Exploration on relationship between flow rate and sound pressure level of piezoelectric pump

2019 ◽  
Vol 26 (2) ◽  
pp. 609-616 ◽  
Author(s):  
Lipeng He ◽  
Xiaoqiang Wu ◽  
Da Zhao ◽  
Wei Li ◽  
Guangming Cheng ◽  
...  
Keyword(s):  
Flow Rate ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Pressure Level ◽  
Piezoelectric Pump

scholarly journals Experimental study of aerodynamic noise performance of improved air distributor for ships

2021 ◽  
Vol 13 (3) ◽  
pp. 168781402110012
Author(s):  
Yuejiao Guo ◽  
Guozeng Feng ◽  
Shuya Lei ◽  
Bo Meng ◽  
Yang Xu
Keyword(s):  
Flow Rate ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Static Pressure ◽  
Resistance Coefficient ◽  
Pressure Level ◽  
Channel Structure ◽  
Aerodynamic Noise ◽  
Frequency Noise ◽  
Reduction Effect

In ships, aerodynamic noise from the variable-air-volume fan is a common problem. This study experimentally explores the strategy of reshaping the traditional C-shaped channel structure to an L-shape to reduce noise. The noise level and resistance coefficient of the improved air distributor are analysed, and the results show that the noise of the original air distributor is 56.3 dB(A) under the rated working conditions (static pressure of 800 Pa and flow rate of 350 m3/h), which exceeds the International Maritime Organisation’s (IMO) ship noise limit (55 dB(A)). For the improved air distributor, the noise pressure level is 38.5 dB(A), the sound pressure level of high-frequency noise is reduced by 48% and the peak sound pressure level appears at 125 to 250 Hz, a frequency below the threshold of human hearing. Thus, the reshaping of the channel has a significant noise reduction effect. When the static pressure is 400 Pa and the flow rate is 100 to 500 m3/h, the sound pressure level of the improved air distributor is reduced by 29.9% to 32.2% to become less than 55 dB(A). Thus, the sound pressure level at the outlet of the improved air distributor meets the IMO ship noise standard.

OPTIMIZATION OF LOW NOISE BIONIC FAN USING GRAY RELATIONAL ANALYSIS COUPLED WITH ENTROPY MEASUREMENT

2014 ◽  
Vol 13 (01) ◽  
pp. 1450005 ◽  
Author(s):  
SHUMING CHEN ◽  
YONGQI GUO ◽  
DENGFENG WANG ◽  
SHAOMING SUN
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Pressure Level ◽  
Gray Relational Analysis ◽  
Acoustic Performance ◽  
Relational Analysis ◽  
Entropy Measurement

This research presents a hybrid optimization method for the determination of the optimal geometry parameters which can minimize the A-weighted sound pressure level of bionic fan on condition that the mass flow rate of the bionic fan is as high as possible. A hybrid approach of gray relational analysis (GRA), Taguchi method, and entropy measurement has been used to obtain better acoustic performances with three basic geometry parameters, which are blade number, boss ratio, and blade stagger angle. A L9(34) orthogonal array has been used for conducting the experiment for optimization of flow and acoustic performances. The problem of multiple performance indices is simplified into single performance index by using gray relational grade. The designed experimental results are utilized in GRA, and the weights of the flow and acoustic performances are determined by using the entropy measurement method. Meanwhile, the optimal combination of bionic fan parameters is determined by using GRA method. Moreover, the validation tests show that the overall sound pressure level (SPL) reduces by 15.50% at the cost of mass flow rate reducing by 3.00%. The comparison of the A-weighted SPL for acoustic tests between original fan and optimized bionic fan demonstrates that the acoustic performance obviously improve from 20 Hz to 6300 Hz. Therefore, it is clearly shown that the proposed approach in this paper can be an useful tool to improve acoustic performance of bionic fan.

Regulatory Mechanism of Voice Intensity Variation

1964 ◽  
Vol 7 (1) ◽  
pp. 17-29 ◽  
Author(s):  
Nobuhiko Isshiki
Keyword(s):  
Flow Rate ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Low Frequency ◽  
Intensity Variation ◽  
Pressure Level ◽  
Expiratory Muscle ◽  
Laryngeal Control ◽  
The Relationship ◽  
The Voice

The relationship between the voice intensity (sound pressure level), the subglottic pressure, the air flow rate, and the glottal resistance was investigated. Simultaneous recordings were made of the sound pressure level of voice, the subglottic pressure, the flow rate, and the volume of air utilized during phonation. The glottal resistance, the subglottic power, and the efficiency of voice were calculated from the data. It was found that on very low frequency phonation the flow rate remained almost unchanged or even slightly decreased with the increase in voice intensity while the glottal resistance showed a tendency to augment with increased voice intensity. In contrast to this, the flow rate on high frequency phonation was found to increase greatly, while the glottal resistance remained almost unchanged as the voice intensity increased. On the basis of the data it was concluded that at very low pitches, the glottal resistance is dominant in controlling intensity (laryngeal control), becoming less so as the pitch is raised, until at extremely high pitch the intensity is controlled almost entirely by the flow rate (expiratory muscle control).

Behavior of Jet From an Orifice in a Pipe Under Pulsating Flow

2007 ◽  
Author(s):  
Ema Tamura ◽  
Junjiro Iwamoto
Keyword(s):  
Unsteady Flow ◽  
Flow Rate ◽  
Sound Pressure Level ◽  
Measurement Errors ◽  
Sound Pressure ◽  
Pressure Level ◽  
Flow Meter ◽  
Orifice Flow ◽  
Accuracy Of Measurement ◽  
Orifice Flow Meter

An orifice flow meter is widely used in industry to measure the flow rate of gas or liquid in the pipe because of its simplicity. The accuracy of measurement is acceptable when the steady flow is measured. However, it is often the case in industry that the unsteady flow must be measured. It is not yet known, under unsteady flow conditions, how accurate the flow rate can be measured using the orifice flow meter and where the measurement errors come from. In the present paper to answer these questions a pulsating air flow is considered as the simplest of the various types of unsteady flow patterns and the measurement of the flow field in the pipe with orifice is made in detail. The sound pressure level is also measured by probe tube microphone. A comparison is made of power spectrum densities obtained by measurement of sound pressure level and by the velocity measurement from laser Doppler anemometer.

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.

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