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Acta Aeronautica et Astronautica Sinica ›› 2024, Vol. 45 ›› Issue (9): 529084-529084.doi: 10.7527/S1000-6893.2023.29084

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Flow control drag reduction of hub on coaxial rigid rotor aircraft

Chang WANG1,2, Long HE2, Dongxia XU2(), Min TANG2, Shuai MA5, Ximing WU4   

  1. 1.School of Aerospace Engineering,Tsinghua University,Beijing 100084,China
    2.Low Speed Aerodynamics Institute,China Aerodynamics Research and Development Center,Mianyang 621000,China
    3.School of Aeronautic Science and Engineering,Beihang University,Beijing 100191,China
    4.Chinese Aeronautical Establishment,Beijing 100029,China
    5.Computational Aerodynamics Institute,China Aerodynamics Research and Development Center,Mianyang 621000,China
  • Received:2023-05-30 Revised:2023-08-07 Accepted:2023-11-13 Online:2024-05-15 Published:2024-02-02
  • Contact: Dongxia XU E-mail:dongxiaxu@163.com
  • Supported by:
    Provincial and Ministerial Level Project(221GJBJK0016)

Abstract:

In response to the issue that the hub drag accounts for a significant portion of the overall drag in the coaxial rigid rotor helicopter during high-speed forward flight, the flow mechanism of the hub model without blades is studied through numerical simulation and wind tunnel tests. The outer shape of the intermediate shaft fairing is optimized to achieve better drag reduction effects. Meanwhile,based on the optimized hub shape and flow field analysis results, an active flow control strategy with jet blowing is introduced, and its impact on hub drag reduction is investigated through wind tunnel tests using different slot configurations, gap sizes, jet angles, and jet momentum coefficients. The feasibility of using active flow control technology for hub drag reduction in coaxial dual-rotor hubs is demonstrated. The intermediate shaft fairing can effectively reduce the airflow separation at the rear of the intermediate shaft, achieving the goal of reducing the drag of the coaxial rigid rotor hub. The drag area of the HBF2 configuration is reduced by 30.3% compared to that of the HBS configuration. The drag area of the hub model with blade roots in rotation is larger than that without blade roots. The proposed active flow control technology can suppress the flow separation at the trailing edge of the intermediate shaft fairing to achieve drag reduction. The oblique jet configuration has a better drag reduction effect than the straight jet configuration. When using the oblique slot configuration with a gap size of 1 mm, jet angle of 30°, and jet momentum coefficient of 0.33, the hub drag can be further reduced by 13% compared to that based on the optimized intermediate shaft fairing shape, achieving the best drag reduction effect.

Key words: coaxial rigid rotor, hub drag, intermediate shaft fairing, flow control, numerical simulation, wind tunnel test

CLC Number: