Showing papers on "Turbofan published in 1990"

Variable cycle turbofan-ramjet engine

Abstract: An improved variable cycle turbofan-ramjet engine is disclosed The engine includes a split fan assembly, a bypass channel surrounding a core engine and a mode selector valve for selectively bypassing air around an aft fan and the core engine In a first, single bypass mode of operation, the mode selector valve allows air to flow through both a forward fan and the aft fan, and a portion of which bypasses the core engine In a second, double bypass mode of operation, the mode selector valve allows air from the forward fan to bypass the aft fan and a portion of the air from the forward fan to bypass the core engine In a third, ramjet mode of operation, the mode selector vane bypasses air around the aft fan and the core engine and the core engine is shut down for ramjet operation In the preferred embodiment, the forward fan is allowed to windmill and powers a fuel pump connected thereto for providing fuel to a ram burner of the engine for ramjet operation

Investigation of very high bypass ratio engines for subsonic transports

Abstract: A study of propulsion system performance for a family of high bypass ratio turbofan engines is presented. The bypass ratio range is from 6 to 17.5, and both bare engine performance and nacelle installation performance have been considered. Geared, variable pitch/variable nozzle engines with bypass ratios of 10.6, 14, and 17.5 have been studied parametrically, and the performance of a fixed pitch, gearless engine of bypass ratio 9.6 has been estimated to represent an advanced engine with conventional mechanical complexity. Nacelle performance data for a bypass 5 engine have also been included as a baseline. Thrust reverser design for these engines is also considered. Results of this study indicate that conventional nacelle installation losses do not reverse the trend of improving engine fuel efficiency with bypass ratio out to at least bypass ratio 17.5. If innovative concepts are used, such as reverse thrust from a reverse fan pitch and a short fan cowl, the installed fuel efficiency for highbypass-ratio engines looks even better. The bypass 9.6 engine shows a lower fuel burn benefit than the bypass 17.5 engine, but it offers the potential of reduced mechanical complexity and lower maintenance cost.

A simple dynamic engine model for use in a real-time aircraft simulation with thrust vectoring

Abstract: A simple dynamic engine model was developed at the NASA Ames Research Center, Dryden Flight Research Facility, for use in thrust vectoring control law development and real-time aircraft simulation. The simple dynamic engine model of the F404-GE-400 engine (General Electric, Lynn, Massachusetts) operates within the aircraft simulator. It was developed using tabular data generated from a complete nonlinear dynamic engine model supplied by the manufacturer. Engine dynamics were simulated using a throttle rate limiter and low-pass filter. Included is a description of a method to account for axial thrust loss resulting from thrust vectoring. In addition, the development of the simple dynamic engine model and its incorporation into the F-18 high alpha research vehicle (HARV) thrust vectoring simulation. The simple dynamic engine model was evaluated at Mach 0.2, 35,000 ft altitude and at Mach 0.7, 35,000 ft altitude. The simple dynamic engine model is within 3 percent of the steady state response, and within 25 percent of the transient response of the complete nonlinear dynamic engine model.

Advanced detection, isolation, and accommodation of sensor failures in turbofan engines: Real-time microcomputer implementation

Abstract: The objective of the Advanced Detection, Isolation, and Accommodation Program is to improve the overall demonstrated reliability of digital electronic control systems for turbine engines. For this purpose, an algorithm was developed which detects, isolates, and accommodates sensor failures by using analytical redundancy. The performance of this algorithm was evaluated on a real time engine simulation and was demonstrated on a full scale F100 turbofan engine. The real time implementation of the algorithm is described. The implementation used state-of-the-art microprocessor hardware and software, including parallel processing and high order language programming.

Further Calculations of the Performance of Turbofan Engines Incorporating a Wave Rotor.

