Showing papers on "Leading edge published in 1969"

Evaluation of internal heat-transfer coefficients for impingement-cooled turbine airfoils.

Abstract: Although internal impingement cooling of the leading edge of gas-turbine airfoils has been shown to be effective, previously available heat-transfer data are not generally applicable to present-day turbine designs because of the unique geometry requirements. An experimental system which allows the ready acquisition of heat-transfer data necessary for thermal design of turbine airfoils is described. A cold-flow model is developed, and the measurement of local heat-transfer coefficients on a full-size model is accomplished by considering Joulean dissipation in very thin platinum strips bonded to the model. Heattransfer results are given which show the dependence of Nusselt number on Reynolds number, geometry, and chordwise location on the inside leading-edge region of the airfoil. Dimensionless correlations are presented which allow the designer to predict heat transfer for impingement cooling in these geometries for the range of parameters tested.

The effect of buoyancy forces on the boundary-layer flow over a semi-infinite vertical flat plate in a uniform free stream

Abstract: The boundary-layer flow over a semi-infinite vertical flat plate, heated to a constant temperature in a uniform free stream, is discussed in the two cases when the buoyancy forces aid and oppose the development of the boundary layer. In the former case, two series solutions are obtained, one of which is valid near the leading edge and the other is valid asymptotically. An accurate numerical method is used to describe the flow in the region where the series are not valid. In the latter case, a series, valid near the leading edge is obtained and it is extended by a numerical method to the point where the boundary layer is shown to separate.

Aircraft engine variable highlight inlet

Abstract: AN AIRCRAFT JET ENGINE LEADING EDGE DOUBLE FOIL STRUCTURE COMPRISING A PIVOTALLY MOUNTED EXTERIOR FOIL WHICH FORMS THE LEADING EDGE CONTOUR AND EXTERIOR COWL FAIRING IN A CLOSED POSITION DURING HIGH-SPEED FLIGHT AND WHICH IS RESPONSIVE TO AERODYNAMIC PRESSURES TO PIVOT TO EXPAND THE LEADING EDGE DIAMETER OR HIGHLIGHT DURING TAKE-OFF LOW-SPEED FLIGHT. A PIVOTALLY MOUNTED INTERIOR FOIL ACTS AS AN INTERNAL COWLING FAIRING FOR HIGH-SPEED FLIGHT AND PIVOTS TO COMBINE WITH SAID EXTERIOR FOIL TO FORM AN AERODYNAMICALLY CLEAN AUXILIARY AIR LONGITUDINALLY ALONG THE INTERIOR DIRECTS THE AUXILIARY AIR LONGITUDINALLY ALONG THE INTERIOR WALL OF THE INTAKE COWLING, THEREBY PROVIDING BOUNDARY LAYER CONTROL AND DECREASING PRESSURE RECOVERY LOSSES.

Sheet-straightening mechanism

Abstract: An apparatus for straightening sheets of material carried by a conveyor includes a sheet-sensing switch on each side of the conveyor actuated by the leading edge of the sheet to indicate the magnitude and direction of misalignment. A timing circuit computes the time difference between the passage of the leading edge of each side of the sheet and controls the speed of drive motors which thereafter move the sides of the sheet independently of the conveyor to straighten it.

Transient Plasma Sheath—Discovered by Ion‐Acoustic Waves

Abstract: For a high negative voltage V0 placed impulsively at the edge of a plasma, a sheath is formed of thickness X = (2eV0)1/2(4πnie2)−1/2 This sheath is observed by extrapolating the position of the leading edge of an ionic sound‐wave pulse back to zero time. The ion number density can be obtained from this sheath.

Predictions of vortex-lift characteristics based on a leading-edge suction analogy.

Abstract: Leading edge suction analogy for predicting low speed lift and drag-due-to-lift characteristics of sharp edge delta and related wing planforms

On the singularity method of subsonic lifting- surface theory.

