scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Three-Dimensional Study of Multiple-Jet Cross Flow Cooling System with Single Array of Heat Sources

TL;DR: In this article, the role of three dimensional flow structures, horseshoe vortex and counter rotating vortex pair in overall heat transfer distribution is examined, and a parametric study is performed to analyze the performance of jets in cross flow for various Reynolds numbers (Re = 100, 250, 500) and velocity ratios (VR = 1.0, 5.0 and 10.0).
Abstract: ABSTRACT The objective of this study is to predict fluid flow and thermal characteristics associated with forced convection cooling of an array of heat sources mounted in a three-dimensional duct by impinging jets in the presence of cross flow. The equations governing fluid flow and heat transfer are solved using Streamline Upwind / Petrov - Galerkin based finite element method. The role of three dimensional flow structures, horseshoe vortex and counter rotating vortex pair in overall heat transfer distribution is examined. A parametric study is performed to analyze the performance of jets in cross flow for various Reynolds numbers (Re = 100, 250, 500) and velocity ratios (VR = 1.0, 5.0, 10.0). It is observed that with the increase in velocity ratio, the enhancement of heat transfer from heat sources occurs due to increase in the dominance of jet flow accompanied by an unfavorable reduction in heat transfer owing to the increase in size of horseshoe vortex. From numerical studies, it can be concluded that VR = 5.0 exhibits higher overall surface averaged Nusselt number (51.7% over VR = 1.0 and 44.1% over VR = 10.0 for Re = 500) compared to other velocity ratios considered in this study.
Citations
More filters
Journal ArticleDOI
TL;DR: In this article, the authors investigated the fluid flow and heat transfer behaviors of jet impingement in cross-flow modified by a vortex generator pair (VGP), and they demonstrated that the heat transfer on the target wall is dominated by the wall-normal velocity of the impingements and the turbulent kinetic energy, rather than the streamwise velocity along the crossflow direction.

23 citations

Journal ArticleDOI
TL;DR: In this article, numerical studies on fluid flow and heat transfer through a two-dimensional 180-degree sharp bend are performed using an in-house code based on streamline upwind Petrov-Galerkin finite element meth.
Abstract: Numerical studies on fluid flow and heat transfer through a two-dimensional 180-degree sharp bend are performed using an in-house code based on streamline upwind Petrov-Galerkin finite element meth...

5 citations

Journal ArticleDOI
TL;DR: In this article, an in-house finite element method code based on a square configuration of four elliptic cylinders arranged in square configuration was proposed to investigate the flow and heat transfer characteristics of the four cylinders.
Abstract: Fluid flow and heat transfer characteristics past four elliptic cylinders arranged in square configuration are numerically investigated in this study. An in-house finite element method code based o...

3 citations

Journal ArticleDOI
TL;DR: In this article, numerical investigation on the flow field structure of a hollow cone spray injected transversely into a confined crossflow is presented, and the unsteady turbulent flow is predicted by a...
Abstract: In this paper, numerical investigation on the flow field structure of a hollow cone spray injected transversely into a confined crossflow is presented. The unsteady turbulent flow is predicted by a...

2 citations

Journal ArticleDOI
TL;DR: In this article , a flat heating surface placed in a flow channel, including single jet cooling, in-line double jet cooling and combined crossflow and jet cooling was investigated, and it was found that heat transfer depends on the jet distance because one jet may produce a crossflow effect on the other jet, affecting the formation of longitudinal vortices.
Abstract: Jet impingement cooling was investigated on a flat heating surface placed in a flow channel, including single jet cooling, in-line double jet cooling, and combined crossflow and jet cooling; cross-flow cooling was a baseline for comparison. In addition, the in-line double jet cooling was explored with various jet distances. Local Nusselt number distribution was experimentally achieved by the liquid crystal method, and the measurements were carried out under various jet pressures ranging from 1 bar to 4 bar. It was found that heat transfer depends on the jet distance because one jet may produce a crossflow effect on the other jet, affecting the formation of longitudinal vortices which could enhance heat transfer. It was seen that in comparison to the crossflow cooling, the average Nusselt number is enhanced by 110%, 150%, and 380% by the single jet cooling, the in-line double jet cooling, and the combined cooling, respectively, and correspondingly the maximum Nusselt number is enhanced by 160%, 240%, and 540%, respectively. In the combined cooling, there is a deflection distance ranging from 0 mm to 10 mm depending on the jet pressure.

1 citations

References
More filters
Journal ArticleDOI
TL;DR: In this article, a new finite element formulation for convection dominated flows is developed, based on the streamline upwind concept, which provides an accurate multidimensional generalization of optimal one-dimensional upwind schemes.

