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Numerical Simulation of Heat Transfer in Jet Cooling System on

Concave Surface

Sushilkumar M. Jogdankar1, Ashok T. Pise2, Ramesh D. Misal3

1CFD Engineer, Mechwell Industries Ltd, Nasik, Maharashtra state, India

2Professor Mechanical, Govt. College of Engg, Karad, Maharashtra state,

India

3Scientist ‘E’, DIAT, Pune, Maharashtra state, India

Address correspondence to Sushilkumar M. Jogdankar, 1CFD Engineer, A-328 Karnik Nagar,

Akkalkot Road, Solapur, Maharashtra state, India. E-mail: suvai79@gmail.com Phone Number: 0

(+91) 217 2391862.

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ABSTRACT

For cooling the leading blade edge of turbine, jets impinging on the target

surface are one of the most effective cooling methods. Thus the paper

describes the CFD carried out for jet impingement studies, which helps for

cooling of turbine blades. Computations performed to get effect of jet

Reynolds number, target distance to jet diameter carried out to find out

variation of Nusselt number on the leading edge of the blade. Analysis had

been carried out for Reynolds Number range 6000 to 12000, ratios of target

distance to jet diameter 4 to 8, ratio of target spacing to jet diameter 1.67

mm to 3.33 mm. Simulated results with contours of the streamlines for

various jet velocities and jet-to-target distances over the leading blade edge

in the computational domain are shown in this paper. Using CFD package

FLUENT and 3D segregated solver, steady state condition and viscous

model with K-Epsilon, a good agreement is obtained for Reynolds Number

range 6000 to 12000, ratios of target distance to jet diameter 4 to 8, ratio of

target spacing to jet diameters 1.67 mm to 3.33 mm to find out variation of

Nusselt number on the leading edge of the blade. The CFD results are in

good agreement with experimental results.

Key words: Heat transfer, Jet impingement, concave surface, cooling turbine blade,

CFD

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INTRODUCTION

The impinging jet can be defined as a high-velocity coolant mass ejected from a

hole or slot that impinges on the heat transfer. A characteristic feature of this flow

arrangement is an intensive heat transfer rate between the end wall and the fluid. It

predetermines the fluid jets to be widely used in industrial applications where intensive

heat transfer rates are needed, for example for cooling of turbine blades, laser mirrors and

electronic components, for drying papers, and so forth. The use of impingement jets for the

cooling of various regions of modern gas turbines is wide spread, most especially within

the high-pressure turbines. Since the cooling effectiveness of impingement jets is very

high, this method of cooling Vane end walls, blade platforms, and unattached shrouds may

all have specific local cooling requirements well suited to the use of individual jet cooling.

Impingement jets are also used on rotor disk cavity faces and in some applications may

provide additional functions of sealing. The use of impingement cooling is not confined to

the turbine components, however, as combustor components such as liners, transition

pieces, and splash plates also make good use of both individual and array impingement

cooling.

Heat transfer analysis was done primarily with walls of both flat and concave

surfaces, for individual jets, lines of jets, and arrays of jets. The heat transfer due to a

single axisymmetric jet impinging on a smooth flat plate with free spent air discharge was

investigated by Gardon and Coponpue[1], while Gardon and Akfirat [1] studied the heat

transfer due to a two dimensional impinging jet in the same situation. These studies

determined the basic effects of jet-to-target spacing and jet Reynolds number on stagnation

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region and radial heat transfer. Cases involving the use of a single line of impinging jets

have explored the heat transfer within airfoil leading edge regions. Metzger and Larson[2]

and Chupp et al.,[3] studied the heat transfer within a semicircular concave region with a

line of circular jet impinging at the apex. The effects of target spacing, hole spacing, and

jet Reynolds numbers were correlated. Tabakoff and Clevenger [4] extended this

information to include cases of two dimensional jet impingement as well as jet array

impingement within a semicircular concave region. More recently, Metzger and Bunker[5]

showed the detailed local heat transfer distributions due to line jet impingement within

leading edge regions, without and with film extraction effects, respectively. Galitseyskiy

[3] experimentally investigated of local heat transfer characteristics in jet cooling system of

a leading blade edge. Their results were referred to the specific geometry but it was not

practically extended to real conditions.

