scholarly journals Erosion Mechanism of a Cavitating Jet on Groove Roughness

Fluids ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 6
Author(s):  
Nobuyuki Fujisawa ◽  
Takayuki Yamagata ◽  
Ryotaro Seki ◽  
Motofumi Ohki
Keyword(s):  
Mass Loss ◽  
Cavitation Bubble ◽  
Intensity Fluctuation ◽  
Observation Time ◽  
Time Resolved ◽  
Focusing Effect ◽  
Erosion Mechanism ◽  
Impulsive Forces ◽  
Flow Visualizations ◽  
Cavitating Jet

The erosion behavior of a cavitating jet on groove roughness was investigated experimentally using mass-loss characteristics, scanning electron microscopy (SEM) observation, time-resolved shadowgraph, and schlieren flow visualizations. The wall morphology of the cavitating-jet erosion on the groove roughness indicated an increased mass loss, which was highly increased along the groove rather than across the groove. Furthermore, increased erosion pits were observed on the groove bottom along the grooves. The shadowgraph imaging of the cavitating jet on the rough wall showed noncircular cavitation bubble distributions along and across the grooves, which corresponds to the increased number of cavitation bubbles along the grooves and the decreased number of bubbles across the grooves. This result is consistent with the erosion morphology of the groove roughness. Schlieren imaging indicated that the frequency and intensity fluctuation of the shockwave formation did not change significantly on the groove roughness along and across the grooves. The findings in the study show that the increased erosion mechanism on groove roughness is caused by the increased number of impulsive forces and the shockwave focusing effect on the groove bottom.

Early Dynamics of a Laser-induced Underwater Shock Wave

2021 ◽  
Author(s):  
Guihua Lai ◽  
Siyuan Geng ◽  
Hanwen Zheng ◽  
Zhifeng Yao ◽  
Qiang Zhong ◽  
...  
Keyword(s):  
Shock Wave ◽  
Numerical Method ◽  
Cavitation Bubble ◽  
Laser Energy ◽  
Optical Breakdown ◽  
Pulsed Laser ◽  
Underwater Shock Wave ◽  
Time Resolved ◽  
High Attenuation ◽  
Nanosecond Pulsed Laser

Abstract The objective of this paper is to observe and investigate the early evolution of the shock wave, induced by a nanosecond pulsed laser in still water. A numerical method is performed to calculate the propagation of the shock wave within 1µs, after optical breakdown, based on the Gilmore model and the Kirkwood-Bethe hypothesis. The input parameters of the numerical method include the laser pulse duration, the size of the plasma and the maximally extended cavitation bubble, which are measured utilizing a high time-resolved shadowgraph system. The calculation results are verified by shock wave observation experiments at the cavitation bubble expansion stage. The relative errors of the radiuses and the velocity of the shock wave front, reach the maximum value of 45% at 5 ns after breakdown and decrease to less than 20% within 20 ns. The high attenuation characteristics of the shock wave after the optical breakdown, are predicted by the numerical method. The quick time and space evolution of the shock wave are carefully analyzed. The normalized shock wave width is found to be independent of the laser energy and duration, and the energy partitions ratio is around 2.0 using the nanosecond pulsed laser.

Experimental study on pit formation and erosion mechanism of cavitating jet

2018 ◽  
Vol 2018.55 (0) ◽  
pp. F012
Author(s):  
Toshihiro HORIUCHI ◽  
Takayuki YAMAGATA ◽  
Nobuyuki FUJISAWA
Keyword(s):  
Experimental Study ◽  
Erosion Mechanism ◽  
Pit Formation ◽  
Cavitating Jet

scholarly journals Fourier Analysis of Slow and Fast Image Propagation through Single and Coupled Image Resonators

2012 ◽  
Vol 2012 ◽  
pp. 1-9
Author(s):  
Parvin Sultana ◽  
Takahiro Matsumoto ◽  
Makoto Tomita
Keyword(s):  
Transfer Functions ◽  
Phase Transfer ◽  
Streak Camera ◽  
Fourier Method ◽  
Observation Time ◽  
Two Dimensional ◽  
Fourier Space ◽  
Time Resolved ◽  
Spatial Image ◽  
Comprehensive Study

We applied Fourier space analysis to a comprehensive study of the propagation of pulsed two-dimensional images through single and coupled image resonators. The Fourier method shows that the image can propagate through the resonator successfully as long as the spatial and temporal Fourier components of the image are within the bandwidth of the amplitude and phase transfer functions. The relevant steep dispersion of the cavity can yield delayed or advanced images. The Fourier method reproduces characteristic aspects of the experimental observations of the image propagation, and also predicts new aspects, such as the spatial image profile dependence on the observation time and the coupling strength. To demonstrate the time evolution of the experiment, space- and time-resolved image propagations were performed using a streak camera.

