1. A
SEMINAR ON
“HEAT TRANSFER OF JET IMPINGEMENT ”
Presented by;
Shinde Sudhir Mohan
MM15M09
Savitribai Phule Pune University
Department of Technology
Pune
Mechanical & Material Science Engineering

2. INTRODUCTION
 It is method for removing a large amount of heat
from striking surface.
 The fluid exist the nozzles located a short distance
from the surface
 It is a method of achieving particularly high heat
transfer coefficients in many engineering
applications.
 like cooling of turbine blades, electronics
components

3. APPLICATION
 Internal cooling of turbine blade
 Cooling of laser weapons, microeletronics
components .
 Quenching and annealing of non ferros sheet
metal.
 cooling in grinding processes

4. LITERATURE REVIEW

5. PRINCIPLE OF IMPINGEMENT

6. NOMENCLATURE
 r/d =radial distance from the stagnation point,
 d = jet or nozzle diameter, m
 h = heat transfer coefficient, W/m2K.
 H = distance between orifice and impingement plates, m
 q = heat flux, W/m2
 Q = volumetric flow rate, m3/s
 r = radial distance from the stagnation point, m
 Re = Reynolds number, dimensionless
 T = temperature, K
 ε = emissivity, dimensionless
 μ = dynamic viscosity, kg/ms
 ρ = density, kg/m3

7. OBJECTIVE
 To study :
The effect of jet width to height ratio
and Reynolds number on the heat
transfer characteristics of a laminar
flow slot jet impinging on a constant
heat flux wall

8. DESIGN CONSIDERATIONS
 Jet type (round of slot)
 Nozzle to target surface spacing
 Location of exhaust ports
 Induced or imposed cross flow
 Surface motion
 Angle of impingement
 Nozzle design
 Temperature differences between the jet and the
 impingement surface

9. NUMBER OF IMPINGEMENT NOZZLES
 Most studies carried out with single nozzles
 All industrial applications use array of nozzles
where the air jets may interact with each other.

10. DISTANCE FROM NOZZLE TO
IMPINGEMENT SURFACE
 Maximum Nusselt number occurs at the stagnation point
when the jet is at a distance of six to eight diameters away
from the impingement surface. This is the end of the
potential core.
 A spatial variation in convective heat transfer coefficient
occurs away from the stagnation point.
 When the distance from nozzle to impingement surface is
small (h/D<6), there is a secondary maximum of Nusselt
number at a radial distance of 0.5 to 2 nozzle diameters
due to the transition from laminar to turbulent boundary
layer flow.

11. EXPERIMENTAL SET-UP
a) air jet impinging
b) water jet impinging
Gas Flow Meter recorded the air flow rate
in standard liters per minute (SLPM)
positive displacement pump 0.75kW
2900rpm

12. JET IMPINGEMENT TEST SECTION
Nozzles of 0.5mm, 1mm and 1.5mm diameter
Orifice plates 5mm thickness
stainless steel foil of 25μm thick
Reynolds number Re from 1000 to 20000
jet to target spacing H from 0.5d to 6d
copper bus bar electrodes
(50mm x 10mm x 10mm)
Temperature measurement a FLIR
ThermaCAM™ A40 infrared camera

13. HEAT TRANSFER COEFFICIENT
 heat flux, q
 Ts surface temperature
REYNOLDS NUMBER
Q = volumetric flow rate, m3/s
ρ = density, kg/m3
μ = dynamic viscosity, kg/ms

14. RESULTS AND DISCUSSION
Air Jet

15.  low Reynolds numbers, high heat transfer
coefficients can be achieved by small diameter
nozzles.
d = 0.5mm; H/d = 2, 4; Re = 1000, 5000

16. d = 0.5mm, 1mm, 1.5mm; H/d = 2; Re =5000;

17. d = 1.5mm, H/d = 1, 2, 4; Re = 20000

18. CONCLUSIONS
 for jet diameters of 0.5mm to 1.5mm, Reynolds numbers of
1000 to 20000 and dimensionless jet-to-target spacings of
1 to 4 was investigated.
 low jet-to-target spacings and high Reynolds numbers.
 the area averaged heat transfer increases with decreasing
jet diameter and this is attributed to the higher jet velocities
involved when smaller nozzles are used.
 The water jets also exhibit secondary peaks, however
these have only been observed at a low Reynolds number
of 10000 and a low H/d of 1

19. REFERENCES
 Babic, D., Murray, D. B., Torrance, A. A., Mist Jet Cooling of
Grinding Processes, Int. J. Mach. Tools Manufact. 45, pp. 1171-
1177, 2005
 Narumanchi, S. V. J., Amon, C. H., Murthy, J. Y., Influence of
Pulsating Submerged Liquid Jets on Chip-Level Thermal
Phenomena, Transactions of the ASME, Vol. 125, pp. 354-361,
2003.
 Hollworth, B. R., Durbin, M., Impingement Cooling of
Electronics, Journal of Heat Transfer, ASME, Vol. 114, pp. 607-
613, 1992.
 Fitzgerald, J. A., Garimella, S. V., Flow Field Effects on Heat
Transfer in Confined Jet Impingement, Transactions of the
ASME, Vol. 119, pp. 630-632, 1997.

20. Thank you!