scholarly journals An MDOE Assessment of Nozzle Vanes for High Bypass Ratio Jet Noise Reduction

2006 ◽  
Author(s):  
Brenda Henderson ◽  
Thomas Norum ◽  
James Bridges
Keyword(s):  
Noise Reduction ◽  
Jet Noise ◽  
Bypass Ratio

scholarly journals Exo-Skeletal Engine: Novel Engine Concept

2003 ◽  
Author(s):  
Christos C. Chamis ◽  
Isaiah M. Blankson
Keyword(s):  
Noise Reduction ◽  
Open Channel ◽  
Jet Noise ◽  
Element Model ◽  
Combined Cycle ◽  
Engine Design ◽  
Potential Benefits ◽  
Immense Potential ◽  
Bypass Ratio ◽  
Engine Concept

The Exo-Skeletal Engine concept represents a new radical engine technology with the potential for a substantial revolution in engine design. It is an all composite drum rotor engine in which conventional heavy shafts and discs are eliminated and are replaced by rotating casings that support the blades in spanwise compression. Thus the rotating blades are in compression rather than in tension. The resulting open channel at the engine centerline has immense potential for jet noise reduction, and can also accommodate an inner combined-cycle thruster such as a ramjet. The Exo-Skeletal Engine is described in some detail with respect to geometry, components and potential benefits. Initial evaluation, results for drum rotors, bearings and weights are summarized. Component configuration, assembly plan and potential fabrication processes are also identified. A finite element model of the assembled engine and its major components are described. Preliminary results obtained thus far show at least 30 percent reduction of engine weight and about 10 db noise reduction, compared to a baseline conventional high bypass-ratio engine. Potential benefits in all aspects of engine technology are identified and tabulated. Quantitative assessments of potential benefits are in progress.

Study of Jet Noise Reduction on Separated Exhaust System Using Chevron Nozzles

2014 ◽  
Vol 1078 ◽  
pp. 228-234
Author(s):  
Wan Ren Shao ◽  
Xi Hai Xu ◽  
Jing Yu He ◽  
Fei Wu
Keyword(s):  
Noise Reduction ◽  
Jet Noise ◽  
Exhaust System ◽  
Scale Model ◽  
Low Frequencies ◽  
Chevron Nozzles ◽  
Field Noise ◽  
Bypass Ratio ◽  
Computational Predictions ◽  
Noise Spectra

The jet noise reduction of chevron nozzles was investigated on high bypass ratio turbofan engine separated exhaust system using both computational predictions and scale model experiments. Six different exhaust nozzles are designed including one baseline nozzle and five different chevron nozzles. The jet noise experiments were carried out in the anechoic chamber. Tam and Auriault’s jet noise prediction theory and MGBK theory were used to predict the noise spectra of different exhaust nozzles. The results show that the far-field noise spectra as well as the noise reduction benefits of chevrons are predicted correctly by the two theories although some discrepancies occur at the high frequency range, and Tam and Auriault’s jet noise theory can give relatively more accurate prediction results. chevron nozzles reduce jet noise at the low frequencies, but increase it at high frequencies.

Computational and Experimental Investigations of Jet Noise Reduction Concepts for Low-Bypass Ratio Military Gas Turbine Engines

2008 ◽  
Author(s):  
N. Sinha ◽  
D. C. Kenzakowski ◽  
R. J. Ungewitter ◽  
S. M. Dash ◽  
J. M. Seiner
Keyword(s):  
Noise Reduction ◽  
Gas Turbine ◽  
Jet Noise ◽  
Cfd Modeling ◽  
Turbine Engines ◽  
Experimental Investigations ◽  
Turbulence Structure ◽  
Gas Turbine Engines ◽  
Bypass Ratio ◽  
Lobed Nozzle

Computational and experimental activities supporting the design and evaluation of jet noise reduction concepts for low bypass-ratio military gas turbine engines are presented. Work has been focused on evaluations of lobed nozzle concepts, utilizing typical Field Carrier Landing Practice (FCLP) engine cycle conditions. At FCLP, the engine operates slightly over-expanded, with the result that jet noise emissions also include shock noise contributions. Reduction of nozzle exit area via introduction of lobes permits the nozzle to operate closer to ideal conditions, while also introducing vortices into the plume that may alter turbulence structure and noise emissions. Structured grid, computational fluid dynamics (CFD) investigations of isolated noise nozzles have been conducted. Determination of the optimal number of lobes for a nozzle has been a key objective of our studies. It was found that a six-lobe configuration is optimal, and that two-, three- and four- and twelve-lobe designs fail to provide performance improvement relative to the six-lobe design. While all lobe designs provided the same amount of area reduction for the baseline nozzle, the twelve-lobe configuration restricted the growth of the vortices introduced into the plume by the lobes. With reduced number of lobes, the far-field mixing of the exhaust plume remained unaffected, although some near-field benefits were observed. However, the turbulence characteristics, and hence noise, were not altered and the six-lobe design provided best performance, as demonstrated during tests at NCPA. The noise attenuation benefits of nozzle beveling were also assessed. These studies demonstrate the strong effect of dual jet interactions for the closely spaced, inward canted exhaust nozzles of a twin-engined aircraft. These dual nozzle plume-plume interactions have been found to have a very large effect on the turbulence structure, and hence noise. The analysis of lobed nozzle concepts with engine-engine interactions and vehicle aerodynamic/plume interactions has required the usage of multi-element unstructured grid numerics. Evaluations of aspirated lobe concepts were also conducted, where mass flux is introduced into the plume at the trailing edge of the lobes. Sensitivities to mass flow rates were examined and laboratory measurements of noise emissions in NCPA’s anechoic chamber are presented. Finally, impact of the lobes on nozzle performance during altitude flight are presented, along with CFD modeling upgrades required for performing simulations of complete aircraft/plume interactions.

Effect of Axial Location of Micro Vortex Generators on Supersonic Jet Noise Reduction

2022 ◽  
Author(s):  
Junhui Liu ◽  
Yu Yu Khine ◽  
Mohammad Saleem ◽  
Omar Lopez Rodriguez ◽  
Ephraim J. Gutmark
Keyword(s):  
Noise Reduction ◽  
Supersonic Jet ◽  
Jet Noise ◽  
Vortex Generators ◽  
Supersonic Jet Noise ◽  
Axial Location

Supersonic Jet Noise Reduction Using Micro Vortex Generators

2021 ◽  
Author(s):  
Junhui Liu ◽  
Yu Yu Khine ◽  
Mohammad Saleem ◽  
Omar Lopez Rodriguez ◽  
Ephraim Gutmark
Keyword(s):  
Noise Reduction ◽  
Supersonic Jet ◽  
Jet Noise ◽  
Vortex Generators ◽  
Supersonic Jet Noise

Adaptation of the Beveled Nozzle for High-Speed Jet Noise Reduction

AIAA Journal ◽  
2011 ◽  
Vol 49 (5) ◽  
pp. 932-944 ◽  
Author(s):  
K. Viswanathan ◽  
M. J. Czech
Keyword(s):  
Noise Reduction ◽  
High Speed ◽  
Jet Noise
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