Grid Approximation is proposed. Through several optimization cases for different objective functions, the improvement of the intake performance is derived. And the capability and the efficiency of the present design tools are successfully demonstrated in three-dimensional high Reynolds turbulent subsonic intake design.