A solar photovoltaic system consists of tilted panels and is prone to extreme wind loads during hurricanes or typhoons. To ensure the proper functioning of the system, it is important to determine its aerodynamic characteristics. Offshore photovoltaic (PV) systems have been developed in recent years. Wind loads are associated with wind, wave climates, and tidal regimes. In this study, the orientation of a single panel is adjusted to different angles of tilt (10°–80°) and angles of incidence for wind (0°–180°) that are pertinent to offshore PV panels. The critical wind loads on a tilted panel are observed at lower angles of incidence for the wind, when the angle of tilt for the panel is greater than 30°.

This study experimentally determines the wind loads on a stand-alone solar array (length-to-width ratio of 0.19; 1/10-scale commercial modules). The freestream velocity in a uniform flow is 14.5 ± 0.1 m/s, and the turbulence intensity is 0.3%. The angle of tilt ranges from 10° to 80° and the wind is incident at angle of 0°–180°. Mean surface pressure measurements on the upper and the lower surface of the inclined solar panels are used to calculate the lift coefficient. For the angle of incidence of 0°–60° for the wind, the variation in the lift coefficient with the angle of tilt is U-shaped. The formation of a strong windward corner vortex results in greater lift force on the right half of the inclined plate for the angle of incidence of 30°–45° for the wind.

This numerical simulation determines the wind loads on a stand-alone solar panel in a marine environment. The initial angle of tilt is 20° and 40° and the wind is incident at an angle of 0–180° (in increments of 45°). The wave angle affects the motion of a pontoon. For a wave angle of 0–180° (in increments of 45°), the variation in the surface pressure pattern and the lift coefficient with the angle of incidence of wind and waves in a single period is determined. The lift force is determined by competing the tilt angle for the upper surface with respect to wind and variation in roll angle for a specific wave angle. The data are pertinent to structural design for photovoltaic systems in a marine environment.

An alula is a small structure of feathers that prevents birds from stalling. In this study, the aerodynamic effect of an alula-like vortex generator (alula-VG) on a revolving wing was investigated using the PIV technique in a water tank. The alula-VG was mounted on a rectangular wing model at two spanwise positions. The wing model with a revolving motion was installed at different angles of attack, which included pre-stall and post-stall conditions. The velocity fields around the wing model with/without an alula-VG were measured and analyzed, including the vorticity contour, the circulation of vortex structures, and the corresponding sectional lift coefficient, which are used to explain the aerodynamic effect induced by an alula-VG. The lift-off and bursting of the leading-edge vortex (LEV) affect the magnitude of the chordwise circulation and the section lift coefficient. The results show that compared to an alula-VG mounted fixed wing model, the flow interactions among the alula-VG induced spanwise flow, the inertial force caused by the revolving motion, and the wing-tip vortex play important roles in the vortex bursting and the resultant aerodynamic performance. The effect of an alula-VG on a revolving wing depends on its spanwise position and the angle of attack of a wing model, which need to be properly matched.

Herein, the pressure-sensitive paint (PSP) was used to quantitatively investigate the aerodynamic effect of an alula-like vortex generator, which is a bio-inspired passive flow control structure. The global pressure distributions on the upper surface at different angles of attack were measured to determine the strength of sectional suction forces on the wing. An alula-like vortex generator equipped at the leading edge of the wing enlarged the area of the suction region (negative pressure coefficient) on the upper surface in both the streamwise and spanwise directions under near-stall and deep-stall conditions, which is related to the generation of lift and avoiding the stall of wing. A wing model equipped with a vortex generator of an 11% height/chord length ratio exhibited the greatest performance at all angles of attack. In this study, the use of PSP technique not only helps to understand the aerodynamic effect of the alula-like vortex generator but also shows a perspective tool for bio-inspired MAVs design.