Effect of Prandtl number on the turbulent thermal field in annular pipe flow

Convective heat transfer from suddenly expanding annular pipe flows are numerically investigated within the steady laminar flow regime. A parametric study is performed to reveal the influence of the annular diameter ratio, k, the Prandtl number, Pr, and the Reynolds number, Re, over the following range of parameters: k = {0, 0.5, 0.7}, Pr = {0.7, 1, 7, 100}, and Re = {25, 50, 100}. Heat transfer enhancement downstream of the expansion plane is only observed for Pr > 1. Peak wall-heat-transfer-rates always appear downstream of the flow reattachment point, in the case of suddenly expanding round pipe flows, i.e. k = 0. However, for suddenly expanding annular pipe flows, i.e., k = 0.5 and 0.7, peak wall-heat-transfer-rates always appear upstream of the flow reattachment point. The observed heat transfer augmentation is more dramatic for suddenly expanding annular flows, in comparison with the one observed for suddenly expanding pipe flows. For a given annular diameter ratio and Reynolds number, increasing the Prandtl number, always results in higher wall-heat-transfer-rates downstream the expansion plane.

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A liquid plug moving in an annular pipe—Flow analysis

Physics of Fluids ◽

10.1063/1.5050258 ◽

2018 ◽

Vol 30 (9) ◽

pp. 093605 ◽

Cited By ~ 2

Author(s):

Yadi Cao ◽

Ri Li

Keyword(s):

Pipe Flow ◽

Flow Analysis ◽

Liquid Plug ◽

Annular Pipe

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Effects of radius ratio on turbulent concentric annular pipe flow and structures

International Journal of Heat and Fluid Flow ◽

10.1016/j.ijheatfluidflow.2020.108725 ◽

2020 ◽

Vol 86 ◽

pp. 108725

Author(s):

Edris Bagheri ◽

Bing-Chen Wang

Keyword(s):

Pipe Flow ◽

Radius Ratio ◽

Annular Pipe

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The Development of Swirling Decaying Laminar Flow in an Annular Pipe

E3S Web of Conferences ◽

10.1051/e3sconf/20185103001 ◽

2018 ◽

Vol 51 ◽

pp. 03001

Author(s):

Baiman Chen ◽

Frank G.F. Qin ◽

Youyuan Shao ◽

Hanmin Xiao ◽

Simin Huang ◽

...

Keyword(s):

Turbulent Flows ◽

Pipe Flow ◽

Tangential Component ◽

Duct Flow ◽

Mean Flow ◽

Entry Length ◽

Swirl Angle ◽

Practical Engineering ◽

Inlet Swirl ◽

Annular Pipe

Work on the hydrodynamic entry length of pipe and duct flow has been well studied over the years. The assumption of fully developed flows is commonly used in many practical engineering applications (e.g. Moody's chart). For laminar axial pipe flow, the hydrodynamic entry length can be found through the monomial proposed by Kays, Shah and Bhatti (KSB) (Lh=0.056ReDh). In contrast, several approximations exist for fully turbulent flows (i.e. 10Dh-150Dh). Through theoretical and numerical investigations, the hydrodynamic entry length for swirling decaying pipe flow in the laminar regime is investigated. It was found that, the development length Lh for the axial velocity profile changes when a tangential component is added to the mean flow. The reduction in the hydrodynamic length was found to be dependent on the inlet swirl angle θ. The results indicate that a modification can be made on the KSB equation for two-dimensional swirling annular pipe flow.

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Patterns in Wall-Bounded Shear Flows

Annual Review of Fluid Mechanics ◽

10.1146/annurev-fluid-010719-060221 ◽

2020 ◽

Vol 52 (1) ◽

pp. 343-367 ◽

Cited By ~ 19

Author(s):

Laurette S. Tuckerman ◽

Matthew Chantry ◽

Dwight Barkley

Keyword(s):

Numerical Simulations ◽

Couette Flow ◽

Poiseuille Flow ◽

Pipe Flow ◽

Shear Flows ◽

Plane Couette Flow ◽

Plane Poiseuille Flow ◽

Flow Focusing ◽

Annular Pipe ◽

Flow Plane

Experiments and numerical simulations have shown that turbulence in transitional wall-bounded shear flows frequently takes the form of long oblique bands if the domains are sufficiently large to accommodate them. These turbulent bands have been observed in plane Couette flow, plane Poiseuille flow, counter-rotating Taylor–Couette flow, torsional Couette flow, and annular pipe flow. At their upper Reynolds number threshold, laminar regions carve out gaps in otherwise uniform turbulence, ultimately forming regular turbulent–laminar patterns with a large spatial wavelength. At the lower threshold, isolated turbulent bands sparsely populate otherwise laminar domains, and complete laminarization takes place via their disappearance. We review results for plane Couette flow, plane Poiseuille flow, and free-slip Waleffe flow, focusing on thresholds, wavelengths, and mean flows, with many of the results coming from numerical simulations in tilted rectangular domains that form the minimal flow unit for the turbulent–laminar bands.

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An Experimental Study of the Effect of Drag Reducing Additive on the Structure of Turbulence in Concentric Annular Pipe Flow Using Particle Image Velocimetry Technique

Volume 7B: Fluids Engineering Systems and Technologies ◽

10.1115/imece2013-64663 ◽

2013 ◽

Author(s):

Fabio Ernesto Rodriguez Corredor ◽

Majid Bizhani ◽

Ergun Kuru

Keyword(s):

Particle Image Velocimetry ◽

Fluid Flow ◽

Pipe Flow ◽

Particle Image ◽

Polymer Concentration ◽

Velocity Fluctuations ◽

Polymer Fluid ◽

Image Velocimetry ◽

Drag Reducing Additive ◽

Annular Pipe

The effect of drag reducing additive on the structure of turbulence in concentric annular pipe flow was investigated using Particle Image Velocimetry (PIV) technique. Experiments were conducted using a 9m long horizontal flow loop with concentric annular geometry (inner to outer pipe radius ratio = 0.4). The drag reducing additive was a commercially available partially hydrolyzed polyacrylamide (PHPA). The experiments were conducted using 0.1% V/V polymer concentration, giving a drag reduction of 26% at a solvent Reynolds number equal to 56400. Near wall local fluctuating velocity values were determined by analysing the PIV data. The root mean square (RMS) values of radial velocity fluctuations showed a significant decrease with the use of drag reducing additive. The RMS values of axial velocity fluctuations near the wall (Y+<10) were similar for both water and polymer fluid flow; though, higher peaks were obtained during the polymer fluid flow. As compared to water flow, a strong reduction in vorticity was observed during polymer fluid flow. The degree of vorticity reduction on the inner wall was higher than that of the outer wall. Results of the viscous dissipation and the shear production terms in the kinetic energy budget showed that less energy was produced and dissipated by the route of turbulence when using polymer fluid.

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