The impact of a 9 mm steel ball, accelerated by a gasgun, is used to produce the liquid slug. Integrated super computational prediction of liquid. A cavitating liquid jet apparatus based on astm g495 was used for liquid droplet impingement erosion tests. The results from previous studies and knowledge are organized and the ldi evaluation system that involves the 1. It provides simulated impingement conditions between high speed rotating blades and liquid droplets for erosion studies. Liquid droplet erosion for the assessment of the erosion resistance of a material it is necessary to verify the dependence on the peripheral velocity and droplet size. Regularities of steel wear under the impact of discrete. Since ldie locally occurs, it is difficult to detect the damaged area. There are two phenomena which are the major contributors to impingement damage. A calculation methodology proposed for liquid droplet.
In the actual pipe wall which numerous droplets always impinge, it is predicted that both a liquid lm exists on a pipe wall surface and, on the other hand, this surface is also eroded by repeated droplet impingement. Integrated super computational prediction of liquid droplet. In this study, the effect of droplet size on liquid impingement erosion was studied for pure aluminum and lowcarbon. Erosion rate increased with increasing sandpaper roughness. Simulation of droplet impingement on a solid surface by. Liquid droplet impingement erosion on groove roughness. Wall thinning of pipelines in power plants occurs mainly by flow acceleration corrosion fac, cavitation erosion ce, and liquid droplet impingement erosion lie. The influence of material hardness on liquid droplet. Therefore, it is possible to prevent the occurrence of liquid impingement erosion by operating power plants at low. This phenomenon is called liquid droplet impingement ldi erosion, which is known as one of the major causes of pipeline leakage in the plants. For current superhydrophobic coating droplet erosion experiment, the impact velocity is extremely low no more than 20ms compared with previous metal erosion studies. Feb 01, 2017 demonstration of a sample rotating apparatus that would be used as part of the standard test method for liquid impingement erosion astm g73. Liquid droplet impingement erosion was studied on rough surface.
In order to evaluate the erosion damage quantitatively, a highspeed erosion test rig utilizing water droplets was used to study the erosion resistance of 12cr steel, cobalt base alloy and titanium alloy. In both, the damage is associated with repeated, smallscale, highintensity pressure pulses acting on the solid surface. The conditions for development of the bubble cavitation as well as its mechanisms and the regularities of its influence. Experiments on liquid droplet impingement erosion on a. This is most beneficial to service environments wherein solid areas are subjected to repetitive impacts by jets or liquid drops. Development of evaluation system of liquid droplet impingement.
The precise failure mechanisms in the solid have been shown to differ. An evaluation system for liquid droplet impingement erosion ldi has been developed to predict the ldi location and the wall thinning rate. The analysis of pipe wall thinning phenomenon is a critical issue for the safety and to increase the operation rate of power plants. Computational fluid dynamics study of liquid droplet. It has been shown that, with an existing relief on the steel surface, the bubble cavitation becomes the predominant wear factor under droplet impingement erosion. K wood 1university of southampton, highfield, southampton, so17 1bj, united kingdom ac. Regarding the effect of the impact angle on liquid droplet impingement erosion, fyall et al. Obviously the most important technical application in this area is the spray cooling of hot surfaces and the impingement of. Determination of erosion ratios and the dependence on input parameters an energetic method that takes into account the plastic deformations and the plastic work performed upon the solid can be used to calculate the erosion ratios. In order to estimate the erosion rate due to liquid droplet impingement ldi erosion, the erosion model has to be established. Demonstration of a sample rotating apparatus that would be used as part of the standard test method for liquid impingement erosion astm g73.
Numerical case study on the ldie degradation occurred in. However, there are differences, since the continuous jet produces stagnation pressure, whereas the discrete impacts in water droplet erosion produce much higher shockwave pressures. The erosion model expresses the relationship between the erosion rate and the droplet parameters, which is normally known as the droplet velocity. Numerical analysis of droplet impingement using the moving particle semiimplicit method jinbiao xiong, seiichi koshizuka and mikio sakai the university of tokyo, 731 hongo bunkyoku, tokyo 18656, japan received july 2, 2009 and accepted in revised form december 18, 2009. Liquid droplet impingement ldi erosion could be regarded to be one of the. Erosion in steam and condensate piping is not limited to the abovementioned erosion caused by liquid droplet impingement ldi or high velocity disentrained condensate. Water droplet erosion wde is a result of repetitive highspeed water droplet impacts on solid surfaces which generate impulsive pressure 1. Liquid droplet impingement erosion ldi is defined as an erosion phenomenon caused by highspeed droplet attack in a steam flow. Erosion in steam and condensate piping tlv a steam. Liquid droplet impingement erosion mechanism of lowalloy steels.
Development of evaluation system for liquid droplet. Jan 08, 2019 impingement corrosion and cavitation are mechanically occurring degradations. The magnetite is formed by controlling the water chemistry and the temperature of fluid inside the facility. Numerical analysis of droplet impingement using the moving. The physics of droplet impingement are related not. Ldie is the phenomenon that the material is damaged by the impact pressure when liquid droplets impinge on the material surface. The effect of liquid film on liquid droplet impingement erosion. The water droplet erosion test was performed using a rotating disk erosion rig with controlled conditions. Request pdf the effect of liquid film on liquid droplet impingement erosion in the present paper, the pipewall thinning due to liquid droplet impingement erosion is studied experimentally by. This article focuses on the core nature of erosion by liquid impingement, due to the greater appreciation of the distinctions between the different forms of erosion. Liquid droplet impingement erosion occurs at the elbows in steam pipes where droplets impinge at high speed. In this study, the effect of droplet size on liquid impingement erosion was studied for pure aluminum. An experimental study on the droplet erosion durability of.
