An experimental and numerical study of stagnation point heat transfer for methane/air laminar flame impinging on a flat surface

2008 ◽  
Vol 51 (13-14) ◽  
pp. 3595-3607 ◽  
Author(s):  
Subhash Chander ◽  
Anjan Ray
Keyword(s):  
Heat Transfer ◽  
Stagnation Point ◽  
Flat Surface ◽  
Laminar Flame ◽  
Numerical Study

A Numerical Study of Turbulent Boundary Layer Flow Over a Flat Surface With a Single Dimple

2000 ◽  
Author(s):  
Mark E. Kithcart ◽  
David E. Klett
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Boundary Layer Flow ◽  
Flat Surface ◽  
Numerical Study ◽  
Heat Transfer Augmentation ◽  
Study Results ◽  
Turbulent Boundary Layer Flow ◽  
Layer Flow

Abstract Turbulent boundary layer flow over a flat surface with a single dimple has been investigated numerically using the FLUENT CFD software package, and compared to an experiment by Ezerskii and Shekhov [1989], which studied the same configuration. The impetus for this work developed as a result of previous studies. Kithcart and Klett [1996], and Afanas’yev and Chudnovskiy [1992], showed that dimpled surfaces enhance heat transfer comparably to surfaces with protrusion roughness elements, but with a much lower drag penalty. However, the actual physical mechanisms involved in this phenomena were only partially known prior this study. Results obtained numerically are in good agreement with the experiment, most notably the confirmation of the existence of a region of enhanced heat transfer created by interaction of the flow with the dimple. In particular, the simulation indicates that heat transfer augmentation is a consequence of the development of a stagnation flow region within the dimple geometry, and the existence of coherent vortical structures which create a periodic flow-field within and immediately downstream of the dimple. This periodicity appears to govern the magnitude of the heat transfer augmentation.

Mist/Steam Heat Transfer With Jet Impingement Onto a Concave Surface

2002 ◽  
Author(s):  
Xianchang Li ◽  
J. Leo Gaddis ◽  
Ting Wang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Stagnation Point ◽  
Flat Surface ◽  
Leading Edge ◽  
Jet Impingement ◽  
Heat Fluxes ◽  
General Level ◽  
Transfer Enhancement ◽  
Surface Cooling

Internal mist/steam blade cooling technology has been considered for the future generation of Advanced Turbine Systems (ATS). Fine water droplets about 5 μm were carried by steam through a single slot jet onto a concave heated target surface in a confined channel to simulate inner surface cooling at the leading edge of a turbine blade. Experiments covered Reynolds numbers from 7,500 to 22,000 and heat fluxes from 3 to 21 kW/m2. The general level of heat transfer coefficient is, within experimental uncertainty, the same as the flat surface at comparable conditions. The experimental results indicate that the cooling is enhanced significantly near the stagnation point by the mist, decreasing downstream. Unlike impingement onto a flat plate the enhancement continues at all points downstream. Similar to the results of the flat surface, the heat transfer enhancement declines at higher heat fluxes. Up to 200% heat transfer enhancement at the stagnation point was achieved by injecting approximately 0.5% of mist.

scholarly journals Oblique stagnation point flow of a non-Newtonian nanofluid over stretching surface with radiation: A numerical study

2017 ◽  
Vol 21 (5) ◽  
pp. 2139-2153 ◽  
Author(s):  
Abuzar Ghaffari ◽  
Tariq Javed ◽  
Fotini Labropulu
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Differential Equations ◽  
Layer Thickness ◽  
Stagnation Point ◽  
Boundary Layer Thickness ◽  
Numerical Study ◽  
Convective Boundary Condition ◽  
Stretching Surface ◽  
Convective Boundary

In this study, we discussed the enhancement of thermal conductivity of elasticoviscous fluid filled with nanoparticles, due to the implementation of radiation and convective boundary condition. The flow is considered impinging obliquely in the region of oblique stagnation point on the stretching surface. The obtained governing partial differential equations are transformed into a system of ordinary differential equations by employing a suitable transformation. The solution of the resulting equations is computed numerically using Chebyshev spectral newton iterative scheme. An excellent agreement with the results available in literature is obtained and shown through tables. The effects of involving parameters on the fluid flow and heat transfer are observed and shown through graphs. It is importantly noted that the larger values of Biot number imply the enhancement in heat transfer, thermal boundary layer thickness, and concentration boundary layer thickness.

Effect of Swirl Intensity on Heat Transfer Characteristics of Swirling Flame Impinging on a Flat Surface

2013 ◽  
Author(s):  
Gurpreet Singh ◽  
Subhash Chander
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Stagnation Point ◽  
Flat Surface ◽  
Operating Conditions ◽  
Uniform Heat Flux ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Swirl Intensity ◽  
Swirling Flame

An experimental investigation has been carried out to determine the effect of swirl intensity on heat transfer characteristics of swirling flame impinging on a flat surface. The swirl intensity was varied by using helical vane swirlers having angles of 15°, 30° and 60° (low, medium and high swirl). Qualitative flame structures were studied by taking direct photographs of impinging flames. Experiments were conducted for different helical vane swirlers at different dimensionless separation distances (H/d = 1–6) for fixed value of Reynolds number (Re = 5000) and equivalence ratio (ϕ = 1.0). A dip in heat flux was observed at stagnation point for all levels of swirl. Peak heat flux was observed slightly away from the stagnation point due to centrifugal effect. A comparison of stagnation point heat flux has been done for different swirl intensities and for fixed operating conditions. Most uniform heat flux distribution was obtained corresponds to 30° helical vane swirler (medium swirl) at all separation distances.

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