Showing papers on "Nacelle published in 1993"

Nacelle and mounting arrangement for an aircraft engine

Abstract: A nacelle and mounting arrangement for a high bypass ratio ducted fan aircraft engine mounted external to the aircraft main structure is disclosed. The nacelle and mounting arrangement isolate the engine from the adverse effects of certain aerodynamic forces acting on the nacelle by transferring substantially all of those forces directly from the nacelle to the aircraft and transferring substantially none of those forces to the engine. Various arrangements of the nacelle components which facilitate engine removal while avoiding the placement of nacelle component interfaces in highly stressed regions of the nacelle are also disclosed.

Microwave-powered aircraft

Abstract: An unmanned, remotely controlled microwave-powered aircraft for use as a stationary communications platform. The aircraft is generally a flying wing with a large, flat inner wing having a rectenna on the underside. Rectennas may also be provided on the underside of the wings, the combined output from the rectenna being used to provide power to two electric motors housed within torpedo-shaped nacelles which drive two rear propellers. The rectenna converts a microwave signal at 35 GHz generated by a ground power station utilizing dual gyrotrons and a 34-meter diameter antenna dish. The aircraft has a preferred airfoil cross section throughout and is constructed of lightweight but strong materials in order to provide an enhanced flying time of several months. A power management and distribution system manages the DC power produced by the rectenna to supply power to the flight controls, propulsion system and payload.

Design Optimization of Aircraft Engine-Mount Systems

Abstract: The engine is modeled as a rigid body connected to a flexible isolation base representing the nacelle. The base is modeled with mass and stiffness matrices and strucural damping using finite element modeling. The objective is to select the stiffness coefficients and orientation angles of the individual mounts in order to minimize the transmitted forces from the engine to the nacelle

Optimization of aircraft engine suspension systems

Abstract: An interactive computer program has been developed to design aircraft engine mounting systems used for vibration isolation. Mount design is largely driven by two competing criteria. Mounts must be soft enough to provide vibration isolation, yet stiff enough to support the engine without excessive motions. The constrained variable metric optimization technique is used to determine the mount design parameters which minimize the transmitted forces in the mounts, subject to constraints on the maximum allowable deflection of the engine to static forces. The design parameters are the stiffness and orientation of each individual engine mount. The aircraft engine is modeled as a rigid body that is mounted to a rigid base representing the nacelle. An example is used to show that the optimization technique is effective in designing engine mounting system.

Collapsible wheeled carrier for duck and goose decoys and the like

Abstract: Presented is a wheeled carrier defining a nacelle within which may be carried articles to be transported, such as duck and goose decoys. The carrier includes a main frame joined by a bottom frame structure to form the nacelle. Wheel assemblies are pivotally mounted on the main frame and may be attached or detached from the bottom frame structure for use or for storage.

Mounting arrangement for a gas turbine engine

Abstract: A nacelle of a gas turbine engine is attached via a pylon to an aircraft wing from which the engine is to be mounted. The nacelle is split to form a pair of opposing arcuate doors which are moveable between an open position and a closed position. When the doors are closed a ring on the fan casing locates in a correspondingly shaped groove on the inner surface of the arcuate doors. The nacelle is structurally integrated with the fan casing with the ring so that all the engine loads are transmitted through the nacelle. Telescopic struts are provided to connect the engine casings directly to the pylon so that when the arcuate doors are open, to allow access to the engine, the struts 50-60 support the engine.

Aerodynamic optimization of an HSCT configuration using variable-complexity modeling

Abstract: An approach to aerodynamic configuration optimization is presented for the high-speed civil transport (HSCT). A method to parameterize the wing shape, fuselage shape and nacelle placement is described. Variable-complexity design strategies are used to combine conceptual and preliminary-level design approaches, both to preserve interdisciplinary design influences and to reduce computational expense. Conceptual-design-level (approximate) methods are used to estimate aircraft weight, supersonic wave drag and drag due to lift, and landing angle of attack. The drag due to lift, wave drag and landing angle of attack are also evaluated using more detailed, preliminary-design-level techniques. New, approximate methods for estimating supersonic wave drag and drag due to lift are described. The methodology is applied to the minimization of the gross weight of an HSCT that flies at Mach 2.4 with a range of 5500 n.mi. Results are presented for wing planform shape optimization and for combined wing and fuselage optimization with nacelle placement. Case studies include both all-metal wings and advanced composite wings.

