Effect of impact velocity on time-dependent force and droplet pressure in high-speed liquid droplet impingement

2022 ◽  
Vol 166 ◽  
pp. 108814
Author(s):  
Kei Fujisawa
Keyword(s):  
Impact Velocity ◽  
High Speed ◽  
Liquid Droplet ◽  
Time Dependent ◽  
Droplet Impingement

Numerical Analysis of Influence of Roughness of Material Surface on High-Speed Liquid Droplet Impingement

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Hirotoshi Sasaki ◽  
Yuka Iga
Keyword(s):  
Numerical Analysis ◽  
High Speed ◽  
Erosion Rate ◽  
Liquid Droplet ◽  
Material Surface ◽  
Liquid Droplets ◽  
Fluid Machinery ◽  
Droplet Impingement ◽  
Surface Liquid ◽  
Droplet Impingement Erosion

This study explains why the deep erosion pits are formed in liquid droplet impingement erosion even though the droplets uniformly impinge on the entire material surface. Liquid droplet impingement erosion occurs in fluid machinery on which droplets impinge at high speed. In the process of erosion, the material surface becomes completely roughened by erosion pits. In addition, most material surface is not completely smooth and has some degree of initial roughness from manufacturing and processing and so on. In this study, to consider the influence of the roughness on the material surface under droplet impingement, a numerical analysis of droplets impinging on the material surface with a single wedge and a single bump was conducted with changing offsets between the droplet impingement centers and the roughness centers on each a wedge bottom and a bump top. As results, two mechanisms are predicted from the present numerical results: the erosion rate accelerates and transitions from the incubation stage to the acceleration stage once roughness occurs on the material surface; the other is that deep erosion pits are formed even in the case of liquid droplets impinging uniformly on the entire material surface.

Study on Pipe Wastage Mechanism by Liquid Droplet Impingement Erosion

2009 ◽  
Author(s):  
Yuma Higashi ◽  
Tadashi Narabayashi ◽  
Yoichiro Shimazu ◽  
Masashi Tsuji ◽  
Syuichi Ohmori ◽  
...  
Keyword(s):  
Test Piece ◽  
High Speed ◽  
Nuclear Power ◽  
Mass Measurement ◽  
Liquid Droplet ◽  
Mass Difference ◽  
Rotating Disk ◽  
Droplet Impingement ◽  
Accelerated Corrosion ◽  
Droplet Impingement Erosion

Evaluation of wastage speed for nuclear power plant maintains plant reliability and power up rating is important. There are two main cause of wastage flow accelerated corrosion (FAC) and mechanical erosion. This study is to develop evaluating the wastage speed by liquid droplet impingement erosion (LDIE). LDIE often occurs at downstream of corner of pipe or orifice. In this study, the liquid drop impinging tests were conducted with the test pieces mounted on a high speed rotating disk that cross thin water down jet and produced LDIE phenomena. The amount of the wastage by LDIE was evaluated by changing the rotational speed, the impingement frequency, and test piece materials. In addition, the generation mechanism of erosion was investigated by observing the surface of the test piece with a microscope. There is a method of evaluating by the mass difference before and after experiments. But this method is not correct because error becomes larger for mass measurement in the experiment, for the lost mass by LDIE is very little amount. Therefore, the method was developed to measure the volume in the erosion part. In this method, depth of LDIE was measured by the accuracy of ±0.01μm; therefore accurate measurement of the wastage can be improved.

scholarly journals 603 Evaluation of Liquid Droplet Impingement Erosion by High-speed Spray and Proposal of Erosion Model

2012 ◽  
Vol 2012 (0) ◽  
pp. 152-153
Author(s):  
Kengo Saito ◽  
Kanto Hayashi ◽  
Takayuki Yamagata ◽  
Nobuyuki Fujisawa
Keyword(s):  
High Speed ◽  
Liquid Droplet ◽  
Droplet Impingement ◽  
Erosion Model ◽  
Droplet Impingement Erosion

