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.

Demonstrating the more electric engine: a step towards the power optimised aircraft

Abstract: Early in 2008, as part of the European funded power optimised aircraft (POA) technology project, Rolls-Royce ran a substantial engine test programme to demonstrate the feasibility of more electric engine technologies. This study outlines the technologies that were developed as replacements for conventional turbofan engine components, discussing the key features of the power electronics, generation and motor drive systems integrated within the aircraft engine and goes on to discuss outcomes from the test programme and draw conclusions to the applicability of more electric technologies for future applications. The main findings of systems-level modelling and simulation, which was employed to de-risk the engine electrical network design ahead of the hardware build, are also discussed. The study presents a summary of the major technical challenges faced in the development and operation of the engine system together with the solutions employed to overcome them. A selection of test results is provided to illustrate examples of the electrical system operation and to show a comparison between the modelled and tested results. The study concludes by exploring how the technical achievements of the engine demonstration and of the wider POA programme are providing the foundation for further work to realise the full potential of the more electric aircraft.

Turbofan gas turbine engine with variable fan outlet guide vanes

Abstract: A turbofan gas turbine engine (10) includes a forward fan section (33) with a row of fan rotor blades (32), a core engine (18), and a fan bypass duct (40) downstream of the forward fan section (33) and radially outwardly of the core engine (18). The forward fan section (33) has only a single stage of variable fan guide vanes which are variable fan outlet guide vanes (35) downstream of the forward fan rotor blades (32). An exemplary embodiment of the engine includes an afterburner (130) downstream of the fan bypass duct (40) between the core engine (18) and an exhaust nozzle (68). The variable fan outlet guide vanes (35) are operable to pivot from a nominal OGV position at take-off to an open OGV position at a high flight Mach Number which may be in a range of between about 2.5 - 4+. Struts (31) extend radially across a radially inwardly curved portion (131) of a flowpath (29) of the engine (10) between the forward fan section (33) and the core engine (18).

Turbofan Performance Deterioration Tracking Using Nonlinear Models and Optimization Techniques

Abstract: A method of identifying the gradual deterioration in the components of jet engines is presented. It is based on the use of an engine model which has the capability to adapt component condition parameters, so that measured quantities are matched. The main feature of the method is that it gives the possibility to identify performance deviations in a number of parameters larger than the number of measured quantities. This is achieved by optimizing a cost function which incorporates not only measurement matching terms but also terms expressing various constraints resulting from the physical knowledge of the deterioration process. Time series of data representing deterioration scenarios are used to demonstrate the method’s capabilities. The test case considered is a twin spool partially mixed turbofan, representative of present day large civil aero engines. Implementation aspects, related to both the measurement set and the identification algorithms are discussed. An interpretation of the output of the method in function of different parameters entering the diagnostic problem is presented.Copyright © 2002 by ASME

Self-trimming control for turbofan engines

Abstract: A twin spool turbofan engine control is designed which maintains engine thrust and stall margin at nominal levels as the operating characteristics of the engine high spool deteriorates with operating hours, increased altitude or increased power extraction. An electronic supervisory control monitors the high rotor speed and the fan turbine inlet temperature relationships for all engine power settings from intermediate to maximum, and the electronic supervisory control schedules are adjusted based upon shifts in the relationships. In one embodiment the fuel flow to the engine is trimmed in response to a desired fan turbine inlet temperature schedule determined as a function of engine inlet temperature and main burner pressure, the schedule being modified in response to the difference between operating high rotor speed and a reference rotor speed which in turn is a function of engine inlet temperature. In another embodiment the engine fuel flow is trimmed in response to a high rotor speed schedule determined as a function of engine inlet temperature and biased by the difference between a sensed fan turbine inlet temperature and a reference fan turbine inlet temperature. In both embodiments the area of a variable geometry nozzle in the engine is trimmed to modify the fan airflow.