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.

A Propulsion System Analysis of Oil Free Turbomachinery for Aviation Turbofan Engines

Abstract: A strategy for the elimination of lubricating oil systems from aviation turbofans incorporates the use of foil bearings in place of traditional rolling element bearings. A foil bearing is a hydrodynamic device that utilizes air as the working fluid to separate a rigid shaft from a compliant static (non-rotating) structure. Modern developments in foil bearing design have increased the state of the art to the level where it is now appropriate to consider such devices for application in aircraft engines. This analysis is the first published work that quantifies the benefits of oil free turbomachinery. Conceptual designs are carried out for oil free gas turbine propulsions systems, which facilitate the calculation of the improved thrust to weight ratios that these engines could achieve. These engines are then applied to 50-passenger regional jet and 10-passenger supersonic business jet models to resize the vehicles and compute system benefits. Oil Free technology was applied to both the modern state of the art engines as well as advanced technology engines, which incorporate additional feature sponsored by the NASA Ultra Efficient Engine Technology Program. The figures of merit computed in this analysis include take-off gross weight, mission fuel, mission NOx, and landing and take-off operation NOx. The current state of the art 50 passenger vehicle achieved a 3.4% reduction in TOGW while the notional supersonic business jet achieved a 2.7% reduction.

Afterburner flow mixing means in turbofan jet engine

Abstract: A short length afterburner assembly for a jet propulsion engine having a fan bypass includes cold and hot air cross-over passages and a plurality of flame stabilization swirler vanes associated with a balanced load controller for positioning the vanes parallel to hot gas stream flow from a jet engine core when the afterburner is off and in an inclined position to such gas stream flow when fuel is injected therein during afterburner operation thereby to produce flame spread within the afterburner core by a combination of translatory and swirling motions; and wherein atomized fuel for afterburner combustion is injected into hot gases ducted through hot air cross-over passages from the jet engine core to produce premix and prevaporization of fuel upstream of fixed flameholders and wherein cold fan bypass air cross-over passages have movable turbulator grids positioned during afterburner operation for mixing cold air flow with the bypassed hot core gas at the fixed flameholders during afterburner operation and wherein the turbulator grids are positioned parallel to gas flow when the afterburner is not in operation by means of the balanced load controller to produce a balanced variable geometry mechanical load to that on the flame stabilization swirler vanes.

Gas turbine engines

Abstract: A turbofan gas turbine engine comprises a forward fan 50 and a rearward fan 80 arranged to rotate in opposite directions within a bypass duct 22 The forward fan 50 is driven by a first drum rotor 42 of a compressor 14, the first drum rotor rotating in the same direction but at a relatively slower speed than a second drum rotor 52 of the compressor The rearward fan 80 is driven by a first turbine drum rotor 72 of a turbine 18, the first turbine drum rotor rotating in the opposite direction but at a relatively slower speed than a second turbine drum rotor 82 of the turbine The second turbine drum rotor is arranged to drive the second drum rotor of the compressor A combustor 16 is positioned axially between the forward and rearward fans, and may be stationary or arranged to rotate independently or with the first turbine drum rotor Contra-rotating propellers may be driven in a similar way

Control system for an augmented turbofan engine

Abstract: The engine includes a main engine fuel flow, an augmentation fuel flow, and a variable area exhaust nozzle. Primary speed control means is powered by first electrical power supply means. Fan speed is controlled by modulation of main engine fuel flow. Loss of electrical power to the primary speed control means during augmented operation results in a reversion from fan speed control to core engine speed control while simultaneously reducing the augmentation fuel flow toward a minimum level and closing the variable area exhaust nozzle. Backup speed control means is coupled to the primary speed control means for limiting fan overspeed in augmented operation during loss of electrical power to the primary speed control means. The backup speed control means is powered by second electrical power supply means which is independent of the first power supply means. For example, in one embodiment involving aircraft application, the first electrical power supply means comprises an engine-driven alternator and the second electrical power supply means comprises an aircraft positioned power supply. The primary and backup speed control means may be coupled to separate windings of a single torque motor.

The application of actuator disks to calculations of the flow in turbofan installations

Abstract: This paper discusses the application of an actuator disk model to the problem of calculating the asymmetric performance of a turbofan operating behind a nonaxisymmetric intake and due to the presence of the engine pylon. Good agreement between predictions and experimental results is demonstrated. Further validation of the model is obtained by comparison with the results of a three-dimensional calculation of an isolated fan operating with a nonaxisymmetric inlet. Some justification of the neglect of unsteady aspects of the flow in the fan is presented. The quantitative features of the interaction of the pylon and fan flow fields are discussed.