C223 Study on Liquid Droplet Impingement Erosion : High Speed Rotating Disk LDI Experiment

2011 ◽  
Vol 2011.16 (0) ◽  
pp. 325-328
Author(s):  
William Khoo Chong Weng ◽  
Yuma HIGASHI ◽  
Tadashi NARABAYASHI ◽  
Takahiro SUZUKI ◽  
Shuichi OMORI ◽  
...  
Keyword(s):  
High Speed ◽  
Liquid Droplet ◽  
Rotating Disk ◽  
Droplet Impingement ◽  
Droplet Impingement Erosion

Experiments on liquid droplet impingement erosion by high-speed spray

2012 ◽  
Vol 250 ◽  
pp. 101-107 ◽  
Author(s):  
Nobuyuki Fujisawa ◽  
Takayuki Yamagata ◽  
Kanto Hayashi ◽  
Tsuyoshi Takano
Keyword(s):  
High Speed ◽  
Liquid Droplet ◽  
Droplet Impingement ◽  
Droplet Impingement Erosion

scholarly journals Numerical Simulation of Single-Droplet Dynamics, Vaporization, and Heat Transfer from Impingement onto Static and Vibrating Surfaces

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 188
Author(s):  
J. Thalackottore Jose ◽  
J. F. Dunne
Keyword(s):  
Heat Transfer ◽  
Impact Velocity ◽  
Liquid Droplet ◽  
Droplet Diameter ◽  
Droplet Evaporation ◽  
Time Interval ◽  
Initial Contact ◽  
Droplet Impingement ◽  
The Impact ◽  
Minimum Impact

A numerical study is presented to examine the behavior of a single liquid droplet initially passing through air or steam, followed by impingement onto a static or vibrating surface. The fluid dynamic equations are solved using the Volume of Fluid method, which includes both viscous and surface tension effects, and the possibility of droplet evaporation when the impact surface is hot. Initially, dynamic behavior is examined for isothermal impingement of a droplet moving through air, first without and then with boundary vibration. Isothermal simulations are used to establish how droplet rebound conditions and the time interval between initial contact to detachment vary with droplet diameter for droplet impingement onto a stationary boundary. Heat transfer is then assessed for a liquid droplet initially at saturation temperature passing through steam, followed by contact with a hot vibrating boundary, in which droplet evaporation commences. The paper shows that, for droplet impingement onto a static boundary, the minimum impact velocity for rebound reduces linearly with droplet diameter, whereas the time interval between initial contact and detachment appears to increase linearly with droplet diameter. With the introduction of a vibrating surface, the minimum relative impact velocity for isothermal rebound is found to be higher than the minimum impact velocity for static boundary droplet rebound. For impingement onto a hot surface, in which droplet evaporation commences, it is shown that large-amplitude surface vibration reduces heat transfer, whereas low-amplitude high-frequency vibration appears to increase heat transfer.

Development of a Wall Thinning Rate Model for Liquid Droplet Impingement Erosion

2012 ◽  
Author(s):  
Ryo Morita ◽  
Yuta Uchiyama
Keyword(s):  
Power Plant ◽  
High Speed ◽  
Liquid Droplet ◽  
Steam Flow ◽  
Wet Steam ◽  
Droplet Impingement ◽  
Wall Thinning ◽  
Wet Steam Flow ◽  
Thinning Rate ◽  
Droplet Impingement Erosion

Liquid droplet impingement erosion (LDI) is defined as an erosion phenomenon caused by high-speed droplet attack in a wet steam flow. Pipe wall thinning due to LDI is sometimes observed in a steam piping system of a power plant. In this study, for more realistic LDI evaluation in the power plant, we conducted LDI experiments in wet steam flow with steam apparatus, and tried to develop a new thinning rate prediction model (LDI model). High speed wet steam flow simulating the actual plant condition was employed in the experiments. As a result, the cushioning effect of liquid film on a material surface was observed and was incorporated into LDI model as a empirical equation with fluid parameter.

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