Showing papers on "Fin published in 1973"

A generalized slender-body theory for fish-like forms

Abstract: A consistent slender-body approximation is developed for the flow past a fish- like body with arbitrary combinations of body thickness and low-aspect-ratio fin appendages, but with the fins confined to the plane of symmetry of the body. Attention is focused on the interaction of the fin lifting surfaces with the body thickness, and especially on the dynamics of the vortex sheets shed from the fin trailing edges. This vorticity is convected by the (non-lifting) flow past the stretched-straight body, and departs significantly from the purely longitudinal orientation of conventional lifting-surface theory. Explicit results are given for axisymmetric bodies having fins with abrupt trailing edges, and calculations of the total lift force are presented for bodies with symmetric and asymmetric fin configurations, moving with a constant angle of attack.

Method of modifying a finned tube for boiling enhancement

Abstract: Tubing having circumferentially extending fins, either annular or helical, is modified by forming or bending the fins transversely so that the tip of each fin convolution is closely adjacent to a portion of the next adjacent fin convolution providing small continuous or discrete gaps of predetermined and controlled average size into substantially confined spaces between adjacent fin convolutions.

Boat propulsion means

Abstract: Flexible, webbed or pivoted fins project from a watercraft and provide thrust to propel the craft when the craft is caused to rock from side to side either by the rider or by wave action. The fins may be pivoted having the axis of rotation at their leading edge and having a spring tending to maintain the position of the fin, or the fins may be of a webbed construction.

Self propelled projectile with fins

Abstract: The invention relates to a fin arrangement for a self-propelled projectile which comprises a sleeve mounted coaxially and slidingly over the rear part of the venture of the projectile. The fins are hinged to said sleeve. The sleeve is displaced under the acceleration force of the projectile, after having left the launching tube, from a forward rest position to a rearward service position. This rectilinear displacement of the sleeve causes the unfolding of the fins, the rear part of which are guided by means of guiding ramps, fast with the projectile, during said displacement.

Heat exchanger and method of making same

Abstract: A heat exchanger and method of making same is provided and such heat exchanger comprises a plurality of tubes arranged in parallel relation and a plurality of planar fins each having integral tubular collars extending therefrom which engage and are supported concentrically around the tubes with the collars extending from each planar fin being defined by a first set of collars extending in one direction and a second set of collars extending in a direction opposite from the one direction. The fins are fixed against the tubes in substantially parallel relation with the first set of collars of one fin adjoining and cooperating with the second set of collars of an immediately adjacent fin to provide a precise spacing between fins along the tubes.

Subterranean penetrator steering system utilizing fixed and rotatable fins

Abstract: A steering system for a subterranean penetrator includes a fixed fin and a rotatable fin. The fixed fin is advantageously attached to the exterior rear portion of the penetrator at an angle of approximately 25 DEG with the penetrator's longitudinal axis. The rotatable fin is located diametrically opposite to the fixed fin, the axis of rotation thereof being perpendicular to and intersecting the penetrator's longitudinal axis. An associated actuating mechanism located within the penetrator adjustably orients the position of the rotatable fin. Rotation of the penetrator about its longitudinal axis is effected when the rotatable fin is antiparallel to the fixed fin or to a lesser degree when the rotatable fin is substantially parallel to the penetrator's long axis. Curvilinear penetrator motion along the desired steering plane is effected when the rotatable fin is parallel to the fixed fin, the axis of rotation of the rotatable fin being perpendicular to this plane. In one embodiment of this invention, the rear portion of the penetrator which houses the fins is inwardly tapered at approximately 4 DEG to allow use of substantially smaller fins and/or produce higher steering rates for a given length penetrator. It is an advantage of this invention that it does not require the articulatable tail and its associated actuating mechanism of prior art subterranean penetrators.

The Effect of Wrap-Around Fins on Aerodynamic Stability and Rolling Moment Variations

Abstract: : This report presents the results of an investigation of the effect of wrap-around fins on missile rolling moment coefficient. This investigation was conducted for four fin configurations at free stream Mach numbers ranging from 0.3 to 2.86. The wrap-around fin was found to have a self induced roll moment at zero angle of attack that varies with Mach number. This effect was studied for several fin geometric configurations for the static moment case. Comparisons between the moments caused by the fin cant and wrap-around fins are shown for the rolling case.

