The present work investigates experimentally the effects of grid-generated turbulence on the transition and the hydrodynamic entrance length in a developing duct flow. Particle Image Velocimetry (PIV) and hot-wire anemometry are used to characterize the flow in a rectangular duct with a length of 1m (∼40Dh) and an aspect ratio of 2 (20mm × 40mm). The inlet turbulence intensity is controlled using different grids, and experiments are performed for a Reynolds number based on hydraulic diameter ReDh = 17,750. Hot-wire and PIV results show that the inlet turbulence intensity has a substantial effect on the flow evolution in the duct, as it substantially changes the boundary layer characteristics in the hydrodynamic entrance region. Analysis shows that, as expected, transition to turbulence advances upstream as the inlet turbulence intensity increases, leading to the decrease in the entrance length. The primary effect is confined to boundary layer development, as the turbulence intensity decays rapidly in the core flow, becoming independent of the initial conditions after about 10 hydraulic diameter (Dh) downstream from the grid. Thus, the analysis is focused on characterizing the boundary layer development and quantifying the associated changes in the flow development along the duct.
- Fluids Engineering Division
Investigation of the Effect of Inlet Turbulence on Transitional Wall-Bounded Flows
- Views Icon Views
- Share Icon Share
- Search Site
Tuna, BA, Li, X, & Yarusevych, S. "Investigation of the Effect of Inlet Turbulence on Transitional Wall-Bounded Flows." Proceedings of the ASME 2017 Fluids Engineering Division Summer Meeting. Volume 1B, Symposia: Fluid Measurement and Instrumentation; Fluid Dynamics of Wind Energy; Renewable and Sustainable Energy Conversion; Energy and Process Engineering; Microfluidics and Nanofluidics; Development and Applications in Computational Fluid Dynamics; DNS/LES and Hybrid RANS/LES Methods. Waikoloa, Hawaii, USA. July 30–August 3, 2017. V01BT06A010. ASME. https://doi.org/10.1115/FEDSM2017-69321
Download citation file: