Aerodynamic Characteristic Computations On Iced Airfoils,Multi-Element Airfoil And Rudder

The condition of icing accretion, the style of icing accretion, the parameters of icing accretion in flight, and the influence of icing accretion on the aerodynamic characteristics of an airplane are analyzed in this thesis. CFD method are applied to compute and analyze the aerodynamic characteristics of the iced airfoils. The grids on iced part are refined and smoothed. The hybrid algebraic/elliptic differential equation method is used to generate the multi-block structured viscous grids automatically for iced airfoils, and the rudder angle of an airfoil is controllable. The cell-centered finite-volume method is used to solve the two-dimensional Navier-Stokes equations, and the second-order five-stage Runge-Kutta explicit scheme is used for time marching. In order to prevent odd-even decoupling of the solution and oscillations near the shock waves, a blend of adaptive second- and fourth-order artificial dissipation is added. Local time step, implicit residue averaging, enthalpy damping are used to accelerate the convergence. For a turbulent flow, the S-A one-equation turbulence model is adopted, which allows for reasonably accurate predictions of turbulent flows with adverse pressure gradient. Finally, lift, drag and pressure of iced airfoil or iced multi-element airfoil, and hinge moment of rudder are obtained. Results of test cases prove the validity of the present method. As a result, a computational method for iced airfoils, which is applicable to real problems in engineering, is established.