CUED Publications database

Experimental study of homogenisation in grid turbulence

Cardesa-Dueñas, JI and Nickels, TB and Dawson, JR (2011) Experimental study of homogenisation in grid turbulence. Journal of Physics: Conference Series, 318. ISSN 1742-6588

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Turbulence statistics have been measured immediately downstream of a regular grid made of round rods with rod spacing M. 2D-2C PIV was used to analyse a measurement area of 14M x 4M in the down and cross-stream directions respectively. The relevant Reynolds number span the range Re M = U ∞ M/ν = 5 500 - 16 500. The Reynolds shear stresses recorded on two parallel measurement planes differently located relative to the grid exhibit significant discrepancies over the first 5M, but have completely homogenised in the cross-stream direction by x/M = 7. The downstream evolution of the two-point velocity correlation functions shows a progressive loss of coherence and a clear trend towards the expected isotropic behavior. The same conclusions apply to measurements taken in the wake of another regular grid made of square rods. Changes in the vortex shedding pattern from the grid were observed at the lowest Reynolds number, with two of the four rod wakes captured shedding in phase with each other but in anti-phase with a third one. The impact of this early flow coherence on the turbulence statistics did not persist due to the homogenisation process.

Item Type: Article
Divisions: Div A > Fluid Mechanics
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:41
Last Modified: 03 Aug 2017 03:12