Numerical Simulation Of Flows Around Various Airfoils Based On Hybird Cartesian Grid

Currently, the application of computational fluid dynamics is applied more and more popular inthe engineering practice. How to carry on the numerical simulation of flow over objects with complexshapes has become a problem, which must be solved. After the study of the overlapping grid method,this thesis has developed a grid generation method with high degree of automation. In this method, thehybird cartesian grid for single object or multiple objects can be created automatically. However thehybird cartesian grid can’t follow the feature information changes and this makes the numerical resultsinaccurate, this thesis has developed the cartesian grid adaptive technology based on the flow fieldcharacteristics.The curl and divergence of velocity are chosen as the criterion of adaptive solution.The criterion of velocity curl is used to capture the shear layer, and velocity divergence is used tocapture the shock wave. The cartesian grid adaptive technology greatly improves the calculationprecision, and eventually forms the adaptive hybird cartesian grid technology.In addition, when solving the two-dimensional Navier-Stokes equation, AUSM+format withlow numerical dissipation properties is used to spatially discretize the equation, by solving the linearreconstruction to obtain the second order accuracy. At the same time, we adopt Venkatakrishnanlimiter to suppress the nonphysical oscillations in the areas of the gap, and use four-step Runge-Kutta scheme to perform temporal discretization. Because SST k-ω turbulence model has highprecision for free shear turbulence, the boundary layer turbulence and moderate separation, we chooseit as the turbulence model.In this thesis, different types of two-dimensional airfoils are selected as examples, including asymmetric airfoil, a transonic airfoil, double airfoils and period of airfoils. The comparison of thecalculated results with experimental dates shows that this grid generation method and numericalsolver are suitable for the numerical simulation of various airfoils. Especially when dealing withmultiple period of airfoils, they show the advantage of high precision, fast and automatical gridgeneration and strong adaptive capacity.