Investigation on collision-coalescence of droplets under the synergistic effect of charge and sound waves: orthogonal design optimization

2021 ◽  
Author(s):  
Fuyou He ◽  
li jiawei_hust ◽  
Chuan Li ◽  
Pengyu Wang ◽  
Zutao Wang ◽  
...  
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Orthogonal Design ◽  
Pressure Level ◽  
Collision Probability ◽  
Droplet Growth ◽  
Sound Waves ◽  
Growth Ratio ◽  
Acoustic Frequency ◽  
The Impact

Abstract As an efficient approach to improve the visibility, defogging technology is essential for the operation of ports and airports. This paper proposes a new and hybrid defogging technology, i.e. electric–acoustic defogging method. Specifically, the droplets are charged by corona discharge, which is beneficial to overcome the hydrodynamic interaction force to improve the droplet collision efficiency. Meanwhile, sound waves (especially acoustic turbulence) promote the relative movement of droplets to increase the collision probability. In this study, the effects of acoustic frequency ( f ), sound pressure level (SPL), and voltage (V) on the droplet growth ratio were studied by orthogonal design analysis. The results of difference analysis and multi-factor variance analysis show that frequency and sound pressure level are the dominant factors that affect the collision of droplets, and the effect of voltage is relatively weak. And f = 400 Hz, SPL = 132 dB, and V = -7.2 kV are the optimal parameters in our experiment. In addition, we further studied the impact of single factor on droplet growth ratio. The results show that there is an optimal frequency of 400 Hz. That is, the impact of frequency is non-linear. The droplet growth ratio increases with sound pressure level and voltage level. The new technology proposed in this paper can provide a new approach for defogging in open space.

Interaction between Strong Sound Waves and Cloud Droplets: Theoretical Analysis

2021 ◽  
Author(s):  
Ying-Hui Jia ◽  
Fang-Fang Li ◽  
Kun Fang ◽  
Guang-Qian Wang ◽  
Jun Qiu
Keyword(s):  
Sound Wave ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Sound Field ◽  
Pressure Level ◽  
Velocity Variation ◽  
Time Range ◽  
Sound Waves ◽  
Cloud Droplets ◽  
Acoustic Frequency

AbstractRecently strong sound wave was proposed to enhance precipitation. The theoretical basis of this proposal has not been effectively studied either experimentally or theoretically. Based on the microscopic parameters of atmospheric cloud physics, this paper solved the complex nonlinear differential equation to show the movement characteristics of cloud droplets under the action of sound waves. The motion process of individual cloud droplet in a cloud layer in the acoustic field is discussed as well as the relative motion between two cloud droplets. The effects of different particle sizes and sound field characteristics on particle motion and collision are studied to analyze the dynamic effects of thunder-level sound waves on cloud droplets. The amplitude of velocity variation has positive correlation with Sound Pressure Level (SPL) and negative correlation with the frequency of the surrounding sound field. Under the action of low-frequency sound waves with sufficient intensity, individual cloud droplets could be forced to oscillate significantly. The droplet smaller than 40μm can be easily driven by sound waves of 50 Hz and 123.4 dB. The calculation of the collision process of two droplets reveals that the disorder of motion for polydisperse droplets is intensified, resulting in the broadening of the collision time range and spatial range. When the acoustic frequency is less than 100Hz (@ 123.4dB) or the Sound Pressure Level (SPL) is greater than 117.4dB (@ 50Hz), the sound wave can affect the collision of cloud droplets significantly. This study provides theoretical perspective of acoustic effect to the microphysics of atmospheric clouds.

Comparison of Sound Pressure Level of Conventional and Modified Mufflers by using CFD Analysis

2021 ◽  
Vol 8 (01) ◽  
pp. 63-67
Author(s):  
Zahoor Ullah ◽  
◽  
Hassan Ahmed ◽  
Kareem Akhtar ◽  
◽  
...  
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Combustion Engine ◽  
Pressure Level ◽  
Destructive Interference ◽  
Cfd Analysis ◽  
Sound Waves ◽  
Reflected Waves ◽  
Engine Cylinder ◽  
Real Challenge

The reduction of noise emitted from the exhaust of internal combustion engine is a real challenge for all automotive industries. Mufflers are designed to reflect sound waves produced by the engine in such a way to cancel the effect of each other by destructive interference between the incoming waves from engine cylinder and reflected waves from the muffler of the 2 stroke motorbike engine. Numerical simulation is carried out to study the sound pressure level (SPL) and flow variable like velocity and pressure of conventional and proposed modified reactive muffler.

