57 research outputs found
Jet aircraft configuration Patent
Upper surface, external flow, jet-augmented flap configuration for high wing jet aircraft for noise reductio
Internal-flow systems for aircraft
An investigation has been made to determine efficient arrangements for an internal-flow system of an aircraft when such a system operates by itself or in combination with other flow systems. The investigation included a theoretical treatment of the problem and tests in the NACA 5-foot vertical wind tunnel of inlet and outlet openings in a flat plate and in a wing
Wind-Tunnel Development of Ailerons for the Curtiss XP-60 Airplanem Special Report
An investigation was made in the LWAL 7- by 10-foot tunnel of internally balanced, sealed ailerons for the Curtiss XP-60 airplane. Ailerons with tabs and. with various amounts of balance were tested. Stick forces were estimated for several aileron arrangements including an arrangement recommended for the airplane. Flight tests of the recommended arrangement are discussed briefly in an appendix, The results of the wind-tunnel and flight tests indicate that the ailerons of large or fast airplanes may be satisfactorily balanced by the method developed
Wind-tunnel investigation of an NACA 23012 airfoil with 30 percent-chord venetian-blind flaps
Report presents the results of an investigation made in the NACA 7 by 10-foot wind tunnel of a NACA 23012 airfoil with 30-percent-chord venetian-blind flaps having one, two, three, and four slats of Clark y section. The three-slat arrangements was aerodynamically the best of those tested but showed practically no improvement over the comparable arrangement used in the preliminary tests published in NACA Technical Report No. 689. The multiple-slat flaps gave slightly higher lift coefficients than the one-slat (Fowler) flap but gave considerably greater pitching-moment coefficients. An analysis of test data indicates that substitution of a thicker and more cambered section for the Clark y slats should improve the aerodynamic and the structural characteristics of the venetian-blind flap
Internal-flow systems for aircraft
An investigation has been made to determine efficient arrangements for an internal-flow system of an aircraft when such a system operates by itself or in combination with other flow systems. The investigation included a theoretical treatment of a problem and tests in the NACA 5-foot vertical wind tunnel of inlet and outlet openings in a flat plate and in a wing. When an internal-flow system tends to decrease the final velocity of it's wake, the results showed that it should be arranged in series with the propulsive system; the inlet opening should be located at a forward stagnation point; and the outlet opening should be so shaped and located as to recover the kinetic energy of the jet without increasing the drag of other portions of the aircraft. When an internal-flow system tends to increase the final velocity new b's wake, as does a propeller, location of the inlet opening in the boundary layer or in the wake of the wing or in the fuselage may be desirable
Double scaling and intermittency in shear dominated flows
The Refined Kolmogorov Similarity Hypothesis is a valuable tool for the
description of intermittency in isotropic conditions. For flows in presence of
a substantial mean shear, the nature of intermittency changes since the process
of energy transfer is affected by the turbulent kinetic energy production
associated with the Reynolds stresses. In these conditions a new form of
refined similarity law has been found able to describe the increased level of
intermittency which characterizes shear dominated flows. Ideally a length scale
associated with the mean shear separates the two ranges, i.e. the classical
Kolmogorov-like inertial range, below, and the shear dominated range, above.
However, the data analyzed in previous papers correspond to conditions where
the two scaling regimes can only be observed individually.
In the present letter we give evidence of the coexistence of the two regimes
and support the conjecture that the statistical properties of the dissipation
field are practically insensible to the mean shear. This allows for a
theoretical prediction of the scaling exponents of structure functions in the
shear dominated range based on the known intermittency corrections for
isotropic flows. The prediction is found to closely match the available
numerical and experimental data.Comment: 7 pages, 3 figures, submitted to PR
Local shell-to-shell energy transfer via nonlocal Interactions in fluid turbulence
In this paper we analytically compute the strength of nonlinear interactions
in a triad, and the energy exchanges between wavenumber shells in
incompressible fluid turbulence. The computation has been done using
first-order perturbative field theory. In three dimension, magnitude of triad
interactions is large for nonlocal triads, and small for local triads. However,
the shell-to-shell energy transfer rate is found to be local and forward. This
result is due to the fact that the nonlocal triads occupy much less Fourier
space volume than the local ones. The analytical results on three-dimensional
shell-to-shell energy transfer match with their numerical counterparts. In
two-dimensional turbulence, the energy transfer rates to the near-by shells are
forward, but to the distant shells are backward; the cumulative effect is an
inverse cascade of energy.Comment: 10 pages, Revtex
Recommended from our members
NACA Advanced Confidential Reports
"Test data of balanced ailerons have been collected from NACA and British sources. These data, which are presented in the form of charts, are grouped as A - ailerons with Frise balances, B - ailerons with blunt-nose balances, C - ailerons with internal balances, D - ailerons with contour modifications, and E - ailerons with tabs. Results of flight tests and of wind-tunnel tests in both two- and three-dimensional flow are presented but no correlation nor resume of the data has been included" (p. 1)
- …