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Acta Aeronautica et Astronautica Sinica ›› 2024, Vol. 45 ›› Issue (7): 128047-128047.doi: 10.7527/S1000-6893.2022.28047

• Fluid Mechanics and Flight Mechanics • Previous Articles     Next Articles

Adaptive fast optical flow solution to velocity field of fluorescent oil film

Zhangbo CAI1, Zhengyu ZHANG2(), Hao YU2, Shuheng ZHAN1   

  1. 1.School of Information Engineering,Southwest University of Science and Technology,Mianyang 621000,China
    2.High Speed Aerodynamics Institute,China Aerodynamics Research and Development Center,Mianyang 621000,China
  • Received:2022-09-26 Revised:2022-11-14 Accepted:2022-12-12 Online:2024-04-15 Published:2023-01-01
  • Contact: Zhengyu ZHANG E-mail:zhang_zy@189.cn
  • Supported by:
    National Natural Science Foundation of China(11872069)

Abstract:

The existing optical flow methods takes a long time to solve the friction measurement equations based on the fluorescent oil film, restricting the application of fluorescent oil film tests in the wind tunnel. Therefore, a spatially adaptive fast optical flow method for the fluorescent oil film velocity field is proposed. The conjugate iterative formula of the optical flow is constructed, with a smaller storage capacity, higher convergence and stability than those of theJacobian-like matrix segmentation iteration used by the existing optical flow methods. On the other hand, based on the grayscale gradients of a given fluorescent oil film image, the prominent flow structures can be quickly obtained by a spatially adaptive down sampling method, then up sampling to obtain the refined flow structures by conjugate iteration and executing global optimization, and the speed of solving the velocity field of the fluorescent oil film is significantly improved. Simulation examples show that the calculation speed of this algorithm is 26.6% higher than that of the existing optical flow method under the given convergence error limits, the average errors are reduced by 1.4%, and the maximum error is reduced by 2.3% under the same preset number of iterations. The results of the oil film tests in the wind tunnel show that the wall flow phenomenon measured by this algorithm is correct, and the flow spectrum is clear and precise. Compared with the existing optical flow method, this new method has a speed increase of 23% on average, exhibiting important application value in engineering.

Key words: optical flow, conjugate gradient method, adaptive sampling, fluorescent oil film, velocity field

CLC Number: