Acoustic Sound Source Identification in a Gasoline DI Pump for High Pressure Fuel Flows

2014 ◽  
Author(s):  
Prashanth Avireddi ◽  
Nikhil Seera ◽  
Harsha Badarinarayan
Keyword(s):  
High Pressure ◽  
Simulation Model ◽  
Numerical Simulations ◽  
Combustion Chamber ◽  
Sound Pressure Level ◽  
Fuel Economy ◽  
Sound Pressure ◽  
Pressure Level ◽  
Liquid Domain ◽  
Jet Impact

The passenger class automobiles operating with gasoline direct injection (DI) pump have a better fuel economy than the automobiles operating with gasoline port fuel injection (PFI) pump. The fuel economy is higher because DI pump injects fuel directly into combustion chamber at pressures over 150 bar compared to a PFI pump which injects fuel into combustion chamber through inlet port at pressures over 50 bar. By injecting fuel directly into the combustion chamber, DI system prevents condensation of fuel, pressure leakage and improves atomization of fuel for internal combustion process. However, the disadvantage of high pressure operation is that the DI pump is noisier than a PFI pump. The loud sound in a DI pump is generated due to phenomenon such as high pressure pulsations, liquid jet impact and high velocity flows. To investigate the sound production in a DI pump, High fidelity hybrid numerical simulations were developed using CFD and Acoustic tools to simulate the operational effects and identify the behavior of internal components of DI pump. The fidelity of the numerical simulations depends on the transient boundary conditions and the fluid structure interactions in the DI pump. The CFD simulation model of DI pump has 8 million mesh elements and the simulation model is computed using 256 cores of super computer operating at a rate of 2 TFLOPS. The results derived from the CFD simulations were processed using a commercial acoustics tool for computing sound pressure level in liquid domain. Sound pressure level in liquid domain is used as a relative parameter for distinguishing the behavior of liquid-acoustic sources. The results from the numerical simulations provide a good account of the behavior of internal components in DI pump and the simulation results are in good agreement with the experiments performed on DI pump.

On the Performance of Porous Sound Absorbent Ceramic Lining in a Combustion Chamber Test Rig

2013 ◽  
Author(s):  
Hans-Christoph Ries ◽  
Mateus Vieira Carlesso ◽  
Christian Eigenbrod ◽  
Stephen Kroll ◽  
Kurosch Rezwan
Keyword(s):  
Combustion Chamber ◽  
Sound Pressure Level ◽  
Gas Turbines ◽  
Sound Pressure ◽  
Porous Ceramic ◽  
Pressure Level ◽  
Test Rig ◽  
Resonance Frequencies ◽  
Lean Premixed ◽  
Ceramic Lining

This paper discusses the potential of using porous ceramic lining as insulating material in combustion chambers with respect to their sound absorbent ability to suppress thermoacoustic instabilities. For this purpose a combustion chamber test rig was developed and different types of ceramic linings were tested. The examined range of power was between 40 and 250 kW and the air-propane equivalence ratio was between 1.2 and 2.0. The overall sound pressure level and frequency domain of a lean premixed swirl stabilized and piloted burner are presented. The resonance frequencies and sound pressure levels are obtained and compared for the different combustion chamber linings. The results show a significant decrease in overall sound pressure level by up to 23.5 dB for sound absorbent lining in comparison to the common sound reflecting combustion chamber lining. In summary, sound absorbent ceramic combustion chamber lining can contribute to improve the stability of lean premixed gas turbines.

Contributions of Voice and Nonverbal Communication to Perceived Masculinity–Femininity for Cisgender and Transgender Communicators

2020 ◽  
Vol 63 (4) ◽  
pp. 931-947
Author(s):  
Teresa L. D. Hardy ◽  
Carol A. Boliek ◽  
Daniel Aalto ◽  
Justin Lewicke ◽  
Kristopher Wells ◽  
...  
Keyword(s):  
Fundamental Frequency ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Vocal Tract ◽  
Presentation Mode ◽  
Pressure Level ◽  
Presentation Modes ◽  
Audiovisual Stimuli ◽  
Vocal Tract Resonance ◽  
Point Light

