Spinning Frame Noise Sources

1976 ◽  
Vol 98 (3) ◽  
pp. 840-844 ◽  
Author(s):  
N. D. Stewart ◽  
P. D. Emerson ◽  
J. R. Bailey
Keyword(s):  
Noise Reduction ◽  
Frequency Analysis ◽  
Textile Industry ◽  
Narrow Band ◽  
Vacuum System ◽  
Relative Importance ◽  
Noise Sources ◽  
Band Frequency ◽  
Reduction Program

As part of a Coordinated Textile Industry Noise Reduction Program, a study of the sources of spinning frame noise has been conducted. Techniques of source modification and narrow-band frequency analysis were used. Several machines were studied. Major noise sources were found to be the ring-traveler and spindle-bobbin systems. Other sources identified were the drive cylinder, drive tapes, idler pulleys, vacuum system, and gears. Relative importance of the sources and differences among machines is discussed. Suggestions are offered for ways to reduce noise from some of the sources. Work is continuing to evaluate and develop the most feasible methods of spinning frame noise reduction.

Trailing-edge noise reduction of a wing by a surface modification

2021 ◽  
Vol 263 (3) ◽  
pp. 3194-3201
Author(s):  
Varun Bharadwaj Ananthan ◽  
R.A.D. Akkermans ◽  
Dragan Kozulovic
Keyword(s):  
Noise Reduction ◽  
Stochastic Approach ◽  
Slight Reduction ◽  
Noise Sources ◽  
Trailing Edge ◽  
Sound Sources ◽  
Airframe Noise ◽  
Trailing Edge Noise ◽  
Random Particle ◽  
Noise Production

There is an increased emphasis on reducing airframe noise in the last decades. Airframe noise is sound generated by the interaction of a turbulent flow with the aircraft geometry, and significantly contributes to the overall noise production during the landing phase. One examples of airframe noise is the noise generated at a wing's trailing edge, i.e., trailing-edge noise. In this contribution, we numerically explore the local application of riblets for the purpose of trailing-edge noise reduction. Two configurations are studied: i) a clean NACA0012 wing section as a reference, and ii) the same configuration with riblets installed at the wing's aft part. The numerical investigation follows a hybrid computational aeroacoustics approach, where the time-average flow is studied by means of RANS. Noise sources are generated by means of a stochastic approach called Fast Random Particle Mesh method. The results show a deceleration of the flow behind the riblets. Furthermore, the turbulent kinetic energy indicates increased unsteadiness behind the riblets which is shifted away from the wall due to the presence of the riblets. Lastly, the sound sources are investigated by means of the 3D Lamb-vector, which indicates a slight reduction in magnitude near the trailing edge.

Coordinated diameter oscillations at arteriolar bifurcations in skeletal muscle

1987 ◽  
Vol 253 (3) ◽  
pp. H568-H573 ◽  
Author(s):  
J. U. Meyer ◽  
L. Lindbom ◽  
M. Intaglietta
Keyword(s):  
Skeletal Muscle ◽  
Fundamental Frequency ◽  
Narrow Band ◽  
Photometric System ◽  
Band Frequency ◽  
Skeletal Muscle Microcirculation

The spontaneous rhythmical luminal changes (vasomotion) at bifurcations in the microvasculature of the rabbit tenuissimus muscle were investigated by means of a microscope video photometric system. Video scenes, containing two terminal arterioles originating from one transverse arteriole, showed that adjacent terminal arterioles constricted synchronously in 26 out of 31 contraction cycles. The onset of 60 constrictions in the parent transverse vessels was synchronized with the activity in terminal arterioles in 75% of the cycles and delayed in 25%. Vasomotion in the parent transverse vessels was notably smaller than in the terminal vessels. All the terminal arterioles in the different animals oscillated at the fundamental frequency of 18.9 +/- 3.5 cycles/min. We conclude that in the skeletal muscle microcirculation 1) coordinated spontaneous diameter oscillations occur in arterioles that are in proximity, 2) diameter changes are most pronounced in the terminal arterioles, and 3) coordinated vasomotion in this tissue exhibits a characteristic narrow band frequency. The presence of a microvascular pacemaker is hypothesized.

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