Showing papers on "Turbofan published in 1969"
01 Sep 1969
TL;DR: Analytical and experimental studies for predicting noise attenuation in acoustically treated ducts for turbofan engines are presented in this article. But the results are limited to a single engine.
Abstract: Analytical and experimental studies for predicting noise attenuation in acoustically treated ducts for turbofan engines
37 citations
Patent•
25 Nov 1969TL;DR: In this article, a control system for a gas turbine engine having an augmenter combustion system and a variable area exhaust nozzle is presented, which is applicable to both turbofan and straight turbojet engines.
Abstract: A control system for a gas turbine engine having an augmenter combustion system and a variable area exhaust nozzle. The control system is applicable to both turbofan and to straight turbojet engines. In the turbofan application, a signal generator schedules the exhaust nozzle area as a function of throttle position and augmenter fuel flow as a function of exhaust nozzle area. An error signal generated between desired fan duct mach number and actual fan duct mach number is integrated and applied to both the augmenter fuel rate generator and the exhaust nozzle area generator. In this manner, during steady state operations, the exhaust nozzle position maintains a desired mach number and the throttle lever position maintains augmenter fuel flow rates. During transients, the exhaust nozzle area position controls the augmenter fuel flow. In the turbojet application the fan duct mach number error signal is replaced by a turbine temperature error signal and the system operates essentially as described above.
7 citations
01 Jun 1969
TL;DR: Performance and stall limits of YTF30-P-1 turbofan engine with uniform compressor inlet flow as discussed by the authors, with uniform compressors inlet and inlet manifold.
Abstract: Performance and stall limits of YTF30-P-1 turbofan engine with uniform compressor inlet flow
6 citations
01 Nov 1969
5 citations
Patent•
21 Aug 1969
TL;DR: A thrust diverter valve for turbofan jet engines produces two different angular flow patterns for the fan exhaust from a turboran jet engine, which includes two similar spherical curved portions of half of a split substantially hemispherical shell, which are concentrically rotatable in opposite directions in a confining chamber around the axis of a turbo-propagation engine, with the axes of rotation of each portion of the shell disposed in canted relation with respect to horizontal and vertical flow directions as discussed by the authors.
Abstract: A thrust diverter valve for turbofan jet engines producing two different angular flow patterns for the fan exhaust from a turbofan jet engine, which includes two similar spherical curved portions of half of a split substantially hemispherical shell which are concentrically rotatable in opposite directions in a confining chamber around the axis of a turbofan jet engine with the axis of rotation of each portion of the shell disposed in canted relation with respect to horizontal and vertical flow directions. The spherical shell portions are rotatable about their axis in opposite directions into one position in the path of flow from the fan to form an inclined hemispherical deflector shell and deflect the flow from the fan downwardly at substantially 90* to the fan axis for vertical thrust, and movable about their axis in the opposite directions out of the flow path from the fan and allow the fan flow to pass between the spherical shell portions parallel to the axis of the turbofan jet, without deflection, to provide for horizontal thrust.
5 citations
01 Jun 1969
TL;DR: Steady state and dynamic distortion influence on performance and stall of turbofan engine, discussing compressor instrumentation, tests and simulation data as discussed by the authors. But this is not the case for all turbofans.
Abstract: Steady state and dynamic distortion influence on performance and stall of turbofan engine, discussing compressor instrumentation, tests and simulation data
3 citations
09 Mar 1969
TL;DR: The JT15D as discussed by the authors is a small turbofan engine intended for business aircraft with the main design objectives of low initial cost, low fuel consumption, high reliability, low maintenance costs, ease of installation and operation, and good growth potential.
Abstract: An analysis of the market potential for a small turbofan engine intended for business aircraft has led to the design of the JT15D. The main design objectives were low initial cost, low fuel consumption, high reliability, low maintenance costs, ease of installation and operation, and good growth potential. These objectives have been achieved using a minimum number of components and providing a simple layout. Mounting of the engine is highly flexible, and operation is straightforward. Extensive component testing has been carried out. Guaranteed engine performance was achieved early in the development programme.Copyright © 1969 by ASME
3 citations
TL;DR: In this article, design studies of various acoustically treated inlet and fan-exhaust ducts were conducted for the JT3D turbofan engine installation on DC-8 airplanes.
Abstract: Design studies of various acoustically treated inlet and fan‐exhaust ducts were conducted for the JT3D turbofan engine installation on DC‐8 airplanes. These design studies resulted in the selection of two configurations of treated engine inlets and one configuration of treated fan‐exhaust ducts for full‐scale fabrication and testing. On the basis of ground runup test results, one configuration was chosen for subsequent flyover noise and cruise‐performance flight testing. This paper discusses some of the design concepts that were studied, presents some of the results of the full‐scale ground runup tests, and also presents predictions of the change in flyover perceived noise level owing to installation of treated nacelles on DC‐8–50/61 airplanes.
