scholarly journals Small Diameter Film Cooling Hole Heat Transfer: The Influence of the Hole Length

1991 ◽  
Author(s):  
G. E. Andrews ◽  
F. Bazdidi-Tehrani ◽  
C. I. Hussain ◽  
J. P. Pearson
Keyword(s):  
Heat Transfer ◽  
Surface Area ◽  
Film Cooling ◽  
Small Diameter ◽  
Internal Surface ◽  
Internal Surface Area ◽  
Metal Thickness ◽  
Data Scatter ◽  
Cooling Hole

The overall surface averaged heat transfer was determined for air passing through arrays of small diameter holes drilled at 90° through thin metal walls. The influence of the wall metal thickness, L, was investigated for a range of hole diameters, D, and pitch, X. L/D was varied from 0.43 to 8.3 using 13 different test geometries. It was found that although the influence of L/D was significant, there was only a ±20% data scatter on a correlation of the results that ignored the influence of L/D for 0.8<L/D<10. The results showed that the heat transfer was dominated by the hole approach flow and this surface area Ax was the appropriate heat transfer area for the determination of the heat transfer coefficient. The dominant parameters that affected the heat transfer were G and X/D. An improved correlation for a range of L/D was achieved if the heat transfer surface area was taken as the sum of Ax and Ah, the hole internal surface area.

scholarly journals Small Diameter Film Cooling Hole Heat Transfer: The Influence of the Number of Holes

1989 ◽  
Author(s):  
G. E. Andrews ◽  
F. Bazdidi-Tehrani
Keyword(s):  
Heat Transfer ◽  
Surface Area ◽  
Film Cooling ◽  
Small Diameter ◽  
Diameter Ratio ◽  
Heat Transfer Correlation ◽  
Flow Acceleration ◽  
Overall Heat Transfer Coefficient ◽  
Cooling Hole ◽  
Air Passage

The overall surface averaged heat transfer was determined for air passing through arras of small diameter holes drilled at 90 through thin metal walls. The influence of the number of holes and hence of the pitch to diameter ratio, X/D, was investigated over the range 4.7 to 21 for a fixed hole size of 1.4 mm and hole L/D of 4.5. A transient cooling technique was used to determine the overall heat transfer coefficient for the cooling due to the air passage through the wall. It was shown that the dominant heat transfer was that on the hole approach surface area due to flow acceleration into the hole. The hole approach surface area was used in the heat transfer correlation. The results of the authors were combined with previous results for the variation of X/D at constant X to give a heat transfer correlation, independent of L/D.

scholarly journals Heat-Up Performance of Catalyst Carriers—A Parameter Study and Thermodynamic Analysis

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 964
Author(s):  
Thomas Steiner ◽  
Daniel Neurauter ◽  
Peer Moewius ◽  
Christoph Pfeifer ◽  
Verena Schallhart ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Surface Area ◽  
Internal Surface ◽  
Installation Space ◽  
Parameter Study ◽  
Thin Wall ◽  
Primary Role ◽  
Internal Surface Area

This study investigates geometric parameters of commercially available or recently published models of catalyst substrates for passenger vehicles and provides a numerical evaluation of their influence on heat-up behavior. Parameters considered to have a significant impact on the thermal economy of a monolith are: internal surface area, heat transfer coefficient, and mass of the converter, as well as its heat capacity. During simulation experiments, it could be determined that the primary role is played by the mass of the monolith and its internal surface area, while the heat transfer coefficient only has a secondary role. Furthermore, an optimization loop was implemented, whereby the internal surface area of a commonly used substrate was chosen as a reference. The lengths of the thin wall and high cell density monoliths investigated were adapted consecutively to obtain the reference internal surface area. The results obtained by this optimization process contribute to improving the heat-up performance while simultaneously reducing the valuable installation space required.

Small Diameter Film Cooling Holes: Wall Convective Heat Transfer

1986 ◽  
Author(s):  
G. E. Andrews ◽  
M. Alikhanizadeh ◽  
A. A. Asere ◽  
C. I. Hussain ◽  
M. S. Khoshkbar Azari ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Small Diameter ◽  
Internal Heat ◽  
Metal Plate ◽  
Transfer Rates ◽  
Flow Heat ◽  
Available Information ◽  
Film Cooling Holes

The wall heat transfer resulting from small diameter holes drilled at 90° through gas turbine combustion chamber and turbine blade walls is considered. Available information is briefly reviewed and shown to generally omit the hole approach surface heat transfer and to relate only to the internal hole heat transfer. Experimental techniques are described for the determination of the overall heat transfer in a metal plate with a large number of coolant holes drilled at 90°. The results are compared with conventional short-tube internal heat transfer measurements and shown to involve much higher heat transfer rates and this mainly resulted from the additional hole approach flow heat transfer.

scholarly journals Small Diameter Film Cooling Holes: Wall Convective Heat Transfer