Abstract: Subsonic lifting surface theory including leading edge, discussing singularities in solution of integral equation for determination of aerodynamic properties

Airfoil with porous leading edge

Abstract: A HOLLOW AIRFOIL FOR USE AS A TURBINE VANE OR BLADE IS MADE UP OF A NUMBER OF SHEET METAL LAYERS BONDED TOGETHER AND FOLDED AT THE LEADING EDGE. HOLES FOR TRANSPIRATION COOLING OF THE BLADE ARE FORMED IN THE LEADING EDGE, THE HOLES IN THE SUCCESSIVE LAYERS BEING DISPOSED IN SPANWISE ROWS WITH THE HOLES IN EACH LAYER PARTIALLY OVERLAPPING THE HOLES IN THE CORRESPONDING ROW IN ADJACENT LAYERS. THESE HOLES IMPROVE THE FOLDING PROPERTIES OF THE LEADING EDGE. SOME OF THEM ARE CONNECTED TO CONDUCT AIR TO THE FORWARD PORTION OF THE POROUS SIDE WALLS OF THE AIRFOIL.

Aircraft engine leading edge auxiliary air inlet

Abstract: A primary and an auxiliary inlet system for an aircraft jet engine. A rigid leading edge ring pivotally supports exterior and interior foil members which in a first position provide a portion of the cowling forebody fairing and which in a second position coact to provide one wall of an auxiliary inlet. The foils are spring-biased into their first positions for cruise flight and are responsive to aerodynamic pressures caused by changing flight conditions to pivot into said second position for low-speed flight and takeoff conditions.

Kinetic Theory of the Sharp Leading Edge Problem in Supersonic Flow

Abstract: The sharp leading edge problem is studied within the framework of the kinetic theory of gases. The Boltzmann equation with the Bhatnagar‐Gross‐Krook model is used as the governing equation. The method of discrete ordinates developed by Huang is applied. The local distribution functions for the entire flow field have been calculated for the case of supersonic flow, M∞ = 1.5; thus, the complete flow field has been generated for various plate temperature values. The calculated results offer considerable insight into the behavior of a rarefied gas flow as it traverses the complete spectrum of flow regimes from near‐free molecular to continuum, and present a meaningful connection between the near‐free molecule solution at the leading edge and the extended continuum theories in the interaction regimes. Comparison with the existing theories and experimental data show reasonably good agreement in all flow properties. For higher Mach numbers, however, a higher‐order quadrature is necessary. It is felt that the onl...

Measurement of Elastic and Plastic Unloading Wave Profiles in 2024‐T4 Aluminum Alloy

Abstract: Velocities for one‐dimensional release waves in 2024‐T4 aluminum alloy have been obtained between 30 and 132 kbar. Stress‐time records were obtained with piezoresistive manganin gauges. The release wave clearly showed the existence of two release systems. The leading edge of the release wave was 27% faster than the bulk sound velocity calculated from the ideal fluid model. The second release system was identified by a change in slope of the release wave profile. The peak velocity of this release system did correspond more closely to the hydrodynamic bulk sound velocity. These results imply elastic behavior of aluminum at high pressure. The shape of the release wave, however, cannot be fitted by a perfect elastic‐plastic model, thus pointing out the need of a more elaborate description.

Edge connector with polarizing member

Abstract: A connector having a socket for receiving the leading edge of a printed circuit board includes a polarizing and keying member adapted to engage an indexing slot adjacent the printed circuit board leading edge in a given direction. The engaging keyingindexing member and slot are disposed in the socket intermediate the socket bottom and the contact region of a contact element, permitting the contact element and the indexing-keying means to be aligned in the given direction.

Hypersonic interactions near sharp leading edges.

Abstract: : Numerical solutions of a set of parabolic equations, uniformly valid throughout the entire continuum flow domain, were obtained for the axi-symmetric flow over slender sharp nose cones at zero angle of attack, the hypersonic interference flow between two finite length flat plates and the flow over a sharp flat plate of finite span. The regions of interest are the leading edge merged layer and the initial portion of the strong interaction flow. The analysis represents an extension of the theory first used successfully for the flow over two-dimensional sharp flat plates. Merged layer interference, the merging of streams at different pressures in the wake of the channel geometry, the three-dimensional flow and shock structure, as well as the significant differences between two-dimensional, and axi-symmetric or three-dimensional flow fields are discussed. Comparisons with available experimental data are good, as evidenced by surface pressure and heat transfer results, for the flow over cones. (Author)

Laser with combined q-switch and synchronized cavity dump circuit

Abstract: A high voltage electrical waveform generator circuit is provided which generates a voltage waveform having a positive d.c. voltage leading edge and a negative d.c. voltage trailing edge to the modulator. A gas trigger tube is provided in the circuit which generates a positive d.c. voltage leading edge in its plate circuit when it is independently triggered by a trigger signal. Another gas trigger tube generates a positive voltage when it is triggered by another trigger signal. A coupling circuit which couples the plate circuits of the trigger tubes includes capacitor which converts the positive voltage generated by the other trigger tube into the negative d.c. voltage trailing therefor edge of the voltage waveform. The coupling circuit may also include differentiator which allows the voltage levels on the trigger tube plates to be independently varied without affecting each other.

