Bypass transition induced by free-stream noise in flow past a blade cascade

Xuerui Mao*, Tamer Zaki, Spencer Sherwin, Hugh Blackburn

*此作品的通讯作者

科研成果: 会议稿件论文同行评审

摘要

Flow past a NACA 65 blade cascade at Reynolds number 138, 500 is studied through weighted transient growth and Direct Numerical Simulations (DNS). The mechanism of bypass transition on the pressure side around the leading edge observed in a previous work [1] is examined. The weighted optimal initial perturbations have spanwise wavenumber 40π and are amplified via the Orr mechanism. At higher spanwise wavenumber, e.g. 120π, a free-stream optimal initial perturbation, upstream of the leading edge in the form of streamwise vortices, is obtained. In nonlinear evolution, this high-wavenumber optimal perturbation tilts the mean shear and generates spanwise periodic high and low-speed streaks. Then through a nonlinear lift-up mechanism, the low-speed streaks are lifted above the high-speed ones and generate a mean shear with inflectional points. This layout of streaks activates secondary instabilities and both inner and outer instabilities addressed in literature are observed.

源语言英语
出版状态已出版 - 2019
已对外发布
活动16th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery, ISROMAC 2016 - Honolulu, 美国
期限: 10 4月 201615 4月 2016

会议

会议16th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery, ISROMAC 2016
国家/地区美国
Honolulu
时期10/04/1615/04/16

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