3 citations
16 Nov 1969
TL;DR: In this paper, the design and specifications for low-noise output turbofan engine for long-range subsonic transport aircraft are presented for a single-passenger aircraft.
Abstract: Design and specifications for low-noise output turbofan engine for long-range subsonic transport aircraft
16 Nov 1969
TL;DR: In this paper, the presence of noise from the turbine of a turbojet or turbofan engine was found to be a significant contributor to the overall engine noise, and the authors showed that the turbine noise was a significant contributing factor to the engine noise.
Abstract: The authors show the presence of noise from the turbine of a turbojet or turbofan engine to be a significant contributor the overall engine noise. They review currently available information from both full-scale engines and model turbines and correlate it along lines following those previously developed for fans and compressors.Copyright © 1969 by ASME
09 Jun 1969
19 Mar 1969
TL;DR: A team of engineers, computing analysts, and mathematicians has been assigned to investigate methods to make these Pratt and Whitney Aircraft engine simulations converge more quickly, with higher stability and reliability.
Abstract: : Gas turbine performance computer programs have become the principal method of describing engine performance. These programs are used in the thousands of computations necessary in the design and performance evaluation of modern aircraft propulsion systems. A team of engineers, computing analysts, and mathematicians has been assigned to investigate methods to make these Pratt and Whitney Aircraft engine simulations converge more quickly, with higher stability and reliability. This paper presents the results of their research to date. (Author)
TL;DR: The engine parameters which most obviously must improve to contribute to the continued lowering of aircraft Direct Operating Costs are those of prices, weight, volume and fuel consumption as mentioned in this paper, which affect the base-line performance characteristics of the aircraft and in any formula for estimating direct operating costs they will appear in the general cost of flying a load of passengers or freight from A to B.
Abstract: The engine parameters which most obviously must improve to contribute to the continued lowering of aircraft Direct Operating Costs are those of prices, weight, volume and fuel consumption. These affect the base-line performance characteristics of the aircraft and in any formula for estimating Direct Operating Costs they will appear in the general cost of flying a load of passengers or freight from A to B. Engines also unfortunately generate other costs in their own right. These include: Maintenance labour while mounted on the aircraft. Repair and overhaul shop labour (including time to remove and re-install the engine). Replacement parts cost. Spare engine holding. Spare parts holding. Overhaul shop overheads.
20 Oct 1969
01 Sep 1969
TL;DR: In this article, the effects of known values of these two factors on the performance of a typical high bypass turbofan engine were given, and the observed loss in thrust of 1·7 per cent was satisfactorily explained.
Abstract: The changes are considered which might be present within a jet engine during the ‘thermal soak’ transient to cause the engine's performance to differ from the equilibrium performance. The effects of known values of these changes are given for a simple jet engine over a wide range of engine pressure ratios. Values of these changes are then predicted for a typical engine, and the observed loss in thrust of 1·7 per cent is satisfactorily explained. Two of the major factors giving loss of thrust in the simple jet engine were heat absorption in the turbine metal and heat absorption in the compressor metal. The effects of known values of these two factors on the performance of a typical high by-pass turbofan engine are given. For similar fractional heat absorptions, the losses in thrust of the turbofan engine are roughly double those of the simple jet engine.
01 May 1969
TL;DR: In this article, the effectiveness of changes in aircraft operating procedures and aircraft hardware regarding the reduction noise near airports were rated by determining the changes in land areas falling within the Noise Exposure Forecast contours.
Abstract: : The effectiveness of changes in aircraft operating procedures and aircraft hardware regarding the reduction noise near airports were rated by determining the changes in land areas falling within the Noise Exposure Forecast contours. Sets of NEF contours were constructed for two different aircraft types operating from a single runway airport; the number of operations per day was varied from 200 to 1000. The changes included power cutbacks after takeoff, two segment approaches and retrofit of four-engine turbofan aircraft with acoustically-lined nacelles or with a 'quiet engine'.
01 Jun 1969
TL;DR: In this article, the authors presented the results of an analytic study of a convertible turbofan/turboshaft engine embodying a variable-pitch fan rotor and found that by moving the fan blades into minimum pitch, their power absorption is reduced to about 15% of the power available from the low pressure turbine; thus the remaining power is available as external shaft power.
Abstract: : The report presents the results of an analytic study of a convertible turbofan/turboshaft engine embodying a variable-pitch fan rotor. By moving the fan blades into minimum pitch, their power absorption is reduced to about 15% of the power available from the low pressure turbine; thus, the remaining power is available as external shaft power. A novel method of variable-pitch fan blade attachment was devised. Estimated performance and weight of the engine are presented.