High/low aspect ratio dual-mode fin design

Abstract: A dual-mode fin design for gun-launched, rocket-assisted, guided projectiles in which, from a flush position against the body, the fins rotate radially at launch to deploy in the low aspect-ratio mode for stability during the supersonic fly-out phase with transition to the high aspect-ratio mode for the transonic termianl maneuvering phase Deployment of the fins to high aspect-ratio mode is effected by shearing restraining pins which allow the fins to rotate rearwardly about pivot pins and under the air stream influence

Ship stabilizer fin

Abstract: A light-weight, strong, low cost fin for ship stabilization. The fin is composed of plastics materials, such as polystyrene, polyurethane, and the like. The fin is strong and durable in its use as a ship stabilizer. However, the type of materials used in the fin permit the fin to be readily crushed or broken upon impact with other objects, to prevent transmission of forces to the ship which might damage the ship which is stabilized by the fin.

Cooling arrangement for electric generators of underwater power plants

Abstract: A cooling arrangement is provided for an electric generator of an underwater power plant contained in a body wherein a coolant is circulated for cooling the generator. The cooling arrangement includes a cowl that covers the end-face of the generator and forms a portion of the body. The outer surface of the cowl is exposed to the turbine water and the inner surface of the cowl defines a path for conducting the coolant therealong for recooling the coolant. A plurality of cooling fins are provided and each of the fins has two end-portions bent toward each other to give the fin a hook-like configuration. Each fin is fixedly mounted to the inner surface of the cowl at one of the end-portions thereof. The fins are short relative to the length of the path.

Heat transfer device employing fins in a fluid stream

Abstract: The heat exchanger comprises a device coupled in heat exchanging relation with a fluid stream by means of an arcuate array of radially directed, circumferentially spaced, thermally conductive fins with the mean plane of each fin being generally parallel of the axis of revolution of the arcuate array. The fins are corrugated into a wave-like geometry, with the waves increasing in amplitude with increase in radial distance from the axis of revolution, and with the wave fronts running generally laterally to the axis of revolution of the array. The fluid stream flows between adjacent fins in a serpentine path through the array in the axial direction.

Frequency-sensitive resistor and electrical transmission system embodying such resistor

Abstract: A frequency-sensitive resistor whose resistance increases with increase in frequency, and which is particularly adapted for insertion in or in combination with an electrical transmission line for the purpose of damping or attenuating undesirable high frequency electrical transients. In one embodiment of the invention, the frequency-sensitive device comprises a center conductor of copper or other good conductive material on which are mounted in axially spaced relation to each other a plurality of fins such as disks or the like. The fins are formed of or at least coated with a material having a higher resistance than the material of the center conductor. At low power frequencies such as 60 hertz, the resistor device has negligible resistance since currents at low power frequencies pass substantially entirely along the center low resistance conductor and do not enter the higher resistance material of the fins. Upon the occurrence of high frequency electrical transients, due to the skin effect phenomenon the high frequency transients flow in a relatively thin skin across the higher resistance surfaces of the fin members, to thereby cause substantial damping or attenuation of the high frequency transients. In a modified construction in accordance with the invention, a shell-like member formed of or coated with a higher resistance material, and having a corrugated or undulating outer peripheral surface, is mounted in place of the plurality of fins on the low resistance center conductor, but functions in a manner similar to the fins to substantially damp or attenuate high frequency transients. In both embodiments, a relatively long and circuitous high resistance path is provided for the high frequency transients which promotes the damping or attenuation of the high frequency transients.

Diffusers for conditioned air

Abstract: A diffuser for conditioned air has interconnected frames, each frame supporting adjustable fin and damper units and separate adjustable fins. Each fin and damper unit has a pair of dampers as one component, a fin as another component, and a pivot. The two components include interfitting portions that enable the dampers and fin to be separately pivoted. One component has pivot-fitting and confining surfaces, at least when the two components are interconnected. The interconnecting portions permit of unit assembly only on relative movement between them in a direction lengthwise of the axis the pivot-confining surfaces define. The frames are formed from mitered lengths of extruded stock having a lengthwise channel with means dividing the channels into spaced, pivot-receiving sockets and with the channels facilitating the interconnection of the mitered ends.