Purpose The purpose of this study was twofold: (a) to identify a set of communication-based predictors (including both acoustic and gestural variables) of masculinity–femininity ratings and (b) to explore differences in ratings between audio and audiovisual presentation modes for transgender and cisgender communicators. Method The voices and gestures of a group of cisgender men and women ( n = 10 of each) and transgender women ( n = 20) communicators were recorded while they recounted the story of a cartoon using acoustic and motion capture recording systems. A total of 17 acoustic and gestural variables were measured from these recordings. A group of observers ( n = 20) rated each communicator's masculinity–femininity based on 30- to 45-s samples of the cartoon description presented in three modes: audio, visual, and audio visual. Visual and audiovisual stimuli contained point light displays standardized for size. Ratings were made using a direct magnitude estimation scale without modulus. Communication-based predictors of masculinity–femininity ratings were identified using multiple regression, and analysis of variance was used to determine the effect of presentation mode on perceptual ratings. Results Fundamental frequency, average vowel formant, and sound pressure level were identified as significant predictors of masculinity–femininity ratings for these communicators. Communicators were rated significantly more feminine in the audio than the audiovisual mode and unreliably in the visual-only mode. Conclusions Both study purposes were met. Results support continued emphasis on fundamental frequency and vocal tract resonance in voice and communication modification training with transgender individuals and provide evidence for the potential benefit of modifying sound pressure level, especially when a masculine presentation is desired.

Case study: Theoretical calculation model and variable condition analysis research on the water-splashing noise for natural draft wet cooling towers

2020 ◽  
Vol 68 (2) ◽  
pp. 137-145
Author(s):  
Yang Zhouo ◽  
Ming Gao ◽  
Suoying He ◽  
Yuetao Shi ◽  
Fengzhong Sun
Keyword(s):  
Theoretical Model ◽  
Sound Pressure Level ◽  
Water Droplet ◽  
Water Distribution ◽  
Sound Pressure ◽  
Cooling Tower ◽  
Distribution Patterns ◽  
Calculation Model ◽  
Pressure Level ◽  
Cooling Towers

Based on the basic theory of water droplets impact noise, the generation mechanism and calculation model of the water-splashing noise for natural draft wet cooling towers were established in this study, and then by means of the custom software, the water-splashing noise was studied under different water droplet diameters and water-spraying densities as well as partition water distribution patterns conditions. Comparedwith the water-splashing noise of the field test, the average difference of the theoretical and the measured value is 0.82 dB, which validates the accuracy of the established theoretical model. The results based on theoretical model showed that, when the water droplet diameters are smaller in cooling tower, the attenuation of total sound pressure level of the water-splashing noise is greater. From 0 m to 8 m away from the cooling tower, the sound pressure level of the watersplashing noise of 3 mm and 6 mm water droplets decreases by 8.20 dB and 4.36 dB, respectively. Additionally, when the water-spraying density becomes twice of the designed value, the sound pressure level of water-splashing noise all increases by 3.01 dB for the cooling towers of 300 MW, 600 MW and 1000 MW units. Finally, under the partition water distribution patterns, the change of the sound pressure level is small. For the R s/2 and Rs/3 partition radius (Rs is the radius of water-spraying area), when the water-spraying density ratio between the outer and inner zone increases from 1 to 3, the sound pressure level of water-splashing noise increases by 0.7 dB and 0.3 dB, respectively.

Analysis of the Noise Level Generated by Axial Flow Fan Composed of Radial-Bladed Centrifugal Rotor

2014 ◽  
Author(s):  
S. S. Borges ◽  
R. Barbieri ◽  
P. S. B. Zdanski
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Axial Flow ◽  
Acoustic Resonance ◽  
Pressure Level ◽  
Resonance Mode ◽  
Numerical Techniques ◽  
Cooling Systems ◽  
Centrifugal Fans ◽  
Motor Cooling

The objective of this work is to present, by means of experimental, analytical and numerical techniques that sound pressure level generated by radial-bladed centrifugal fans of electric motor cooling systems may be expressed by a logarithmical ratio of the peripheral velocity of rotor, volumetric flow and efficiency of the fan. The proposed methodology proved to be efficient and simple in the prediction of generated noise by radial-bladed centrifugal fans of TEFC motors with accuracy of ± 3 dB. In addition, the acoustic resonance mode of the fan cavity were determined by means of numerical simulations, which its results were validated through experiments using waterfall spectrum.

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