Fast Computational Aerodynamic Methods For Propeller-driven Aircrafts Based On Actuator Disk Theory

The complex unsteady flow field generated by propeller rotation has always been a hot spot of research.Slipstream is one of the main aerodynamic effects of propeller.In order to achieve the goal of rapid analysis for slipstream effect in the optimal design phase of propeller-driven aircraft,this paper develops and improves the original self-development program Star based on the actuator disk theory.The program solves the steady RANS equation by simplifying the actual propeller configuration and simulate the influence of the propeller slipstream on the aerodynamic characteristics of the aircrafts.1)The existing RANS equation solving program is improved and the aerodynamic characteristics under different working conditions are analyzed for the non-powered configurations of two propeller-driven aircrafts.The numerical simulation results can well reflect the trend of experimental data and can well capture stall angle of attack at the same time.2)Based on propeller momentum theory and blade elemental theory,the effects of propeller slipstream are added in the program as the form of actuator disk source term.The radial load distribution of actuator disk can be divided into constant distribution,linear distribution,triangular distribution and the distribution based on the blade elements theory.Through the calculation and analysis of the classical example,while verifying the reliability of the source items of the developed actuator disk,the radial triangular load distribution and the load distribution based on the blade elements theory are selected for subsequent calculations because of more accurate results.3)The computational aerodynamic methods developed in this paper are used to analyze the on the aerodynamic performance of two propeller-driven aircrafts.The results show that the lift and drag coefficient of aircrafts increases with different degrees under the influence of propeller slipstream.The flow rotation effect causes asymmetric distribution of wing surface pressure coefficient on both sides of the nacelle,and this distribution is related to the propeller rotation direction.At the same time,the acceleration effect of the slipstream improves the lift of the flaps and the tail.The results of the program match the wind tunnel data well and the flow field structure is reasonable.It is concluded that this method can effectively deal with the propeller slipstream problem.