Enhancement of Two-Dimensional Impingement Jet Heat Transfer with Rib Turbulators Placed in Wall Jet Region

In the near future, when designing and using Double Wall Airfoils, which will be manufactured by 3D printers, the positional relationship between the impingement cooling nozzle and the heat transfer enhancement ribs on the target plate naturally becomes more accurate. Taking these circumstances into account, an experimental study was conducted to enhance the heat transfer of the wall jet region of a round impingement jet cooling system. This was done by installing circular ribs or vortex generators (VGs) in the impingement cooling wall jet region. The local heat transfer coefficient was measured using the naphthalene sublimation method, which utilizes the analogy between heat and mass transfer. As a result, it was clarified that, within the ranges of geometries and Reynolds numbers at which the experiments were conducted, it is possible to improve the averaged Nusselt number Nu up to 21% for circular ribs and up to 51% for VGs.

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Recent Trends of Impingement Cooling System Enhancement for Gas Turbine

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.465-466.496 ◽

2013 ◽

Vol 465-466 ◽

pp. 496-499

Author(s):

Mohd Firdaus Bin Abas ◽

Abdullah Aslam ◽

Hamidon bin Salleh ◽

Nor Adrian Bin Nor Salim

Keyword(s):

Heat Transfer ◽

Cooling System ◽

Turbine Blades ◽

Impinging Jets ◽

Target Plate ◽

Impingement Cooling ◽

Impingement Jet ◽

Rib Turbulators ◽

Recent Trends ◽

Plate Distance

Efforts have been given to improve the turbine blades ability to withstand high temperature for a long period of time by implementing effective cooling system. There are many aspects that should be considered when implementing impingement cooling. This paper will only cover two trending aspects in impingement cooling implementation; the jet-to-target plate distance and the application of ribs in promoting better impingement cooling performance. For target plate distance to impingement jet diameter value, H/d > 1, the area-averaged Nusselt number also decreases as the H/d value increases. This may have been due to a reduction of the amount of momentum exerted by the impinging jets onto the target plate. For H/d < 1, the results have been proven otherwise. Heat transfer in impingement/effusion cooling system in crossflow with rib turbulators showed higher heat transfer rate than that of a surface without ribs because the ribs prevent the wall jets from being swept away by the crossflow and increase local turbulence of the flow near the surface. It could be concluded that both H/d ratio and ribs installation play an important role in enhancing impingement cooling systems heat transfer effectiveness.

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Heat Transfer to Plane Turbulent Wall Jets

Journal of Heat Transfer ◽

10.1115/1.3686069 ◽

1963 ◽

Vol 85 (3) ◽

pp. 209-213 ◽

Cited By ~ 12

Author(s):

G. E. Myers ◽

J. J. Schauer ◽

R. H. Eustis

Keyword(s):

Heat Transfer ◽

Boundary Layer ◽

Temperature Distribution ◽

Wall Jet ◽

Analytical Prediction ◽

Two Dimensional ◽

Heat Transfer Characteristics ◽

Wall Jets ◽

Turbulent Wall Jets ◽

Turbulent Wall

The heat-transfer characteristics of two-dimensional, incompressible, turbulent wall jets are discussed. An analytical prediction is made for the local Stanton number and data are presented for a step wall temperature distribution. The method for extending these data to arbitrary heating conditions is shown. Temperature surveys in the wall jet boundary layer are also presented.

