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ACTA AERONAUTICAET ASTRONAUTICA SINICA ›› 2022, Vol. 43 ›› Issue (11): 527330-527330.doi: 10.7527/S1000-6893.2022.27330

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Natural laminar flow optimization and transition sensitivity analysis of axisymmetric nacelle

CAO Fan, ZHANG Meifang, HU Xiao, TANG Zhili   

  1. Key Laboratory of Unsteady Aerodynamics and Flow Control, Ministry of Industry and Information Technology, College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
  • Received:2022-04-27 Revised:2022-07-04 Online:2022-11-15 Published:2022-08-17
  • Supported by:
    National Natural Science Foundation of China (12032011,11772154);A Project Funded by the Priority Academia Program Development of Jiangsu Higher Education Institutions (PAPD)

Abstract: The turbofan engine nacelle with a large bypass ratio has large friction drag. At a high Reynolds number, reducing the friction drag on the nacelle surface using the Natural Laminar Flow (NLF) is an effective measure to reduce the total drag of the nacelle. To improve the efficiency of aerodynamic optimization, a hybrid evolutionary/deterministic optimization algorithm is developed, and, combined with a 6th order Class and Shape Transformation (CST) parameterization and a turning model, it is applied to the design of axisymmetric nacelles with NLF and geometric constraints at a high Reynolds number. Sensitivity studies on the local geometry sensitivity, the Mass Flow Ratio (MFR) and the Mach number (Ma) of the designed axisymmetric laminar nacelle are conducted to maintain stable laminar flow performance. The results show that the hybrid optimization algorithm can significantly improve the optimization efficiency and is successfully applied to the nacelle aerodynamic shape optimization. Under the influence of univariate geometric parameters, the head region of the nacelle shape has the most significant effect on the pressure distribution and laminar flow range, which is the key area of concern for laminar flow design. The variation of the flow coefficient and Mach number causes the large fluctuation of the laminar flow range. The designed nacelle can maintain the laminar flow in the range of more than 20% at the design point MFR=0.7 and Ma=0.85.

Key words: natural laminar flow nacelle, transition prediction, hybrid optimization algorithm, CST parameterization, sensitivity analysis

CLC Number: