Showing papers on "Turbofan published in 1972"

Design study of an air pump and integral lift engine ALF-504 using the Lycoming 502 core

Abstract: Design studies were conducted for an integral lift fan engine utilizing the Lycoming 502 fan core with the final MQT power turbine. The fan is designed for a 12.5 bypass ratio and 1.25:1 pressure ratio, and provides supercharging for the core. Maximum sea level static thrust is 8370 pounds with a specific fuel consumption of 0.302 lb/hr-lb. The dry engine weight without starter is 1419 pounds including full-length duct and sound-attenuating rings. The engine envelope including duct treatment but not localized accessory protrusion is 53.25 inches in diameter and 59.2 inches long from exhaust nozzle exit to fan inlet flange. Detailed analyses include fan aerodynamics, fan and reduction gear mechanical design, fan dynamic analysis, engine noise analysis, engine performance, and weight analysis.

Integrated engine-generator concept for aircraft electric secondary power

Abstract: The integrated engine-generator concept of locating an electric generator inside an aircraft turbojet or turbofan engine concentric with, and driven by, one of the main engine shafts is discussed. When properly rated, the generator can serve as an engine starter as well as a generator of electric power. The electric power conversion equipment and generator controls are conveniently located in the aircraft. Preliminary layouts of generators in a large engine together with their physical sizes and weights indicate that this concept is a technically feasible approach to aircraft secondary power.

Effects of installation caused flow distortion on noise from a fan designed for turbofan engines

Abstract: Far-field noise measurements were taken for three different installations of essentially the same fan. The installation with the most uniform inlet flow resulted in fan-blade-passage tone sound pressure levels more than 10 dB lower than the installation with more nonuniform inflow. Perceived noise levels were computed for the various installations and compared. Some measurements of inlet flow distortion were made and used in a blade-passage noise generation theory to predict the effects of distortion on noise. Good agreement was obtained between the prediction and the measured effect. Possible origins of the distortion were identified by observation of tuft action in the vicinity of the inlet.

Experimental evaluation of a TF30-P-3 turbofan engine in an altitude facility: Afterburner performance and engine-afterburner operating limits

Abstract: For distortion free steady state operation at the maximum (full afterburning) throttle position, the afterburner combustion efficiency decreased from 0.91 to 0.68 as engine inlet Reynolds number index was reduced from 0.80 to 0.25. Engine afterburner operational limits were obtained for transient and fixed throttle operation over a range of engine inlet distortions. At limiting conditions, time histories of pressures in the fan compressor during throttle transients between military and maximum showed the development of rotating stall in the fan hub which quickly propagated and produced complete stall in the high pressure compressor.

Design and cold-air investigation of a turbine for a small low-cost turbofan engine

Abstract: An 8.00-in mean diameter two-stage turbine was investigated over a range of speeds from 0 to 110 percent of equivalent design speed and over a range of pressure ratios from 1.79 to 5.14. Presented are design information and turbine performance for first-stage and two-stage operation. Results are presented in terms of equivalent specific work, torque, mass flow, rotor exit flow angle, and efficiency.

Installation caused flow distortion and its effect on noise from a fan designed for turbofan engines

Abstract: A ground test stand was used to obtain acoustic data on a full scale prototype fan designed for quiet subsonic aircraft engines. The fan was installed in three different ways in the test stand. In two of the installations the fan was driven by a shaft in the inlet; in the third installation the fan was driven from the rear. These three installations, and the structures associated with them, resulted in various amounts of inlet flow distortion to the fan. The rear drive installation had less inlet flow distortion than the two front drive installations. Some measurements of inlet flow distortion were made and used in a blade passage noise generation theory to predict the effects of distortion on noise. Good agreement was obtained when the predicted and measured power level differences between the front drive and rear drive installations were compared.

Engine selection for transport and combat aircraft

Abstract: Review of the procedures used to select engines for transport and combat aircraft by illustrating the procedures for a long haul CTOL transport, a short haul VTOL transport, a long range SST, and a fighter aircraft. For the CTOL transport, it is shown that advances in noise technology and advanced turbine cooling technology will greatly reduce the airplane performance penalties associated with achieving low noise goals. A remote lift fan powered by a turbofan air generator is considered for the VTOL aircraft. In this case, the lift fan pressure ratio which maximizes payload also comes closest to meeting the noise goal. High turbine temperature in three different engines is considered for the SST. Without noise constraints it leads to an appreciable drop in DOC, but with noise constraints the reduction in DOC is very modest. For the fighter aircraft it is shown how specific excess power requirements play the same role in engine selection as noise constraints for commercial airplanes.

Nested toroid nozzle apparatus

Abstract: A nested toroid nozzle apparatus for vertical or short takeoff aircraft in which the source of power may be a turbofan, turbotip fan, or turbojet engine thrust unit housed in an aerodynamically clean nacelle. The nacelle also carries the nozzle components making it possible to integrate the continuity of lift and cruise thrust throughout the range required to convert from vertical lift to forward acceleration and into cruise flight. The nozzle components provide a close coupling between the thrust fan plane and the centerline of the downwardly vectored thrust. The nozzle components have a toroidal shape for maximum nozzle efficiency, compactness and lightweight, assumption of primary thrust loads in hoop tension, and diffuser designed for minimum pressure losses during the vectored lift mode and conventional cruise mode.

Jet aircraft operations: impact on the air environment.

Abstract: This paper is directed to those concerned with the air environment and its degradation by the burden of pollution from jet aircraft operations A summary is presented of the results of a comprehensive air pollution study of jet aircraft operations at the Los Angeles International Airport (LAX) Included in the data obtained from this study are jet engine exhaust measurements for currently used turboprop, turbojet and turbofan engines; measurements of specific contaminants in the atmosphere inside and outside of passenger terminals and ticketing areas, and in aircraft cabins during ground operations including passenger loading and taxiing prior to takeoff; also presented are ambient air measurements in a two-mile radius of the airport An evaluation is made of the emissions of contaminants from air transport operations and all related ground activities including motor vehicles, that contribute to the total atmospheric contaminant burden at the airport

Application of theoretical acoustics to the reduction of jet engine noise

Abstract: Theoretical investigations of noise produced by jet engines should have the following objectives: (i) to understand the noise generation and propagation mechanisms; (ii) to suggest methods of reducing noise levels; (iii) to predict noise levels from various engine configurations. Because of the complex geometries associated with modern turbofan engines, idealized mathematical and simplified experimental models need to be studied and correlated with full-scale data. In the first part of this paper, a now classical example of the application of theory to rotor-stator interaction noise is discussed to illustrate how the first two objectives can be obtained essentially from a simple theoretical model. Some of the problems arising from predicting noise levels of interaction tone noise are considered, and a recent test is described that illuminates certain features of these problems. The second part of the paper describes some of the more recent work associated with the study of combination tone or multiple pure tone noise. This noise is produced in the inlets of turbofan engines whenever the fan blades have supersonic relative tip speeds. Results of large-scale fan tests are used to illustrate the physical characteristics of this noise. A mathematical model is introduced that determines the importance of blade shock-wave spacing in the noise generation process. Finally, a method of estimating the standard deviation of shock-wave spacing is presented and compared with full-scale data. These, and other similar models, are helping to achieve the three objectives mentioned. They are being incorporated in procedures for predicting noise of advanced engine designs.

A computer program for calculating design and off-design performance of two- and three-spool turbofans with as many as three nozzles

Abstract: A computer program which calculates steady-state design and off-design jet engine performance for two- or three-spool turbofans with one, two, or three nozzles is described. Included in the report are complete FORTRAN 4 listings of the program with sample results for nine basic turbofan engines that can be calculated: (1) three-spool, three-stream engine; (2) two-spool, three-stream, boosted-fan engine; (3) two-spool, three-stream, supercharged-compressor engine; (4) three-spool, two-stream engine; (5) two-spool, two-stream engine; (6) three-spool, three-stream, aft-fan engine; (7) two-spool, three-stream, aft-fan engine; (8) two-spool, two-stream, aft-engine; and (9) three-spool, two-stream, aft-fan engine. The simulation of other engines by using logical variables built into the program is also described.

Fan noise and performance

Abstract: Tradeoffs between aerodynamic and acoustic properties of various fan configurations led to the selection of a variety of fans that produce noise levels in the range of 100 to 120 PNdb Fan configuration and design pressure ratio required for specific mission operations depend in part on the type of mission to be performed Noise data obtained for single-stage low speed fans, single-stage high speed fans, and two-stage fan engines are presented in table form

Acoustically treated ground test nacelle for the General Electric TF34 turbofan

Abstract: A description is given of the ground test quiet nacelle for the TF34 engine. The suppression treatment consists of cylindrical splitters in the inlet and fan exhaust ducts plus duct wall treatment and core exhaust wall treatment. Aerodynamic design analysis of the inlet and exhaust ducts and overall engine performance with pressure losses from the acoustic treatment is included. The objectives of the test program are to obtain noise data for a heavily suppressed high bypass turbofan with various arrangements of exhaust systems and acoustic treatment, and to provide a basis for the power plants of the Quiet Experimental STOL Aircraft (Questol).

