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.

Engine And Installation Configurations For A Silent Aircraft

Abstract: The Silent Aircraft Initiative is a research projec t funded by the Cambridge-MIT Institute aimed at reducing aircraft noise to the point where it is imperceptible in the urban environments around airp orts. The aircraft that fulfils this objective must also be economically competitive with conventional aircraft of the future and therefore fuel consumption is a key consideration for the design. This paper identifies some key features of a propulsion system that can achiev e the Silent Aircraft noise target and explores the relat ionships between the factors that affect fuel consumption. I t also considers the different demands made of an engine a t different operating conditions in the flight envelo pe. These studies are used to propose viable engine and installation configurations that could meet the Sil ent Aircraft noise requirements. The findings point tow ards a multiple turbofan system with a variable geometry exhaust and a novel, embedded installation.

Engine System Performance of Pulse Detonation Concepts Using the NPSS Program

Abstract: The Numerical Propulsion Systems S imulation (NPSS) tool has been used to analyze several Pulse Detonation Engine (PDE) concepts that have been of interest lately The PDE cycle approximates a constant volume combustion process which results in both a temperature and pressure rise across t he device In this study, the PDE was modeled using standard shock tube relationships and flow into and out of the device was assumed to be steady state The capabilities of NPSS in modeling this concept will be discussed An analysis was completed comp aring a PDE to a conventional ramjet For the purposes of the study, the PDE was modeled as a ramjet with a detonation chamber instead of the conventional combustor (basic PDE) Comparisons were made on thrust, specific fuel consumption (SFC), and engine pressure ratio over a range of peak temperatures The unsteady flow characteristic of the PDE has the potential to degrade inlet and nozzle performance relative to steady flow A short parametric study was completed to gauge the overall performance impa ct of changes to inlet and nozzle performance The incorporation of a detonation tube into the core of a high bypass turbofan engine (~100,000 lb thrust class) was also investigated Thrust and SFC comparisons are made along with comments on changes req uired to the system in order to incorporate such a device into a high bypass turbofan engine Finally, a brief discussion is included on the usefulness of this level of analysis of PDE concepts Areas of concern will be noted with possible workarounds id entified NPSS Analysis Tool

Turbofan duct mode measurements using a continuously rotating microphone rake

Abstract: An experimental measurement system was developed and implemented at the NASA Glenn Research Center in the 1990s to measure fan duct acoustic modes. The system is a radial array of microphones inserted into the duct that continuously rotates about the duct centerline. This Rotating Rake provides a complete map of the acoustic duct modes at fan harmonics in a ducted fan. It has been used on a variety of test articles: from a low-speed, concept test fan rig, to a full-scale production turbofan engine. The Rotating Rake has been critical in developing and evaluating a number of noise reduction concepts as well as providing experimental databases for verification of several aero-acoustic codes.

Scale model performance test investigation of exhaust system mixers for an Energy Efficient Engine /E3/ propulsion system

Abstract: A scale model performance test was conducted as part of the NASA Energy Efficient Engine (E3) Program, to investigate the geometric variables that influence the aerodynamic design of exhaust system mixers for high-bypass, mixed-flow engines. Mixer configuration variables included lobe number, penetration and perimeter, as well as several cutback mixer geometries. Mixing effectiveness and mixer pressure loss were determined using measured thrust and nozzle exit total pressure and temperature surveys. Results provide a data base to aid the analysis and design development of the E3 mixed-flow exhaust system.