1988 ◽  
Author(s):  
G. E. Andrews ◽  
M. Alikhanizadeh ◽  
A. A. Asere ◽  
C. I. Hussain ◽  
M. S. Khoshkbar Azari ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Small Diameter ◽  
Internal Heat ◽  
Metal Plate ◽  
Transfer Rates ◽  
Flow Heat ◽  
Available Information ◽  
Film Cooling Holes

The wall heat transfer resulting from small diameter holes drilled at 90° through gas turbine combustion chamber and turbine blade walls is considered. Available information is briefly reviewed and shown to generally omit the hole approach surface heat transfer and to relate only to the internal hole heat transfer. Experimental techniques are described for the determination of the overall heat transfer in a metal plate with a large number of coolant holes drilled at 90°. The results are compared with conventional short-tube internal heat transfer measurements and shown to involve much higher heat transfer rates and this mainly resulted from the additional hole approach flow heat transfer.

Small Diameter Film Cooling Holes: Wall Convective Heat Transfer

1986 ◽  
Vol 108 (2) ◽  
pp. 283-289 ◽  
Author(s):  
G. E. Andrews ◽  
M. Alikhanizadeh ◽  
A. A. Asere ◽  
C. I. Hussain ◽  
M. S. Khoshkbar Azari ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Small Diameter ◽  
Internal Heat ◽  
Metal Plate ◽  
Transfer Rates ◽  
Flow Heat ◽  
Available Information ◽  
Film Cooling Holes

The wall heat transfer resulting from small diameter holes drilled at 90 deg through gas turbine combustion chamber and turbine blade walls is considered. Available information is briefly reviewed and shown to generally omit the hole approach surface heat transfer and to relate only to the internal hole heat transfer. Experimental techniques are described for the determination of the overall heat transfer in a metal plate with a large number of coolant holes drilled at 90 deg. The results are compared with conventional short-tube internal heat transfer measurements and shown to involve much higher heat transfer rates and this mainly resulted from the additional hole approach flow heat transfer.

Combined Experimental and CFD Study of a HP Blade Multi-Pass Cooling System

2009 ◽  
Author(s):  
D. Jackson ◽  
P. Ireland ◽  
B. Cheong
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Cooling System ◽  
Detailed Comparison ◽  
Bulk Temperature ◽  
Internal Cooling ◽  
3 Dimensional ◽  
Turbine Cooling ◽  
Cooling Hole ◽  
The Difference

Progress in the computing power available for CFD predictions now means that full geometry, 3 dimensional predictions are now routinely used in internal cooling system design. This paper reports recent work at Rolls-Royce which has compared the flow and htc predictions in a modern HP turbine cooling system to experiments. The triple pass cooling system includes film cooling vents and inclined ribs. The high resolution heat transfer experiments show that different cooling performance features are predicted with different levels of fidelity by the CFD. The research also revealed the sensitivity of the prediction to accurate modelling of the film cooling hole discharge coefficients and a detailed comparison of the authors’ computer predictions to data available in the literature is reported. Mixed bulk temperature is frequently used in the determination of heat transfer coefficient from experimental data. The current CFD data is used to compare the mixed bulk temperature to the duct centreline temperature. The latter is measured experimentally and the effect of the difference between mixed bulk and centreline temperature is considered in detail.

Effect of a Ceramic Matrix Composite Surface on Film Cooling

2021 ◽  
Author(s):  
Peter H. Wilkins ◽  
Stephen P. Lynch ◽  
Karen A. Thole ◽  
San Quach ◽  
Tyler Vincent ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Matrix Composite ◽  
Film Cooling ◽  
Gas Turbines ◽  
Ceramic Matrix Composite ◽  
Ceramic Matrix ◽  
Composite Surface ◽  
Minimal Impact ◽  
Cooling Hole ◽  
Adiabatic Effectiveness

Abstract Ceramic matrix composite (CMC) parts create the opportunity for increased turbine entry temperatures within gas turbines. To achieve the highest temperatures possible, film cooling will play an important role in allowing turbine entry temperatures to exceed acceptable surface temperatures for CMC components, just as it does for the current generation of gas turbine components. Film cooling over a CMC surface introduces new challenges including roughness features downstream of the cooling holes and changes to the hole exit due to uneven surface topography. To better understand these impacts, this study presents flowfield and adiabatic effectiveness CFD for a 7-7-7 shaped film cooling hole at two CMC weave orientations. The CMC surface selected is a 5 Harness Satin weave pattern that is examined at two different orientations. To understand the ability of steady RANS to predict flow and convective heat transfer over a CMC surface, the weave surface is initially simulated without film and compared to previous experimental results. The simulation of the weave orientation of 0°, with fewer features projecting into the flow, matches fairly well to the experiment, and demonstrates a minimal impact on film cooling leading to only slightly lower adiabatic effectiveness compared to a smooth surface. However, the simulation of the 90° orientation with a large number of protruding features does not match the experimentally observed surface heat transfer. The additional protruding surface produces degraded film cooling performance at low blowing ratios but is less sensitive to blowing ratio, leading to improved relative performance at higher blowing ratios, particularly in regions far downstream of the hole.

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