STOL noise sources and fan noise treatment

Abstract: STOL noise goals, noise sources, and their affects on engine and propulsion systems design are considered It is shown that major noise sources constitute the blown-flap system with its turbofan engine and the augmentor wing propulsion system Most of the problem areas associated with STOL propulsion systems are defined and the development of a multistage fan engine with proper rotor-stator spacings and low noise core exhaust jet is illustrated A variable-area acoustic inlet provides near sonic flow conditions during takeoff and landing

Thrust Reverser and Thrust Vectoring Literature Review

Abstract: : The state-of-the-art of thrust reverser and thrust vectoring technology has been surveyed to identify the available test data and prediction methods in the literature The literature review resulted in a bibliography of documents related to thrust reverser and thrust vectoring systems The bibliography contains references to approximately 160 reports and is organized in three sections: Literature review summary, abstracts and data review summary

Experience with low cost jet engines.

Abstract: A summary is given of the results of a NASA program for reducing the cost of turbojet and turbofan engines The design, construction, and testing of a simple turbojet, designed for use in missiles, is described Low cost axial stage fabrication, the design of a fan jet engine, suitable for propulsion of light aircraft, and application of such engines to provide higher flight speeds, are discussed

An altitude test facility for large turbofan engines

Abstract: The altitude test facility at NGTE has been progressively developed over many years and now includes a test cell capable of testing large turbofan engines over a wide range of simulated flight conditions. The cell enables measurements to be made during rapid engine transients as well as at steady state conditions. Icing, freezing fog and tropical rain conditions can also be simulated. The cell is described and its basic test capability outlined. The methods used to measure the main engine performance parameters and the techniques for calibrating the measurement systems and defining their degrees of precision are described.

Integrated engine-generator for aircraft secondary power.

Abstract: An integrated engine-generator for aircraft secondary power generation is described. The concept consists of an electric generator located inside a turbojet or turbofan engine and both concentric with and driven by one of the main engine shafts. The electric power conversion equipment and generator controls are located in the aircraft. When properly rated, the generator serves as an engine starter as well as a source of electric power. This configuration reduces or eliminates the need for an external gear box on the engine and permits reduction in the nacelle diameter.

Multi-Mission Turbine Engine Propulsion Simulator Applications Study.

Abstract: : The turbine engine propulsion simulator being developed by the Air Force Aero Propulsion Laboratory is a promising wind tunnel testing tool which may be used to improve the procedure for aircraft performance prediction This study identifies the type of applications which will afford the most successful utilization of the simulator and the model designs which will yield the best results Three aircraft configurations have been used for this study (advanced tactical fighter, advanced bomber, and single-engine-lightweight fighter) These aircraft are representative of a wide range of engine installation types, and hence serve to identify most of the problem to be encountered in using the simulator The first part of this report addresses how the propulsion simulator should be used with wind tunnel test models and when in the development cycle of an aircraft it should be utilized In the second part, the feasibility of model designs incorporating the propulsion simulator is investigated Different balance arrangements and support systems have been developed for the three aircraft configurations The data accuracy, cost, and testing complexity for these designs have been evaluated The last section defines a program plan for developing and evaluating wind tunnel test techniques using the propulsion simulator (Author)

Propulsion technology for an advanced subsonic transport

Abstract: Engine design studies for future subsonic commercial transport aircraft were conducted in parallel with airframe studies. These studies surveyed a broad distribution of design variables, including aircraft configuration, payload, range, and speed, with particular emphasis on reducing noise and exhaust emissions without severe economic and performance penalties. The results indicated that an engine for an advanced transport would be similar to the currently emerging turbofan engines. Application of current technology in the areas of noise suppression and combustors imposed severe performance and economic penalties.

