An Analysis of Natural Convection in Leading Edge Wing Compartments

2008 ◽  
Author(s):  
V. Egan ◽  
D. Moore ◽  
D. Newport ◽  
V. Lacarac ◽  
B. Estebe
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Convection Heat Transfer ◽  
Internal Heat ◽  
Leading Edge ◽  
Test Facility ◽  
Civil Aircraft ◽  
Aeronautical Industry ◽  
Building Ventilation ◽  
Good Agreement

Enclosure natural convection has applications in many engineering disciplines such as electronic component cooling, building ventilation and heating, and renewable energy systems such as solar collectors. To date there has been little research on its application in the aeronautical industry where it plays an important role in aircraft heat transfer. Standard civil aircraft comprise of a number of vented and non-vented compartments. One such compartment is the leading edge which houses the main aircraft bleed duct and several electronic devices. Natural convection heat transfer in the leading edge compartment is important during aircraft turn around while systems are running and the exterior of the aircraft is subjected to solar loading. The objective of this paper is to investigate the heat transfer in a leading edge. The effect of an internal heat generating source, a bleed duct, is also investigated. A dimensional analysis of the governing equations is carried out to determine the appropriate scaling groups for the natural convection cases and a numerical simulation is run on a commercial CFD package. The numerical results are compared with experimental measurements obtained from a leading edge test facility. The effect of bleed duct placement is also investigated both experimentally and numerically with good agreement achieved. It was found that bleed duct placement can have a significant effect on the overall temperature distribution within a leading edge compartment. The results provide a basis for the optimisation of natural convection in such aircraft wing compartments.

Heat Transfer Measurements in a Leading Edge Geometry With Racetrack Holes and Film Cooling Extraction

2012 ◽  
Author(s):  
Luca Andrei ◽  
Carlo Carcasci ◽  
Riccardo Da Soghe ◽  
Bruno Facchini ◽  
Francesco Maiuolo ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Mass Flow ◽  
Film Cooling ◽  
Large Scale ◽  
Internal Heat ◽  
Leading Edge ◽  
Jet Impingement ◽  
Internal Surface ◽  
Test Facility ◽  
Supply Channel

An experimental survey on a state of the art leading edge cooling scheme was performed to evaluate heat transfer coefficients (HTC) on a large scale test facility simulating an high pressure turbine airfoil leading edge cavity. Test section includes a trapezoidal supply channel with three large racetrack impingement holes. On the internal surface of the leading edge, four big fins are placed in order to confine impingement jets. The coolant flow impacts the leading edge internal surface and it is extracted from the leading edge cavity through 24 showerhead holes and 24 film cooling holes. The aim of the present study is to investigate the combined effects of jet impingement and mass flow extraction on the internal heat transfer of the leading edge. A non uniform mass flow extraction was also imposed to reproduce the effects of pressure side and suction side external pressure. Measurements were performed by means of a transient technique using narrow band Thermo-chromic Liquid Crystals (TLC). Jet Reynolds number and crossflow conditions into the supply channel were varied in order to cover the typical engine conditions of these cooling systems (Rej = 10000–40000). Experiments were compared with a numerical analysis on the same test case in order to better understand flow interaction inside the cavity. Results are reported in terms of detailed 2D maps, radial-wise and span-wise averaged values of Nusselt number.

Heat Transfer Measurements in a Leading Edge Geometry With Racetrack Holes and Film Cooling Extraction

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Luca Andrei ◽  
Carlo Carcasci ◽  
Riccardo Da Soghe ◽  
Bruno Facchini ◽  
Francesco Maiuolo ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Mass Flow ◽  
Film Cooling ◽  
Large Scale ◽  
Internal Heat ◽  
Leading Edge ◽  
Jet Impingement ◽  
Internal Surface ◽  
Test Facility ◽  
Supply Channel

An experimental survey on a state of the art leading edge cooling scheme was performed to evaluate heat transfer coefficients (HTC) on a large scale test facility simulating a high pressure turbine airfoil leading edge cavity. The test section includes a trapezoidal supply channel with three large racetrack impingement holes. On the internal surface of the leading edge, four big fins are placed in order to confine impingement jets. The coolant flow impacts the leading edge internal surface, and it is extracted from the leading edge cavity through 24 showerhead holes and 24 film cooling holes. The aim of the present study is to investigate the combined effects of jet impingement and mass flow extraction on the internal heat transfer of the leading edge. A nonuniform mass flow extraction was also imposed to reproduce the effects of the pressure side and suction side external pressure. Measurements were performed by means of a transient technique using narrow band thermochromic liquid crystals (TLCs). Jet Reynolds number and crossflow conditions into the supply channel were varied in order to cover the typical engine conditions of these cooling systems (Rej=10,000-40,000). Experiments were compared with a numerical analysis on the same test case in order to better understand flow interaction inside the cavity. Results are reported in terms of detailed 2D maps, radial-wise, and span-wise averaged values of Nusselt number.

