scholarly journals Ultrasonic-Driven Spreading of Liquid Solder on Nonwetting Substrates

2020 ◽  
Vol 99 (6) ◽  
pp. 163s-174s
Author(s):  
ZHIWU XU ◽  
◽  
ZHENGWEI LI ◽  
LIN MA ◽  
JUNLAN BO ◽  
...  
Keyword(s):  
Wave Propagation ◽  
High Speed ◽  
Capillary Wave ◽  
Characteristic Impedance ◽  
Ultrasonic Power ◽  
High Speed Camera ◽  
Liquid Solder ◽  
Physical Processes ◽  
Fast Spreading ◽  
Tc4 Alloy

In this work, the spreading of a solder droplet on a substrate agitated by ultrasonic vibration was recorded by a high-speed camera. The dynamics and physical processes of the spreading, such as corrugate formation and atomization, were investigated. Results showed the solder droplet was able to spread on a nonwetting substrate, and it presented periodic expanding-shrinking spreading characteristics with a periodicity of dozens of acoustic periods. Corrugates formed as a result of the capillary wave propagation on the droplet, and the formation became intensive on a violently vibrating surface. Atomization preferentially occurred at the spreading front during solder expansion, where the liquid solder appeared as a film and burst on the whole droplet with strong vibration. High ultrasonic power resulted in fast spreading and a large spreading diameter. In particular, the solder droplet exhibited fast spreading and a large spreading diameter on the TC4 alloy with high characteristic impedance. The Sn-4Cu solder with large viscosity spread slowly and exhibited a small spreading diameter.

Interaction of Impact Liquid Drop With Splat in Spray Cooling

2019 ◽  
Author(s):  
Gangtao Liang ◽  
Haibing Yu ◽  
Liuzhu Chen ◽  
Shengqiang Shen
Keyword(s):  
Wave Propagation ◽  
Weber Number ◽  
High Speed ◽  
Liquid Drop ◽  
Capillary Wave ◽  
Propagation Speed ◽  
Spray Cooling ◽  
Capillary Waves ◽  
Kinematic Wave ◽  
Discontinuity Theory

Abstract This study investigates the interaction between an impacting liquid drop and a splat generated on a solid prior to impact, focusing mainly on the wave production and propagation on the splat with low impact velocity. Using high-speed video, the wave generation concerning the effects of Weber number is observed and analyzed, including the first wave caused by drop kinematic energy, the secondary and tertiary capillary waves subjected to surface tension. Also, the wave propagation magnitude is discussed, the purpose of which is to provide a suitable method for predicting the wave diameter. Results show that the increasing of Weber number is slightly against the wave propagation, but this effect weakens gradually. The kinematic discontinuity theory devised for crown propagation can be applied to predict the wave propagation magnitude with an excellent agreement, for both the kinematic wave and the capillary wave. In addition, the propagation speed of the wave during the drop-splat interaction is also analyzed.

scholarly journals Getting High: High Fidelity Simulation of High Granularity Calorimeters with High Speed

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Erik Buhmann ◽  
Sascha Diefenbacher ◽  
Engin Eren ◽  
Frank Gaede ◽  
Gregor Kasieczka ◽  
...  
Keyword(s):  
Particle Physics ◽  
High Speed ◽  
Deep Neural Networks ◽  
High Fidelity ◽  
High Fidelity Simulation ◽  
Physical Processes ◽  
Electromagnetic Showers ◽  
Information Bottleneck ◽  
First Time ◽  
Processing Network

AbstractAccurate simulation of physical processes is crucial for the success of modern particle physics. However, simulating the development and interaction of particle showers with calorimeter detectors is a time consuming process and drives the computing needs of large experiments at the LHC and future colliders. Recently, generative machine learning models based on deep neural networks have shown promise in speeding up this task by several orders of magnitude. We investigate the use of a new architecture—the Bounded Information Bottleneck Autoencoder—for modelling electromagnetic showers in the central region of the Silicon-Tungsten calorimeter of the proposed International Large Detector. Combined with a novel second post-processing network, this approach achieves an accurate simulation of differential distributions including for the first time the shape of the minimum-ionizing-particle peak compared to a full Geant4 simulation for a high-granularity calorimeter with 27k simulated channels. The results are validated by comparing to established architectures. Our results further strengthen the case of using generative networks for fast simulation and demonstrate that physically relevant differential distributions can be described with high accuracy.