Aircraft gas turbine engine backbone deflection thermal control

Abstract: A gas turbine engine thermal backbone deflection control apparatus to counter the effects of backbone bending due to nacelle aerodynamic, thrust, and maneuver loads by introducing a controlled backbone counter-bending moment by applying an uneven temperature or thermal field around the backbone to induce controlled compression and/or tensioning forces in the backbone or casing between axially spaced apart frames connected by the backbone. One embodiment of the invention provides for flowing thermal control air along an axially and circumferentially sector of the engine casing. The thermal backbone deflection control apparatus is controlled by the engines digital electronic control system using input signals generated by engine thrust load, inlet moment load sensors and/or blade tip clearance sensors.

Ducted boundary layer diverter

Abstract: Boundary layer control apparatus is provided (22). The boundary layer control apparatus (22) is for use with an aircraft propulsion nacelle (12) positioned such that the air inlet (14) of the propulsion nacelle is located proximate an aircraft surface (10), wherein a boundary layer is established on the surface when the aircraft is propelled through an atmosphere, causing air to flow over the surface. The boundary layer control apparatus (22) includes a duct having an entrance (24) positioned between the aircraft surface (10) and the inlet (14) of the propulsion nacelle (12) for capturing the boundary layer air passing over the aircraft surface and diverting the boundary layer air away from the inlet.

Arrangement for maintaining laminar air flow over gaps in aircraft engine nacelle surfaces

Abstract: A system for eliminating turbulence in aerodynamic surfaces, such as engine nacelles, resulting from air passing over joints and gaps in the aerodynamic surface Basically, this system includes a suction chamber within the nacelle and extending along the inner skin wall adjacent to gaps or joints, such as around access doors, at the interface between the nose cowl and the fan cowl door, etc Typically, a series of apertures extend through a top portion of the suction chamber below the gap to permit air to pass from the gap to the suction chamber At least one duct communicates with the chamber and extends to a suction pump In operation, the pump sucks air through the duct, suction chamber, apertures and gap, to prevent the formation of a transition from low drag laminar flow to high drag turbulent flow at the gap

Method for forming aircraft engine nacelle exhaust mixers and similar products

Abstract: A method for forming aircraft nacelle mixers by rolling and welding a cylinder of metal to a predetermined diameter and then taper machining to an empirically determined thickness which allows it to be end sealed, longitudinally end loaded, and pressure formed to a preform die before final pressure forming to a finish die.

Method and device for tying blade in place in wind power generator

Abstract: PURPOSE: To provide a method and a device for tying blades in place in a wind power generator, whereby wind power generator blades can be installed and removed in a short time through operations done at a high place and without using large equipment. CONSTITUTION: A device for tying blades in place includes a nacelle 2 provided at the upper and of a long tower 1, having a built-in generator, and being horizontally rotatable; a plurality of blades 3 each of which rotates about an almost horizontal axis H and is removably secured to a hub 4 for driving the generator; and blade tying devices 10, 20 for securing the blades in place along the tower. The nacelle 2 is rotated to stop each of the plurality of blades 3 along the tower, and the blades 3 are secured to the tower using the blade tying devices and then separated from the hub 4. COPYRIGHT: (C)1994,JPO&Japio

Efficient anti-ice exhaust method

Abstract: An anti-icing system for a nacelle of a gas turbine powerplant is disclosed. Various construction details have been developed which provide means to exhaust fluid from an inlet shell cavity and into an external medium. In one embodiment, the exhaust means (62) includes a plurality of aerodynamically shaped vanes (66) disposed within the inlet shell cavity (52) and a plurality of exhaust slots (68) wherein each of the vanes is adjacent one of the exhaust slots. The vanes are adapted to turn a portion of the body of fluid flowing within the inlet shell cavity to a direction substantially normal to the direction of flow of the external medium.