Natural Convection Heat Transfer from the Upper Plate of a Colinear, Separated Pair of Vertical Plates

1980 ◽  
Vol 102 (4) ◽  
pp. 623-629 ◽  
Author(s):  
E. M. Sparrow ◽  
M. Faghri
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Natural Convection ◽  
Vertical Plate ◽  
Convection Heat Transfer ◽  
Leading Edge ◽  
Lower Plate ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Plate Heat

The effect of a buoyant boundary layer spawned by a heated vertical plate on the natural convection heat transfer from an upper colinear vertical plate has been determined analytically. The interplate spacing was varied parametrically, as were the relative temperatures and relative lengths of the two plates; the Prandtl number was equal to 0.7 for all cases. Heat transfer at the upper plate was found to be affected both by the preheating and by the finite velocity imparted to the fluid by the first plate, respectively tending to degrade and to enhance the heat transfer. The upper-plate heat transfer was compared to that of an otherwise identical vertical plate, but with the lower plate absent. When the temperatures of the upper and lower plates are the same, the overall upper-plate heat transfer is less than that of its single-plate counterpart for small interplate spacings, with the opposite relationship at larger spacings. If the temperature of the upper plate is substantially below that of the lower plate, the overall heat transfer is degraded. On the other hand, heat transfer enhancement generally occurs when the upper plate is relatively hot. In general, the heat transfer from relatively short upper plates is very sensitive to the presence of the lower plate, with a lessening sensitivity with increasing plate length. The computed temperature and velocity profiles demonstrated that near the leading edge of the upper plate, a new boundary layer develops within the already existing boundary layer spawned by the first plate.

Boundary Condition Dependent Natural Convection in a Rectangular Pool With Internal Heat Sources

2006 ◽  
Vol 129 (5) ◽  
pp. 679-682 ◽  
Author(s):  
Seung Dong Lee ◽  
Jong Kuk Lee ◽  
Kune Y. Suh
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Natural Convection ◽  
Convection Heat Transfer ◽  
Internal Heat ◽  
Working Fluid ◽  
Natural Convection Heat Transfer ◽  
Heat Sources ◽  
Internal Heat Sources ◽  
Volumetric Heat Generation

This paper presents results of steady-state experiments concerned with natural convection heat transfer of air in a rectangular pool in terms of the Nusselt number (Nu) versus the modified Rayleigh number (Ra′) varying from 109 to 1012. Cartridge heaters were immersed in the working fluid to simulate uniform volumetric heat generation. Two types of boundary conditions were adopted in the test: (I) top cooled, and (II) top and bottom cooled. The other sides were kept insulated. In the case of boundary condition II, the upward heat transfer ratio, Nuup∕(Nuup+Nudn), turned out to be 0.7–0.8 in the range of Ra′ between 1.05×1010 and 3.68×1011.

Experimental Investigation of Natural Convection in Partitioned Enclosures

1982 ◽  
Vol 104 (3) ◽  
pp. 527-532 ◽  
Author(s):  
S. M. Bajorek ◽  
J. R. Lloyd
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Convection Heat Transfer ◽  
Core Region ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
The Core ◽  
Different Temperatures ◽  
Vertical Walls ◽  
Good Agreement

Natural convection heat transfer within a two-dimensional, partitioned enclosure of aspect ratio 1 was investigated experimentally using a Mach-Zehnder interferometer. The vertical walls were maintained isothermal at different temperatures, while the horizontal walls and the partitions were insulated. Local and average heat-transfer coefficients were determined for the air and carbon dioxide filled enclosures both with and without partitions for Grashof numbers between 1.7×105 and 3.0×106. Good agreement was found between the results in the present study for the nonpartitioned enclosure and those previously published. The partitions were found to significantly influence the convective heat transfer. Observations of the interferometric fringes indicated that the core region is unsteady, with the unsteadiness occasionally affecting the flow along the vertical isothermal walls, beginning at Grashof numbers as low as 5×105.

Modeling the Natural Convection Heat Transfer and Dryout Heat Flux in a Porous Debris Bed

2008 ◽  
Vol 130 (10) ◽  
Author(s):  
R. Sinha ◽  
A. K. Nayak ◽  
B. R. Sehgal
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Convection Heat Transfer ◽  
Severe Accident ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Wide Range ◽  
Particulate Debris ◽  
Limiting Condition ◽  
Good Agreement

An empirical model for natural convection heat transfer for film-boiling condition has been developed for volumetrically heated particulate debris beds when flooded with water at the top of the bed. The model has been derived from the quenching data generated in the POMECO facility located at KTH, Stockholm. A dryout model is also developed for countercurrent flooding limiting condition when the heat generating saturated debris bed is flooded with water from the top. The model is in good agreement with the experimental data over a wide range of particle size and porosity as compared to the existing models. The implication of the models with respect to quenching of porous debris bed formed during postulated severe accident condition is discussed.

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