scholarly journals Tracking by Deblatting

2021 ◽  
Author(s):  
Denys Rozumnyi ◽  
Jan Kotera ◽  
Filip Šroubek ◽  
Jiří Matas
Keyword(s):  
High Speed ◽  
High Performance ◽  
Motion Blur ◽  
Velocity Estimation ◽  
High Speed Camera ◽  
Trajectory Function ◽  
Novel Approach ◽  
Blind Deblurring ◽  
Object Trajectories ◽  
Complex Trajectories

AbstractObjects moving at high speed along complex trajectories often appear in videos, especially videos of sports. Such objects travel a considerable distance during exposure time of a single frame, and therefore, their position in the frame is not well defined. They appear as semi-transparent streaks due to the motion blur and cannot be reliably tracked by general trackers. We propose a novel approach called Tracking by Deblatting based on the observation that motion blur is directly related to the intra-frame trajectory of an object. Blur is estimated by solving two intertwined inverse problems, blind deblurring and image matting, which we call deblatting. By postprocessing, non-causal Tracking by Deblatting estimates continuous, complete, and accurate object trajectories for the whole sequence. Tracked objects are precisely localized with higher temporal resolution than by conventional trackers. Energy minimization by dynamic programming is used to detect abrupt changes of motion, called bounces. High-order polynomials are then fitted to smooth trajectory segments between bounces. The output is a continuous trajectory function that assigns location for every real-valued time stamp from zero to the number of frames. The proposed algorithm was evaluated on a newly created dataset of videos from a high-speed camera using a novel Trajectory-IoU metric that generalizes the traditional Intersection over Union and measures the accuracy of the intra-frame trajectory. The proposed method outperforms the baselines both in recall and trajectory accuracy. Additionally, we show that from the trajectory function precise physical calculations are possible, such as radius, gravity, and sub-frame object velocity. Velocity estimation is compared to the high-speed camera measurements and radars. Results show high performance of the proposed method in terms of Trajectory-IoU, recall, and velocity estimation.

Influence of Main Swirler Vane Angle on the Ignition Performance of TeLESS-II Combustor

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Bo Wang ◽  
Chi Zhang ◽  
Yuzhen Lin ◽  
Xin Hui ◽  
Jibao Li
Keyword(s):  
High Speed ◽  
Inlet Temperature ◽  
Main Stage ◽  
Ignition Process ◽  
High Speed Camera ◽  
Fuel Distribution ◽  
Fuel Droplets ◽  
Planar Laser ◽  
Cfd Method ◽  
Vane Angle

In order to balance the low emission and wide stabilization for lean premixed prevaporized (LPP) combustion, the centrally staged layout is preferred in advanced aero-engine combustors. However, compared with the conventional combustor, it is more difficult for the centrally staged combustor to light up as the main stage air layer will prevent the pilot fuel droplets arriving at igniter tip. The goal of the present paper is to study the effect of the main stage air on the ignition of the centrally staged combustor. Two cases of the main swirler vane angle of the TeLESS-II combustor, 20 deg and 30 deg are researched. The ignition results at room inlet temperature and pressure show that the ignition performance of the 30 deg vane angle case is better than that of the 20 deg vane angle case. High-speed camera, planar laser induced fluorescence (PLIF), and computational fluids dynamics (CFD) are used to better understand the ignition results. The high-speed camera has recorded the ignition process, indicated that an initial kernel forms just adjacent the liner wall after the igniter is turned on, the kernel propagates along the radial direction to the combustor center and begins to grow into a big flame, and then it spreads to the exit of the pilot stage, and eventually stabilizes the flame. CFD of the cold flow field coupled with spray field is conducted. A verification of the CFD method has been applied with PLIF measurement, and the simulation results can qualitatively represent the experimental data in terms of fuel distribution. The CFD results show that the radial dimensions of the primary recirculation zone of the two cases are very similar, and the dominant cause of the different ignition results is the vapor distribution of the fuel. The concentration of kerosene vapor of the 30 deg vane angle case is much larger than that of the 20 deg vane angle case close to the igniter tip and along the propagation route of the kernel, therefore, the 30 deg vane angle case has a better ignition performance. For the consideration of the ignition performance, a larger main swirler vane angle of 30 deg is suggested for the better fuel distribution when designing a centrally staged combustor.

