Numerical Simulation of Helicopter Rotor Flow through Free Wake Analytical Technique and CFD Method

摘要

A combined free wake analytical technique and CFD method is used to include realistic wake effects in CFD solutions for rotor flow. The free wake analytical technique for predicting rotor wake is described to investigate the motion of the helical tip vortex. Beginning with the generalized wake model, a Semi-Empirical Correction for the vortex core effect on rotor wake is made. Then on the condition of circulation and wake geometry convergence, the free wake calculation is accomplished. Finally, Euler/NS Equations are solved for transonic rotor flow employing Jameson's finite-volume explicit Runge-Kutta time-stepping scheme. The results are compared with the respective references and experimental data. For engineering applications in rotorcraft design, the method developed in this paper can be used to predict rotor load, rotor aerodynamic performance, and rotor effect on the aerodynamic performances of the helicopter's other components. In terms of theory, the technical thinking in this paper may provide a basis of reference for studying the formation mode of the rotor tip vortex and vortex core interior structure.