Imperial College London

ProfessorSpencerSherwin

Faculty of EngineeringDepartment of Aeronautics

Professor of Computational Fluid Mechanics
 
 
 
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Contact

 

+44 (0)20 7594 5052s.sherwin Website

 
 
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Location

 

313BCity and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Mao:2017:10.1017/jfm.2017.240,
author = {Mao, X and Zaki, TA and Sherwin, SJ and Blackburn, HM},
doi = {10.1017/jfm.2017.240},
journal = {Journal of Fluid Mechanics},
pages = {604--632},
title = {Transition induced by linear and nonlinear perturbation growth in flow past a compressor blade},
url = {http://dx.doi.org/10.1017/jfm.2017.240},
volume = {820},
year = {2017}
}

RIS format (EndNote, RefMan)

TY  - JOUR
AB - Flow past a NACA 65 blade at chord-based Reynolds number 138 500 is studied using stability analysis, generalized (spatially weighted) transient growth analysis and direct numerical simulations (DNS). The mechanisms of transition on various sections of the blade observed in previous work by Zaki et al. (J. Fluid Mech., vol. 665, 2010, pp. 57-98) are examined, with a focus on the pressure side around the leading edge. In this region, the linearly most energetic perturbation has spanwise wavenumber 40π (five boundary-layer thicknesses) and is tilted against the mean shear to take advantage of the Orr mechanism. In a DNS, the nonlinear development of this optimal perturbation induces Λ structures, which are further stretched to hairpin vortices before breaking down to turbulence. At higher spanwise wavenumber, e.g. 120π, a free-stream optimal perturbation is obtained upstream of the leading edge, in the form of streamwise vortices. During its nonlinear evolution, this 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. This layout of streaks generates a mean shear with two inflectional points and activates secondary instabilities, namely inner and outer instabilities previously reported in the literature.
AU - Mao,X
AU - Zaki,TA
AU - Sherwin,SJ
AU - Blackburn,HM
DO - 10.1017/jfm.2017.240
EP - 632
PY - 2017///
SN - 0022-1120
SP - 604
TI - Transition induced by linear and nonlinear perturbation growth in flow past a compressor blade
T2 - Journal of Fluid Mechanics
UR - http://dx.doi.org/10.1017/jfm.2017.240
UR - http://hdl.handle.net/10044/1/57182
VL - 820
ER -