Several studies have also been performed to correlate the heat transfer under an

array of impinging circular jets, primarily for normal impingement on flat surfaces.

Kercher and Tabakoff [6] tested a matrix of square arrays of in-line jets over ranges of

target spacing and Reynolds number, correlating stream wise heat transfer with geometry

and flow parameters. The heat transfer to a flat plate beneath arrays of impingement jets

was determined, including in line and staggered arrays and various effects of initial and

developing cross flow. Various jet array geometries were investigated in these studies,

providing a major portion of the current database for heat transfer correlations of

impingement arrays.

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After the literature reviewed shows that most of the studies are conducted on simple

geometries like flat plate or smooth cylinders considering factors like Reynolds numbers,

jet-to pitch distances and ratio of hole diameter to center-to-center spacing. As the shape of

turbine blades are curved. So in this paper the study is carried on concave surface which is

similar to leading blade edge of gas turbine has been done.

The objective of this work is numerically to investigate the effect of jet velocity and

jet-to-target surface with respect to heat transfer coefficient and Nusselt number variation

over the leading blade edge. Air is used as coolant since it is the most preferred and

cheapest medium in thermal management. Also the results are validated with experimental

that was carried by Jogdankar [1].

PROBLEM MODELLING

The present study explores heat transfer on the target and jet issue walls due to jet

array impingement within a confined channel. Figure 1 shows the computational domain of

concave surface for defined problem. The configuration of problem modelling is given

below

Configuration

The cooling of a leading blade edge of a turbine is done by air passes through jet

with uniform velocity and it is impinged on target surface. The leading blade edge is

having diameter of 80 mm and height of 65 mm and length and thickness of the target

surface is 270 mm and 5 mm respectively. The length of the computational domain in

the radial direction is 80 mm while in axial direction (Zn) it is equal to the 65 mm. The

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geometry is considered as axisymmetric about the axis of the jet thus the results would

get by simulating in 2D model but due to its consideration of reverse flow there is need to

consider 3D model with some assumptions.

Assumptions

1. Air is used as working fluid, it is compressible fluid

2. Problem is considered 3D and steady state

3. Surface considered in geometry are smooth air flow over it is frictionless.

4. Ambient temperature is considered constant.

5. Flow is assumed to be turbulent.

6. Turbulence specification method of turbulent intensity and viscosity ratio with 5

% and 10 respectively. By default these values are can be taken 3 % and 3

respectively or calculated as per model. Here it is been assumed that turbulence

will be more so approximately value has been taken by doing trial and error for

convergence of model results.

GOVERNING EQUATION

The solver used in fluent solves the following equation with respect to continuity,

momentum and energy equation to get the desired results.

These equations are described below

Continuity Equation

( ) mSvt

−∇+∂∂ ρρ

. = 0 (1)

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Momentum Equation

( ) ( ) Fgpvvvt

++∇+−∇=∇+∂∂ ρτρρ ).(. (2)

Here, τ is stress tensor and given as

(3)

Energy Equation

( ) ( )( )

hj

effjjeff SvjhTk

pEvEt

+

+−∇∇

=+∇+∂∂

∑ ..

.

τ

ρρ (4)

2

2

p vE h

ρ= − + (5)

Where sensible enthalpy h is defined for ideal gases as

j jj

h Y h=∑ (6)

and for incompressible flows as

j jj

ph Y h

ρ= +∑ (7)

Yj is the mass fraction of species j and

T

j p

Tref

h c jdT= ∫ (8)

Reynolds number, Ren calculated from velocity of air flow for inlet condition and it based

on the hydraulic diameter of the equivalent to nozzle diameter.

( ) 2.