5,157 citations


"Three-Dimensional Study of Multiple..." refers methods in this paper

  • ...The governing equations are iteratively solved by Eulerian velocity correction approach based on projection scheme of Chorin [14] and discretized using Streamline Upwind Petrov-Galerkin (SUPG) based finite element formulation proposed by Brooks andHughes [15]....

    [...]

Journal ArticleDOI
TL;DR: In this article, a numerical method for solving incompressible viscous flow problems is introduced, which uses the velocities and the pressure as variables and is equally applicable to problems in two and three space dimensions.

2,797 citations


"Three-Dimensional Study of Multiple..." refers methods in this paper

  • ...The governing equations are iteratively solved by Eulerian velocity correction approach based on projection scheme of Chorin [14] and discretized using Streamline Upwind Petrov-Galerkin (SUPG) based finite element formulation proposed by Brooks andHughes [15]....

    [...]

Journal ArticleDOI
TL;DR: In this article, structural features resulting from the interaction of a turbulent jet issuing transversely into a uniform stream are described with the help of flow visualization and hot-wire anemometry.
Abstract: Structural features resulting from the interaction of a turbulent jet issuing transversely into a uniform stream are described with the help of flow visualization and hot-wire anemometry. Jet-to-crossflow velocity ratios from 2 to 10 were investigated at crossflow Reynolds numbers from 3800 to 11400. In particular, the origin and formation of the vortices in the wake are described and shown to be fundamentally different from the well-known phenomenon of vortex shedding from solid bluff bodies. The flow around a transverse jet does not separate from the jet and does not shed vorticity into the wake. Instead, the wake vortices have their origins in the laminar boundary layer of the wall from which the jet issues. It is argued that the closed flow around the jet imposes an adverse pressure gradient on the wall, on the downstream lateral sides of the jet, provoking 'separation events’ in the wall boundary layer on each side. These result in eruptions of boundary-layer fluid and formation of wake vortices that are convected downstream. The measured wake Strouhal frequencies, which depend on the jet-crossflow velocity ratio, match the measured frequencies of the separation events. The wake structure is most orderly and the corresponding wake Strouhal number (0.13) is most sharply defined for velocity ratios near the value 4. Measured wake profiles show deficits of both momentum and total pressure.

1,186 citations


"Three-Dimensional Study of Multiple..." refers methods in this paper

  • ...Roshko [7] also carried out similar experiments with flow visualization and hot-wire anemometry to describe the structural features especially the origin and evolution of wake vortices of jet in cross flow for jet to cross flow velocity ratios from 2 to 10....

    [...]

Journal ArticleDOI
TL;DR: In this article, the structure of round jets in cross-flow was studied using flow visualization techniques and flying-hot-wire measurements, restricted to jet to freestream velocity ratios ranging from 2.0 to 6.0.
Abstract: The structure of round jets in cross-flow was studied using flow visualization techniques and flying-hot-wire measurements. The study was restricted to jet to freestream velocity ratios ranging from 2.0 to 6.0 and Reynolds numbers based on the jet diameter and free-stream velocity in the range of 440 to 6200.Flow visualization studies, together with time-averaged flying-hot-wire measurements in both vertical and horizontal sectional planes, have allowed the mean topological features of the jet in cross-flow to be identified using critical point theory. These features include the horseshoe (or necklace) vortex system originating just upstream of the jet, a separation region inside the pipe upstream of the pipe exit, the roll-up of the jet shear layer which initiates the counter-rotating vortex pair and the separation of the flat-wall boundary layer leading to the formation of the wake vortex system beneath the downstream side of the jet.The topology of the vortex ring roll-up of the jet shear layer was studied in detail using phase-averaged flying-hot-wire measurements of the velocity field when the roll-up was forced. From these data it is possible to examine the evolution of the shear layer topology. These results are supported by the flow visualization studies which also aid in their interpretation.The study also shows that, for velocity ratios ranging from 4.0 to 6.0, the unsteady upright vortices in the wake may form by different mechanisms, depending on the Reynolds number. It is found that at high Reynolds numbers, the upright vortex orientation in the wake may change intermittently from one configuration of vortex street to another. Three mechanisms are proposed to explain these observations.

720 citations


"Three-Dimensional Study of Multiple..." refers background in this paper

  • ...[6] studied the structure of round jets in cross flow with aid of flow visualization studies and hot-wire measurements for velocity ratios varying from 2....

    [...]

Journal ArticleDOI
TL;DR: In this paper, the local heat transfer to an impinging air jet with and without a cross flow of air was investigated and a correlation was obtained for the average heat transfer in the absence of cross flow.

191 citations


"Three-Dimensional Study of Multiple..." refers background in this paper

  • ...Goldstein and Behbahani [5] experimentally investigated the local heat transfer coefficients of a heated surface subjected to impinging air jet with and without cross flow for jet to plate spacing 6 and 12....

    [...]