Turbofan

About: Turbofan is a research topic. Over the lifetime, 4114 publications have been published within this topic receiving 39490 citations. The topic is also known as: fanjet & turbofan engine.

Method and apparatus for rapid thrust increases in a turbofan engine

Abstract: Upon a landing approach, the normal compressor stator schedule of a fan speed controlled turbofan engine is temporarily varied to substantially close the stators to thereby increase the fuel flow and compressor speed in order to maintain fan speed and thrust. This running of the compressor at an off-design speed substantially reduces the time required to subsequently advance the engine speed to the takeoff thrust level by advancing the throttle and opening the compressor stators.

Aircraft and technology for low noise short take-off and landing

Abstract: This paper discusses characteristic multi-disciplinary issues related to quiet short take-off and landing for civil transport aircraft with a typical short to medium range mission. The work reported here is focussing on the noise aspects and is embedded in the collaborative research centre CRC880 in Braunschweig, Germany. This long term aircraft Research initiative focusses on a new transport aircraft segment for operation on airports with shorter runway length in commercial air transport. This calls for a community-friendly aircraft designed for operations much closer to the home of its passengers than today. This Scenario sets challenging, seemingly contradictory aircraft technology requirements, namely those for extreme lift augmentation at low noise. The Research Centre CRC880 has therefore devised a range of technology projects that aim at significant noise reductions and at the generation of e�cffient and flexible high lift. The research also addresses flight Dynamics of aircraft at takeoff and landing. It is envisaged that in general significant noise reduction -compared to a reference turbofan driven aircraft of year 2000 technology- necessarily requires component noise reduction in combination with a low noise a/c concept. Results are presented from all the acoustics related projects of CRC880 which cover the aeroacoustic simulation of the source noise reduction by flow permeable materials, the characterization, development, manufacturing and operation of (porous) materials especially tailored to aeroacoustics, new UHBR turbofan arrangements for minimum exterior noise due to acoustic shielding as well as the prediction of jet noise vibration excitation of cabin noise by UHBR engines compared to conventional turbofans at cruise.

Turbofan engine construction

Abstract: A turbofan engine construction has a stator portion coupled to and centra disposed within a rigid casing. A rotor portion is disposed between the rigid casing and the stator portion for rotation about the stator portion. A portion of fluids entering the turbofan are heated between the stator and rotor portions prior to expulsion thereof. The remainder of the fluids entering the turbofan pass unheated through the stator portion prior to expulsion. As a result, the heated fluids are expelled annularly about the unheated fluids.

Analysis of gas turbine engines using water and oxygen injection to achieve high Mach numbers and high thrust

Abstract: An analysis of gas turbine engines using water and oxygen injection to enhance performance by increasing Mach number capability and by increasing thrust is described. The liquids are injected, either separately or together, into the subsonic diffuser ahead of the engine compressor. A turbojet engine and a mixed-flow turbofan engine (MFTF) are examined, and in pursuit of maximum thrust, both engines are fitted with afterburners. The results indicate that water injection alone can extend the performance envelope of both engine types by one and one-half Mach numbers at which point water-air ratios reach 17 or 18 percent and liquid specific impulse is reduced to some 390 to 470 seconds, a level about equal to the impulse of a high energy rocket engine. The envelope can be further extended, but only with increasing sacrifices in liquid specific impulse. Oxygen-airflow ratios as high as 15 percent were investigated for increasing thrust. Using 15 percent oxygen in combination with water injection at high supersonic Mach numbers resulted in thrust augmentation as high as 76 percent without any significant decrease in liquid specific impulse. The stoichiometric afterburner exit temperature increased with increasing oxygen flow, reaching 4822 deg R in the turbojet engine at a Mach number of 3.5. At the transonic Mach number of 0.95 where no water injection is needed, an oxygen-air ratio of 15 percent increased thrust by some 55 percent in both engines, along with a decrease in liquid specific impulse of 62 percent. Afterburner temperature was approximately 4700 deg R at this high thrust condition. Water and/or oxygen injection are simple and straightforward strategies to improve engine performance and they will add little to engine weight. However, if large Mach number and thrust increases are required, liquid flows become significant, so that operation at these conditions will necessarily be of short duration.

In-flight balancing of fan on turbofan jet engine

Abstract: An apparatus and a method for in-flight balancing of fan 10 on a turbofan jet engine, after a loss of blade 12, involves detecting an imbalance due to the loss of a blade, by means of a vibration monitor 50, optical sensors 56, a blade locator magnet (68 fig. 2), and coil (55), and a strain gauge (69 fig. 2). A computer 51 is linked via a radio link 54,62,60 to a computer 63, and a power switch 64 and voltage regulator 65 are provided. When a blade 12 is lost, the power switch 64 is caused to send electrical impulses to selected membrane valves 35, the membranes of which burn, melt or are ruptured by an explosive charge, whereby fluid communication between a tyre-shaped ring 30 and selective blade cavities 15, is effected to admit fluid to the selected cavities 15 in fan blades 12, adjacent to the place of the lost blade, to compensate for the lost mass. Fluid is supplied to the ring via a delivery line 22, centrifugal force then urging fluid into lines 34. Electrical power is supplied generated by coils (66 fig. 2) on the hub 11 rotating in relation to stationary magnets (67).