C215 Development of Evaluation Method of Thinning Rate Distribution by Liquid Droplet Impingement Erosion

An evaluation system for liquid droplet impingement erosion (LDI) has been developed to predict the LDI location and the wall thinning rate. The results from previous studies and knowledge are organized and the LDI evaluation system that involves the “1. Flow Evaluation Step” and “2. LDI Evaluation Step” is suggested. The flow evaluation step includes the mass flow rate evaluation, flow distribution evaluation and droplet behavior evaluation. The LDI evaluation is conducted with LDI sensitivity function. The LDI sensitivity was test-evaluated in the steam piping model. The results show that the 1st and last elbows have higher LDI sensitivity because of the velocity condition. We also found that the droplet collision frequency is important when evaluating the LDI sensitivity.

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

Volume 6: Materials and Fabrication, Parts A and B ◽

10.1115/pvp2012-78443 ◽

2012 ◽

Cited By ~ 3

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

Journal of Pressure Vessel Technology ◽

10.1115/1.4043320 ◽

2019 ◽

Vol 141 (3) ◽

Cited By ~ 1

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.

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