Numerical Simulation Of Propeller-wing Interaction On Micro Air Vehicle

Micro Air Vehicles (MAVs) are widely used in military and civilian applications according totheir dramatic advantages. The micromation and Low-Reynolds numbers of MAVs give a significantdifferent flow field behavior from conventional airplanes. For fixed-wing MAVs, the streamlineregion caused by the propeller has a crucial interference on the wing. This paper focuses on thepropeller-wing interaction on an fixed wing MAV by two different approches: Actuator Disk modeland overset grid technique.The simulation of the low Reynolds and low Mach number flow field would lead problems ofpoor convergence and accuracy. Normally speaking, low Mach number flow is imcompressible andpressure technique is employed through iteration of the pressure correction to satisfy the continuslyequations. For the perdomonaut low speed flow embedded with high speed flow in some regions, thereal aerodynamic performance can not directly obtained by imcompressible solution, moreover, thelow speed region can cause the “system stiff” when compressible method is employed.Preconditioning can eliminate the system stiff by adding a precondioning matrix in the N-S equations.Actuator Disk model is a quasi-steady method by employing an infinite or small thickness diskto represent the sweeping plane of the propeller, simulates the real propeller’s working state throughmodifying the flow parameters on both sides of the disk. This paper develops an actuator disk modelbased on momentum source term. The velocity difference and pressure jump will be obtained byadding a source term in the N-S equation. The application of the actuator disk model on a certainMAV proves that this model which is developed here owns the capability to simulate real propellers.Overset grid is used for performing simulation of flow with deformation and moving boundaries,pecilized in the complex configuration flow and large movement. In this paper, the overset gridtechnique is employed to calculate the propeller-wing interction of an MAV and the unsteady flowfield behavior is captured as well.The comparison between the two methods follows with conclusions as below. Both methods cansimulate the real working state of propeller. Actuator disk is simple with a high caculation effiencyand low dependency on the hardwares by sacrificing the unsteady characteristics. Full blade modelingby overset grid technique can definitely provide much unsteady flow information, however, it is muchtime consuming. Both methods can provide realiable and precision results.