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Tv v vIτ µ = ∇ + ∇ − ∇

r r r

8

µρ njet

n

dv=Re (9)

Convective heat transfer coefficient, h is calculated by equation 10 in this the required

temperature (surface temperature Ts) i.e. surface temperature through analysis is been

taken after getting converged results. Ta is the ambient temperature.

as TTA

Qh

−= (10)

Nusselt’s number can be calculated based on diameter of the nozzle jet.

k

hdNu n= (11)

Boundary Conditions

X = 0, y = Zn, z = 0

u = 0, v= Vjet w = 0

Target surface: constant heat flux i.e. q = Q/A

Inflow BC : u = 0 v = Vjet w = 0

Outflow BC : Outlet condition is given as pressure ‘P’ equal to atmospheric pressure at

ambient temperature ‘T’.

The procedure adopted to solve the problem using CFD commercial software fluent 6.1.22

is as follows [1].

Grid Generation

The model and meshing of this problem as shown in the Figs. 2-4 is done by

using Gambit software. In Gambit software, the mesh is to done by using edge mesh type

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in which the number of nodes is supposed to be given by type of first/last ratio of 8 by

selecting the edges and giving the number of counts as per length of edge. After

completing the edge meshing then face meshing is to be done by selecting the Tri

element along with pave type for compilation of surface mesh as shown in Fig.3-4.

Element type is to be selected as per structure of model. Volume mesh is done with

hex/wedge element along with cooper type for circular nozzle jets. Tet/Hybrid element

along with T-Grid type is used for concave surface as shown in Fig. 2. As specified

number of nodes in edge mesh hence it is not required to give again in face and volume

mesh. After completing meshing, quality of mesh is checked by examine mesh. In this

the equiangular skew is checked by 3D element in the range of 0-1 by showing worst

element. If the range is exceeding then mesh is remeshed it. Boundary conditions are

defined in Gambit and its values are to be given in Fluent.

Code Validation

It was necessary to confirm the efficiency of the finite-volume code FLUENT

(Version 6.1.22) as a tool. The solution procedures were benchmarked against

experimental data and results for the air-jet impingement over a leading blade edge and

were analyzed Jogdankar [1]. Computations are performed by varying Reynolds number

ranging from 6000 to 12000, ratio of center to center spacing and hole diameter ranging

from 1.67 to 3.33, and also ratio of target spacing to hole diameter ranging from 4 to 8.

All simulations used a generalized coordinate, finite volume code (Fluent 6.1.22) with

Simple pressure velocity coupling with second order upwind for momentum, kinetic

energy and dissipation rate is used. For each case computation time required around 10

hrs to get the desired accuracy.

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1. The problem were solved for the different combination of parameters as shown in

Table 1 (i.e. velocity (Vjet) equal to 8.7, 13.0 and 17.3 m/s, Cn/dn equal to 1.67,

2.22 and 3.33, & Zn/dn is equal to 4 6 and 8) with ambient temperature of 303 0 K

and heat flux of 837 watt/m2.

2. The accuracy of 10-4 was considered for getting solution convergence. After

getting convergence the results are described below.

RESULTS AND DISCUSSION

The results obtained by numerical simulation of varying the different parameters

like hole and jet diameters, target spacing, and flow Reynolds number (see Table 1) are

broadly divided into flow field and heat transfer. These are discussed as below.

Flow Field

The flow field around concave surface is far more complex than for the single flat

jets impinging on the target surface. A thin boundary layer approaches at the corner of the

target surface, where separation occurs. It is a thin curved; highly turbulent region

develops along the separated shear layer. Only quantitative analyses are to be done, as no

flow measurements are available. The flow is parallel to the jet axis at the exit from jet

and develops into a free jet. This developed jet decelerates as it impinges on the top of the

concave surface. From the obtained results for the various jet velocities and jet-to-target

distances for the different Reynolds number the contours of the streamlines of the flow

the sample case for Ren equal to 12000 and Zn/dn equal to 6 are explained with the help of

Figs. 6 -7

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Figs. 6-7a shows the contours of the velocity vectors to the radial plane of axis of

geometry, this clearly shows the jet flow and recirculation’s occurring on the corner side

of the leading blade edge of gas turbine blade. At corner of leading edge velocity is

approximately 9 to 10 m/s. Due to turbulence, the vortex is formed with lesser velocity.

