0
Research Papers

Conjugate Heat Transfer Computational Fluid Dynamic Predictions of Impingement Heat Transfer: The Influence of Hole Pitch to Diameter Ratio X/D at Constant Impingement Gap Z

[+] Author and Article Information
A. M. El-Jummah

Energy Research Institute,
School of Chemical and Process Engineering,
University of Leeds,
Leeds LS2 9JT, UK
e-mail: al-jummah@hotmail.com

R. A. A. Abdul Husain

Energy Research Institute,
School of Chemical and Process Engineering,
University of Leeds,
Leeds LS2 9JT, UK
e-mail: mnamej@leeds.ac.uk

G. E. Andrews

Energy Research Institute,
School of Chemical and Process Engineering,
University of Leeds,
Leeds LS2 9JT, UK
e-mail: profgeandrews@hotmail.com

J. E. J. Staggs

Energy Research Institute,
School of Chemical and Process Engineering,
University of Leeds,
Leeds LS2 9JT, UK
e-mail: J.E.J.Stagggs@leeds.ac.uk

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) Division of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received July 7, 2014; final manuscript received July 17, 2014; published online August 26, 2014. Editor: Ronald Bunker.

J. Turbomach 136(12), 121002 (Aug 26, 2014) (16 pages) Paper No: TURBO-14-1118; doi: 10.1115/1.4028232 History: Received July 07, 2014; Revised July 17, 2014

Conjugate heat transfer (CHT) computational fluid dynamic (CFD) predictions were carried out for a 10 × 10 square array of impingement holes, for a range of pitch to diameter ratio X/D from 1.9 to 11.0 at a constant impingement gap Z of 10 mm and pitch X of 15.24 mm. The variation of X/D changes the impingement wall pressure loss for the same coolant mass flow rate and also changes the interaction with the impingement gap cross-flow. The experimental technique to determine the surface averaged heat transfer used the lumped capacity method with Nimonic-75 metal walls with imbedded thermocouples and a step change in the hot wall cooling to determine the heat transfer coefficient h from the transient cooling of the metal wall. The test wall was electrically heated to about 80  °C and then transiently cooled by the impingement flow and the lumped capacitance method was used to measure the locally surface average heat transfer coefficient. The predictions and measurements were carried out at an impingement jet mass flux of 1.93 kg/s m2 bar, which is a typical coolant flow rate for regenerative impingement cooling of low NOx gas turbine combustor walls. The computations were conducted for a fixed hot side temperature of 353 K that was imposed at the hot face of the target wall. The wall temperatures as a function of distance along the gap were computed together with the impingement gap aerodynamics. Surface average heat transfer coefficient h and pressure loss predictions were in good agreement with the experimental measurements. However, there was less good agreement for the axial variation of the local surface averaged h for lower values of X/D. The surface averaged heat transfer to the impingement jet wall was also computed and shown to be roughly 70% of target wall impingement heat transfer.

Copyright © 2014 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Fig. 1

Schematic of regenerative cooled combustor

Grahic Jump Location
Fig. 2

Impingement jet cooling geometrical setup

Grahic Jump Location
Fig. 3

Schematic diagram of impingement jet cooling geometrical setup with gap cross-flow pressure gradient [7]

Grahic Jump Location
Fig. 4

Impingement cooling experimental test rig and test plates configurations with thermocouples locations: (a) test rig and (b) test plates

Grahic Jump Location
Fig. 5

Impingement cooling computational domain: (a) symmetrical elements and (b) model grids

Grahic Jump Location
Fig. 6

Grid impingement cooling air holes for variable X/D and D (mm) at constant X of 15.24 mm

Grahic Jump Location
Fig. 7

Flow-maldistribution in the impingement plate holes for variable X/D and constant G of 1.93 kg/s m2 bar

Grahic Jump Location
Fig. 8

Comparison of predicted flow-maldistribution with previous CFD prediction showing influence of Z/D

Grahic Jump Location
Fig. 9

Contours of velocity magnitude (m/s) in the impingement gap (in-line with and between rows of holes) for variable X/D. Gray color stripes are Nimonic-75 walls: (a) higher X/D velocities and (b) lower X/D velocities.

Grahic Jump Location
Fig. 10

Predictions of outlet impingement holes pressure loss for variable X/D at constant G of 1.93 kg/s m2 bar

Grahic Jump Location
Fig. 11

Comparison of predicted pressure loss with experiment for range of X/D at constant G of 1.93 kg/s m2 bar

Grahic Jump Location
Fig. 12

Comparison of predicted pressure loss with previous CFD prediction showing influence of Z/D

Grahic Jump Location
Fig. 13

Contours of TKE (m2/s2) on the target wall surface for variable X/D at constant G of 1.93 kg/s m2 bar: (a) higher X/D TKE and (b) lower X/D TKE

Grahic Jump Location
Fig. 14

Contours of TKE (m2/s2) in the impingement gap inline with the jet for variable X/D at constant G. Gray color stripes are Nimonic-75 walls: (a) higher X/D TKE and (b) lower X/D TKE.

Grahic Jump Location
Fig. 15

Contours of TKE (m2/s2) on the air hole surface for variable X/D at constant G. Arrow indicates flow direction: (a) higher X/D TKE and (b) lower X/D TKE.

Grahic Jump Location
Fig. 16

Contours of Nusselt number on target (top) and inside impingement (bottom) surfaces for variable X/D

Grahic Jump Location
Fig. 17

Contours of Nusselt number on inside impingement hole surfaces for variable X/D at constant mass velocity. The arrow indicates flow direction.

Grahic Jump Location
Fig. 18

Comparison of target surface average heat transfer coefficient h and prediction of impingement plate HTC h

Grahic Jump Location
Fig. 19

Comparison of target X2 average heat transfer coefficient h at constant mass velocity G of 1.93 kg/s m2 bar: (a) higher X/D TKE and (b) lower X/D TKE

Grahic Jump Location
Fig. 20

Comparison of predicted X2 average h with previous CFD prediction showing influence of Z/D

Grahic Jump Location
Fig. 21

Prediction of X2 average heat transfer coefficient h on the inside impingement wall surface at G of 1.93 kg/s m2 bar

Grahic Jump Location
Fig. 22

Contours of normalized temperature on target wall surface for variable X/D at constant mass velocity G

Grahic Jump Location
Fig. 23

Contours of normalized temperature in the impingement gap (inline with and between N rows of holes) of variable X/D at constant mass velocity G

Grahic Jump Location
Fig. 24

Lower X/D prediction of normalize temperature gradient in the target wall thickness of 6.35 mm: (a) lower X/D TKE and (b) higher X/D TKE

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In