The Acoustically Excited Flame

1976 ◽  
Vol 98 (2) ◽  
pp. 147-157 ◽  
Author(s):  
P. J. Vermeulen ◽  
M. S. Danilowich ◽  
E. P. Heydlauff ◽  
T. W. Price
Keyword(s):  
Fundamental Frequency ◽  
High Speed ◽  
Acoustic Measurements ◽  
Frequency Range ◽  
Hydrodynamic Behavior ◽  
Measurement Frequency ◽  
Forced Vortex ◽  
Sound Amplification ◽  
Premixed Laminar

A premixed laminar propane-air flame burning at the exit of a nozzle, was acoustically excited upstream by a speaker-driver unit. Detailed acoustic measurements were made to show that sound amplification and attenuation can occur over the measurement frequency range from 50 Hz to 350 Hz. The effect of excitation strength and fuel-air ratio was also investigated. Two acoustic phenomena related by forced vortex hydrodynamic behavior have been identified, and were investigated by means of high speed schlieren photographic measurements. The generation of a one-half harmonic of the fundamental frequency was explored and explained in terms of vortex hydrodynamic behavior. The work contributes to the understanding of the origin of noise from acoustically excited combustors.

The dynamic amplification factors for continuous beam bridges along high-speed railways

2021 ◽  
pp. 136943322110032
Author(s):  
Lin Ma ◽  
Wei Zhang ◽  
Steve C.S. Cai ◽  
Shaofan Li
Keyword(s):  
Fundamental Frequency ◽  
High Speed ◽  
Continuous Beam ◽  
Empirical Formulas ◽  
High Speed Railway ◽  
Amplification Factors ◽  
Girder Bridges ◽  
Continuous Beam Bridge ◽  
Train Speed ◽  
Dynamic Amplification

In this paper, the dynamic amplification factors (DAFs) of high-speed railway continuous girder bridges are studied. The vehicle-bridge interactions (VBIs) of 13 concrete continuous girder bridges with spans ranging from 48 to 130 m are analyzed, the influences of the train speed, the train marshalling and the bridge fundamental frequency on the DAF are investigated, and the DAF design standard for high-speed railway bridges is discussed. The results indicate that for the continuous beam bridge whose fundamental frequency is less than 3.0 Hz, the maximum DAF is no more than 1.15; while for the bridge examples with a fundamental frequency larger than 3.0 Hz, the maximum DAF reaches 1.25 because the resonance occurs at high train speed. The empirical formulas of the DAFs in the Japan Railway Technical Research Institute (JRTRI) code could provide a conservative estimation of the DAFs of high-speed railway continuous bridges.

Acoustic Measurements of High-Speed Jets from Rectangular Nozzle with Thrust Vectoring

AIAA Journal ◽  
2009 ◽  
Vol 47 (6) ◽  
pp. 1482-1490 ◽  
Author(s):  
Adam E. Goss ◽  
Jérémy Veltin ◽  
Jaehyung Lee ◽  
Dennis K. McLaughlin
Keyword(s):  
High Speed ◽  
Acoustic Measurements ◽  
Thrust Vectoring ◽  
Rectangular Nozzle

Developmental Outcome Prediction From Acoustic Cry Analysis in Term and Preterm Infants

PEDIATRICS ◽  
1987 ◽  
Vol 80 (4) ◽  
pp. 529-534
Author(s):  
Barry M. Lester
Keyword(s):  
Fundamental Frequency ◽  
High Speed ◽  
Infant Development ◽  
Developmental Outcome ◽  
Term Infants ◽  
Perceptual Performance ◽  
The Mean ◽  
Speed Computer ◽  
Potential Use ◽  
Bayley Scales

It has been suggested that the cry may reflect the neurophysiologic integrity of the infant and relate to later developmental outcome. In this study, the cry was recorded at term conceptional age in 18 preterm and 13 term infants using a standardized procedure and analyzed by high-speed computer. At 18 months of age, a significant number of infants were correctly classified as scoring high or low on the Bayley Scales of Infant Development based on the mean and variability in the fundamental frequency, variability in the first formant, and the amplitude of the cry. At 5 years of age, a significant number of infants were correctly classified on the McCarthy General Cognitive Index and on the verbal, perceptual-performance, and quantitative subscales based on the variability of the fundamental frequency, variability of the first formant, and amplitude and duration of the cry. Although preliminary, this study supports the potential use of the cry as a noninvasive measure to detect developmental outcome in the infant at risk.

scholarly journals Experimental study of particle concentration fluctuations in a turbulent steady flow

2008 ◽  
Vol 49 ◽  
pp. 121-126 ◽  
Author(s):  
François-Xavier Cierco ◽  
Mohamed Naaim ◽  
Florence Naaim-Bouvet
Keyword(s):  
Image Processing ◽  
Experimental Study ◽  
High Speed ◽  
Particle Concentration ◽  
Free Stream ◽  
Frequency Range ◽  
Wind Tunnel Experiments ◽  
Simple Theoretical Model ◽  
Over Time

AbstractSpecific features of the physics of blown sand and PVC particles were investigated in wind-tunnel experiments. The fluctuations in particle concentration over time were derived from image processing of high-speed films (500 Hz). Spectral analysis of these time series showed a slowly decreasing slope within a frequency range that could be larger than the inertial sub-range of the free stream. A specific transport regime also appears in the lower part of the flow for frequencies less than 10 Hz. The role of turbulence in the generation of this regime is discussed using a simple theoretical model able to describe the aerodynamic behavior of a particle.

High-speed digital imaging laryngoscopy of the neoglottis following supracricoid laryngectomy with cricohyoidoepiglottopexy

2010 ◽  
Vol 124 (11) ◽  
pp. 1234-1238 ◽  
Author(s):  
S Hayashi ◽  
H Hirose ◽  
N Tayama ◽  
H Imagawa ◽  
M Nakayama ◽  
...  
Keyword(s):  
Fundamental Frequency ◽  
Sound Source ◽  
Digital Imaging ◽  
High Speed ◽  
Imaging System ◽  
Vocal Performance ◽  
Inverse Filtering ◽  
Imaging Analysis ◽  
Supracricoid Laryngectomy ◽  
Digital Imaging System

AbstractObjectives:This study aimed to analyse vocal performance and to investigate the nature of the neoglottal sound source in patients who had undergone supracricoid laryngectomy with cricohyoidoepiglottopexy, using a high-speed digital imaging system.Methods:High-speed digital imaging analysis of neoglottal kinetics was performed in two patients who had undergone supracricoid laryngectomy with cricohyoidoepiglottopexy; laryngotopography, inverse filtering analysis and multiline kymography were also undertaken.Results:In case one, laryngotopography demonstrated two vibrating areas: one matched with the primary (i.e. fundamental) frequency (75 Hz) and the other with the secondary frequency (150 Hz) at the neoglottis. In case two, laryngotopography showed two vibrating areas matched with the fundamental frequency (172 Hz) at the neoglottis. The interaction between the two areas was considered to be the sound source in both patients. The waveform of the estimated volume flow at the neoglottis, obtained by inverse filtering analysis, corresponded well to the neoglottal vibration patterns derived by multiline kymography. These findings indicated that the specific sites identified at the neoglottis by the present method were likely to be the sound source in each patient.Conclusions:High-speed digital imaging analysis is effective in locating the sites responsible for voice production in patients who have undergone supracricoid laryngectomy with cricohyoidoepiglottopexy. This is the first study to clearly identify the neoglottal sound source in such patients, using a high-speed digital imaging system.

Sign in / Sign up

Export Citation Format

Share Document