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Acta Aeronautica et Astronautica Sinica ›› 2025, Vol. 46 ›› Issue (12): 131395.doi: 10.7527/S1000-6893.2025.31395

• Fluid Mechanics and Flight Mechanics • Previous Articles    

Rotor vortex ring state inflow model suitable for flight mechanics analysis

Jinghan WEN1, Honglei JI1(), Haoxuan DENG2, Chang WANG2   

  1. 1.College of Aerospace Engineering,Chongqing University,Chongqing 400044,China
    2.Key Laboratory of Rotor Aerodynamics,China Aerodynamics Research and Development Center,Mianyang 621000,China
  • Received:2024-10-12 Revised:2024-12-02 Accepted:2025-01-22 Online:2025-02-17 Published:2025-02-10
  • Contact: Honglei JI E-mail:jhl@cqu.edu.cn
  • Supported by:
    National Level Project(FKFB20231108015┫?);Natural Science Foundation of Chongqing(CSTB2022NSCQ-MSX1592);Open Research Program of Key Laboratory of Rotor Aerodynamics, China Aerodynamics Research and Development Center(RAL202302-3);National Natural Science Foundation of China(11902052)

Abstract:

To meet the application requirements of helicopter special situation simulation, a rotor vortex ring state inflow model is established for flight mechanics analysis. Based on the turning relationship of the helicopter vertical motion damping in the rotor vortex ring state, the joint tip vortex motion equation and the modified rotor momentum theory equation are solved to obtain the critical damping boundary of the rotor vortex ring state. The climb rates and induced velocities of the rotor entering and exiting the vortex ring state are given. Cubic spline functions are used to establish a rotor vortex ring state induced velocity model, and the dynamic delay time of the rotor vortex ring state induced velocity is derived from the evolution relationship of the concentrated vorticity in the vortex ring state. Thus, a unified critical damping boundary for the rotor vortex ring state and dynamic inflow model are formed. On this basis, the rotor aerodynamic load model and the flight dynamics model of the helicopter vortex ring state are established, and the wind tunnel and flight test data are used to verify the model. The results show that the proposed model can reasonably and accurately predict the critical damping boundary of the rotor vortex ring state and the changes of the rotor induced velocity with the helicopter descent rate and forward flight speed. Combined with the rotor aerodynamic load model, the proposed model can accurately predict the changes of the rotor tension and increment of torque coefficient with the helicopter descent rate trend. Comparison with flight test data shows that the proposed model accurately simulates the dynamic characteristics of helicopter vertical damping in the rotor vortex ring state, and is suitable for flight mechanics analysis applications.

Key words: helicopter, rotor, vortex ring state, induced velocity, flight dynamics

CLC Number: