Parameter Optimization Research on Lift-enhancing of Multi-element Airfoil Using Air-blowing

Based on the response surface methodology and the grid method combining with numerical simulation of Reynolds-averaged Navier-Stokes equations,the lift-enhancing optimizations of three-element airfoil parameters and its air-blowing flow control parameters are carried out. The finite volume method is adopted to discretize the Reynolds-averaged Navier-Stokes equations in space, the second-order upwind scheme is used in time advance, and SST k – ω turbulence model is used to compute turbulence viscosity. The objective function is obtained with the response surface methodology,and the optimal solution is made using nonlinear programming with the grid method. On the base of multi-element airfoil parameter optimization, the influencing parameters ofair-blowing effect are analyzed and selected, the optimization design variables are determinedas the air-blowing slotlocations, angles and air-blowing momentumcoefficients, and lift-enhancing aerodynamic optimization ofair-blowing flow control parameters on multi-element airfoil is completed. It is shown from the results that the optimization method combining response surface methodology with the grid method is fit for parameter optimizationof multi-element airfoil and its flow control with air-blowing on the flap forlift-enhancing; the flow around the multi-element airfoil can be well controlled and its aerodynamic performance is greatly improved, then the maximum lift coefficient achieves 4.9589which is usually the maximum lift coefficient of the five-element airfoil; after optimization the air-blowing slot anglesare of about 20° on the trailing edge flapsand the air-blowing momentum coefficientsof slotsexist an optimum value.