Velocity statistics along the stagnation line of an axi-symmetric stagnating turbulent flow

Toshihisa Ueda, H. Imaizumi, M. Mizomoto, I. G. Shepherd

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Velocity statistics along the stagnation line of an axi-symmetric wall stagnating turbulent flow are studied experimentally. A low turbulence, uniform air flow from a nozzle type air supply with an exit diameter of 50 mm stagnates at a wall located 50 mm downstream. A flow velocity is set to 3 m/s, 10 mm downstream from the exit of the air supply. Instantaneous values of streamwise and radial velocities are measured by laser-Doppler velocimetry. The turbulence level in the air flow is changed by use of turbulence generator. When the turbulence generator is not installed in the air supply, the mean velocity profile in the streamwise direction fits well with that of a laminar viscous flow with the rms value of velocity fluctuations low near the wall. With the turbulence generator installed, a significant turbulence structure appears near the wall. When the wall is approached, the rms value of velocity fluctuations in the streamwise direction decreases monoloncally while the profile of the rms value in the radial direction reaches a maximum near the wall. The increase in the rms value of velocity fluctuations in the radial direction near the wall is attributed to the bi-modal histogram of the fluctuating velocity in the radial direction. Near the wall. the instantaneous stagnation streamline fluctuates and the probability of the mean location of the stagnation point reaches a maximum not at the stagnation line but on a circle around the stagnation line, resulting in the bi-modal histogram. Turbulence statistics, the rms value of velocity fluctuation and the turbulent kinetic energy, can be normalized successfully by similarity parameters based on the strain rate and the reference turbulent kinetic energy introduced by Champion and Libby.

Original languageEnglish
Pages (from-to)473-481
Number of pages9
JournalExperiments in Fluids
Volume22
Issue number6
Publication statusPublished - 1997

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turbulent flow
Turbulent flow
Statistics
statistics
Turbulence
turbulence
Air
generators
air flow
histograms
Kinetic energy
air
kinetic energy
low turbulence
stagnation point
viscous flow
Viscous flow
Flow velocity
radial velocity
Velocity measurement

ASJC Scopus subject areas

  • Mechanical Engineering
  • Fluid Flow and Transfer Processes
  • Mechanics of Materials
  • Computational Mechanics

Cite this

Ueda, T., Imaizumi, H., Mizomoto, M., & Shepherd, I. G. (1997). Velocity statistics along the stagnation line of an axi-symmetric stagnating turbulent flow. Experiments in Fluids, 22(6), 473-481.

Velocity statistics along the stagnation line of an axi-symmetric stagnating turbulent flow. / Ueda, Toshihisa; Imaizumi, H.; Mizomoto, M.; Shepherd, I. G.

In: Experiments in Fluids, Vol. 22, No. 6, 1997, p. 473-481.

Research output: Contribution to journalArticle

Ueda, T, Imaizumi, H, Mizomoto, M & Shepherd, IG 1997, 'Velocity statistics along the stagnation line of an axi-symmetric stagnating turbulent flow', Experiments in Fluids, vol. 22, no. 6, pp. 473-481.
Ueda, Toshihisa ; Imaizumi, H. ; Mizomoto, M. ; Shepherd, I. G. / Velocity statistics along the stagnation line of an axi-symmetric stagnating turbulent flow. In: Experiments in Fluids. 1997 ; Vol. 22, No. 6. pp. 473-481.
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