Comparatively flow is reaching towards the leading edge i.e concave surface, which

effects on heat transfer rate for cooling purpose. The contours of the velocity magnitude,

in the axial plane are shown in the Fig. 7b. It shows that the velocity of air flow is

flowing much more from the central jets as compared to the corner of left and right side

of the jets which affect the heat transfer rate.

Due to lesser velocity of air flow from the corner of left and right side of jet and

turbulence creation, led the vortex is generated. Thus as shown in Fig 7b much more flow

is required to reach towards the concave surface i.e. leading edge along the radial

direction of leading edge then the design more of jets i.e. selection of number of jets

should be in proper way.

Effect of Reynolds number: Overall leading edge turbulence flow is increased as the

Reynolds number is increased.

Effect of Jet Diameter and Target Spacing: Overall leading edge turbulence flow is

increased as the center-to-center spacing-to-diameter ratio, Cn / dn, is decreased from 3.33

to 1.67

Effect of jet Diameter and Nozzle Target spacing: The maximum turbulence flow is

occurred at Zn / dn ranging from 4 to 8 at Ren equal to 6000.

Heat Transfer

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For each case, the heat transfer analysis is carried out. For the visualizations of

contours of the static temperature, jet flow of the Ren equal to 12000 ( jet-velocity is

equal to17.3m/s and ratio of target spacing to hole diameter equal to 6. are shown in

Figure 8(a-b).

Heat Transfer in Radial plane

Figure 8(a) shows the contours of the static temperature profile in radial plane.

This clearly shows the jet flow and recirculation’s occurring on the side of the leading

blade edge. The closed geometry at the side of the leading blade edge of gas turbine

blade shows there is recirculation of the fluid due to jet effect formed at the corner of the

leading blade edge of gas turbine blade. A general trend was observed; the heat transfer

coefficient has a local constant in the vicinity of the stagnation point and then increases

sharply as the corner.

Heat Transfer in Axial Plane

Figure 8(b) shows that the static temperature at the centre of the leading blade

edge is more stagnant as compared to left and right side of the leading blade edge of gas

turbine blade along the axial direction.

In this case air is flow equally through jet but for reaching towards the leading

blade edge takes more time thus heat transfer is more at the left and right side of leading

blade edge. Thus the convective heat transfer gets reduced at stagnation point. Also due

to steady boundary layer at stagnation point, some part of the cool air coming from the jet

might not be in contact with stagnation region. Also some part of the new cool air may

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bypasses from exit, which gives the minimum heat transfer. This is the general trend

observed during each observation for various Ren and jet-to-target spacing.

Effect of Constant Cn/dn on Heat Transfer.

Effect of the constant ratios of Cn/dn with the varying Zn/dn (4 to 8) and Ren (6000

to 12000) is analysed. The heat transfer characteristics is observed maximum at Zn/dn

equal to 4 and Ren equal to 12000 at Cn/dn equal to 1.67. Also trend shows that the heat

transfer characteristic gets decreased as Zn/dn gets increase and increased with increase in

Reynolds number. Similar trends were observed for Cn/dn equal to 2.22 and 3.33

Effect of constant (Zn/dn) on Heat Transfer

If the ratio Zn/dn is kept constant around 4, ratio of Cn/dn (1.67 to 3.33) and Ren

(6000 to 12000) are varied. The results are observed that heat transfer characteristic is

maximum for Cn/dn equal to 2.22 i.e. heat transfer characteristic gets increased with

increase in Ren. But for Zn/dn equal to 6 and 8 heat transfer characteristics is maximum

for Cn/dn equal to 1.67.