V-22 Nacelle Conversion Actuator

Abstract: A design outline is given of the actuator that rotates the engine and rotor nacelles on the V-22 aircraft The actuator comprises a two-stage telescopic ballscrew that is driven either hydraulicall

Evaluation of two cockpit display concepts for civil tiltrotor instrument operations on steep approaches

Abstract: A piloted simulation experiment was conducted using the NASA Ames Research Center Vertical Motion Simulator to evaluate two cockpit display formats designed for manual control on steep instrument approaches for a civil transport tiltrotor aircraft. The first display included a four-cue (pitch, roll, power lever position, and nacelle angle movement prompt) flight director. The second display format provided instantaneous flight path angle information together with other symbols for terminal area guidance. Pilots evaluated these display formats for an instrument approach task which required a level flight conversion from airplane-mode flight to helicopter-mode flight while decelerating to the nominal approach airspeed. Pilots tracked glide slopes of 6, 9, 15 and 25 degrees, terminating in a hover for a vertical landing on a 150 feet square vertipad. Approaches were conducted with low visibility and ceilings and with crosswinds and turbulence, with all aircraft systems functioning normally and were carried through to a landing. Desired approach and tracking performance was achieved with generally satisfactory handling qualities using either display format on glide slopes up through 15 degrees. Evaluations with both display formats for a 25 degree glide slope revealed serious problems with glide slope tracking at low airspeeds in crosswinds and the loss of the intended landing spot from the cockpit field of view.

Supersonic flow visualization of a nacelle in close proximity to a simulated wing

Abstract: A flow visualization study was made in the 9 x 9 inch supersonic wind tunnel at Wichita State University to examine shock and boundary layer flow interaction for a nacelle in close proximity to the lower surface of a simulated wing. The test matrix included variations of angle of attack from -2 degrees to +4 degrees, nacelle-wing gap from 0.5 to 3-nacelle inlet diameter (0.12 inch), and Reynolds number based on nacelle length (1.164 inch) from 1.16 x 10(exp 6) to 1.45 x 10(exp 6) at a nominal Mach number of 2. Schlieren pictures of wing and nacelle flowfield were recorded by a video camera during each tunnel run. Results show that the nacelle inlet shock wave remains attached to the inlet lip and its impingement does not significantly affect the wing boundary layer. At the nacelle trailing edge location, the wing boundary layer thickness is approximately one nacelle inlet diameter at alpha = 0 degrees and it decreases with increase of angle of attack.

Analysis of a high bypass ratio engine installation using the chimera domain decomposition technique

Abstract: This paper describes the work performed at GE Aircraft Engines to develop an analytical capability to assess the aerodynamic performance of engine installations. The paper starts by discussing the choices of gridding ‘and solution procedures that are available. This is followed by a brief descriptions of the chimera domain decomposition technique that has been adopted at GE Aircraft Engines. To demonstrate the method, the gridding and solution of a wind tunnel model of a modem high bypass ratio engine installed onanadvancedwingisdescribed. Theresultsfrom theCFD analysis are compared with the wind tunnel test data and conclusions are drawn about the aerodynamic interaction between the nacelle and wing.

Exhaust vent for de-icing system of aircraft nacelle

Abstract: An anti-icing system for a nacelle of a gas turbine powerplant is disclosed. Various construction details have been developed which provide means to exhaust fluid from an inlet shell cavity and into an external medium. In one embodiment, the exhaust means (62) includes a plurality of aerodynamically shaped vanes (66) disposed within the inlet shell cavity (52) and a plurality of exhaust slots (68) wherein each of the vanes is adjacent one of the exhaust slots. The vanes are adapted to turn a portion of the body of fluid flowing within the inlet shell cavity to a direction substantially normal to the direction of flow of the external medium.

Integration of high bypass ratio engines on modern transonic wings for regional aircraft

Abstract: Changing airline scenarios and aggravated congestion have led to an increasing demand for new regional aircraft which will cover ranges of more than 1500 nm and accommodate 80 to 130 passengers. These far exceed the capability of today's commuter types. In the required thrust range of 15-5-20 klb only a very limited number of older engines with high SFC is available. Recently the manufacturers have begun offering new turbofans based on modern core technology and internal mixing (long duct) with lower SFC. The underwing turbofan installation aspects are well understood from earlier wide and narrowbody aircraft but installing a long-duct nacelle on such a small aircraft means a significant increase in interference problems which may lead to close coupling and new methods for minimisation of the mutual interference. After a survey of installation problems on previous jet transports up to the Airbus family the state of the art of experimental and theoretical methods for interference analysis is discussed. By means of an inverse design method a local lofting change on a given wing design confined to 20% span area was derived in order to sustain the isobar pattern of the clean wing with the pod/pylon on. The design modification was checked by means of a 3D-Euler code and verified on a large half-model in the NLR-HST wind tunnel. From the analysis of the resulting conclusions concerning the feasibility of such a lofting change, further improvements are made.

