Showing papers on "Turbofan published in 1989"

High bypass turbofan engine having a partially geared fan drive turbine

Abstract: The present invention provides a high bypass turbofan engine configuration wherein a fan drive turbine is divided into first and second turbine sections mounted for independent rotation within the engine frame. The first, higher pressure, higher speed turbine section is coupled to the fan section drive shaft via a gear box which reduces the rotational speed of the power delivered by the higher pressure first turbine section to match the design rotational speed of the fan section. The second turbine section, having a larger diameter and lower rotational speed as compared to the first turbine section, is directly connected to the fan section and drives the fan section at the same rotational speed as that of the second turbine section. In this manner, the fan drive shaft horsepower is provided while reducing the weight and size of the necessary gearing between the fan drive turbine and the fan. The weight and size of the fan drive turbine and the booster compressor are also reduced.

Turbofan engine having a counterrotating partially geared fan drive turbine

Abstract: A high bypass ratio turbofan engine having a fan section, a booster compressor disposed aft of the fan section relative to the flow of combustion gases through the engine, and a core section disposed aft of the booster compressor. A low pressure counterrotating turbine, disposed aft of the core section, is used for driving the fan section and the booster compressor. The counterrotating turbine includes at least one set of rotating turbine blades and at least one set of oppositely rotating counterrotating turbine blades. A twin spool shaft is provided for coupling the turbine blades to the booster compressor and for coupling the counterrotating turbine blades to the fan section. A reduction gear is disposed in the drive shaft for coupling the turbine blades to the fan section and for reducing the rotational speed of the turbine output power to match the rotational speed of the fan section thereby splitting the usable work of the turbine blades between the fan section and the booster.

Thrust reverser for turbofan engine

Abstract: A gas turbine jet engine is disclosed with a fan delivering into a bypass duct to generate mainly propulsion thrust, and with a thrust reversing device having flaps which for reverse thrust operation pivot into the fan air stream and cooperate with an axially extended extreme section of the outer wall of the bypass duct to uncover delection ports arranged at breakthroughs in the outer wall. The extreme section of the outer wall and the thrust reverser flaps are linked one with the other for relative movement between them such that in a first phase of actuation relative to a fixed extreme nozzle section, the extreme section provides an additional fan nozzle area which communicates with the inlet flow areas formed by the flaps relative to the bypass duct.

Air deflector for a turbofan engine thrust reverser

Abstract: The present invention provides a movable air deflector which, in a first position, deflects air passing through the cold flow air duct of a turbofan engine in a direction such that it approximates the theoretical air flow line and does not enter a cavity defined by the interior of the thrust reverser door when the door is in its closed position. A linkage mechanism connects the air deflector to the door actuator, such that, when the door is moved to its opened or thrust reversing position, the deflector is moved to a second position so as to minimize its interference with the thrust reversing air flow.

Measured far-field flight noise of a counterrotation turboprop at cruise conditions

Abstract: Modern high speed propeller (advanced turboprop) aircraft are expected to operate on 50 to 60 percent less fuel than the 1980 vintage turbofan fleet while at the same time matching the flight speed and performance of those aircraft. Counterrotation turboprop engines offer additional fuel savings by means of upstream propeller swirl recovery. This paper presents acoustic sideline results for a full-scale counterrotation turboprop engine at cruise conditions. The engine was installed on a Boeing 727 aircraft in place of the right-side turbofan engine. Acoustic data were taken from an instrumented Learjet chase plane. Sideline acoustic results are presented for 0.50 and 0.72 Mach cruise conditions. A scale model of the engine propeller was tested in a wind tunnel at 0.72 Mach cruise conditions. The model data were adjusted to flight acquisition conditions and were in general agreement with the flight results.