Abstract: : Two recent computer programs, WRCOMP and ENGINE, by A. Mathur, were used to examine the performance to be gained by incorporating a wave rotor component in a turbofan engine with mixed exhausts. The programs were transferred to a VAX-2000 computer, extended, and test cases reported by A. Mathur were successfully reproduced. A comparison was made between ENGINE, in which real gas effects are accounted for, and ONX (by J. Mattingly) in which constant specific heats are used. The inclusion of real gas effects proved to have a significant impact on the predicted performance. An extension of Mathur's results was made by varying the overall pressure ratio in the wave-turbofan engine. Further cycle studies and experiments to measure wave rotor component performance are recommended.

High bypass ratio turbofan engine

Abstract: PURPOSE: To enhance the output power by coupling double reversion type turbine blades to a fan part and a booster compressor through an shaft device in a lower pressure turbine device, and by dividing the transmitted force to the fan part and the booster compressor by means of a reduction gear device. CONSTITUTION: A turbofan engine incorporates a fan part 12, a booster compressor 14, a core part 18 having a high pressure compressor and a low pressure double reversion type turbine device for driving the fan part 12 and the booster compressor 14, which are arranged successively in the mentioned order. The double inversion turbine includes a set of rotary turbine blades 22 extended from an inner drum 24, and a set of reversible rotary turbine blades 26 extending from an outer drum 28, and in this arrangement, an inner shaft 36 and an outer shaft 38 connect between the inner drum 24 and the fan part 12 and between the outer drum 28 and the booster compressor 14, respectively. Further, the engine incorporates a reduction gear device 34 for dividing the power which can be used for the turbine blades, into a power for the booster compressor 14 and a power for the fan part 12.

Foreign matter diverter systems for turbofan engines

Abstract: The axial gap (30) between a turbofan section (18) in a turbofan aircraft engine (10) is enlarged so that foreign matter thrown radially outwardly by the fan blades (48) will travel vectors (52, 54) which are located forwardly of the forward boundary (28) of the splitter wall (26). This results in the foreign matter being expelled through the fan duct (14) the engine (10), preventing it from entering into the engine core (20). Forward extensions (56, 58) of the fan blades can also be used for shifting the vectors (52, 54) forwardly. Smaller forward extensions (56, 58) can be used in combination with a partially widened gap (30) for positioning the vectors (52, 54) forwardly of the splitter wall forward boundary (28).

Use of swirl for flow control in propulsion nozzles

Abstract: In certain off-design conditions it is desirable to vary the effective area of turbofan propulsion nozzles, e.g., to aid component matching or to reduce fan noise on approach. It has been suggested that the mass flux reductions associated with swirl could be used to achieve such variations. This paper addresses the questions of whether swirl can achieve the required mass flux reductions and whether this can be done with minimal thrust losses. A quasicylindrical theory is used to analyze the swirling flow, and comparisons are made with variablearea nozzles for specific case studies. For a low-specific thrust engine of high bypass ratio (BPR = 12) the required fan nozzle mass flux reduction cannot be achieved using swirl, and in any case, swirl gives a far faster rate of decay of thrust with fan nozzle mass flux than does a variable-area nozzle. For a ducted fan of BPR -4, a 10% reduction in core nozzle mass flux can be achieved with swirl for slightly less thrust loss than with a variable-area nozzle. The swirl profile, however, needs to be carefully optimized.

Analytical and Experimental Simulation of Fan Blade Behaviour and Damage Under Bird Impact

Abstract: An extensive analytical and experimental program has been undertaken to investigate the Foreign Object Damage resistance capabilities of external components for small gas turbofan engines. A transient nonlinear impact analysis has been used to predict the structural response of fan blades under bird ingestion conditions. This analysis is based on finite elements, a 3-D bird load model and an interactive structure-to-bird contact algorithm. Experiments were designed and carried out to record large blade deformations during bird impact, and were used to validate and calibrate the analytical models. The analytical models and testing program are described, and dominant fan blade response and failure modes are presented. Predicted results demonstrate good correlation with test. Analysis application to fan blade design and other engine components is recommended.Copyright © 1990 by ASME

On the Leading Edge: Combining Maturity and Advanced Technology on the F404 Turbofan Engine