Aircraft engine nacelle with arc contour

Abstract: PURPOSE: To provide an elliptical nacelle having a minimum vertical height with improved airflow characteristics used for an aircraft engine. CONSTITUTION: A nacelle 90 has an inlet 92 whose front view portrays an elliptical shape and whose side view represents an arcuate profile. The arcuate profile is determined by three hilite points located at an extreme top position 94, a side position 98, 100, and an extreme bottom position 96 of the nacelle. Each hilite location is set at an individually predetermined distance from a plane which is perpendicular to an inlet centerline.

Anti-icing system

Abstract: An anti-icing system for a nacelle of a gas turbine powerplant is disclosed. Various construction details have been developed which provide means to exhaust fluid from an inlet shell cavity and into an external medium. In one embodiment, the exhaust means (62) includes a plurality of aerodynamically shaped vanes (66) disposed within the inlet shell cavity (52) and a plurality of exhaust slots (68) wherein each of the vanes is adjacent one of the exhaust slots. The vanes are adapted to turn a portion of the body of fluid flowing within the inlet shell cavity to a direction substantially normal to the direction of flow of the external medium.

Turbojet engine with supersonic compression

Abstract: Engine for supersonic cruise aircraft comprising a supersonic compressor (114) capable of operating in a supersonic compression mode, the compressor being so mounted upstream of a core engine assembly (116,120,122) within an engine nacelle that the entire exit flow of the supersonic compressor enters the core engine assembly when the aircraft is operating at transonic and supersonic speeds. Preferably, the compressor is further capable of operating in a subsonic compression mode when the aircraft is operating at subsonic speeds. In this case, a portion of the exit flow of the supersonic compressor bypasses (126,130) the core engine assembly. The engine may further comprise means for diverting a portion of the compressor exit flow to the exterior (128) of the engine nacelle when the aircraft is operating subsonically.

An installed nacelle design method using multiblock Euler solver

Abstract: An efficient multiblock Euler design method was developed for designing a nacelle installed on geometrically complex airplane configurations. This approach employed a design module based on a direct iterative surface curvature method developed at NASA-Langley. A multiblock Euler flow solver was used for computing flow around complex geometries. The flow solver used a finite-volume formulation with explicit time-stepping to solve the Euler equations. It used a multiblock version of the multigrid method to accelerate the convergence of the calculations. The design module successively updated the surface geometry to reduce the difference between the computed and target pressure distributions. In the flow solver, the change in surface geometry was simulated by applying surface transpiration boundary conditions to avoid repeated grid generation during design iterations. Smoothness of the designed surface was ensured by alternate application of streamwise and circumferential smoothings.

Use of CFD Methods to Design Engine Nacelles

Abstract: The challenge for current and future nacelles of commercial engines is to obtain: -low transonic drag in cruise condition, -low weight and reduced dimensions without reducing the low speed operating domain (maximum incidence, crosswind, etc) and low noise level. This paper explains how various designs can be improved by using modern numerical methods.Concerning air inlets, 3D Euler code and boundary layer code are used for prediction of divergence Mach number and drag in cruise conditions. Low speed behaviour is also obtained for various flight conditions which cause high local incidences on air inlet sections. Attention is mainly focused on attached flow limits. CFD method calibrations based on existing tests results are needed for that work.Bypass and core nozzle design use axisymmetric Navier-Stokes calculations for the prediction of thrust and flow coefficients relative values. This calculation also helps on development of adequate designs of the throat region and provides detailed analysis of the core nozzle flowfield including interaction of outer cold jet.These methods are applied to the design of an advanced nacelle for a high bypass ratio engine. This nacelle is equiped with an original core cowl doors thrust reverser. Consequently the nacelle length and weight have been significantly reduced.The main numerical results obtained on this nacelle are presented including some results for the installation of this nacelle under a wing.Copyright © 1993 by ASME