Effect of constant Ren on Heat Transfer

If Ren is kept constant around 6000, ratio of Cn/dn (1.67 to 3.33), and Zn/dns (4 to

8) are varied. The heat transfer is observed maximum for Cn/dn equal to 3.33 i.e heat

transfer characteristic gets decreased as Zn/dn gets increased. But for Ren equal to 9000

and 12000 heat transfer characteristics is maximum for Cn/dn equal to 1.67.

Effect of Reynolds number: Overall leading edge heat transfer is increased as the

Reynolds number is increased.

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Effect of Jet Diameter and Target Spacing: Overall leading edge heat transfer is

increased as the center-to-center spacing-to-diameter ratio, Cn / dn, is decreased from 3.33

to 1.67.

Effect of jet Diameter and Nozzle Target spacing: The maximum heat transfer is

occurred at Zn / dn ranging from 4 to 8 at Ren equal to 6000.

After solving all the cases as explained earlier, the correlations for the average

heat transfer coefficients have been correlated in terms of Zn /dn, and Ren, & Nuav. The

correlation can be represented as:

15.021.0 )/(Re71.0 nnnav dZNu = (12)

For,

120006000Re

&84/,33.367.1/

to

todZtodC

n

nnnn

===

(13)

VALIDATION OF THE RESULTS

Also Jogdankar [1] has done an experimental work using same specification

geometries with variation of all these parameters listed in the Table 1. Their results

obtained are compared with CFD results as shown in Fig. 9 and Table 2. CFD results are

in good agreement with experimental results and their values are higher.

1. For case Cn/dn = 1.67, & Zn/dn = 6, it is seen that the CFD results are in good

agreement with experimental results for Ren equal to 6000.

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2. The deviation of Nu number at low Ren is lesser as compared to high Ren and

this variation is around average of 32 % as compared to experimental results

[1].

3. The rate of heat transfer is increasing periodically by CFD results as compared

to experimental results thus CFD results are in good agreement compared to

experimental results.

Experimental results may be varying due less accuracy maintaining in creating

blade profile while in CFD analysis the blade profile is assumed smooth and frictionless

other reason is the ambient temperature considered while experimentation which is

varying with respect to time in actual condition while in CFD it is assumed to be steady

state.

CONCLUSION

After the extensive analysis of this studies following concluding remarks can be made.

1. Overall leading edge heat transfer is increased as the ratio of, Cn / dn and Zn/dn is

decreased with increased in Ren.

2. The heat transfer rate of impinging jets on concave surface for Cn / dn equal to

1.67 is higher than that for Cn / dn equal to 3.33.

3. Heat transfer characteristics gives good results for Cn/dn equal to 1.67, Zn/dn equal

to 4 & Reynolds number equal to 12000 rather than for Cn/dn equal to 3.33, Zn/dn

equal to 8 & Reynolds number equal to 6000.

4. The numerical results are good agreement with experimental results.

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5. At the left and right side of the leading blade edge of gas turbine blade in radial

direction, the recirculation of the fluid due to jet effect is formed at the corner.

6. Also recirculation’s occurring on the corner side of the leading blade edge and

formation of turbulence, the vortex is formed with lesser velocity.

In this work only heat transfer analysis is carried one can extend this work with

pressure distribution. Also analysis can be extended for flowing of air at different angles to

obtain uniform cooling effect in the complete length of cooling section, other parameters

such as increasing or decreasing number of holes in the design should be considered in

future work so as to eliminate low thermal effect between jet impingements and creating

more enhancement of heat transfer between jets.

ACKNOWLEDGEMENT

Author’s express sincere thanks to the organization of Defense Institute Advanced

Technology (DIAT) providing partial funding and sponsoring this work.