Projectile or rocket preferably with unfolded tail unit

Abstract: A projectile, preferably a rocket with an unfoldable tail or rudder fin unit with a plurality of guiding fins movable between a storage position extending tangentially along the projectile to a flight position extending radially of the projectile longitudinal axis. A sliding sleeve is arranged in the projectile for engagement with pivot levers on the guiding fins so as to maintain the guiding fins in the storage position until a predetermined instant in the launching of the projectile, at which time the sliding sleeve engages the pivot levers to unfold the fins and force them into their flight position. The sliding sleeve is maintained in a first arresting position for holding the pivot levers and guide fins in the storage position by means of a connecting disk abutting the rear end of the sleeve. This connecting disk is attached to the projectile in such a manner that ignition of propellant charge means disposed rearwardly of the disk cause a disconnection of the disk with respect to the projectile, with a consequent falling away of the disk after the projectile has left a gun barrel so that a rocket engine disposed forwardly of the disk can operate unimpeded by the disk. The disk is provided with a throttle opening for accommodating transfer of propellant charge gases to ignite the rocket cruising engine and to assist a compression spring in moving the sleeve rearwardly to unfold the guiding fins. Preferred embodiments utilize the disk arrangement for accommodating the propellant charge initial acceleration and the later operation of the cruising engine with or without the further inclusion of the sliding sleeve for controlling foldable guide fins. Other features include a cup spring arrangement for holding a warhead detonator in position between detachably connected parts of the projectile, as well as novel conduit means for transferring the propellant charge gases to an ignition element for the crusing engine.

Fuel element for a reactor

Abstract: The outer surface of a cladding tube of a nuclear fuel element is -- for the purpose of improving the heat exchange between the cladding tube and a surrounding coolant -- provided with a plurality of parallel fin rows extending normal to the cladding tube axis Each row is constituted by a plurality of spaced, individual fins; the fins of any one row are offset with respect to the fins of an immediately adjacent row

Electromagnetic assembly resisting axial armature movement for working or finning tubing

Abstract: Fins or threads are formed on the exterior surface of infinite length tubing restrained against rotation and continuously fed longitudinally to a rotating fin forming head. A mandrel initially positioned within the tubing presents a backup tool in the region of the fin forming head, the mandrel being formed from alternate sections of magnetic and non-magnetic material and being held against axial movement by magnets surrounding the tubing and presenting alternate sections of magnetic and non-magnetic material so located that magnetic flux enters and leaves the mandrel at a plurality of locations along the length of each magnet. The fin forming head is free to move axially to avoid stressing the fin forming elements which engage and form helical threads or fins on the exterior surface of the tubing. Initially, the speed of rotation of the fin forming head is adjusted so the rate of formation of fins on the tubing equals the linear speed at which the tubing is fed through the apparatus. If the speed at which the tubing is fed changes, the finning head is free to move axially and actuates a control to either increase or decrease the speed of rotation of the head so fin forming proceeds at the new rate at which the tubing is fed. Emergency shut off means are provided to shut off critical portions of the apparatus in the event of a malfunction such as axial movement of the backup mandrel or axial movement of the rotating finning head beyond certain positions.

Fin Induced Laminar Interactions on Sharp and Spherically Blunted Cones

Abstract: The flowfield structure (surface streamlines and shock patterns), and pressure and heat-transfer distributions associated with small fins mounted near the base of a 7° half-angle cone are measured. The tests are conducted in a hypersonic freestream at a Mach number of 10, freestream unit Reynolds numbers of 0.12 and 0.6 x 10 6/ foot, and wall to total temperature ratio of 0.27. Vehicle geometry (nose bluntness, and fin sweep, shape, thickness, and cant) and orientation (angles of attack and roll) are systematically varied. Fin leading-edge pressure and heat transfer agree with swept infinite cylinder predictions; fin side heating agrees with blunt swept slab theory. Flow patterns, heating and pressure in the fin-cone region are characteristic of corner flow geometries.

Control flap unit for projectiles or rockets

Abstract: A control flap unit for a projectile of the type having a rudder carrier extending longitudinally and a plurality of guiding fins attached to the rudder carrier for pivotal movement about respective pivot axes extending perpendicular to the longitudinal axis of the projectile. A sliding sleeve is disposed internally of the rudder carrier for engagement with pivot levers mounted eccentrically with respect to the fin pivot axes so as to move the fins from a folded condition extending longitudinally along the outside of the rudder carrier to an in-flight position extending radially with respect to the rudder carrier. Lateral guide slots are provided in the rudder carrier for guiding the mounting end portions of the fins. Also, curved pivot lever guide slots are provided in the rudder carrier wall for guiding the pivot levers to effect the pivotal movement of the fins in response to longitudinal movement of the pivot levers resulting from engagement with the movable sliding sleeve. These pivot lever guide slots are constructed with an extension forwardly of the lateral slots so as to accommodate attachment and detachment of the fins with fixedly attached pivot levers onto the rudder carrier by merely inserting the pivot levers through the most forward portions of the pivot lever guide slot and then moving the fin into position in the lateral slots where the fins are pivotally connected to the rudder carrier by way of further connecting means through aligned apertures in the fins and the rudder carrier.

