Research of the Propulsion Characteristics of Neil Pryde RS:X Pumping Based on Wind Tunnel

Objective: Investigating the effects of pumping factors on the aerodynamic and propulsion characteristics of the sail wing.Methods: The experiment of RS: X wing model was conducted in the low turbulence wind tunnel and the system of modified flapping. Results: While planning, the aerodynamic force of the sail wing increased with the increasing of attack angle and wind speed. The lift coefficient of the sail wing was similar when the wind speed was 5 m/s and 6 m/s, but the drag coefficient was lower when the wind speed was 6 m/s than 5 m/s. While pumping, aerodynamic force of the sail wing changed periodically, the lift force increased and the drag force decreased slightly when the pumping frequency increased. As the course angle was 35°, the thrust coefficient had no increase when attack angle increased, but a phase difference was observed, the coefficient of instantaneous energy consumption cost increased obviously. The propulsion of the sail wing could be improved by increasing pumping frequency or amplitude. Meanwhile, the instantaneous energy consumption cost was doubled, but more energy consumption was needed when the pumping frequency was increased than that of pumping amplitude. Conclusions: The pumping could improve the aerodynamic force of the sail wing more effectively than planning, wind speed was the main factor affecting the characteristics of aerodynamic and propulsion. Adjusting the attack angle according to the wind-force during competition was the foundation to ensure the maneuverability of the sail wing. Increasing the frequency of pumping could improve the propulsion of the sail, but the instantaneous energy consumption cost was large, which required the athletes high levels of both physical fitness and ability of sail maneuverability. Briefly, coordination of the frequency and amplitude of the pumping guaranteed the high efficency propulsion of the sail wing.