Experimental Analysis on Pitching Moment for Embedment Cylinder to Flat Plate High Altitude Platform Station

Due to the evolution of advanced technologies and their broad range of applications in numerous domains such as military, industrial, and scientific purposes, worldwide interest in High Altitude Platform Stations (HAPS) continue to rise. Researchers and experts worldwide have taken the initiative and conducted studies to create and build high-efficiency and safe HAPS. However, far too little attention has been paid to designing HAPS by embedding cylinders into a flat plate. The primary concern of the design is whether the approach of injecting the Magnus effect would be able to improve the aerodynamics and stability of the flat plate. To date, a new Cylinder to Flat Plate to Cylinder (CyFlaP) HAPS has been designed that incorporates the Magnus effect on a bluff body with the goal of increasing its aerodynamic performance. This project intends to analyze the pitching moment coefficient due to the rotational direction and rotational speed of the rotating cylinders. The tests were conducted for different Reynolds numbers (Re) ranging from Re = 2.55 × 105 to 9.10 × 105 which implicitly implied different free stream velocities varying from 2.80 to 10.05 m/s for different angles of attack ranging from α = −20° to α = 20°. Data for this study were collected using experimental analysis of the model in the closed-loop wind tunnel. Among the documented data, only the ones that had a higher rotational speed with clockwise rotating cylinders displayed a negative slope of moment coefficient over the specified range of angle of attack, with the highest negative moment coefficient recorded to be \({C}_{M}\)  = −0.04 at the angle of attack, α = 10°. The analysis shows that the CyFlaP is able to fly in a longitudinal static stable state at 10.05 m/s (Re = 9.10 × 105) when the rotating cylinders are rotated in the clockwise-clockwise direction at a speed of 2322 RPM. This highlights the capability of the CyFlaP to fly steadily.