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ACTA AERONAUTICAET ASTRONAUTICA SINICA ›› 2016, Vol. 37 ›› Issue (8): 2490-2497.doi: 10.7527/S1000-6893.2015.0363

• Numerical Simulation Investigations of Unsteady Flow • Previous Articles     Next Articles

A method for effectiveness analysis of flow separation control by local actuation based on Lagrangian coherent structures

KANG Wei1, ZHANG Quanqi1, DAI Xiangyan2, LIU Lei1   

  1. 1. School of Astronautics, Northwestern Polytechnical University, Xi'an 710072, China;
    2. Science and Technology on Plasma Dynamics Laboratory, School of Aeronautics and Astronautics Engineering, Airforce Engineering University, Xi'an 710038, China
  • Received:2015-09-16 Revised:2015-12-30 Online:2016-08-15 Published:2016-01-25
  • Supported by:

    National Natural Science Foundation of China (11402212);the Fundamental Research Funds for the Central Universities (3102014JCQ01002)

Abstract:

A numerical method for the effectiveness analysis for the flow separation control by local periodic actuation is presented from the perspective of fluid transport. Finite time invariant manifold theory is used for the establishment for fluid transport analysis of unsteady flow. The attracting Lagrangian coherent structures (LCSs) and the repelling LCSs are extracted from the unsteady flow field using numerical method to describe the behaviors of fluid transport. Study on the flow separation control of local periodic excitation indicates that there exist three kinds of fluid transport mode with actuating frequency affecting the aerodynamic performance of the airfoil. In particular, as the actuation with lock-in frequency is activated, the material spike formed at the leading edge from the attracting LCSs effectively enhances the fluid exchange between mainstream and separation region, which reduces the area of separation zone, and significantly improves the airfoil lift.

Key words: flow separation, flow control, frequency lock-in, fluid transport, Lagrangian coherent structure, lift enhancement

CLC Number: