Showing papers on "Turbofan published in 1971"
TL;DR: In this paper, a review of recent published data on low velocity jet noise is given together with previously unpublished results taken from the Rolls-Royce Noise Research Programme on model rigs and full-scale engines.
48 citations
TL;DR: In this article, the applicability of a deterministic model which was developed by Mansfield and which describes the rate at which new product innovations are adopted was applied to the commercial aircraft jet engine market.
45 citations
Patent•
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TL;DR: In this paper, an aircraft powered by a turbofan gas turbine engine is provided with an aircraft/engine installation in which either the nacelle which surrounds the fan or the core engine nacelles is area ruled to give a flow relief in the region of the wing pylon which extends into the fan passageway.
Abstract: An aircraft powered by a turbofan gas turbine engine is provided with an aircraft/engine installation in which either the nacelle which surrounds the fan or the core engine nacelle is area ruled to give a flow relief in the region of the wing pylon which extends into the fan passageway. The flow relief reduces the local static pressure upstream of the pylon and thus eliminates the distortion effects on the fan thereby increasing installed thrust and also reducing interference drag. The same area rule principle is also applied to regions of the fan passageway upstream of any obstruction, such as an engine control or accessory mounted on the core engine casing.
29 citations
Patent•
04 Jan 1971
TL;DR: A turbofan engine thrust reverser comprising a plurality of pivotally mounted duct members forming an integral part of the engine cowl as discussed by the authors redirects the exhaust air of the fan forward and outward at such velocity and angle that the suction of the inlet is insufficient to cause reingestion.
Abstract: A turbofan engine thrust reverser comprising a plurality of pivotally mounted duct members forming an integral part of the engine cowl. These members redirect the exhaust air of the fan forward and outward at such velocity and angle that the suction of the engine inlet is insufficient to cause reingestion.
26 citations
Patent•
10 Sep 1971
TL;DR: In this paper, the wing is provided with a plurality of spanwise extending slots or ducts having inlet and outlet openings in the suction and pressure surfaces respectively of the wing.
Abstract: The invention relates to an aircraft with VTOL or STOL operational capability. In accordance with the invention, the wing, or airfoil contour, is provided with a plurality of spanwise extending slots or ducts having inlet and outlet openings in the suction and pressure surfaces respectively of the wing. The slot openings are normally closed by spanwise extending flaps which fair into the airfoil contour and when the slots are open cooperate therewith to form individual thrust augmenting ducts. A large number of primary nozzles are provided for injecting high pressure air, derived for example from the bypass air of a conventional turbofan engine, into the ducts. The injected air is delivered as individual jets moving downward in the direction from the suction to the pressure surface of the airfoil and inducing a flow of ambient air from above the wing to mix with the primary air from the jets. The increased mass flow from the thrust augmentor ducts will give rise to vertical thrust or lift which may be of the order to twice the thrust which would have been produced by the primary air alone. The flaps on at least the suction surface are individually operable both as to magnitude and rate of displacement so as to provide for varying conditions of flight operation.
20 citations
14 Jun 1971
16 citations
TL;DR: In this paper, a method for reducing the approach-landing noise of commercial jet transports by means of acoustic linings for attenuating the noise generated by the fan-compressor in turbofan engines and radiated from the intake and fan-exit ducts is described.
15 citations
01 Apr 1971
TL;DR: Two variations of gas generator method to calculate thrust of afterburning turbofan engines installed in F-111A aircraft were used in this article to calculate the thrust of F-1A aircraft.
Abstract: Two variations of gas generator method to calculate thrust of afterburning turbofan engines installed in F-111A aircraft
10 citations
01 Feb 1971
TL;DR: In this article, a study of fan and compressor noise was undertaken for the development of an accurate prediction system, based on theoretical concepts and/or empirical data, which would enable the selection of proper acoustical design choices for future engines.
Abstract: : A study of fan and compressor noise was undertaken for the development of an accurate prediction system, based on theoretical concepts and/or empirical data, which would enable the selection of proper acoustical design choices for future engines. Experimental programs were conducted using a variety of test rigs to provide acoustic data and to validate theoretical concepts. Mathematical models were developed for each type of fan noise, and their applicability to actual engines was evaluated. Although more work is needed to reduce further the contribution of fan and compressor noise to the total noise levels of future engines, the material presented represents significant progress in the understanding of particular noise-generating mechanisms and the capability to predict fan noise. (Author)
9 citations
Patent•
04 Nov 1971
TL;DR: In this paper, a double, thrust diverter valve assembly for a bypass engine applicable to the VTOL and V/STOL types of aircraft and having a by-pass annulus and fan for directing the flow of bypass air thereinto, is presented.
Abstract: A double, thrust diverter valve assembly for a by-pass engine applicable to the VTOL and V/STOL-types of aircraft and having a by-pass annulus and fan for directing the flow of bypass air thereinto, and in which an inflatable valve mechanism, operated from a compressed air source and mounted in a first, thrustaugmentation by-pass air flow-passage with a rearwardly-directed exhaust, is combined with a cascade valve mounted in a second, by-pass air flow-passage having a vertically-downward directed exhaust and thereby controlling the flow of by-pass air in the vertical flight mode.
8 citations
01 Feb 1971
TL;DR: For turbofan engines with noise suppressors, the performance of six foot diameter fan with noise suppression was evaluated in this paper, and the results showed that the fan achieved a better acoustic and aerodynamic performance.
Abstract: Acoustic and aerodynamic performance of six foot diameter fan for turbofan engines with noise suppressors
TL;DR: In this article, the effects on aircraft structures of high frequency fan noise from high bypass ratio turbofan engines are discussed and a proper failure diagnosis is outlined and precautionary measures for future design efforts are suggested.
01 Jan 1971
01 Mar 1971
TL;DR: In this article, the effect of engine position and high lift devices on aerodynamic characteristics of external flow, jet flap STOL model was investigated and graphs were generated to show the relationship between engine position, high lift and external flow.
Abstract: Effect of engine position and high lift devices on aerodynamic characteristics of external flow, jet flap STOL model - graphs
TL;DR: In this paper, the effect of higher turbine inlet temperature on the performance of an aircraft gas turbine engine can be quite dramatic, and it can be used to increase the exhaust velocity of a dry turbojet to provide a higher specific thrust; increase the bypass ratio of a turbofan engine to improve its propulsive efficiency; optimise the thermodynamic cycle at a higher pressure ratio to improve the specific fuel consumption; reduce the amount of afterburner fuel flow in an augmented turbojet, or increase the work output of a turbo-shaft engine.
Abstract: The effect of higher turbine inlet temperature on the performance of an aircraft gas turbine engine can be quite dramatic. It can be used to increase the exhaust velocity of a dry turbojet to provide a higher specific thrust; to increase the by-pass ratio of a turbofan engine to improve its propulsive efficiency; to optimise the thermodynamic cycle at a higher pressure ratio to improve its specific fuel consumption; to reduce the amount of afterburner fuel flow in an augmented turbojet to improve its specific fuel consumption, or to increase the work output of a turbo-shaft engine. If the thrust or power of the engine is held constant, a size, cost and/or weight reduction can result. If the size of the engine is held constant growth capability can be provided.
01 Jul 1971
TL;DR: In this article, a test of a full set of 30 first-stage, composite fan blades in a Pratt & Whitney JT8D turbofan engine has demonstrated that advanced composite materials are very attractive for application to gas turbine engines.
Abstract: A test of a full set of 30 first-stage, composite fan blades in a Pratt & Whitney JT8D turbofan engine has demonstrated that advanced composite materials are very attractive for application to gas turbine engines. Borsic-fiber-reinforced aluminum composite is particularly attractive because of its high modulus, high strength, and low density. This paper presents the blade design considerations and fabrication development techniques using this new material and discusses component and engine testing. Advanced analytical techniques to determine the stresses and dynamic characteristics of blades made of anisotropic materials were required. An extensive fabrication development was conducted before structurally sound composite blades were made. Consequent improvements in blade design resulted in a direct weight reduction of 40% as well as indirect weight savings and improvements in performance.
01 May 1971
TL;DR: Turbofan STOL transport application to air transportation congestion is discussed, discussing conditioning landing field length, navigational/control problems and jet flap concepts.
Abstract: Turbofan STOL transport application to air transportation congestion, discussing conditioning landing field length, navigational/control problems and jet flap concepts
01 Mar 1971
TL;DR: In this paper, a full scale duct burner for a supersonic turbofan engine was constructed for a full-scale DCFS-based DCFS engine, including a diffuser and combustor assembly.
Abstract: Annular diffuser and combustor assembly in full scale duct burner for supersonic turbofan engine
01 Apr 1971
TL;DR: Fan induced low speed jet noise from turbofan engines was discussed in this article, where results of far field sound measurements for simulated nacelle configurations with and without acoustic liners were discussed.