Abstract: The overall design concept of the F404 afterburning turbofan engine is reviewed together with some of the lessons learned from over 2 million flight hours in service. GE Aircraft Engines’ derivative and growth plans for the F404 family are then reviewed including the “Building Block” component development approach. Examples of advanced technologies under development for introduction into new F404 derivative engine models are presented in the areas of materials, digital and fiber optic controls systems, and vectoring exhaust nozzles. The design concept and details of the F404-GE-402, F412-GE-400 and other derivative engines under full scale development are described. Studies for future growth variants and the benefits of the F404 derivative approach to development of afterburning engines in the 18–24,000 pounds (80–107 kN) thrust class and non-afterburning engines in the 12–19,000 pounds (53–85 kN) class are discussed.Copyright © 1990 by ASME

Optical Fan Blade Profile Measurement in Rotating Turbomachinery

Abstract: An optical technique for measuring the profile of a fan blade at a range of radial heights in a rotating turbofan by laser triangulation has been developed and tested. The technique has been successfully used on fan rigs and on full size engines. The data thus obtained is now being used to verify the current models of fan blade behaviour.Copyright © 1990 by ASME

Aspects of Theoretical and Experimental Investigations on Airframe/Engine Integration Problems

Abstract: The study describes the flow field around an Airbus-type configuration with a conventional turbofan engine. The three-dimensional Euler equations were solved using a cell-vertex method using a multi-block structure. A half model with a turbo-powered simulator was investigatedat low speed. Results show good agreement between theory and experiment.

Intermetallic and ceramic matrix composites for 815 to 1370 C (1500 to 2500 F) gas turbine engine applications

Abstract: Revolutionary improvements in gas turbine engine specific fuel consumption and specific thrust are expected to be gained through incorporation of CMCs and of MMCs (whose intermetallic matrices are reinforced by highly refractory ceramic fibers). A status development evaluation is presented for NASA's Advanced High Temperature Engine Materials Technology Program, with a view to projections of early-21st century transport aircraft performance levels obtainable through the use of MMCs and CMCs in ultrahigh bypass turbofan engines.

Engine testing of thermographic phosphors

Abstract: A thermographic phosphor technique is being developed for nonintrusive high temperature analysis of the hostile environments associated with turbomachinery. This unique noncontact measurement system will eventually be applied to high-speed, rotating surfaces whose direct analysis has been unobtainable with current temperature-sensing devices and systems. Two experiments are reported which involve static surface temperature measurements in a Pratt Whitney PW2037 turbine engine, and dynamic surface temperature measurements in a Pratt Whitney JT15D turbofan jet engine. The thermographic phosphor materials applied to these engine environments were europium-doped yttrium oxide (T{sub 2}O{sub 3}:E{sub u}) and europium-doped yttrium vanadate (YVO{sub 4}:E{sub u}). The excitation energy was supplied by a tripled neodymium YAG (Nd:YAG) laser at 355 nm. 11 refs., 14 figs.

Calculation of Transonic Flows for Novel Engine-Airframe Installations

Abstract: Currently the transport industry is embarked on programs for the development of a new generation of fuel-efficient aircraft. This class of airplanes incorporates the superfan and the ultra-high-bypass (UHB) propulsion systems. The superfan engine is an advanced derivative of the turbofan powerplant, while the UHB concept employs a multibladed counterrotating unshrouded fan. A schematic top view of the airplane with the alternative engines is shown in Fig. 1.

A hypersonic research vehicle to develop scramjet engines

Abstract: Four student design teams produced conceptual designs for a research vehicle to develop the supersonic combustion ramjet (scramjet) engines necessary for efficient hypersonic flight. This research aircraft would provide flight test data for prototype scramjets that is not available in groundbased test facilities. The design specifications call for a research aircraft to be launched from a carrier aircraft at 40,000 feet and a Mach number of 0.8. The aircraft must accelerate to Mach 6 while climbing to a 100,000 foot altitude and then ignite the experimental scramjet engines for acceleration to Mach 10. The research vehicle must then be recovered for another flight. The students responded with four different designs, two piloted waverider configurations, and two unmanned vehicles, one with a blended body-wing configuration, the other with a delta wing shape. All aircraft made use of an engine database provided by the General Electric Aircraft Engine Group; both turbofan ramjet and scramjet engine performance using liquid hydrogen fuel was available. Explained here are the students' conceptual designs and the aerodynamic and propulsion concepts that made their designs feasible.