scholarly journals The Impact of the Bass Drum on Human Dance Movement

2012 ◽  
Vol 30 (4) ◽  
pp. 349-359 ◽  
Author(s):  
Edith Van Dyck ◽  
Dirk Moelants ◽  
Michiel Demey ◽  
Alexander Deweppe ◽  
Pieter Coussement ◽  
...  
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Pressure Level ◽  
Head Movements ◽  
Contemporary Dance ◽  
Dance Music ◽  
Dance Movement ◽  
Dynamic Level ◽  
Adult Participants ◽  
The Impact

The present study aims to gain better insight into the connection between music and dance by examining the dynamic effects of the bass drum on a dancing audience in a club-like environment. One hundred adult participants moved freely in groups of five to a musical sequence that comprised six songs. Each song consisted of one section that was repeated three times, each time with a different sound pressure level of the bass drum. Hip and head movements were recorded using motion capture and motion sensing. The study demonstrates that people modify their bodily behavior according to the dynamic level of the bass drum when moving to contemporary dance music in a social context. Participants moved more actively and displayed a higher degree of tempo entrainment as the sound pressure level of the bass drum increased. These results indicate that the prominence of the bass drum in contemporary dance music serves not merely as a stylistic element; indeed, it has a strong influence on dancing itself.

scholarly journals Pengujian Alat Pemanen Energi Akustik Berbasis Loudspeaker Dengan Sumber Kebisingan Acak Dari Mesin Kendaraan Bermotor

2019 ◽  
Vol 4 ◽  
pp. 152
Author(s):  
Untung Adi Santosa ◽  
Ikhsan Setiawan ◽  
B.S. Utomo
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Random Noise ◽  
Electrical Power ◽  
Dominant Frequency ◽  
Pressure Level ◽  
Acoustic Energy ◽  
Noise Sources ◽  
Quarter Wavelength ◽  
The Impact

<p class="AbstractEnglish"><strong>Abstract: </strong>This paper reports the test results of a loudspeaker-based acoustic energy harvester with acoustic random noise sources from a motorcycle. The harvester consists of a quarter wavelength resonator and a subwoofer type loudspeaker with a nominal diameter of 6 inches. The motorcycle used in this experiment is 135 cc Bajaj Pulsar motorsport with modified exhaust from the GBS-Motosport Jakarta. The motor engine is operated at 3000 rpm, resulting in noise with a fluctuating Sound Pressure Level (SPL) in the range of (90-93) dB. Six variations of resonator lengths are used, those are 21 cm, 31 cm, 58 cm, 85 cm, 112 cm, and 139 cm. In this test, data of dominant frequency, SPL, and output rms voltage were taken for 15 minutes. The rms voltage is measured at 100 Ω load resistor. The results show that the 112 cm resonator produces the highest average rms electrical power, that is (0.21 ± 0.01) mW, which is obtained at frequency that fluctuates within (95-120) Hz. In addition, with random sound sources, SPL and its dominant frequency fluctuate greatly, so it will greatly affect the generated electric power. Further research is needed to enhance the output electrical power and anticipate the impact of frequency fluctuation which exists in random noise sources.</p><p class="AbstractEnglish"><strong>Abstrak: </strong>Paper ini memaparkan hasil pengujian alat pemanen energi akustik berbasis <em>loudspeaker </em>dengan sumber kebisingan acak dari mesin kendaraan bermotor. Alat pemanen energi akustik ini terdiri dari resonator seperempat panjang gelombang dan <em>loudspeaker</em> jenis <em>subwoofer</em> dengan diameter nominal 6 inci. Sumber kebisingan yang digunakan adalah motor Bajaj Pulsar 135 cc dengan knalpot modifikasi dari GBS-Motosport Jakarta. Mesin motor dioperasikan pada laju putaran tetap 3000 rpm, sehingga menghasilkan kebisingan dengan <em>SPL</em> (<em>sound pressure level</em>) yang berfluktuasi dalam interval (90-93) dB. Digunakan enam variasi panjang resonator, yaitu 21 cm, 31 cm, 58 cm, 85 cm, 112 cm, dan 139 cm. Dalam pengujian ini, data frekuensi dominan kebisingan, <em>SPL</em> kebisingan, dan tegangan keluaran alat pemanen energi akustik diambil selama 15 menit. Tegangan <em>rms</em> keluaran diukur pada resistor beban 100 Ω. Hasil eksperimen menunjukkan bahwa resonator dengan panjang 112 cm menghasilkan daya listrik <em>rms</em> rata-rata tertinggi yaitu sebesar (0,21 ± 0,01) mW, diperoleh pada frekuensi yang berfluktuasi antara 95 Hz sampai 120 Hz. Selain itu, hasil eksperimen ini menunjukkan bahwa dengan sumber bunyi acak, <em>SPL</em> kebisingan dan frekuensi dominannya sangat berfluktuasi, sehingga akan sangat berpengaruh terhadap daya listrik yang dihasilkan. Penelitian lebih lanjut diperlukan untuk meningkatkan daya listrik keluaran dan mengantisipasi dampak fluktuasi frekuensi sumber kebisingan acak.</p>

