A computation study on the aerodynamic influence of interaction wing-propeller for a tilt-body MAV

Purpose – The purpose of this paper is to investigate the influence of a propeller slipstream on the aerodynamic characteristics of a fixed-wing micro air vehicle (MAV) by simplifying a propeller to an actuator disk and an actuator volume. Design/methodology/approach – A computational fluid dynamic (CFD) approach. Findings – The simulation flows are found and show that the propeller slipstream changes the flow field around the wing, which improves the aerodynamic performance of the wing. The aerodynamic performance is improved first, when the separation of the boundary flow at the upper surface wing is delayed. Second, the flow region of the boundary layer is boosted close to the wing surface again at a high incidence angle. And finally, the velocity inlet of the wing is increased by the propeller-induced flow. Research limitations/implications – The incidence angle is in the range of 0-80°with an increment of 20°. The free stream velocity and RPM used are 6 m/s and 5,000 rpm, respectively. Originality/value – A propeller is simplified to an actuator disk and an actuator volume

Aerodynamic Characteristics of a Low Aspect Ratio Wing and Propeller Interaction for a Tilt-Body MAV

An experimental investigation of the interaction of a propeller-wing configuration for a tilt body MAV VTOL was performed in the low speed wind tunnel. This study’s primary objective is to present the effect of the interactions between a low aspect ratio wing and propeller for a range of incidence in transition between horizontal and vertical flight. During the transition from horizontal flight to vertical flight or vice versa, the flow patterns seen by the wing are the result of the combination between the free-stream and the propeller flow. This was reflected in the change of the aerodynamic forces and moments of the wing. The model is a tractor configuration propeller and with a wing of aspect ratio equal to one, the airfoil of the wing is a NACA 0012. All tests were conducted at low speeds in a range from 2 to 8 m/s. In order to simulate the transition flight of a tilt-body MAV VTOL a range of incidence from -10 to 90 degrees was used. The results show that the flow of the propeller certainly improves the aerodynamic characteristics of the wing, increasing the lift and delaying stall with respect to the flight path of the MAV

SPRING-IN ANGLE PREDICTION FOR THERMAL SHRINKAGE IN CROSS-PLY LAMINATE

   Thermal shrinkage in advanced composite manufacturing causes residual stress in a cylindrical anisotropic segment. The residual stress later induces a spring-in angle when  the temperature change is negative. The superposition method in the finite element method (FEM) by ABAQUS©  proves that only the residual stress in the circumferential direction controls the spring-in angle and induces the radial residual stress. To predict the angle change, the residual stress is firstly determined by using the closed-loop geometry in FEM and then implemented into the cylindrical cross-ply symmetric laminate segment. Consequently, the geometry creates the spring-in angle under the traction-free surface. The angle change is in good agreement with the Radford equation and is found to depend on the coefficient of thermal expansion (CTE) in the circumferential and radial directions rather than other material properties and geometry dimensions.  The study found a new limitation of the Radford equation, in that it is accurate when the part is anisotropic symmetric laminate, but not when it is unsymmetric. The accuracy of the Radford equation is further explored with the double curve geometry. Using the superposition method, the circumferential residual stress along the major curve is found to have an influence on the angle change not only of the major curve, but also of the minor curve. The negative temperature change produces the spring-in angle on the major curve, and both spring-in and -off angles on the minor curve, which rely on the radius ratio. In addition, the spring-in angle on the major curve is coincident with the Radford equation. In sum, knowing the spring-in angle is very helpful in designing a tool in advanced composite manufacturing, and the superposition method and the Radford equation are applicable to predict the spring-in angle.</p