Research On Design Method For Rotor Airfoils Based On Navier-Stokes Equations

role in the unsteady flowfield and aerodynamic characteristics of helicopter rotor. The aerodynamic design method for rotor airfoils has become an important part of helicopter aerodynamic. Considering viscous effects, an inverse method based on residual correction principle and N-S equations for helicopter rotor aerodynamic airfoils design has been established. The main research contents are as follows:As the background and premise, several main airfoil design methods and the domestic and overseas research and development have been briefly discussed. Based on analyzing the characteristics of various airfoil design methods, it is pointed out that the inverse design based on CFD method especially using N-S equations is important and essential for the research of the airfoil inverse design for helicopter rotor.In Chapter 2, by analyzing the characteristics of the rotor movement and taking into account the requirements on the grids during the process of airfoil inverse design, a structured grid generation method has been established by solving Poisson equations. By this method, the viscous body-fitted grids around the rotor airfoils are generated, and the viscous grids around the transition airfoils can be automatically updated during the process of inverse design iterations. Based on the airfoils grid generation method, the rotor grids generation method has been developed, and the moving-embedded grid method for predictding the forward flight flowfield has been established.In Chapter 3, based on the present generated viscous structured grids, by Jameson finite volume method and the embedded grid method, a calculation method by N-S equations for unsteady forward flight flowfield is established. By the present method, the flowfield and aerodynamic characteristics of different airfoils, rotor in hover and forward flight are calculated, and the effectiveness of this flowfield solution is verified.In Chapter 4, by using the MGM equation which is based on the residual correction principle as inverse design equation in this paper, and deducing the corresponging discretization scheme, a rotor airfoil inverse design method which is suitable for unsteady forward flight flowfield has been established, considering different aerodynamic environment of rotor in various azimuth, and the design process are gived in detail.In Chapter 5, the inverse design calculation and analysis for two-dimensional symmetric and asymmetric airfoils, rotor airfoils in hover and forward flight are performed respectively by using the present inverse design method, and the comparison and analysis of the airfoil pressure coefficient and airfoil geometry among target airfoils, design airfoils and initial airfoils are performed, and the effectiveness of this rotor airfoils inverse design method is verified.