Search NASA⌕ Search

SEARCH · Search NASA

Results for “NACELLE”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

AiResearch QCGAT engine, airplane, and nacelle design features

The quiet, clean, general aviation turbofan engine and nacelle system was designed and tested. The engine utilized the core of the AiResearch model TFE731-3 engine and incorporated several unique noise- and emissions-reduction features. Components that were successfully adapted to this core include the fan, gearbox, combustor, low-pressure turbine, and associated structure. A highly versatile workhorse nacelle incorporating interchangeable acoustic and hardwall duct liners, showed that large-engine attenuation technology could be applied to small propulsion engines. The application of the mixer compound nozzle demonstrated both performance and noise advantages on the engine. Major performance, emissions, and noise goals were demonstrated.

Heldenbrand, R. W.↗
NASA NTRS1980

Development of a Kevlar/PMR-15 reduced drag DC-9 nacelle fairing

The paper describes an advanced composite fairing designed to reduce drag on DC-9 nacelles as a part of the NASA Engine Component Improvement Program. This fairing is the aft enclosure for the thrust reverser actuator system on JT8D engine nacelles and is subjected to a 500 F exhaust flow during the reverse thrust. A reduced-drag configuration was developed by using in-flight tuft surveys for flow visualization in order to identify areas with low-quality flow, and then modifying the aerodynamic lines to improve the flow. A fabrication method for molding the part in an autoclave was developed; this material system is suitable for 500 F. The resultant composite fairing reduces the overall aircraft drag 1% with a weight reduction of 40% when compared with a metal component.

Kawai, R. T.↗
NASA NTRS1982

Experimental determination of flow-interference effects of wing-mounted, two-dimensional, full-capture propulsion nacelles in close proximity to a vehicle body at a Mach number of 6

Experimental tests have been conducted to determine possible aerodynamic interference effects due to the lateral positioning of two dimensional propulsion nacelles mounted on a wing surface in close proximity to a vehicle body. The tests were conducted at a Mach number of 6 and a Reynolds number 7 million per foot. The angle of attack range for force tests was -9 deg to 9 deg. The model configurations consisted of combinations of rectangular and trapezoidal cross section bodies with a wing swept 65 and a rectangular planform wing. A pair of two dimensional, flow through propulsion nacelles simulated full capture inlet operation.

Vahl, W. A.↗
NASA NTRS1982

Shadowgraph techniques in transonic tests with powered nacelles

Shadowgraph photography techniques in transonic wind tunnel tests are described. The system was used in tests with powered nacelle rings to visualize the shock wave pattern in the exhaust flow. The technique is also used for installed nacelle tests on a floor mounted half model with a turbine powered fan engine simulator.

Hutton, P. G.↗
NASA NTRS1982

Transonic perturbation analysis of wing-fuselage-nacelle-pylon configurations with powered jet exhausts

A transonic small perturbation method has been developed for the analysis of general wing-fuselage-nacelle-pylon configurations with powered jet exhausts. Finite difference successive line relaxation algorithm is used to solve the small disturbance potential equation in conservative form. The nacelle tangency condition and the jet exhaust plume contact conditions are fulfilled in a quasi-cylindrical fashion on a surface fitting the Cartesian grid. The pylon tangency condition is treated in a quasi-planar manner as for the wing. Viscous displacement effects on the wing are modeled by suitable shape changes including the placement of a viscous ramp at the base of the shock. Computed results of a transport configuration show satisfactory correlation with test data.

Wai, J. C.↗
NASA NTRS1982

Aerodynamic characteristics of a large-scale, twin tilt-nacelle V/STOL model

A subsonic tilt-nacelle V/STOL aircraft configuration is described which is powered by two turbofan engines, mounted on a single carry-through structure that is designed to maintain the thrust axis close to the center of gravity at nacelle incidences of 5-95 deg. Control during V/STOL operation, often from small ship platforms, is achieved by means of a vane assembly that is immersed in each turbofan's exhaust. Wind tunnel test data have been obtained with an 11.2-m wing span model for the vertical-to-horizontal flight transition capability of the concept. It is found that the aircraft can operate over a broad transition corridor, with sufficient maneuver capability about the trim points. The control vane exhibited linear response characteristics over a large deflection range, with little influence from power, angle of attack or ground proximity in hover. The model induced a positive ground effect in hover that increased as wheel height was approached and strake angle increased.

