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naca-tn-4091

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National Advisory Committee for Aeronautics, Technical Notes - Experimental Investigation of Transpiration Cooling for a Turbulent Boundary Layer in Subsonic Flow Using Air as a Coolant

Experiments were performed to determine the effect of injecting
coolant air through a porous sintered bronze plate into a constant-area
tunnel through which hot air was flowing. The boundary layer was
turbulent over the porous plate for all test runs. Tests were made with
either a constant coolant injection rate or a constant wall temperature.
The Mach number was approximately 0.6 at the upstream edge of the porous
plate and increased in the downstream direction. The mainstream stagna-
tion temperature was approximately 2150 F, and the coolant temperature
was either in the range -l5° to 5° F or the range -70° to -55° F.

It was difficult to run at the desired injection flow conditions,
because the permeability of the sintered bronze plate varied erratically
with both time and position. Nevertheless, a definite correlation ex-
isted between the porous wall temperature and the injected coolant-flow
rate; wall temperature decreased as coolant-flow rate increased. This
correlation for a given station along the porous plate appeared independ—
ent of the type of test when based on local conditions. A comparison of
the results with a theory for transpiration into a turbulent boundary
layer with an isothermal wall showed only qualitative agreement. This
was not unexpected, since some of the important assumptions of the theory
could not be completely satisfied in the experimental setup.

The problem of cooling a surface in contact with hot gases has be-
come increasingly important. Seweral methods of cooling have been stud-
ied. In reference 1, an analytical comparison of convection cooling,
film cooling, and transpiration cooling showed transpiration cooling to
be the most efficient method of the three. In transpiration cooling, the
coolant is passed through the heated surface and injected directly into
the boundary layer. This requires that the heated surface be constructed
of a porous material.

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naca-tn-4091

  • Version
  • 91 Downloads
  • 1.51 MB File Size
  • 1 File Count
  • January 31, 2017 Create Date
  • January 31, 2017 Last Updated
Scroll for Details

National Advisory Committee for Aeronautics, Technical Notes - Experimental Investigation of Transpiration Cooling for a Turbulent Boundary Layer in Subsonic Flow Using Air as a Coolant

Experiments were performed to determine the effect of injecting
coolant air through a porous sintered bronze plate into a constant-area
tunnel through which hot air was flowing. The boundary layer was
turbulent over the porous plate for all test runs. Tests were made with
either a constant coolant injection rate or a constant wall temperature.
The Mach number was approximately 0.6 at the upstream edge of the porous
plate and increased in the downstream direction. The mainstream stagna-
tion temperature was approximately 2150 F, and the coolant temperature
was either in the range -l5° to 5° F or the range -70° to -55° F.

It was difficult to run at the desired injection flow conditions,
because the permeability of the sintered bronze plate varied erratically
with both time and position. Nevertheless, a definite correlation ex-
isted between the porous wall temperature and the injected coolant-flow
rate; wall temperature decreased as coolant-flow rate increased. This
correlation for a given station along the porous plate appeared independ—
ent of the type of test when based on local conditions. A comparison of
the results with a theory for transpiration into a turbulent boundary
layer with an isothermal wall showed only qualitative agreement. This
was not unexpected, since some of the important assumptions of the theory
could not be completely satisfied in the experimental setup.

The problem of cooling a surface in contact with hot gases has be-
come increasingly important. Seweral methods of cooling have been stud-
ied. In reference 1, an analytical comparison of convection cooling,
film cooling, and transpiration cooling showed transpiration cooling to
be the most efficient method of the three. In transpiration cooling, the
coolant is passed through the heated surface and injected directly into
the boundary layer. This requires that the heated surface be constructed
of a porous material.

FileAction
naca-tn-4091 Experimental Investigation of Transpiration Cooling for a Turbulent Boundary Layer in Subsonic Flow Using Air as a Coolant.pdfDownload 
17,005 Documents in our Technical Library
2449574 Total Downloads

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Newest Additions

NASA-RP-1060 Subsonic Aircraft: Evolution and the Matching of Size to Performance
NASA-RP-1060 Subsonic Aircraft: Evolution and the Matching of Size to Performance
AA-CP-20212-001
AA-CP-20212-001
ADPO10769 Occurrence of Corrosion in Airframes
The purpose of this lecture is to provide an overview ...
MIL-STD-1759 Rivets and Rivet Type Fasteners Preferred for Design
The purpose of this book form standard is to provide ...
MIL-STD-810G Environmental Engineering Considerations and Laboratory Tests
This standard contains materiel acquisition program planning and engineering direction ...