|Statement||by F.B. Greatrex and D.M. Brown.|
|Contributions||Brown, D. M.|
With the progress of high-bypass turbofan and the innovation of silencing nacelle in engine noise reduction, airframe noise has now become another important sound source besides the engine noise. Progress in Engine Noise Reduction and Future Challenges Joe Walsh CEng FRAeS jet velocities Variable area nozzle UltraFanTM Turbine technologies Rolls-Royce Proprietary Information Environmental trades Rolls-Royce Proprietary Information Sustainable Aviation Noise File Size: 2MB. While progress has been made in reducing both airframe and engine noise, historically, most of the aircraft noise reduction efforts have concentrated on the engines. It offers unique coverage of Pulse Detonation Engines, which add tremendous power to jet thrust by combining high pressure with ignition of the air/fuel mixture. Readers will learn about the advances in the reduction of jet noise and toxic fuel emissions—something that is being heavily regulated by relevant government agencies.
Prediction of jet mixing noise with Lighthill's Acoustic Analogy and geometrical acoustics 28 February | The Journal of the Acoustical Society of America, Vol. , No. 2 Modeling of Noise Reduction in Complex Multistream Jets. In a jet representing the coaxial exhaust of a turbofan engine, this is achieved by tilting downward, by a few degrees, the bypass (secondary) plume relative to the core (primary) plume. The misalignment of the two ﬂows creates a thick low-speed secondary core on the underside of the high-speed primary ﬂow. The implementation of advanced low-emission aircraft engine technologies and the reduction of noise from airframe, fan, and jet exhaust have made noise contributions from an engine core increasingly important. Therefore, meeting future ambitious noise-reduction goals requires the consideration of engine-core noise. 2 NOISE REDUCTION A common development path for noise reduction concepts is to first explore an idea in sub-scale model tests. This is usually done in two steps: 1) Proof of concept experiments designed by either experimental intuition or guided by analyses, and 2) Higher fidelity experiments that.
The introduction of jet-propelled passenger transport aircraft fifty-five years ago ushered in an era of unprecedented human mobility. Equally, it was associated with noise and local air quality issues that were painfully obvious to those living near airports. Today, these aircraft emissions are . Engine Noise Reduction for Large Quad - Sideline Results From P&W Study 72 87 72 87 72 87 81 88 83 80 81 81 78 65 70 75 80 85 90 95 Airframe Combustor Fan Exhaust Fan Inlet Jet **Engine Sum EPNdB P&W '92 Tech. BPR=5+Source Red. the straight-jet engine to the high-bypass ratio front-fan engine has not only greatly reduced its radiated noise, but also resulted in a reduction in the fuel burn and a consequent economic beneﬁt to civil aviation. It is not often that a solution to noise reduction is accompanied by a gain in economic performance and cost beneﬁt. "A new 1,page reference book, "Handbook of Noise and Vibration Control," intended to be the definitive source on noise and vibration control for engineers, scientists, and researchers. The new reference book addresses a range of topics in acoustics and vibration, focusing on industrial needs.".