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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Subsonic Investigation of a Leading-Edge Boundary Layer Control Suction System on a High-Speed Civil Transport Configuration

A wind tunnel investigation of a leading edge boundary layer control system was conducted on a High Speed Civil Transport (HSCT) configuration in the Langley 14- by 22-Foot Subsonic Tunnel. Data were obtained over a Mach number range of 0.08 to 0.27, with corresponding chord Reynolds numbers of 1.79 x 10(exp 6) to 5.76 x 10(exp 6). Variations in the amount of suction, as well as the size and location of the suction area, were tested with outboard leading edge flaps deflected 0 and 30 deg and trailing-edge flaps deflected 0 and 20 deg. The longitudinal and lateral aerodynamic data are presented without analysis. A complete tabulated data listing is also presented herein.

Campbell, Bryan A.↗
NASA NTRS1974

The design and performance of axially symmetrical contoured wall diffusers employing suction boundary layer control

This paper presents a procedure for the design and the performance prediction of axially symmetrical contoured wall diffusers employing suction boundary layer control. An inverse problem approach was used in the potential flow design of the diffuser wall contours. The experimentally observed flow characteristics and the stability of flows within the diffuser are also described. Guidelines for the design of low suction (less than 10 percent of the inlet flow) and thus high effectiveness contoured wall diffusers are also provided based on the results of the experimental program.

Nelson, C. D., Jr.↗
NASA NTRS1960

An Experimental Investigation of Boundary-Layer Control for Drag Reduction of a Swept-Wing Section at Low Speed and High Reynolds Numbers

An investigation of laminar boundary-layer control by suction for purposes of drag reduction at low speed and high Reynolds numbers has been conducted in the Ames 12-Foot Pressure Wind Tunnel. The model was a 72.96-inch-chord wing panel, swept back 30 deg., which was installed between end plates to approximate a wing of infinite span. The airfoil section employed was a modified NACA 66-012 in the streamwise direction. Tests were limited to controlling the flow over only the upper surface of the model. Seventeen individually controllable suction chambers were provided below the surface to induce flow through 93 spanwise slots in the surface between the 0.0052- and 0.97-chord stations. Tests were made at angles of attack of 0 deg., +/- 1.0 deg., +/- 1.5 deg., and -2.0 deg. for Reynolds numbers from approximately 1.5 x 10(exp 6) to 4.0 x 10(exp 6) per foot. In general, essentially full-chord laminar flow was obtained for all conditions with small suction quantities. Minimum profile-drag coefficients of about 0.0005 to 0.0006 were obtained for the slotted surface at maximum values of the Reynolds number; these values include the Power required to induce suction as an equivalent drag.

Gault, Donald E.↗
NASA NTRS1960

Flight Investigation of the Low-Speed Characteristics of a 45 deg Swept-Wing Fighter-Type Airplane with Blowing Boundary-Layer Control Applied to the Leading- and Trailing-Edge Flaps

A flight investigation has been conducted to study how pilots use the high lift available with blowing-type boundary-layer control applied to the leading- and trailing-edge flaps of a 45 deg. swept-wing airplane. The study includes documentation of the low-speed handling qualities as well as the pilots' evaluations of the landing-approach characteristics. All the pilots who flew the airplane considered it more comfortable to fly at low speeds than any other F-100 configuration they had flown. The major improvements noted were the reduced stall speed, the improved longitudinal stability at high lift, and the reduction in low-speed buffet. The study has shown the minimum comfortable landing-approach speeds are between 120.5 and 126.5 knots compared to 134 for the airplane with a slatted leading edge and the same trailing-edge flap. The limiting factors in the pilots' choices of landing-approach speeds were the limits of ability to control flight-path angle, lack of visibility, trim change with thrust, low static directional stability, and sluggish longitudinal control. Several of these factors were found to be associated with the high angles of attack, between 13 deg. and 15 deg., required for the low approach speeds. The angle of attack for maximum lift coefficient was 28 deg.