Real-time simulation of an F110/STOVL turbofan engine

Abstract: A traditional F110-type turbofan engine model was extended to include a ventral nozzle and two thrust-augmenting ejectors for Short Take-Off Vertical Landing (STOVL) aircraft applications Development of the real-time F110/STOVL simulation required special attention to the modeling approach to component performance maps, the low pressure turbine exit mixing region, and the tailpipe dynamic approximation Simulation validation derives by comparing output from the ADSIM simulation with the output for a validated F110/STOVL General Electric Aircraft Engines FORTRAN deck General Electric substantiated basic engine component characteristics through factory testing and full scale ejector data

Nacelle/pylon interference study on a 1/17th-scale, twin-engine, low-wing transport model

Abstract: NASA-Langley has conducted wind tunnel tests of a twin-engine, low-wing transport aircraft configuration with 10.8-aspect ratio supercritical wing, in order to ascertain and compare the wing/nacelle interference effects of through-flow nacelled simulating 'superfan' very high bypass ratio (BPR=20) turbofans and current-technology (BPR=6) turbofans. Measurements of model forces and moments have been obtained, together with extensive external static pressure measurement on the model's wings, nacelles, and pylons in the Mach 0.5-0.8 range, at angles of attack in the -4 to +8 deg range. The superfan nacelles exhibit a significant advantage over current-technology turbofan nacelles, when the superfan's SFC gains are taken into account.

Thrust reverser for a bypass jet engine with moving deviation flaps

Abstract: A door-type thrust reverser (7) forming deflecting obstacles in the secondary channel of a turbofan engine and associated with a deflection edge segment (108a) connected to the front frame (6) of the upstream fixed structure ( 1) of the reverser by movable means (116) which allow it a single degree of freedom. Said deflecting edge (108a) is operated by articulated means (122-125) connecting the cylinder (7a) of the inverter.

Design of a small supersonic oblique-wing transport aircraft

Abstract: Previous work in the early 1970's has shown the merits of a (large) transonic oblique-wing transport. In this paper, the suitability of the oblique-wing planform for a small supersonic transport aircraft will be shown. The aircraft is designed to transport 24 passengers with first-class accommodations at a cruising speed of 1500 km/h over a distance of 5800 km. It complies to the JAR 25 and FAR 25 airworthiness requirements and the FAR 36 stage 3 noise regulations and is powered by two medium bypass turbofan engines. The proposed aircraft offers a typical increase in blockspeed of 53% at ranges of 4000-7000 km compared with similar small transport aircraft, with comparable fuel efficiency, range, and field performances.

Advanced turbofan engine combustion system design and test verification

Abstract: A combustion system design for an advanced turbofan gas turbine engine is discussed. The design process includes the modeling of both the combustor internal and external flowfields. The external flow analysis was conducted to determine the cold side heat-transfer rates and to establish the external pressure field around the outside of the combustor. Following the external flow analysis, the combustor internal flowfield was analyzed to optimize the combustor performance. Various airflow splits and fuel injection locations were evaluated to arrive at the final design. A full-scale annular high-pressure test rig was designed, fabricated, and instrumented to record all the pertinent combustor performance data. The combustor was test evaluated to determine all of the performance parameters, i.e., combustion efficiency, pattern factor, ignition characteristics, lean blowout fuel/air ratios, and liner wall temperatures.

Core engine separating type turbo fan engine

Abstract: PURPOSE: To facilitate the manufacture and to arrange a propulsion device in a required position by constituting a core engine and the propulsion device separately, and by connecting them through a high pressure air duct. CONSTITUTION: A turbo fan engine 1 is constituted of a core engine 2 and a propulsion device 3 which is divided from the core engine 2. In the core engine 2, there are provided a compressor 5, a burner 6 and turbine 7 inside a case 4, and the turbine 7 is connected to the compressor 5 through a shaft 8. Thus, air which is compressed by the compressor 5 is partially introduced to the burner 6 and the turbine 7, and the rest is led to the duct 9. In the propulsion device 3, there are provided a fan 11 inside a shroud 10 and, the burner 13 and the turbine 14 inside the case 12 which is coaxial with the fan 11, and the duct 9 is connected to the burner 13. Thus, the fuel is burned by using the high pressure air in the burner 13 through the duct 9, and thereby the turbine 14 is driven. COPYRIGHT: (C)1990,JPO&Japio

Measurement effects on the calculation of in-flight thrust for an F404 turbofan engine

Abstract: A study has been performed that investigates parameter measurement effects on calculated in-flight thrust for the General Electric F404-GE-400 afterburning turbofan engine which powered the X-29A forward-swept wing research aircraft. Net-thrust uncertainty and influence coefficients were calculated and are presented. Six flight conditions were analyzed at five engine power settings each. Results were obtained using the mass flow-temperature and area-pressure thrust calculation methods, both based on the commonly used gas generator technique. Thrust uncertainty was determined using a common procedure based on the use of measurement uncertainty and influence coefficients. The effects of data nonlinearity on the uncertainty calculation procedure were studied and results are presented. The advantages and disadvantages of using this particular uncertainty procedure are discussed. A brief description of the thrust-calculation technique along with the uncertainty calculation procedure is included.

