Improving the Aerodynamic Performance of Micro-Air-Vehicle-Scale Cycloidal Rotor: An Experimental Approach

Abstract

Performance and flowfield measurements were conducted on a small-scale cyclorotor for application to a micro air vehicle. Detailed parametric studies were conducted to determine the effects of the number of blades, rotational speed, and blade pitching amplitude. The results showed that power loading and rotor efficiency increased when using more blades; this observation was found over a wide range of blade pitching amplitudes. The results also showed that operating the cyclorotor at higher pitching amplitudes resulted in improved performance, independently of the number of blades. A momentum balance performed using the flowfield measurements helped to quantify the vertical and sideward forces produced by the cyclorotor; these results correlated well with the force measurements made using load balance. Increasing the number of blades increased the inclination of the resultant thrust vector with respect to the vertical because of the increasing contribution of the sideward force. The profile drag coefficient of the blade sections computed using a momentum deficit approach correlated well with typical values at these low chord Reynolds numbers. Particle image velocimetry measurements made inside the cage of the cyclorotor showed that there are rotational flows that, when combined with the influence of the upper wake on the lower half of the rotor, explain the relatively low efficiency of the cyclorotor.

Experimental and Computational Studies to Understand the Role of Flow Curvature Effects on the Aerodynamic Performance of a MAV-Scale Cycloidal Rotor in Forward Flight

“…[15]. Previous studies performed at the University of Maryland [10,[15][16][17][18][19][20] included systematic experimental studies on a micro-scale cycloidal rotor with rotor dimensions of approximately 6 inches (0.152 meters) in diameter and span. A wide range of kinematic and geometric parameters were systematically varied to study their impact on rotor performance in hover.…”

Numerical Analysis of Design Parameters With Strong Influence on the Aerodynamic Efficiency of a Small-Scale Self-Pitch VAWT

“…This mechanism, which has proved well for cyclogyros used in aeronautical propulsion [10,[10][11][12][12][13][14][15], is simple, reliable and has the ability to self-adjust the turbine dynamics as a function of the rotating speed of the rotor, and also on the direction and magnitude of the incoming wind. It is noted that the system kinematics also allows for an asymmetric pitching schedule of the blades, which could be beneficial since the frontal area of the rotor operates at a different angle of attack than the rear region.…”

PECyT - Plasma Enhanced Cycloidal Thruster

“…Hwang et al 10,11 developed a four-rotor cyclocopter with elliptic blades that produces a spanwise uniform distribution of the induced velocity, that could open the possibly of exploiting aeroelastic tailoring in such a way that the aerodynamic loads themselves induce twist changes, which will improve the distribution of induced velocity for different operating conditions. A throughout study on the understanding of cyclorotors was taken by Benedict et al 12,13,14,15 They have study 12 the influence of the number of blades on the performance of a 0.152 m in diameter/span cyclorotor composed by NACA0010 airfoils with a uniform chord of 0.0254 m. Their main conclusion was that, for small scale cyclorotors with a number of blades up to five and a maximum pitching amplitude of 40 deg, the power loading increases with the increasing number of blades. Different rotor parameters, like airfoil section, blade flexibility, blade camber, rotor radius, blade span, rotor aspect-ratio, rotor solidity, blade planform and blade kinematics were also analysed by Benedict et al 13,15 They found out that for lowReynolds numbers the airfoil section does not plays a significant role in the aerodynamic performance of a cyclorotor, since the inverted NACA0010 airfoil produces similar values of efficiency when compared with the baseline NACA0010, cambered blades resulted in lower efficiency when compared with symmetrical ones.…”