Method and apparatus for turning over a plate

Abstract: Method and device for turning over a plurality of plates being advanced sequentially in a horizontal plane, a suggested structure including a pair of slotted heads which engage the leading edge of the advancing plate and upon being rotated 180* flip the plate over, so that both top and bottom of the plate may be painted or treated within the horizontal plane.

Continuously operating automatic filling machine

Abstract: THE LEADING EDGE OF A NEW ROOL OF PACKAGING FILM IS AUTOMATICALLY BONDED TO THE TRAILING EDGE OF THE OLD FILM ROLL DURING CONTINUOUS RUNNING OF AN AUTOMATED PACKAGE FILLING MACHINE AND THE LEADING END OF THE NEW ROLL OF BINDING WIRE IS AUTOMATICALLY WELDED TO THE TRAILING END OF THE OLD ROLL OF BINDING WIRE.

Computer printout paper package

Abstract: A technique of packaging a web of computer printout paper to facilitate loading the paper in a carrier or support tray and connecting the trailing edge of the web to the leading edge of a succeeding web carried in another tray. The package includes a box which contains the paper web, folded in a zigzag configuration. The box has a cover which, when removed, exposes an end of the pack, the web being folded so that at least the free, trailing end of the web will be exposed when the cover is removed. The exposed trailing end then may be pulled to withdraw a length of the web and the entire package, including the box, may be laid down on the tray. The box then is pulled free to transfer the folded web to the tray and the withdrawn trailing length of the web then may be attached to the leading end of the succeeding web.

Lockup for thin plates

Abstract: A lockup for a thin printing plate of the type having inwardly bent leading and trailing edges in which a U-shaped longitudinally extending spring is mounted in a slot formed in the printing cylinder with a cam shaft on one side of the spring for pressing the legs of the spring in the same direction for respectively holding the leading edge captive and for hooking onto the trailing edge to lock the plate to the cylinder and to provide continuous automatic takeup as the cylinder revolves.

The behaviour of the leading-edge vortices over a delta wing following a sudden change of incidence

Abstract: The trafisient behaviour of leading-edge vortices over a delta wing subject to a sudden change of incidence is of importance in understanding the wing loadings that can occur in unsteady conditions of flight. In the experiments reported here, changes of incidence have been imposed on delta-shaped plates by application of a constant-velocity plunging motion for a limited time; other related unsteady motions are discussed in the Appendix. Cin6 records of particle tracks and of dye filaments in a water tunnel have been analysed to trace the time history of vortex centres in cross-flow planes following the application of step-changes of incidence. The flows for various combinations of initial incidence, planform, plunging velocity and chordwise position have been examined. Results indicate that after the start of the plunge an effectively steady vortex system is established over the plate in a time approximately equal to that required for one chord length of relative forward travel. Where comparisons can be made, Dore's theoretical calculations of the manner in which the vortices move show fair agreement with the experiment. Effects of the transient movements of the vortices on lift distribution are discussed and the inference is drawn that the changes in the distribution of wing loading occurring for an increase of incidence are not simply reversed when the incidence is decreased. ° 2.

Fabricated two-piece stator assembly for hydrokinetic torque converters

Abstract: A bladed stator assembly comprising two circular bladed sections situated in adjacent relationship, each section complementing the other, one section defining a fluid flow entrance region and the other section defining a fluid flow exit region, and radially displaced blades, each blade including a leading edge portion integrally formed on one stator section and a trailing edge portion integrally formed on the other stator section.

Document stacker apparatus

Abstract: Document stacker apparatus wherein transport belts are continuously in contact with documents as they are transported to a stacking bin. At the stacking bin, roller means forces the trailing edge of the document downwards so that it does not interfere with the leading edge of a succeeding document.