Supersonic through-flow fan engine and aircraft mission performance

Abstract: A study was made to evaluate potential improvement to a commercial supersonic transport by powering it with supersonic through-flow fan turbofan engines. A Mach 3.2 mission was considered. The three supersonic fan engines considered were designed to operate at bypass ratios of 0.25, 0.5, and 0.75 at supersonic cruise. For comparison a turbine bypass turbojet was included in the study. The engines were evaluated on the basis of aircraft takeoff gross weight with a payload of 250 passengers for a fixed range of 5000 N.MI. The installed specific fuel consumption of the supersonic fan engines was 7 to 8 percent lower than that of the turbine bypass engine. The aircraft powered by the supersonic fan engines had takeoff gross weights 9 to 13 percent lower than aircraft powered by turbine bypass engines.

Trends in Military Aircraft Propulsion

Abstract: The major factors determining the choice of engine cycle for a combat aircraft are the requirements of the design mission and those of aircraft speed and agility. The requirement for jet-borne flight in short take-off vertical landing (STOVL) aircraft imposes further demands on cycle and configuration. The changing nature of combat aircraft requirements is the reason for changes in engine design.Specific thrust is shown to be the major parameter defining engine suitability for a particular role. An examination of mixed turbofan characteristics shows that specific thrust is also the key to understanding the relationships between engine characteristics.The future development of combat engines is discussed, in particular the implications of stoichiometric limits on cycle temperatures and the benefits of variable cycle engines are examined. Recent work on advanced STOVL (ASTOVL) aircraft is reviewed and aircraft/engine concepts designed to meet the requirements of the role are assessed.Experience shows that t...

Turbofan gas turbine engine

Abstract: The present invention relates to turbofan gas turbine engines. In conventional high bypass ratio turbofans the large variations in the free air stream flowing into the fan duct inlet is accommodated by a thick lip and a long, thick fan casing to prevent air flow separation from the outer surface of the fan casing, but produces a heavy fan casing and large drag values. In the invention a turbofan comprises a core engine which has a core casing, and a fan assembly positioned downstream of the core engine. The fans operate in a fan duct defined by the fan casing. The core casing has an external form upstream of the fan duct inlet which affects the airflow streamlines flowing into the fan duct inlet to cause it to adopt a flow path which is near alignment with the length of the fan casing to reduce fan casing weight, length and drag.

A real-time simulator of a turbofan engine

Abstract: A real-time digital simulator of a Pratt and Whitney F100 engine has been developed for real-time code verification and for actuator diagnosis during full-scale engine testing. This self-contained unit can operate in an open-loop stand-alone mode or as part of closed-loop control system. It can also be used for control system design and development. Tests conducted in conjunction with the NASA Advanced Detection, Isolation, and Accommodation program show that the simulator is a valuable tool for real-time code verification and as a real-time actuator simulator for actuator fault diagnosis. Although currently a small perturbation model, advances in microprocessor hardware should allow the simulator to evolve into a real-time, full-envelope, full engine simulation.

Advanced core technology: Key to subsonic propulsion benefits

Abstract: A study was conducted to identify the potential performance benefits and key technology drivers associated with advanced cores for subsonic high bypass turbofan engines. Investigated first were the individual sensitivities of varying compressor efficiency, pressure ratio and bleed (turbine cooling); combustor pressure recovery; and turbine efficiency and inlet temperature on thermal efficiency and core specific power output. Then, engine cycle and mission performance benefits were determined for systems incorporating all potentially achievable technology advancements. The individual thermodynamic sensitivities are shown over a range of turbine temperatures (at cruise) from 2900 to 3500 R and for both constant (current technology) and optimum (maximum thermal efficiency) overall pressure ratios. It is seen that no single parameter alone will provide a large increase in core thermal efficiency, which is the thermodynamic parameter of most concern for transport propulsion. However, when all potentially achievable advancements are considered, there occurs a synergism that produces significant cycle and mission performance benefits. The nature of these benefits are presented along with the technology challenges.