Ground power device for aviation turbine engine

Abstract: The utility model relates to a ground power device for an aviation turbine engine The utility model is suitable for the industries of petroleum, chemical and metallurgy A general aviation turbofan engine is used for clogging the duct part of the outer case of the stationary vanes of a fan Moreover, the vane tips of the rotary vanes of a fan, which correspond to the outer case, are cut off A rare earth magneto generator is connected with the front end of the shaft of the engine The excess power of the outer case removed fan is absorbed for maintaining the operating parameter of the engine The generator supplies through a rectifier and an inverter without the limitation of synchronous rotating speed The generator is directly coupled with the engine without a retarding mechanism The high air flow discharged from the rear part of the engine can be used for a steam boiler, a heating furnace, etc The entire device is controlled with an electromechanical integration controlling technology

Airframe/propulsion integration at transonic speeds

Abstract: A significant level of research is ongoing at NASA’s Langley Research center on integrating the propulsion system with the aircraft. This program has included nacelle/pylon/wing integration for turbofan transports, propeller/nacelle/wing integration for turboprop transports, and nozzle/afterbody/empennage integration for high performance aircraft. The studies included in this paper focus more specifically on pylon shaping and nacelle bypass ratio studies for turbofan transports, nacelle and wing contouring and propeller location effects for turboprop transports, empennage effects, and thrust vectoring for high performance aircraft. The studies were primarily conducted in NASA Langley’s 16-Foot Transonic Tunnel at Mach numbers up to 1.20.Copyright © 1990 by ASME

An AD100 implementation of a real-time STOVL aircraft propulsion system

Abstract: A real-time dynamic model of the propulsion system for a Short Take-Off and Vertical Landing (STOVL) aircraft was developed for the AD100 simulation environment. The dynamic model was adapted from a FORTRAN based simulation using the dynamic programming capabilities of the AD100 ADSIM simulation language. The dynamic model includes an aerothermal representation of a turbofan jet engine, actuator and sensor models, and a multivariable control system. The AD100 model was tested for agreement with the FORTRAN model and real-time execution performance. The propulsion system model was also linked to an airframe dynamic model to provide an overall STOVL aircraft simulation for the purposes of integrated flight and propulsion control studies. An evaluation of the AD100 system for use as an aircraft simulation environment is included.

Takeoff characteristics of turbofan engines

Abstract: The present derivation of reliable formulas for the takeoff characteristics of turbofan-powered aircraft, encompassing ground-roll distance and time, fuel consumption, etc, incorporates ground effect-induced drag reduction. This drag reduction factor is varied according to type of aircraft; the turbofans in question may be of high-bypass transport-aircraft type or of low bypass and afterburner-employing configuration, as is typically the case in military aircraft. It is shown that bypass ratio variations have little influence on takeoff ground-rolling distance.

Supersonic combustion engine testbed, heat lightning

Abstract: The design of a supersonic combustion engine testbed (SCET) aircraft is presented. The hypersonic waverider will utilize both supersonic combustion ramjet (SCRAMjet) and turbofan-ramjet engines. The waverider concept, system integration, electrical power, weight analysis, cockpit, landing skids, and configuration modeling are addressed in the configuration considerations. The subsonic, supersonic and hypersonic aerodynamics are presented along with the aerodynamic stability and landing analysis of the aircraft. The propulsion design considerations include: engine selection, turbofan ramjet inlets, SCRAMjet inlets and the SCRAMjet diffuser. The cooling requirements and system are covered along with the topics of materials and the hydrogen fuel tanks and insulation system. A cost analysis is presented and the appendices include: information about the subsonic wind tunnel test, shock expansion calculations, and an aerodynamic heat flux program.