Application of Hartmann Acoustic Generator in Source of Underwater Pyrotechnic Combustion

2013 ◽  
Vol 787 ◽  
pp. 638-643
Author(s):  
Jie Li ◽  
Hua Guan ◽  
Dong Ming Song ◽  
Qi Wang ◽  
Jun Du ◽  
...  
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Acoustic Radiation ◽  
Structural Parameters ◽  
Resonant Cavity ◽  
Experimental Studies ◽  
Combustion Products ◽  
Pressure Level ◽  
Radiation Characteristics ◽  
Acoustic Frequency

In order to investigate acoustic radiation characteristics of underwater pyrotechnic combustion, Hartmann acoustic generator was applied and its main structural parameters effecting acoustic radiation characteristics were studied by using underwater acoustic measurement system. Experimental studies have shown that, when Hartmann acoustic generator was applied, the sound pressure level of underwater pyrotechnic combustion increased significantly because of the strengthening of turbulence degree. The distance between the nozzle and the resonant cavity is an important factor of affecting acoustic radiation characteristics of Hartmann acoustic generator. When the resonant cavity was placed in the unstable pressure area, it could stimulate strong sound waves. On account of the resistance of the water, the combustion products speed of reaching resonant cavity drooped and the collision strength between the feedback combustion products and the newly generated products reduced. So when the distance was larger, the SPL(sound pressure level) was smaller. The SPL of underwater pyrotechnic combustion increased and the acoustic frequency moved to the low frequency with the depth of resonant cavity increased, which is consistent with the acoustic characteristics of Hartmann acoustic generator applied in air.

Acoustic Enhancement of the Rate of Heat Transfer Over a Flat Plate-An Experimental Investigation

1997 ◽  
Vol 119 (4) ◽  
pp. 257-264 ◽  
Author(s):  
J. M. Preston ◽  
W. S. Johnson
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Resonant Frequency ◽  
Flat Plate ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Air Flow ◽  
Copper Plate ◽  
Pressure Level ◽  
Sound Waves

Increasing the rate of heat transfer can improve product quality and lower energy cost for many energy systems. Pulsating fluid flow has been used to increase the rate of heat transfer in some situations. Specifically, sound waves below the audible limit, termed infrasound, have been used to increase the rate of heat transfer from small-diameter wire rods. This study examined the effects of infrasound on the rate of heat transfer from a flat plate. A standing sound wave is formed in the neck of a Helmholtz resonator and may be enhanced by producing sound waves at the resonant frequency at or near the neck of the resonator. In this study, a standing wave of infrasound was produced in a rectangular channel by two loudspeakers driven sinusoidally by a function generator at the resonant frequency of the system. The top of the channel was formed by a copper plate maintained at a constant temperature. Thermocouples placed along the centerline of the channel measured the temperature of the air inside the channel and heat flux gages mounted on the inside surface of the copper plate were used to measure the local rate of heat transfer from the plate to the air inside the channel. Air flow inside the channel was produced by a centrifugal blower and varied by an inlet damper. The use of infrasound increased the rate of heat transfer by approximately an order of magnitude when compared to natural convection. Infrasonic enhancement of the rate of heat transfer over a two-dimensional region in forced convection was more effective in the laminar flow regime, for Reynolds numbers based on the hydraulic diameter between zero and 10,000. Typically for laminar flow, infrasound increased the rate of heat transfer up to five times the rate of heat transfer without infrasound. For turbulent air flow, however, the increase of the rate of heat transfer was almost negligible. The effect of infrasound on the rate of heat transfer was shown to depend on the air velocity inside the channel, the hydraulic diameter of the channel, and the sound pressure level inside the channel. The temperature of the copper plate over the limited range tested did not significantly affect the heat transfer coefficient. The speakers used were limited to a maximum sound pressure level of 121 dB, while infrasonic generators are capable of producing sound pressure levels over 170 dB.

scholarly journals Mitigasi dampak kebisingan bandara terhadap kehidupan pemukiman sekitar bandara SSK II Pekanbaru