Reynolds Number Effects on the Performance of a Turbofan Engine

Abstract: Reynolds Number effects on the matching performance of a small twin-spool turbofan engine were investigated through the altitude tests of the F3-30 engine which was developed to power the Japan Air Self Defence Force’s T-4 intermediate trainer.Analyzing the test results made it clear that the change of the aerodynamic characteristics of the low pressure turbine due to Reynolds Number effects is as significant as these of fan and compressor, and it caused the difference between the predicted and measured engine performance at high altitudes.Correlation factors on the Reynolds Number for each of the component characteristics (pressure ratio, airflow and efficiency of fan and compressor, and gas flow and efficiency of low pressure turbine) were obtained, and simulation of the engine performance using these factors coincided well with the test data which were obtained from the altitude tests of the F3-30 at Arnold Engineering Development Center of U. S. Air Force.Copyright © 1989 by ASME

A supersonic through-flow fan engine airframe integration study

Abstract: Engine airframe integration effects are investigated for supersonic through-flow fan engines installed on a Mach 3.20 supersonic cruise vehicle. Six different supersonic through-flow fan engine installations covering the effects of engine size, nacelle contour, nacelle placement, and approximate bypass plume effects are presented. The different supersonic through-flow fan installations are compared with a conventional turbine bypass engine configuration on the same basic airframe. The supersonic through-flow fan engine integrations are shown to be comparable to the turbine bypass engine configuration on the basis of installed nacelle wave drag. The supersonic through-flow fan engine airframe integrated vehicles have superior aerodynamic performance on the basis of maximum lift-to-drag ratio than the turbine bypass engine installation over the entire operating Mach number range from 1.10 to 3.20. When approximate bypass plume modeling is included, the supersonic through-flow fan engine configuration shows even larger improvements over the turbine bypass engine configuration.

Turbo/air augmented rocket - A combined cycle propulsion system

Abstract: A new concept of combined cycle propulsion system is proposed. In the proposed system, a turbojet (or turbofan) type engine provides compressed air as part or the whole oxidizer to the rocket engine at takeoff and part of the acceleration and climb. At the same time, the turbo-engine provides a portion of the thrust. The system performance shows little sensitivity to rocket chamber pressure, shows comparable performance to turbojet, and is capable to shifting to pure rocket mode at any desired point in the flight trajectory.

Technology readiness for advanced ducted engines

Abstract: The Advanced Ducted Engines (ADEs) currently undergoing development for next-generation passenger aircraft typically possess bypass ratios of the order of 12-25 and specific fuel consumption figures 12-17 percent lower than current advanced turbofans. An extensive technology-readiness program has been mounted on behalf of ADE design definition over the last two years, encompassing among its concerns aircraft/engine-installation interference, low pressure-ratio fan aerodynamics, fan/nacelle interactions (including windmilling and thrust-reversal), acoustic characteristics, transonic-drive turbines, and slender nacelle aerodynamic and mechanical design. Both turbine-driven and geared ADE fans, which may be of single-rotating or contrarotating type, are discussed. 5 refs.

STOVL Propulsion System Volume Dynamics Approximations

Abstract: Two approaches to modeling turbofan engine component volume dynamics are explored and compared with a view toward application to real-time simulation of short take-off vertical landing (STOVL) aircraft propulsion systems. The first (and most popular) approach considers only heat and mass balances; the second approach includes a momentum balance and substitutes the heat equation with a complete energy balance. Results for a practical test case are presented and discussed.

Response of Large Turbofan and Turbojet Engines to a Short-Duration Overpressure

Abstract: The influences of thrust setting and overpressure level on engine operating characteristics have been obtained for two different high-thrust engines. The thrust setting was varied from engine-off to take-off rated thrust (TRT) and the overpressure was varied from 6.9 kPa (1.0 psi) to 19.4 kPa (2.8 psi). The specific engines under consideration were the Pratt/Whitney TF33 low bypass ratio turbofan and the Pratt/Whitney J57 turbojet. The experimental results suggest that overpressure has little influence on either the HP compressor speed or the exhaust gas total temperature

Transonic Analysis of Complex Configurations Using TRANAIR Program

Abstract: The application of a three-dimensional transonic flow analysis method, TRANAIR, is explored from the point of view of a user Detailed features of the program are outlined to give a better understanding of capability Numerous results are presented to show some of the complex configurations which have been analyzed In particular, examples are provided which show the application to turbofan engine installation on transport aircraft