NOMENCLATURE

CFD Computational Fluid Dynamics

Cn center to center spacing between adjacent holes (mm)

Cp specific heat of fluid (J/kg K)

dn diameter of circular nozzle holes (mm)

F External Body Force

jj Diffusion flux of species ‘j'

h Sensible enthalpy

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K Thermal conductivity of fluid (W/m K)

k Effective thermal conductivity

Kt Turbulent thermal conductivity

Q Heat flux (watt/m2)

P Static pressure

r Radial coordinate

twall wall temperature (0K)

tsurr surrounding temperature (0K)

u velocity component in x direction

vjet velocity component in y direction

Y j mass fraction of species ‘j’

Zn nozzle target spacing (mm)

v Velocity

Vs Axial velocity

vr Radial velocity

τ Stress tensor

gρ Gravitational body force

Sm Source term

Dimensionless Number

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Nu Nusselt number k

hd n=

Re Reynolds number µ

ρ njet du=

Greek Letters

µ Dynamic viscosity (kg / m s)

ρ Density of fluid (kg/m3)

υ Kinematic viscosity (m2/s)

Subscript

n Nozzle

p pressure

surr surrounding

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REFERENCES

Journals/Periodicals:

[1] Gardon R. and Akfirat J. (1996, February). Heat transfer characteristics of impinging

two-dimensional air jets. Journal of Heat Transfer, 101-108.

[2] Metzger D. E. & Larson D. E. (1986). Use of melting point surface coatings for local

convection heat transfer measurements in rectangular channel flows with 90-deg turns.

Journal of Heat Transfer, 108, 48-54.

[3] Chupp R., Helms H., Mc Fadden P., & Brown T. (1969). Evaluation of internal heat-

transfer coefficients for impingement-cooled turbine airfoils. Journal of Aircraft, 6(3), 203-

208.

[4] Tabakoff W., & Clevenger W. (1972). Gas turbine blade heat transfer augmentation by

impingement of air jets having various configurations. Journal of Engineering for power,

92, 51-60.

[5] Metzger D., & Bunker R. (1990). Local heat transfer in internally cooled turbine airfoil

leading edge regions: Part-I impingement cooling without coolant extraction. Journal of

Turbo machinery, 112, 459-466.

[6] Kercher D. & Tabakoff W. (1990). Heat transfer by a square array of round air jets

impinging perpendicular to a flat surface including the effects of spent air. Journal of

Engineering for power, 92, 73-82.

[7] Metzger D., Yamashita T., & Jenkins C. (1969) Impingement Cooling of Concave

Surfaces with lines of Circular Air Jets. Journal of engineering for power, 91, 149-158

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Conference Proceedings:

[1] Gardon R., and Cobonpue, J. (1962). Heat transfer between a flat plate and jets of air

impinging on it. Proceedings of the 2nd International heat transfer conference,

International Developments in Heat Transfer, New York: ASME, 454-460.

[2] Kline, S.J., and MccClintock, F.A., “Describing Uncertainties in single Sample

Experiments,” Mechanical Engineering, Vol. 75, January 1953, pp 3-8.

[3] Galitseyskiy B. M. Heat Transfer From Impinging jets to concave surface, Proceedings

of the second ISHMT, Heat and mass transfer 2000, pp 283-88, 2004.

Technical Reports:

[1] Jogdankar S. M., (2006) “Experimental Investigation of Local Heat Transfer

Characteristics and Numerical Simulation from Impinging Jets on Concave Surface” ME

Thesis, Kolhapur University.

Books:

[1] FLUENT 6.1.22, 2002, “User’s and Tutorial Guide”, Fluent Inc., USA

[2] GAMBIT 2.1, 2002, “User’s and Tutorial Guide”, Fluent Inc., USA

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Table 1 Parameters used for analysis

Parameters Range

Diameter of circular nozzle holes dn 6, 9, 12 mm

Center to Center spacing between adjacent holes Cn

20 mm

Ratio of target spacing to jet diameter Cn/ dn

1.67, 2.22, 3.33

Ratio of nozzle target spacing to jet diameter Zn/ dn

4, 6, 8

Heat Flux Q 40 W

Reynolds number Re 6000, 9000, 12000

Heat transfer to area , Q/A 837 W/m2

Density of air 1.225 kg/m3

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Table 2. CFD and Experimental Results at Cn/dn = 1.67 & Zn/dn = 6.