Propagation of Shock Wave At the Cavitation Bubble Expansion Stage Induced by a Nanosecond Laser Pulse

2021 ◽  
Author(s):  
Siyuan Geng ◽  
Zhifeng Yao ◽  
Qiang Zhong ◽  
Yuxin Du ◽  
Ruofu Xiao ◽  
...  
Keyword(s):  
Shock Wave ◽  
Laser Pulse ◽  
Wave Front ◽  
Cavitation Bubble ◽  
Bubble Radius ◽  
Front Velocity ◽  
High Time ◽  
Nanosecond Laser ◽  
Time Resolved ◽  
Expansion Stage

Abstract The objective of this paper is to reveal the attenuation characteristics of a shock wave after optical breakdown in water, with laser pulses of 10-ns duration. A high time-resolved shadowgraph method is applied to capture the temporal evolutions of the cavitation bubble wall and shock wave. The experiments are carried out on a single bubble generated far away from the free surface and the rigid walls with laser pulse energies of 22 mJ, 45 mJ and 60 mJ. The results show that a high, time-resolved, wave front velocity of the shock wave is identified, and the maximum velocity can reach up to around 4000 m/s. An asymmetric shock wave is observed at the very start of the bubble expansion stage, and the process of the sharp attenuation of wave front velocity down to sound velocity, is accomplished within 310-ns. The possible relationship of the cavitation bubble and the shock wave is discussed and a prediction model, using the maximum bubble radius and the corresponding time calculated by the Gilmore model, is proposed to calculate the location of the wave front.

Effect of Surface Roughness on Erosion Mechanism of Cavitating Jet

2020 ◽  
Vol 2020.57 (0) ◽  
pp. M023
Author(s):  
Norikazu SATO ◽  
Nobuyuki FUJISAWA ◽  
Takayuki YAMAGATA
Keyword(s):  
Surface Roughness ◽  
Erosion Mechanism ◽  
Cavitating Jet ◽  
Effect Of Surface

Effect of Nanoscale Species on the Behavior of Polymer Nanocomposites Subjected to Laser Pulse Heating

2012 ◽  
Vol 1519 ◽  
Author(s):  
Stephen F. Bartolucci ◽  
Jeffrey Warrender ◽  
Karen Supan ◽  
Jeffery Wiggins ◽  
Lawrence LaBeaud
Keyword(s):  
Carbon Nanotube ◽  
Mass Loss ◽  
Polymer Nanocomposites ◽  
Surface Characterization ◽  
Single Pulse ◽  
Heating Rates ◽  
Time Resolved ◽  
Nanotube Composites ◽  
Laser Pulse Heating ◽  
Multiple Pulses

ABSTRACTPolymers and polymer nanocomposites have been studied under conditions of extremely high heating rates. Traditionally, these materials have been examined by the flammability research community using methods which have heating rates on the order of 10 degrees C/min. In this study, we have examined how polypropylene-nanoclay (montmorillonite) and polypropylene-carbon nanotube nanocomposites behave subjected to heating rates on the order of one million degrees C/min when irradiated with a 1064 nm Nd-YAG variable pulse millisecond laser. Time-resolved temperature data and mass loss data was collected for each sample as well as post-mortem surface characterization using spectroscopy and electron microscopy. The analysis shows that the nanospecies are effective in providing a protective barrier that decreases the amount of degradation and mass loss to the underlying polymer material. The effect is clearly seen after irradiating with a single pulse and multiple pulses. A comparison between the performance of the nanoclay and carbon nanotube composites is given.

scholarly journals A Review on the Erosion Mechanism in Cavitating Jets and Their Industrial Applications

2021 ◽  
Vol 11 (7) ◽  
pp. 3166
Author(s):  
Mouhammad El Hassan ◽  
Nikolay Bukharin ◽  
Wael Al-Kouz ◽  
Jing-Wei Zhang ◽  
Wei-Feng Li
Keyword(s):  
Industrial Applications ◽  
Operating Conditions ◽  
Extensive Literature ◽  
Well Drilling ◽  
Erosion Mechanism ◽  
Comprehensive Literature Review ◽  
Erosion Effect ◽  
Jet Nozzle ◽  
Cavitating Jets ◽  
Cavitating Jet

Cavitating jets have been widely studied for over a century, but despite the extensive literature on this subject, the implementation of cavitating jets in many industries is still very limited due to technical challenges. The main purpose of the present paper is to provide recommendations on using the cavitating jets based on a comprehensive literature review on the erosion mechanism in these jets. Self-resonating jets are extensively discussed in the present paper due to their importance in amplifying the erosion effect of cavitating jets. The influence of different jet nozzle geometric parameters and the operating conditions of the cavitating jet flow on the erosion mechanism is also discussed. Finally, well drilling in addition to multiple other industrial applications of cavitating jets are examined.

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