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Visualisation on supersonic flow over backward-facing step with or without roughness

Zhu, Yangzhu LU ; Yi, Shihe; Gang, Dundian and He, Lin (2015) In Journal of Turbulence 16(7). p.633-649
Abstract
At Mach number 3.4, visualisation experiments of flowover backward-facing step (BFS) with or without roughness band attached on upstream wall are carried out via traditional schlieren and newly developed nano-tracer-based planar laser scattering (NPLS). The time-averaged flow characteristic of the reattachment region and the instantaneous rich structures of the redeveloping boundary layer in the steamwise-normal plane are both revealed. Additionally, top views in the different planes (y/h = 0.67, 1.00, 1.33, 1.67, 2.00) are imaged with a resolution of 0.064 mm/pixel. By contrasting the NPLS images at different times, the unsteady evolution characteristic of the coherent vortices in the redeveloping boundary layer was discussed. Static wall... (More)
At Mach number 3.4, visualisation experiments of flowover backward-facing step (BFS) with or without roughness band attached on upstream wall are carried out via traditional schlieren and newly developed nano-tracer-based planar laser scattering (NPLS). The time-averaged flow characteristic of the reattachment region and the instantaneous rich structures of the redeveloping boundary layer in the steamwise-normal plane are both revealed. Additionally, top views in the different planes (y/h = 0.67, 1.00, 1.33, 1.67, 2.00) are imaged with a resolution of 0.064 mm/pixel. By contrasting the NPLS images at different times, the unsteady evolution characteristic of the coherent vortices in the redeveloping boundary layer was discussed. Static wall pressure is measured by a micro-pressure scanning system. The incipient formation positions are pointed out statistically. Without roughness, the longitudinal structures with scales of 1.0h and 1.2h form later and distribute in a longer region compared to that with roughness. Fractal analysis is applied and the averaged fractal dimensions of the overall and sectional flow structures are calculated. If roughness is adopted, the fractal dimension will be larger and the turning point in the sectional fractal dimensions is earlier. However, the dimension tends to be one coincided value in the farther downstream. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
supersonic, visualisation, backward-facing step, flow structures, flow, control
in
Journal of Turbulence
volume
16
issue
7
pages
633 - 649
publisher
Taylor & Francis
external identifiers
  • wos:000352610300003
  • scopus:84927623511
ISSN
1468-5248
DOI
10.1080/14685248.2015.1021473
language
English
LU publication?
yes
id
044bcaf8-82e2-4b1a-ba07-65bff547c858 (old id 5402774)
date added to LUP
2015-05-19 13:26:02
date last changed
2017-01-01 06:14:27
@article{044bcaf8-82e2-4b1a-ba07-65bff547c858,
  abstract     = {At Mach number 3.4, visualisation experiments of flowover backward-facing step (BFS) with or without roughness band attached on upstream wall are carried out via traditional schlieren and newly developed nano-tracer-based planar laser scattering (NPLS). The time-averaged flow characteristic of the reattachment region and the instantaneous rich structures of the redeveloping boundary layer in the steamwise-normal plane are both revealed. Additionally, top views in the different planes (y/h = 0.67, 1.00, 1.33, 1.67, 2.00) are imaged with a resolution of 0.064 mm/pixel. By contrasting the NPLS images at different times, the unsteady evolution characteristic of the coherent vortices in the redeveloping boundary layer was discussed. Static wall pressure is measured by a micro-pressure scanning system. The incipient formation positions are pointed out statistically. Without roughness, the longitudinal structures with scales of 1.0h and 1.2h form later and distribute in a longer region compared to that with roughness. Fractal analysis is applied and the averaged fractal dimensions of the overall and sectional flow structures are calculated. If roughness is adopted, the fractal dimension will be larger and the turning point in the sectional fractal dimensions is earlier. However, the dimension tends to be one coincided value in the farther downstream.},
  author       = {Zhu, Yangzhu and Yi, Shihe and Gang, Dundian and He, Lin},
  issn         = {1468-5248},
  keyword      = {supersonic,visualisation,backward-facing step,flow structures,flow,control},
  language     = {eng},
  number       = {7},
  pages        = {633--649},
  publisher    = {Taylor & Francis},
  series       = {Journal of Turbulence},
  title        = {Visualisation on supersonic flow over backward-facing step with or without roughness},
  url          = {http://dx.doi.org/10.1080/14685248.2015.1021473},
  volume       = {16},
  year         = {2015},
}