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Conjugate Heat Transfer Study of a Two-Dimensional Laminar Incompressible Wall Jet Over a Backward-Facing Step

Journal of Heat Transfer ◽

10.1115/1.2424235 ◽

2006 ◽

Vol 129 (2) ◽

pp. 220-231 ◽

Cited By ~ 8

Author(s):

P. Rajesh Kanna ◽

Manab Kumar Das

Keyword(s):

Heat Transfer ◽

Nusselt Number ◽

Average Nusselt Number ◽

Conjugate Heat Transfer ◽

Flow Property ◽

Wall Jet ◽

Two Dimensional ◽

Interface Boundary ◽

Backward Facing Step ◽

Transfer Study

Steady-state conjugate heat transfer study of a slab and a fluid is carried out for a two-dimensional laminar incompressible wall jet over a backward-facing step. Unsteady stream function-vorticity formulation is used to solve the governing equation in the fluid region. An explicit expression has been derived for the conjugate interface boundary. The energy equation in the fluid, interface boundary and the conduction equation in the solid are solved simultaneously. The conjugate heat transfer characteristics, Nusselt number are studied with flow property (Re), fluid property (Pr), and solid to fluid conductivity ratio (k). Average Nusselt number is compared with that of the nonconjugate case. As k is increased, average Nusselt number is increased, asymptotically approaching the non-conjugate value.

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EXPERIMENTAL STUDIES ON DRAG REDUCTION AND HEAT TRANSFER ENHANCEMENT IN A TWO-DIMENSIONAL TURBULENT CHANNEL FLOW(Wall Jet and Wall Flow)

The Proceedings of the International Conference on Jets Wakes and Separated Flows (ICJWSF) ◽

10.1299/jsmeicjwsf.2005.91 ◽

2005 ◽

Vol 2005 (0) ◽

pp. 91-96

Author(s):

Keng Hoo Yeo ◽

Tongming Zhou ◽

Kai Choong Leong

Keyword(s):

Heat Transfer ◽

Drag Reduction ◽

Heat Transfer Enhancement ◽

Channel Flow ◽

Experimental Studies ◽

Turbulent Channel Flow ◽

Wall Jet ◽

Two Dimensional ◽

Transfer Enhancement ◽

Wall Flow

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Analysis of an Impinging Two-Dimensional Jet

Journal of Heat Transfer ◽

10.1115/1.2150841 ◽

2005 ◽

Vol 128 (3) ◽

pp. 307-310 ◽

Cited By ~ 22

Author(s):

A. H. Beitelmal ◽

A. J. Shah ◽

M. A. Saad

Keyword(s):

Heat Transfer ◽

Fluid Dynamics ◽

Analytical Solution ◽

Flat Plate ◽

Potential Flow ◽

Jet Impingement ◽

Impinging Jet ◽

Wall Jet ◽

Two Dimensional ◽

Stagnation Region

Heat transfer in jet impingement is a complicated phenomenon and a general analytical solution is not available. Typical jet impingement studies are conducted experimentally and best-fit correlations are proposed (Beitelmal, Saad, and Patel [2]; Beitelmal [3]; Beitelmal, Saad, and Patel [4]; Schauer and Eustis [7]; McMurray, Myers, and Uyehara [8], Gardon and Akfirat [9]). Separate solutions for the stagnation region and the wall jet region are then combined to determine the overall heat transfer solution for the impinging jet. In this paper, stagnation and wall jet region solutions for a two-dimensional jet normally impinging on a flat surface are developed using heat transfer relations available in the literature. These solutions are analyzed and compared to previous experimental results (Beitelmal, Saad, and Patel [2]; Beitelmal [3]). The potential flow assumption is used for the fluid dynamics analysis at the stagnation region. For the wall jet region, a comparison was achieved through consideration of the classical analytical solution for parallel flow over a flat plate. Analytical solutions as well as semiempirical solutions for the stagnation region and the wall jet reported by previous investigators were also considered. Predictions for heat transfer in the stagnation region using potential flow assumptions were found to be accurate to within 20%. For the wall jet region, previous correlations predicted by McMurray, Myers, and Uyehara [8] and Nizou [10] were found to be the most accurate. At large values of x∕D, the heat transfer properties in the wall jet are shown to be very similar to those of a turbulent boundary layer over a flat plate. Such a simplified analysis in different regions of an impinging jet using some basic fluid dynamics assumptions can greatly facilitate a prediction of the local Nusselt number.

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