Dimensioning of fins with general nonlinear cooling laws

Abstract: An analytic treatment of rectangular and triangular fins is given, the cooling laws are polynoms of the fin temperature. Closed formulas could be found for the fin temperature, for the dissipated heat flux and for the optimization of the fin dimensions with respect to the mass. The usefulness of the relations in fin application and in heat transfer research is discussed. The used quasilinearization technique outlined in the paper may be of interest for other nonlinear heat transfer problems.

Finned tubes for use in heat exchangers

Abstract: A method of manufacturing a finned tube in which fin stock is first formed as a sheath on a liner tube and the sheath is then extruded to form the fins hereon.

Heat transfer and pressure drop in flow transverse across bundles of finned tubes

Abstract: Experimental results of heat transfer and pressure drop of staggered banks of finned tubes are presented for air flows at high from l0 to 10/sup 6/) Re. Experiments include 12 banks of different fin parameters. The results of heat transfer of the banks according to relative heat transfer coefficient are presented in the form of critical equations. Efficiency, volume, weight and other features of the banks are compared. The effect of fin parameters is analyzed, and general relations of heat transfer are derived which determined the influence of the parameters s/d and h/d on the heat

Semi-conductor and heat sink fin assembly

Abstract: A semi-conductor is housed within a metallic can closed at its top and having a base flange and one or more heat sink fins. Each heat sink fin includes a flexible metallic heat conductive body 0.005 inch thick of disc-shape, centrally apertured and snugly and frictionally mounted over said can. Each fin includes a central annular flange. The fins and flanges in registry for uniform spacing.

Drag reduction towing system

Abstract: A cylindrical body suitable for towing has a support secured to its surface. The support and cylindrical body have parallel axes with the support extending aft a distance beyond the body. Horizontal and vertical fins of a dimension of 30 percent to 40 percent of the lateral cross-sectional area of the body are secured to the aft end of the support. A drop fin having an area of 20 to 30 percent of the vertical lateral area of the body is affixed to the aft end of the body. An increased separation between the center of gravity and center of pressure is effected by the above plurality of fins.

Radially finned tubing - made using fin blanks with holes with metal collars

Abstract: The holes and collars have three symmetrically disposed elastically deformable inward projecting flat sections reducing the hole dia. locally and acting as locking elements on fitting over the tube resulting in a slide fit. The fins are positioned by means of tiltable comb like holders attached to an endless conveyor belt working in conjunction with a tripping device. The spacing of the fins is adjustable independent of the height of the collars by means of a step mechanism. The slide fit of the fins is converted into a firm locking fit by expansion of the tubes to a larger diameter. The method is fast simple and more economical than conventional methods.

Stochastic Optimization of Convective-Fin Design

Abstract: In the design of convective fins, stochastic variations in fin dimensions have traditionally been handled by the use of safety factors. Often this process results in a multiplication of safety factors and thus an overly expensive design. This paper presents a probabilistic approach that not only analyzes the probability of system failure but also uses this analysis to synthesize the optimal design. Four methods of varying accuracy and difficulty are described and compared. The method based on the RMS approximation for the variances appears to be most useful for design purposes.

Fix a fin tool

Abstract: A tool for straightening bent and deformed fins of heat exchangers of a type illustrated by heat exchangers used as condensers and evaporators in air conditioners.

Differential equations for asymmetric bending of circular sandwich plates.

Abstract: Calculations using Eq. (1) utilize a strip method in which the flow is divided into several strips parallel to the vehicle surface. At a given axial location, flow properties are assumed constant across each strip, and the heat-transfer coefficient for a point on the leading edge is calculated using the strip at the same geometrical height. Heat flux predictions were obtained from a two-dimensional thermal model of a fin calorimeter, where Eq. (1) was used to define the boundary conditions. These predicted leading-edge heat fluxes are compared with the flight test calorimeter data in Fig. 4. Agreement of the predictions with the data is satisfactory. The agreement of the data, which were obtained on flat-faced fins, with the prediction method for cylindrically-faced leading edges confirms the trend reported in Ref. 1. It was noted in that investigation that there was no significant difference in the measured heat transfer on slender fins with flat or cylindrical faces which were otherwise geometrically identical.