Falarski, M. D.↗
NASA NTRS1983

Three-dimensional Euler solutions for long-duct nacelles

A three-dimensional Euler-equation computational technique has been developed to solve for the transonic flow past flow-through nacelles. The technique employs an approximately-factored alternating-direction implicit numerical algorithm and a radiation treatment of the outflow boundary. Studies are presented which show that the radiation treatment gives better numerical convergence than the condition of specifying the pressure at the outflow boundary. Calculations made with the technique are presented for a long-duct turbofan engine nacelle at a Mach number of 0.80 and angles of attack of 0 deg and 4 deg. Good agreement is shown between the computational results and wind-tunnel data. Problem areas are identified and recommendations are made for further numerical studies.

Compton, W. B., III↗
NASA NTRS1982

Nacelle Aerodynamic and Inertial Loads (NAIL) project

A flight test survey of pressures measured on wing, pylon, and nacelle surfaces and of the operating loads on Boeing 747/Pratt & Whitney JT9D-7A nacelles was made to provide information on airflow patterns surrounding the propulsion system installations and to clarify processes responsible for inservice deterioration of fuel economy. Airloads at takeoff rotation were found to be larger than at any other normal service condition because of the combined effects of high angle of attack and high engine airflow. Inertial loads were smaller than previous estimates indicated. A procedure is given for estimating inlet airloads at low speeds and high angles of attack for any underwing high bypass ratio turbofan installation approximately resembling the one tested. Flight procedure modifications are suggested that may result in better fuel economy retention in service. Pressures were recorded on the core cowls and pylons of both engine installations and on adjacent wing surfaces for use in development of computer codes for analysis of installed propulsion system aerodynamic drag interference effects.

Source record↗
NASA NTRS1983

Installed nacelle drag-improvement tests of an M = 0.8 turboprop transport configuration

An unpowered semispan model of a representative turboprop configuration was tested to determine the effect of configuration modifications on the the nonmetric body and wing juncture. It is indicated that the jet off nacelle-installation drag can be approximately 25% of the cruise drag. However, the losses can be reduced to 17% by changes to the wing leading edge and nacelle intersection. Comparison of test results from a semispan nonmetric fuselage model with those from a full span metric fuselage show differences in angles of attack produced the same lift. It is found that the constant lift drag rise of the semispan model is higher because of the increased angle of attack to achieve the same lift.

Levin, A. D.↗
NASA NTRS1985

Hover test results of a small-scale twin-tilt nacelle model

Characteristics in hover of an 11/36%-scale, powered, twin-tilt nacelle model were measured in the NASA Ames Research Center's 40- by 80-Foot Wind Tunnel. The model was powered by two high-pressure air-driven turbofan propulsion simulators. The position of the sting-mounted model was fixed and a movable ground plane was used to vary ground height and orientation. Hover characteristics were investigated in and out of ground effect for roll angles of -2 deg to +14 deg and pitch angles of -15 deg to +10 deg. Results for the basic configurations are compared with data from hover tests of the full-scale tilt nacelle model. Two methods were investigated to increase vertical vane effectiveness: (1) extending the maximum vane deflection from 20 deg to 70 deg, and (2) adding a third vertical vane. The goal was to increase the roll-control capability to significantly reduce or balance the strong, unfavorable rolling moment created by the loss of one engine. Results indicate that the three-vertical-vane configuration is more effective than two vertical vanes and that extended vane deflections significantly reduce the engine-out roll in hover.

Schmidt, S. B.↗
NASA NTRS1985

Boundary layer effects on the flowfield about flow-through nacelles

A numerical study has been made of boundary layer effects on the flowfield about flow-through nacelles. A viscous-inviscid interacting computational model for investigating the problem was constructed by coupling a three-dimensional explicit Euler solution procedure with a compressible, 'lag-entrainment' integral boundary layer solution technique. Solutions obtained with the interacting model for long-duct turbofan engine nacelles at a free stream Mach number of 0.8 and an angle of attack of 0 deg are compared with experimental data. The numerical experiments have revealed insight into the boundary layer effects on the interactions between the internal and external flows.

Compton, W. B.↗
NASA NTRS1986

Natural laminar flow flight experiments on a turbine engine nacelle fairing

Flight experiments are being conducted with the objective to investigate the interactions between acoustic disturbances and laminar flow in the flight environment. In the experiments, the laminar boundary layer on the nacelles will be exposed to discrete and broadband external noises, and the effect of varying noise levels and frequencies on the stability of the laminar flow will be studied. The present paper provides an overview of the complete project and a status report on the results which have been obtained. The flight experiment is conducted with the aid of a modified research aircraft. The phase I flight tests are concerned with a quick and simple determination of natural laminar flow (NLF) behavior on an engine nacelle. Attention is given to instrumentation, the acoustic noise source, flow visualization, and the test results.