Quigley, Hervey C.↗
NASA NTRS1959

Full-Scale Wind-Tunnel Investigation of a Jet Flap in Conjunction with a Plain Flap with Blowing Boundary-Layer Control on a 35 deg Sweptback-Wing Airplane

Previous investigations have shown that increased blowing at the hinge-line radius of a plain flap will give flap lift increases above that realized with boundary-layer control. Other experiments and theory have shown that blowing from a wing trailing edge, through the jet flap effect, produced lift increases. The present investigation was made to determine whether blowing simultaneously at the hinge-line radius and trailing edge would be more effective than blowing separately at either location. The tests were made at a Reynolds number of 4.5 x 10(exp 6) with a 35 deg sweptback-wing airplane. For this report, only the lift data are presented. Of the three flap blowing arrangements tested, blowing distributed between the trailing edge and the hinge-line radius of a plain flap was found to be superior to blowing at either location separately at the plain flap deflections of interest. Comparison of estimated and experimental jet flap effectiveness was fair.

Aoyagi, Kiyoshi↗
NASA NTRS1948

The Effect of Boundary-layer Control by Suction and Several High-lift Devices on the Longitudinal Aerodynamic Characteristics of a 47.5 Degree Sweptback Wing-fuselage Combination

An investigation has been made in the Langley full-scale tunnel of a 47.5 degree sweptback wing-fuselage combination equipped for boundary-layer control by suction. The wing aspect ratio was 3.5, the taper ratio was 0.5, and the airfoil sections normal to the quarter-chord line were NACA 64(sub 1)-A112. The wing configurations tested included the wing with various combinations of extensible leading-edge and split flaps. The effect of Reynolds number, suction-slot location and suction flow coefficient on the aerodynamic characteristics was determined for the model at zero yaw over a range of angle of attack.

WING-FUSELAGE COMBINATIONS - AIRPLANES↗
NASA NTRS1961

Investigation of Longitudinal and Lateral Stability Characteristics of a Six-Propeller Deflected-Slipstream VTOL Model with Boundary-Layer Control Including Effects of Ground Proximity

An investigation of the longitudinal and lateral stability and control and Performance characteristics of a six-propeller deflected- slipstream vertical-take-off-and-landing (VTOL) model in the transition speed range was conducted in the 17-foot test section of the Langley 300-MPH 7- by 10-foot tunnel. A complete analysis of the data was not conducted. A modest amount of blowing boundary-layer control was necessary to achieve transition without wing stall.

Grunwald, Kalman J.↗
NASA NTRS1978

Injection slot location for boundary-layer control in shock-induced separation

An experimental investigation of the effect of tangential air injection, when the injection slot is located inside of what would otherwise have been the dead air zone in a separated flow, in controlling shock-induced turbulent boundary layer separation is presented. The experiments were carried out at a free-stream Mach number of 2.5 in the separated flow induced by a compression corner with a 20 deg angle. The observations made were wall static pressures, pitot profiles, and schlieren visualizations of the flow. The results show that the present location for injection is more effective in suppressing boundary-layer separation than the more conventional one, where the slot is located upstream of where separation would occur in the absence of injection.

Viswanath, P. R.↗
NASA NTRS1986

Numerical simulation of a controlled boundary layer

The problem of interest is the boundary layer over a flat plate. The three standard laminar flow control (LFC) techniques are pressure gradient, suction, and heating. The parameters used to describe the amount of control in the context of the boundary layer equations are introduced. The numerical method required to find the mean flow, the linear eigenvalues of the Orr-Sommerfeld equation, and the full, nonlinear, 3-D solution of the Navier-Stokes equations are outlined. A secondary instability exists for the parallel boundary subject to uniform pressure gradient, suction, or heating. Selective control of the spanwise mode reduces the secondary instability in the parallel boundary layer at low Reynolds number.

Zang, Thomas A.↗