EFFECT OF INLET TURBULENCE INTENSITY ON TRANSPORT PHENOMENA OVER BLUFF BODIES

Himadri Chattopadhyay; Sudhir Chandra Murmu

doi:10.1615/interjfluidmechres.2020034333

EFFECT OF INLET TURBULENCE INTENSITY ON TRANSPORT PHENOMENA OVER BLUFF BODIES

International Journal of Fluid Mechanics Research ◽

10.1615/interjfluidmechres.2020034333 ◽

2020 ◽

Vol 47 (6) ◽

pp. 485-499

Author(s):

Himadri Chattopadhyay ◽

Sudhir Chandra Murmu

Keyword(s):

Turbulence Intensity ◽

Transport Phenomena ◽

Bluff Bodies

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TRANSPORT PHENOMENA OVER BLUFF BODIES AT VARYING INLET TURBULENT INTENSITY

Heat Transfer Research ◽

10.1615/heattransres.2018019048 ◽

2018 ◽

Cited By ~ 2

Author(s):

Himadri Chattopadhyay ◽

S Murmu

Keyword(s):

Transport Phenomena ◽

Turbulent Intensity ◽

Bluff Bodies

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The Effects of Turbulence and Unsteadiness on Vortex Shedding From Sharp-Edged Bluff Bodies

Journal of Fluids Engineering ◽

10.1115/1.2817501 ◽

1996 ◽

Vol 118 (1) ◽

pp. 18-25 ◽

Cited By ~ 20

Author(s):

M. C. Wolochuk ◽

M. W. Plesniak ◽

J. E. Braun

Keyword(s):

Strouhal Number ◽

Turbulent Flows ◽

Turbulence Intensity ◽

Vortex Shedding ◽

Bluff Body ◽

Base Case ◽

Length Scale ◽

Bluff Bodies ◽

Pressure Amplitude ◽

Flow Meters

Motivated by a desire to evaluate vortex shedding flow meters for measuring velocity in unsteady turbulent flow applications, the objective of our work was to study the effects of flow disturbances on vortex shedding from sharp-edged bluff bodies. In particular, the combined effects of turbulence and unsteadiness were examined, as well as their separate effects using controlled wind tunnel tests. After causing an initial and sudden decrease in the Strouhal number, increasing turbulence intensity from 2.5 to 10 percent resulted in only a 2.4 percent increase in the Strouhal number, for turbulence with a length scale of 0.5 bluff body diameters. Turbulence integral length scale had a significant influence on the Strouhal number, with the greatest effect exhibited for length scales near 3 bluff body diameters. Turbulence of this length scale caused a 26 percent decrease in the Strouhal number, as compared to a low-turbulence base case. Fluctuating pressure amplitude and signal-to-noise ratio were also affected by turbulence, and decreased significantly when the integral length Kali was increased from 0.25 to 0.75 bluff body diameters for a turbulence intensity of 10 percent. Unsteadiness caused lock-on for forcing at the Strouhal frequency, twice and four times the Strouhal frequency, while no lock-on was observed for forcing at half the Strouhal frequency. The range of lock-on increased with increasing perturbation amplitude and was asymmetric about the resonant frequency. For the cases investigated, the effects of combined turbulence and unsteadiness were additive, with the turbulence shifting the Strouhal frequency, and the unsteadiness causing lock-on about the shifted Strouhal frequency. The results of this study suggest that vortex shedding flow meters should be calibrated in turbulent flows and turbulence length scale must be controlled at the bluff body. Lock-on can be avoided by sizing the bluff body so that the shedding frequency is always much greater than any disturbance frequency in the flow.

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