Obara, C. J.↗
NASA NTRS1986

Flight research on natural laminar flow nacelles - A progress report

This paper presents a progress report on an ongoing flight experiment for natural laminar flow nacelles. The results given herein were obtained during the first phase of the experiment, in which an instrumented natural laminar flow nacelle fairing was flight tested in the presence of turbofan engine noise and a controlled noise source. The results indicate that with the controlled noise source off, natural laminar flow was measured as far aft as 37 percent of the fairing length. The transition front was irregular in contour, and the extent of natural laminar flow was significantly affected by the relative flow angle for the fairing. In addition to these test results, the paper discusses the results of some recent computational analyses to predict pressure distributions and transition location, and to explain some of the data trends. Comparisons between measured and predicted data indicate that the analytical methods successfully predicted trends for the baseline (no controlled noise source) studies.

Hastings, E. C., Jr.↗
NASA NTRS1987

Redesign of a supercritical wing in the presence of an engine nacelle

If an obstacle, such as an engine nacelle, is placed in the flow near a virtually shockless wing, shocks of substantial magnitude may appear on the wing. A source distribution method is presently employed in the modeling of an engine nacelle in compressible flow, through incorporation into a free-boundary supercritical wing design code. Code calculation results are presented which show the transonic shock to appear, on average, 10 percent forward of its position on the clean wing. Attention is also given to an associated method for the calculation of wave drag.

Ross, David S.↗
NASA NTRS1988

An analysis for high speed propeller-nacelle aerodynamic performance prediction. Volume 2: User's manual

A user's manual for the computer program developed for the prediction of propeller-nacelle aerodynamic performance reported in, An Analysis for High Speed Propeller-Nacelle Aerodynamic Performance Prediction: Volume 1 -- Theory and Application, is presented. The manual describes the computer program mode of operation requirements, input structure, input data requirements and the program output. In addition, it provides the user with documentation of the internal program structure and the software used in the computer program as it relates to the theory presented in Volume 1. Sample input data setups are provided along with selected printout of the program output for one of the sample setups.

Egolf, T. Alan↗
NASA NTRS1991

Application of laminar flow control to high-bypass-ratio turbofan engine nacelles

Recently, the concept of the application of hybrid laminar flow to modern commercial transport aircraft was successfully flight tested on a Boeing 757 aircraft. In this limited demonstration, in which only part of the upper surface of the swept wing was designed for the attainment of laminar flow, significant local drag reduction was measured. This paper addresses the potential application of this technology to laminarize the external surface of large, modern turbofan engine nacelles which may comprise as much as 5-10 percent of the total wetted area of future commercial transports. A hybrid-laminar-flow-control (HLFC) pressure distribution is specified and the corresponding nacelle geometry is computed utilizing a predictor/corrector design method. Linear stability calculations are conducted to provide predictions of the extent of the laminar boundary layer. Performance studies are presented to determine potential benefits in terms of reduced fuel consumption.

Wie, Y. S.↗
NASA NTRS1992

Viscous flow past a nacelle isolated and in proximity of a flat plate

Linearized-theory design procedures have proven to be useful in preliminary design stages of supersonic aircraft configurations. These procedures are impaired, however, by their inability to account for certain nonlinear effects inherent in complicated flows. The present computations are aimed at providing necessary information for correction and improvement of a particular linearized design method. Three-dimensional, viscous, supersonic flows past nacelle and nacelle-flat plate configurations are investigated. The thin-layer Navier-Stokes equations are solved using an implicit, upwind-biased, finite-volume method. A hybrid domain decomposition technique is utilized to ease the grid generation task. Computations were made for an unit Reynolds number of 2.0 million per foot and Freestream Mach numbers of 1.6, 2.0, and 2.3.

Fouladi, Kamran↗
NASA NTRS1992

Nacelle and forebody considerations in design for reduced sonic boom

Several aspects of designing for reduced sonic boom were investigated to assess the adequacy of the conventional modified linear theory. For a simple test case of a nacelle with a small forecowl angle (2 degrees) mounted below a flat plate, the linear theory compared favorably for a case with simulated nacelle lift and for a computational fluid dynamics (CFD) analysis. In a second study, several methods of analyzing the area distribution due to volume were examined. And finally, in a preliminary study, the effect of forebody shape on the rise time of the bow shock was investigated, indicating a significant increase (several msec) can be obtained by proper forebody shaping.

Haglund, George T.↗