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.

Active control of inlet noise from a turbofan engine using inlet wavenumber sensors

Abstract: In this paper, active control of the inlet noise from a turbofan engine is experimentally investigated with inlet-mounted sensors and actuators. The experimental work is carried out on a running JTlSD turbofan jet engine in a test stand at Virginia Tech. The control inputs were supplied by twelve acoustic sources equipped with neodymium iron cobalt magnets mounted in a single circumferential array upstream of the fan. An inlet sensing technique using an axial array of microphones mounted in the inlet and processed to observe axial wavenumbers traveling down the inlet was used to generate the error signals. The concept of combining active and passive control components together with a hybrid passive-active inlet is also investigated experimentally. The results show that the combination of active and passive control techniques is an effective means of reducing radiated noise from turbofan engines. The wavenumber sensing scheme is shown to be an effective technique for reducing the radiation towards particular directions in the far field when implemented on a passively-lined inlet.

Experimental and Numerical Investigation of a Contra Rotating Open-Rotor Flowfield

Abstract: Contrarotating open rotor propulsion systems have seen renewed interest as a possible economic and environmentally friendly powerplant for future transport aircraft. While the potential efficiency benefits are well accepted, concerns persist regarding the probable rotor-to-rotor interaction-driven noise penalty this type of engine would have in comparison to modern ducted turbofan engines. This paper presents results of a collaborative experimental and numerical study to quantify and study in-depth the complex flowfield of a generic contrarotating open rotor model at wind-tunnel scale. The model has 10 front blades and 8 aft blades, with blade design similar to modern propellers for high-disk loadings. The comparison of flow visualization results obtained through the use of modern stereoscopic particle image velocimetry and unsteady Reynolds-averaged Navier–Stokes simulations helps to improve understanding of the interactions of front-rotor-blade wakes and tip vortices with the aft rotor, which is an important aspect to guide the design of future efficient and quiet contrarotating open rotor engines. The generally good match between the experimental and numerical slipstream results gives confidence in the utility for their analysis capabilities in this field.

Evaluation of Ultra-High Bypass Ratio Engines for an Over-Wing Aircraft Configuration

Abstract: Today, main hub airports are already at their capacity limit and hence, smaller airports get more interesting to provide point-to-point connections. Unfortunately, the use of regional airports induces an increased environmental footprint for the population living around it. In an attempt to solve the related problems, unconventional aircraft and engine designs are required. The research project Coordinated Research Centre 880 aims at examing the fundamentals of a single-aisle aircraft powered by two geared ultra-high bypass turbofan engines mounted over the wing. Low direct operating costs, noise shielding due to the over-wing configuration, and short runway lengths are the main advantages of such an aircraft. Highlighting the performance, economical and noise benefits of a geared ultra-high bypass engine is the key aim of this paper. This assessment includes a correspondingly adjusted aircraft. Open literature values are applied to design the two investigated bypass ratios; an engine with a bypass ratio of 5 respectively 17. Furthermore, a variable bypass nozzle area for the ultra-high bypass ratio engine is analyzed. Finally, the three engines are evaluated based on aircraft direct operating costs and an initial engine noise assessment. This study concludes that increasing the bypass ratio from 5 to 17 drops the direct operating costs by 5.6% and can reduce the sound at the source for a selected operating condition by up to 7dB. During the different flight phases the reduction in specific fuel consumption ranges between 18% to 40%. Applying a variable bypass nozzle leads to a further decrease by 0.6% for the direct operating costs. Opening the bypass nozzle during several flight phases stabilizes the fan shown by the surge margin increase. It is concluded that this unconventional aircraft configuration with ultra-high bypass ratio engines mounted over the wing has the potential to relieve main hub airports by also reducing the environmental impact.

Design of New Three Stage Low Pressure Turbine for the BMW Rolls-Royce BR715 Turbofan Engine

Abstract: In 1990, BMW and Rolls Royce plc (RR) joined to form a new company BWW-Rolls-Royce GmbH (BRR), to develop the BR700 family of engines aimed at the 12K and 25K lbs thrust range, using advanced technology and a modern organisation working in integrated teams to minimise the engine development timescales. After a successful development programme the BR710 engine rated at 14K lbs thrust, will shortly enter service in Gulfstream and Canadair Executive Jets.The recent launch of the BR715 engine at 21K lbs thrust, builds on the high pressure core developed for the BR710, plus a low pressure system with an increased diameter fan and 2 stage booster driven by a three stage turbine.This paper will describe, the advanced design technology incorporated, including the latest three dimensional aerodynamic philosophy using advanced high lift aerofoils for reduced parts count, plus the mechanical design issues addressed to optimise the LP turbine module configuration and the simultaneous design/make process employed to achieve the required parts delivery timescales.Copyright © 1997 by ASME