scholarly journals Leader-chasing behavior in negative artificial triggered lightning flashes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Fukun Wang ◽  
Jianguo Wang ◽  
Li Cai ◽  
Rui Su ◽  
Wenhan Ding ◽  
...  
Keyword(s):  
High Speed ◽  
The Other ◽  
Lightning Flash ◽  
High Speed Camera ◽  
Return Stroke ◽  
Catching Up ◽  
Special Cases ◽  
Triggered Lightning

AbstractTwo special cases of dart leader propagation were observed by the high-speed camera in the leader/return stroke sequences of a classical triggered lightning flash and an altitude-triggered lightning flash, respectively. Different from most of the subsequent return strokes preceded by only one leader, the return stroke in each case was preceded by two leaders occurring successively and competing in the same channel, which herein is named leader-chasing behavior. In one case, the polarity of the latter leader was opposite to that of the former leader and these two combined together to form a new leader, which shared the same polarity with the former leader. In the other case, the latter leader shared the same polarity with the former leader and disappeared after catching up with the former leader. The propagation of the former leader in this case seems not to be significantly influenced by the existence of the latter leader.

scholarly journals Interactive Effects in Two-Droplets Combustion of RP-3 Kerosene under Sub-Atmospheric Pressure

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1229
Author(s):  
Hongtao Zhang ◽  
Zhihua Wang ◽  
Yong He ◽  
Jie Huang ◽  
Kefa Cen
Keyword(s):  
Burning Rate ◽  
Atmospheric Pressure ◽  
High Speed ◽  
Ambient Pressure ◽  
Interactive Effects ◽  
Propagation Time ◽  
High Speed Camera ◽  
Single Droplet ◽  
Fuel Droplets ◽  
Spacing Distance

To improve our understanding of the interactive effects in combustion of binary multicomponent fuel droplets at sub-atmospheric pressure, combustion experiments were conducted on two fibre-supported RP-3 kerosene droplets at pressures from 0.2 to 1.0 bar. The burning life of the interactive droplets was recorded by a high-speed camera and a mirrorless camera. The results showed that the flame propagation time from burning droplet to unburned droplet was proportional to the normalised spacing distance between droplets and the ambient pressure. Meanwhile, the maximum normalised spacing distance from which the left droplet can be ignited has been investigated under different ambient pressure. The burning rate was evaluated and found to have the same trend as the single droplet combustion, which decreased with the reduction in the pressure. For every experiment, the interactive coefficient was less than one owing to the oxygen competition, except for the experiment at L/D0 = 2.5 and P = 1.0 bar. During the interactive combustion, puffing and microexplosion were found to have a significant impact on secondary atomization, ignition and extinction.

High-Speed Camera Imaging of the Ignition Process in a Heaterless Hollow Cathode

2019 ◽  
Vol 47 (2) ◽  
pp. 1487-1491 ◽  
Author(s):  
Hai-Guang Zhang ◽  
Zhong-Xi Ning ◽  
Yong-Jie Ding ◽  
Xi-Ming Zhu ◽  
Bin-Hao Jiang ◽  
...  
Keyword(s):  
Hollow Cathode ◽  
High Speed ◽  
Ignition Process ◽  
High Speed Camera ◽  
Camera Imaging
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