Dynamic Analysis and Design of Pumping Frequency and Amplitude for RS:X Class on the Windward Leg

Objective: To explore the impact of the combination of frequency and amplitude on the pumping propulsion performance of the sail wing, so as to provide personalized and scientific suggestions for athletes to control sailing. Methods: Determining the sailing characteristics and establishing the pumping model firstly, then the SST k-ω turbulence model was employed to solve the aerodynamic variation of the pumping wing based on URANS. Under the condition of 20° attack angle and 3 m/s speed of upwind,the thrust coefficient and energy consumption coefficient of the sail wing with a combination of 0.67—2.00 frequencies and 2—10°amplitudes were investigated. Results: When the pumping frequency was 0.67 Hz to 1.00 Hz, the thrust coefficient and yaw force coefficient were increased with amplitude. When the pumping frequency was 1.30 Hz to 2.00 Hz, both thrust coefficient and yaw force coefficient were increased firstly and then decreased, and the wing propulsion performance was optimal when amplitude was8°. The energy consumption coefficient of the pumping wing was elevated with amplitude and frequency, the energy consumption of large-amplitude plus high-frequency was 25 times higher than that of large-amplitude plus low-frequency, and 10 times higher than that of small-amplitude plus high-frequency. Conclusion: To achieve the optimal propulsion performance, the low frequency pumping should combine with a larger amplitude, while the high frequency pumping should combine with a middle amplitude.