• Version
• 111 Downloads
• 1.04 MB File Size
• 1 File Count
• February 2, 2017 Create Date
• February 2, 2017 Last Updated

National Advisory Committee for Aeronautics, Technical Notes - Effect of Wall Cooling on Inlet Parameter of a Scoop Operating in a Turbulent Boundary Layer on a Flat or Conical Surface for Mach Numbers 2 to 10

Analytical results were obtained for boundary-layer mass flow,
momentum, total—temperature, and total-pressure recovery ratios of a
scoop inlet with a height equal to the boundaryhlayer thickness and oper—
ating in a turbulent boundary layer, for flat and conical surfaces with
wall cooling. When the wall temperature is reduced from the adiabatic
temperature to that of the free-stream static temperature, mass-flow and
momentum ratios increase up to 50 percent, while the total-temperature
ratio of this airflow is reduced'by about 6 percent, and the total—
pressure recovery increases slightly.

At low supersonic speeds boundary-layer scoop inlets may be con-
sidered as operating in the region of no heat transfer or near insulated
walls. The performance characteristics for this case have been pre-
sented for the flat plate in reference 1. At high supersonic speeds,
however, aerodynamic heating becomes significant, and wall cooling may
be necessary to maintain the structural and aerodynamic integrity of the
aircraft. Theoretical studies of wall cooling related to this problem
have been made in references 2 and 3. 'Since boundary—layer auxiliary
inlets may have to operate in flight areas where wall cooling is re-
quired, it therefore becomes necessary to acquire knowledge of the ef—
fect of wall cooling on the performance characteristics of boundary-
layer scoop inlets.

The theoretical analyses for a turbulent-compressible boundary layer
with heat transfer from references 2 and 5 (where the Prandtl number is
assumed equal to unity) were applied to a method similar to that used in
reference 1 in order to determine the mass-flow, momentum, total-pressure,
and total—temperature ratios for a scoop inlet having a height equal to
the boundary-layer thickness. Variations of these inlet parameters, for
flat and conical surfaces, are presented for several wall-to-free-stream
static-temperature ratios and for Mach numbers from 2 to 10.