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In this paper, effects of runback ice accretion on NACA 23012 airfoil have been studied in an experimental and numerical manner. According to this purpose, experiments have been done using runback ice within Reynolds No. 0.6 x 106 over the angle of attack from 0 to 20 degrees and results have been compared with the clean airfoil results. Having examined behavior of the flow pattern and aerodynamic coefficients of the iced airfoil, results were compared with those of the clean airfoil. It can be concluded that icing phenomenon affects aerodynamic performance of the airfoil in two ways; first, it occurs at low angles of attack prior to stalling of the airfoil and the effect is local. In this case ice accretion on the airfoil contributes to formation of the flow separation bubble behind the ice ridge on the upper surface of the airfoil. After numerical simulation of flow field, flow separation bubble behind the ice ridge was observed. The main effect of icing which is related to the second way occurs at angles of attack close to stall and post-stall. In this case flow pattern around the airfoil as well as aerodynamic coefficients undergo fundamental change. ln addition, it was clear runback ice causes stall angle to decrease 2 degrees and maximum lift is reduced about 8 percent. [ABSTRACT FROM AUTHOR]

In this research, a finite volume-lattice Boltzmann method (FVLBM) for simulation of inviscid compressible flows in 1-D and 2-D structured curvilinear coordinate system is presented. In this simulation, LBM, with new method of circular function instead of expansion or correction of Maxwellian function was implemented for evaluation of equilibrium distribution functions. Moreover, in order to capture discontinuities in the flow field, 3rd order MUSCL scheme was implemented for approximation of convective term. Since in lattice Boltzmann method time step is extremely limited by relaxation time (Knudsen number), performance of FVLBM was improved by employing a third-order IMEX Rung-Kutta scheme for temporal discretization of BGK-model for achieving greater time step and lower CPU time. On the other hand, new D1Q7L2 lattice model is developed and validated and the simulation accuracy is increased. Consequently, the present work can be widely used for simulation of actual engineering problems in aerodynamics. Various gas dynamics benchmark problems and applied engineering unsteady problems in curvilinear coordinate grid are solved for validation. The numerical results of the presented method are compared with experimental dates of wind tunnel tests and the results of FVM Euler solutions; there is good agreement between the results of the present method and those of the references. [ABSTRACT FROM AUTHOR]