Suppression of Turbofan and Turbojet Engine Generated Noise

Abstract: Every advance in the transformation of heat energy into mechanical energy has involved a noise problem, and in general it increases with the power production. The jet airplane is a good example: the large-scale turbulence of the exhaust gases in the jet forms an

Jet noise of an augmentor wing-advanced supersonic transport

Abstract: A preliminary mission study was made of the range and jet noise of an advanced supersonic transport (AST) employing an augmentor wing and four duct burning turbofan engines. The airplane weight and aerodynamic characteristics of the Boeing 2707-300 airplane with a gross weight of 750,000 pounds and 234 passengers was used for the study. Engine thrust was fixed at 58,000 pounds per engine and engine size was increased to obtain the required thrust at reduced power settings for jet noise reduction. Turbofan engine core noise was reduced to FAR 36 noise levels and lower by proper selection of turbine inlet temperature, bypass ratio and fan pressure ratio. The study showed that an augmentor wing can reduce the bypass jet noise sufficiently so that total noise levels below FAR 36 can be attained without significant range penalties if the augmentor wing can be designed without severe weight and performance penalties.

An analysis of the takeoff and landing performance of a jet-powered STOL augmentor wing design

Abstract: A preliminary study of the takeoff and landing performance characteristics of a swept wing airplane with augmented jet flap, designed for STOL operation and low noise is presented. The study is based on aerodynamic data from wind tunnel tests of a large-scale swept augmentor wing model, scaled up to a 48,000 pound airplane. Engine characteristics are based on a turbo fan with a fan pressure ratio of 2.5 delivering the major portion of the thrust to the augmentor flap. A description of the overall airplane configuration, the propulsion system, and the use of the aerodynamics is presented. To assess the STOL performance of the airplane, takeoff and landing distances and flight path capabilities were computed at various flap deflections and thrust levels. After evaluating these results in terms of desired STOL performance with required margins, basic takeoff and landing configurations were chosen.

Community Noise Levels of the DC-10 Aircraft

Abstract: The results of recent flyover noise tests show that the McDonnell Douglas DC-10 aircraft powered by General Electric CF6-6D engines is much quieter than the current jet transport aircraft powered by turbojet or low-bypassratio turbofan engines. Several major design features incorporated into the engine and the installation of the engine on the aircraft have accomplished this reduction in noise. The DC-10 will meet the noise level requirements established by the Federal Aviation Administration for new transport aircraft and will, in fact, generate noise levels which are well below the requirements for takeoff and sideline noise. It will also meet the noise level requirements established by the Port of New York Authority and other airport operators at specific noise monitoring stations for normal aircraft operations. The DC-10 represents a major step in the direction of reducing noise pollution in communities around airports.

Calculation of aerodynamic characteristics of STOL aircraft with externally-blown jet-augmented flaps.

Abstract: Analytical methods to predict the interference between lifting surfaces and high-bypass-ratio turbofan engines are described. A three-dimensional nonplanar vortex-lattice lifting surface method is used to predict the characteristics of a wing with leading-edge slat and multiple slotted trailing-edge flaps including effects of externally induced velocity fields. A flow model of the wake of a high-bypass-ratio turbofan is described which is capable of predicting the induced velocity field both inside and outside the jet wake. These methods are combined to predict the longitudinal characteristics of several STOL transport models utilizing externally-blown flaps and comparisons with data are shown. The results indicate good agreement between experiment and theory for various configurations under a wide range of power conditions.

Optimization of engines for a commercial Mach 0.98 transport using advanced turbine cooling methods

Abstract: A study was made of an advanced technology airplane using supercritical aerodynamics. Cruise Mach number was 0.98 at 40,000 feet altitude with a payload of 60,000 pounds and a range of 3000 nautical miles. Separate-flow turbofans were examined parametrically to determine the effect of sea-level-static design turbine-inlet-temperature and noise on takeoff gross weight (TOGW) assuming full-film turbine cooling. The optimum turbine inlet temperature was 2650 F. Two-stage-fan engines, with cruise fan pressure ratio of 2.25, achieved a noise goal of 103.5 EPNdB with todays noise technology while one-stage-fan engines, achieved a noise goal of 98 EPNdB. The take-off gross weight penalty to use the one-stage fan was 6.2 percent.

Production Test Facilities for Turbojet and Turbofan Engines - 1975 to 1995,

Abstract: A review is made of test cell design options in order to identify characteristics of jet engine test facilities to be constructed in the 1970's and designed to be operable for a minimum of twenty years. The necessity of providing replacements for many current facilities is documented, and the factors which will ensure future production capability and economic feasibility are detailed. Present turbine engines are reviewed and projections of future engines and aircraft are made. A confidential supplement is available for qualified recipients. (Author)