Vjet Ren ∆∆∆∆Texp ∆∆∆∆TCFD hexp hCFD Nuexp NuCFD 8.70 6000 28.46 20 10.79 15.35 4.92 7.01 13.00 9000 20.64 15 14.88 20.47 6.79 9.34 17.30 12000 20.23 12 15.18 25.59 6.93 11.68

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List of Figure Captions

Figure 1 Schematic of the Geometry and Computational Domain

Figure 2 Target Surface with Grid Meshing

Figure 3 2D Model of Target Surface and Jet with Grid Meshing

Figure 4 3D Model of Target Surface and Jet with Grid Meshing

Figure 6 Contours of Velocity Vectors for the Flow of Radial Plane (Ren = 12000 and Zn/dn = 6)

Figure 7 (a) Contours of Velocity Magnitude for the Flow Radial Plane (Ren = 12000 & Zn/dn = 6)

Figure 7 (b) Contours of Velocity Magnitude for the Flow of Axial Plane. (Ren = 12000 and Zn/dn =

6)

Figure 8 (a) Contours of Static Temperatures for the flow of Radial Plane (Ren = 12000 and Zn/dn =

6)

Figure 8 (b) Contours of Static Temperatures for the flow of Axial Flow (Ren = 12000 and Zn/dn =

6)

Figure 9 Variation of Nu with Ren for Cn/dn = 1.67 & Zn/dn = 6

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Figure 1 Schematic of the Geometry and Computational Domain

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Figure 2 Target Surface with Grid Meshing

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Fig. 3 2D Model of Target Surface and Jet with Grid Meshing

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Fig. 4 3D Model of Target Surface and Jet with Grid Meshing

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Fig. 6 Contours of Velocity Vectors for the Flow of Radial Plane (Ren = 12000 and Zn/dn =

6)

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Fig. 7 (a) Contours of Velocity Magnitude for the Flow Radial Plane (Ren = 12000 & Zn/dn

= 6)

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Fig. 7 (b) Contours of Velocity Magnitude for the Flow of Axial Plane. (Ren = 12000 and

Zn/dn = 6)

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Fig. 8 (a) Contours of Static Temperatures for the flow of Radial Plane (Ren = 12000 and

Zn/dn = 6)

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Fig. 8 (b) Contours of Static Temperatures for the flow of Axial Flow (Re = 12000 and

Zn/dn = 6)

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Fig. 9 Variation of Nu with Ren for Cn/dn = 1.67 & Zn/dn = 6

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Sushilkumar M. Jogdankar is a Sr. CFD Engineer, at Mechwell Industries Ltd, Nasik, Maharashtra state, India. He received his M.E mechanical degree in Heat Power in 2006 from the Shivaji University, Government College of engg. Karad, Maharashtra state, India. He is currently working on CFD simulation on heat transfer analysis, multiphase flow analysis, flow simulation etc

Dr. A. T. Pise is a Professor and Head of Mechanical Engineering Department at Government College of Engineering, Karad, which is affiliated to Shivaji University, Kolhapur, India. He received his M.E degree from Pune University, India and his Ph.D. degree from the I.I.T Kanpur (India). He has been in teaching profession since 1986. He is Chairman, Board of Studies (Mechanical Engineering) and Management Council Member at Shivaji University, Kolhapur. He is currently working on enhanced heat transfer and multiphase flow, alternative fuels.

R D Misal obtained his B.E. (Mech) from Government College of Engineering, Aurangabad and M. Tech from REC, Warangal. He joined DRDO in 1988. He had worked with MBT Arjun project before joining DIAT in 1991. His research areas are heat transfer & gas Turbines. He is recipient of DRDO Technology Group Award for year 2005 and Research Facility of the year group award in year 2007. He is Life Member of Indian Society of Heat & Mass Transfer. At present he is HOD, Mech Engg at DIAT, Pune.