Atomization apparatus and method

Abstract: An atomization technique which involves the movement of a film of liquid, such as water, over both surfaces of the blades of a multibladed fan rotating about its hub. The liquid is fed in an annular stream or annular series of jets to the rotating blades near the hub of the blades. The leading edge of each blade cuts into the stream and picks up a portion of the liquid. The liquid then travels over both surfaces of each blade progressing from leading edge to trailing edge and also, because of centrifugal forces, outboard from the hub. As the liquid comes off the trailing edge of each rotating blade, it is atomized to the droplet size desired; the droplet size being a function of parameters such as rotational speed, quantity of water fed to the rotating blades, and length of trailing edge. There is also specifically disclosed the application of the invention to snowmaking. In snow-making, the movement of air over the surface of the film of water, that in turn is moving over the surfaces of each blade, causes evaporation. This evaporation cools the water down to somewhere between 10* F. and 15* F., at which temperature the atomized droplets that come off the trailing edge of the blades will, under proper ambient conditions of temperature and humidity, form particles of snow.

Gas turbine airfoil having integral thermocouple

Abstract: A gas turbine airfoil having a thermocouple assembly mounted integrally therewith so as to sense the temperature at the surface of the leading edge of the airfoil without disturbing the gas flow conditions within the engine is disclosed.

Active delay line

Abstract: An electrical delay line including a series of active stages interconnected so that the leading edge of the pulses being propagated through the active stages connected in cascade controls both the turn-on and turnoff of the delayed output pulses to provide delayed pulses having constant amplitude and constant width.

On the singularity method of subsonic lifting- surface theory

Abstract: Subsonic lifting surface theory including leading edge, discussing singularities in solution of integral equation for determination of aerodynamic properties

Regulated inverter using synchronized leading edge pulse width modulation

Abstract: A regulated inverter circuit wherein leading edge pulse width modulation is obtained by employing a modulator control network synchronized with the sinusoidal feedback bias which delays the application of this bias for an interval determined by load voltage variations. Deleting the leading edge of the sinusoidal driving waveform allows the inverter transistors to be efficiently biased from cutoff to saturation and at the same time eliminates the adverse effects of stored charge when the transistors are driven from saturation to cutoff.

Rotary semirigid airfoil

Abstract: A semirigid airfoil for use with rotary wing airborne vehicles. The airfoil includes a rigid spar defining a leading edge, a cable defining the trailing edge and having a root end thereof secured to a root truss and an opposite end thereof secured to a tip truss. Flexible material forms top and bottom airfoil surfaces. Means are provided for controlling the tension in the trailing edge cable during rotation of the airfoil.

Method of electrostatically depositing particles onto the trailing edge of a substrate

Abstract: AN APPARATUS AND A METHOD FOR DEPOSITING CHARGED PARTICLES OF A POWDERY SUBSTANCE ONTO AN EDGE OF A SUBSTRATE. THE APPARATUS MAY INCLUDE MEANS FOR EMITTING PARTICLES OF A POWDERY SUBSTANCE TOWARD THE SUBSTRATE. SUBSTANTIALLY ALL OF THE PARTICLES ARE PROPELLED BEYOND A LEADING EDGE OF THE SUBSTRATE TO THE VINCINITY OF A TRAILING EDGE OF THE SUBSTRATE. ANOTHER MEANS IS ADJACENT THE TRAILING EDGE OF THE SUBSTRATE WHICH IS CAPABLE OF CAUSING ELECTROSTATIC DEPOSITION OF THE PARTICLES ONTO THE TRAILING EDGE OF THE SUBSTRATE.

Foldable semirigid airfoil for airborne vehicles

Abstract: The present invention relates to a foldable, composite rigid and semirigid airfoil for use with airborne vehicles. The airfoil includes a rigid portion. A hinged rigid spar defines a leading edge of the airfoil. The trailing edge of the airfoil is defined by both a rigid aileron structure forming part of the rigid wing portion, and a cable which interconnects the rigid portion of the airfoil with a root point of attachment on the fuselage of the vehicle. Flexible material forms top and bottom airfoil surfaces of the collapsible wing portion when the airfoil is deployed, said airfoil surfaces being continuous with the aerodynamic form of the rigid wing portion.