Jurnal Zona ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 91-106
Author(s):  
Eko Hendi Saputra ◽  
Yusni Ikhwan Siregar ◽  
Hafidawati Hafidawati
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Noise Exposure ◽  
Pressure Level ◽  
Noise Attenuation ◽  
Residential Areas ◽  
Noise Levels ◽  
Residential Communities ◽  
The People ◽  
The Impact

This study aims to determine the level of noise caused by flight activities at Sultan Syarif Kasim II Airport Pekanbaru, analyze noise levels that occur due to flight activities at Sultan Syarif Kasim II Airport Pekanbaru and analyze efforts to control the negative impact of airport noise on the living environment of community settlements. around Sultan Syarif Kasim II Airport Pekanbaru. This research uses field observation method, which is making direct observations at the research location by looking at the condition of the location and the suitability of the location which is the sampling point of the study (the noise level boundary at Sultan Syarif Kasim II Airport). Observations were made for 16 hours (Ls) at an interval of 06.00 - 22.00. Measurement of sound pressure level is carried out on holidays (Sunday) and weekdays (Monday), which starts on November 1, November 2, November 8, and November 9, 2020, which is carried out in residential areas around Sultan Syarif Kasim II Airport Pekanbaru, which are spread across 6 measurement points where the measurement of sound pressure level is done in duplicate, namely: Jl. Kaswari (point 1), Jl. Rawa Indah II (Point 2), Jl. Rawa Indah III (Point 3), Jl. Cinnamon (Point 4), Jl. Pahlawan Kerja gg.Pala 49 (Point 5) and Jl. Nur Asiyah (Point 6) The results of the processing of noise measurement data were made of a mapping model using surfer 11 software and to clarify the noise description at the sampling location, the map of the results of surfer 11 software processing was plotted on the airport area map.     Based on the results of measurements of noise levels around Sultan Syarif Kasim II airport, it is known that the location of point 1 (Jl. Rawa Indah II) experienced the highest noise exposure. These results indicate the location of point 1 should receive serious attention for the people who live around the airport, because the impact of airport noise has the potential to negatively affect the lives of residential communities. From the observations, it was also known that the level of noise attenuation was still low, both in terms of trees around the settlement and height, walls and fences were still not effective at reducing noise.         Based on the results of measurements of noise levels around Sultan Syarif Kasim II airport, it is known that the location of point 1 (Jl. Rawa Indah II) experienced the highest noise exposure. These results indicate that the location of point 1 should receive serious attention for the people who live around the airport, because the impact of airport noise has the potential to negatively affect the lives of residential communities. From the observations, it was also known that the level of noise attenuation was still low, both in terms of trees around the settlement and height, walls and fences were still not effective at reducing noise.         From the results of the research that has been done, several mitigation strategies can be formulated to reduce noise levels around Sultan Syarif Kasim II airport. Planting plants in accordance with the needs of controlling or reducing noise in human settlements. Tree categories suitable for planting in residential areas around the airport are: shady trees that can be planted tightly or with lots of leaves that can grow to a height of about 4 - 15 m (such as acacia, mahogany, flamboyant, ironwood or banyan trees, bamboo or cypress)

scholarly journals Noise Reduction Characteristics of Macroporous Asphalt Pavement Based on A Weighted Sound Pressure Level Sensor

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4356
Author(s):  
Feng Lai ◽  
Zhiyong Huang ◽  
Feng Guo
Keyword(s):  
Noise Reduction ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Asphalt Pavement ◽  
Test System ◽  
Pressure Level ◽  
High Porosity ◽  
Loading Test ◽  
Reduction Effect ◽  
The Impact

Based on the manual of macroporous noise-reducing asphalt pavement design, the indoor main drive pavement function accelerated loading test system was applied to investigate the impact of speed, loading conditions (dry and wet) and structural depth on the noise reduction of macroporous Open Graded Friction Course (OGFC) pavement, as well as its long-term noise reduction. Combined with the noise spectrum of the weighted sound pressure level, the main components and sensitive frequency bands of pavement noise under different factors were analyzed and compared. According to experimental results, the noise reduction effect of different asphalt pavements from strong to weak is as follows: OGFC-13 > SMA-13 > AC-13 > MS-III. The noise reduction effect of OGFC concentrates on the frequency of 1–4 kHz when high porosity effectively reduces the air pump effect. As the effect of wheels increases and the depth of the road structure decreases, the noise reduction effect of OGFC decreases. It indicates the noise reduction performance attenuates at a later stage, similar to the noise level of densely graded roads.

Sign in / Sign up

Export Citation Format

Share Document