Abstract: Fan induced low speed jet noise from turbofan engines, discussing results of far field sound measurements for simulated nacelle configurations with and without acoustic liners
28 Mar 1971
TL;DR: The BORSIC®-Aluminum fan blades for elevated temperature application in gas-turbine power plants have been successfully demonstrated in this paper, where a full set of blades (36) fabricated by diffusion bonding were assembled in a rotor and tested in an aeromechanical rig with both a clean inlet and a distortion inlet at ambient inlet temperature as well as with a heated inlet to produce a blade temperature of 430 F. Total running time was 30.3 hrs, eight of which were at or above design speed.
Abstract: The development of BORSIC®-Aluminum fan blades for elevated temperature application in gas-turbine power plants has been successfully demonstrated. These fan blades are over 40 percent lighter than the titanium blades currently in use. In addition, the high modulus of the reinforcement allows fan blades to be designed without partspan shrouds which will result in a 1 percent increase in fan efficiency. A full set of blades (36) fabricated by diffusion bonding were assembled in a rotor and tested in an aeromechanical rig with both a clean inlet and a distortion inlet at ambient inlet temperature as well as with a heated inlet to produce a blade temperature of 430 F. Total running time was 30.3 hrs, eight of which were at or above design speed. The rig ran for 0.5 hrs at design speed with a blade temperature of 430 F. No severe vibratory stresses were encountered with either a clean inlet or a 2E distortion screen.Copyright © 1971 by ASME
01 Aug 1971
TL;DR: In this paper, cost estimations, noise constraints, and supercritical wing compatibility were taken into account in the optimization of turbofan engines for Mach 0.90 to Mach 1.98 commercial air transports.
Abstract: Cost estimations, noise constraints, and supercritical wing compatibility in optimization of turbofan engines for Mach 0.90 to Mach 0.98 commercial air transports
21 Jan 1971
TL;DR: In this paper, the authors examined the design operating process, principles of control and operational characteristics of jet engines of various types used in civil aviation (including turbojet, turboprop and turbofan).
Abstract: : The book examines the design operating process, principles of control and operational characteristics of jet engines of various types used in civil aviation (including turbojet, turboprop and turbofan). The classification of the engines is given. Special attention is given to the analysis of peculiarities of throttle and high-altitude and high-speed characteristics of gas-turbine aircraft engines and also the study on the effect of various operating conditions on these characteristics.
01 Jun 1971
TL;DR: Afterburning turbofan engine thrust calculation by gas generator method, using F-111A for comparison tests as mentioned in this paper, using FPGA-equipped F-100A and F-110A.
Abstract: Afterburning turbofan engine thrust calculation by gas generator method, using F-111A for comparison tests
01 Oct 1971
TL;DR: In this article, the effects of specific design parameters on fan/compressor noise, including vane- blade spacing, vane and blade numbers, tip speed, blade loading, rotor sweep, inlet guide vanes and vane lean, were investigated.
Abstract: : Mechanisms of fan/compressor noise generation, transmission, radiation and propagation were physically defined and mathematically described in terms of functional relationships between acoustic, geometric and aerodynamic parameters. Based on these mechanisms, analytical and semi-empirical predictions of pure tone, broadband and multiple pure tone fan/compressor noise were established in terms of sound power spectra, directivity indices and the resultant sound pressure spectra. Test data on a variety of fan and compressor vehicles were used to verify the basic prediction techniques and to study the impact of specific design parameters upon fan/compressor noise, including vane- blade spacing, vane and blade numbers, tip speed, blade loading, rotor sweep, inlet guide vanes and vane lean.
01 Nov 1971
TL;DR: In this paper, a study and development program was accomplished to attenuate turbine noise generated in the JT3D turbofan engine, and an acoustic liner for the tailpipe was designed.
Abstract: A study and development program was accomplished to attenuate turbine noise generated in the JT3D turbofan engine. Analytical studies were used to design an acoustic liner for the tailpipe. Engine ground tests defined the tailpipe environmental factors and laboratory tests were used to support the analytical studies. Furnace-brazed, stainless steel, perforated sheet acoustic liners were designed, fabricated, installed, and ground tested in the tailpipe of a JT3D engine. Test results showed the turbine tones were suppressed below the level of the jet exhaust for most far field polar angles.