The factors affecting liquid droplet impingement erosion include flow velocity, droplet size, impact angle and so on. Development of a ldie prediction theory in the condition. Using fullfield measurements to improve understanding of. Pdf study on pipe wastage mechanism by liquid droplet. Analytical consideration of liquid droplet impingement on. Experiments on liquid droplet impingement erosion on a rough surface the influence of material hardness on liquid droplet impingement erosion attenuation of wallthinning rate in deep erosion by liquid droplet impingement. The ldi phenomenon is highly damped out by the influence of the liquid film. Investigations of droplet impingement on cold surfaces. Standard test method for liquid impingement erosion using. Experiments on liquid droplet impingement erosion by high. Effect of impact angle on liquid droplet impingement erosion. After cutting the pipe during refueling outage, it was identified that the leak was. Head diameter of liquid jet 3 mm water droplet erosion has some similarities to continuous jet impingement jetcutting. A welldesigned liquid impingement test is to be preferred for elastomers, coatings, and brittle materials, for which size effects may be quite important.
Sep 22, 2015 water droplet erosion wde is a result of repetitive highspeed water droplet impacts on solid surfaces which generate impulsive pressure 1. Liquid droplet impingement erosion ldi is defined as an erosion phenomenon caused by highspeed droplet attack in a wet steam flow. Observations of droplet impingement on a ceramic porous surface 2379 fro. Pdf computational fluid dynamics study of liquid droplet. In addition, epri 112657, revision ba, revised riskinformed inservice inspection evaluation procedure, includes erosion cavitation in the same flow sensitive. Jul 09, 2010 an evaluation system for liquid droplet impingement erosion ldi has been developed to predict the ldi location and the wall thinning rate.
Pipe wall thinning due to ldi is sometimes observed in a steam. It was designed based on the astm international g73 standard. In a power plant, pipe wall thinning by ldi is observed in steam piping systems. In this paper, threedimensional numerical simulations are conducted for a bent pipe.
The maximum pressure at the groove bottom suffers from the influence of the groove roughness. Serious damages are possibly caused by high speed droplet impingement on a material surface. Numerical study on liquid droplet impingement erosion in bwrs. Erosion initiates from bottom of groove at large relative roughness. Evaluation methods for corrosion damage of components in. Evaluation of erosion by liquid droplet impingement for. Development of evaluation system of liquid droplet. In particular, wear of pipe material by liquid droplet impingement ldi erosion in piping system of nuclear power plant is becoming great problem in recent years because of high aging operation 1. Observations of droplet impingement on a ceramic porous. An experimental study on the droplet erosion durability of a. The impact load increases in proportion with the first to second power of the velocity and the erosion rate with the 4th to 5th power.
Some researchers found a strong increase in erosion with droplet size and the others found a weak dependence. Liquid droplet impingement erosion was numerically and experimentally studied on groove rough surface. The erosion rate in the terminal stage of liquid droplet impingement erosion is evaluated from the experimental data. Simulation of droplet impingement on a solid surface by the level set method junling hu1, ruoxu jia1, kaitak wan2, xingguo xiong3 1department of mechanical engineering, university of bridgeport, bridgeport, ct 06604 usa 2department of mechanical engineering, northeastern university, boston, ma 02115 usa 3department of electrical and computer engineering. A liquid impingement erosion test is a technique for assessing the erosion resistance of certain materials. Study of fluidstructure interaction in liquid droplet impingement phenomena 151 4. Influence of impact speed on water droplet erosion of tial. Numerical analysis of liquid droplet impingement on rough. This experiment allows the evaluation of erosion rate of solid materials due to the impingement of. Request pdf the effect of liquid film on liquid droplet impingement erosion in the present paper, the pipewall thinning due to liquid droplet impingement erosion. Because ldi usually occurs very locally and is difficult to detect, prediction of ldi location is required for the safety of the plant.
May 24, 2017 droplet impingement on solid surfaces is of great importance to inkjet printing 1, spraycooling 2, 3, combustion 4, and coating processes 5. Comparison of cavitation erosion rate with liquid impingement. We found that the volume loss per droplet increases with the 4. Mechanical components such as steam turbine blades may experience heavy damage when subjected to repeated impingement of liquid droplets. The liquid droplet impingement erosion is experimentally studied using the highspeed conical spray under the condition that the circular specimen is smaller than the spray diameter.
The conditions for development of the bubble cavitation as well as its mechanisms. Since the main factors causing ldi are fluidrelated factors such as droplet velocity and diameter, it is possible to predict the location of ldi attack if the local flow conditions such as. Erosion mechanism was examined on single groove roughness. Comprehensive analysis cavitation and liquid impingement. This impact wear phenomenon seen in highspeed moving. Numerical case study on the ldie degradation occurred in the. It is well known that the ldie progress is classified into three stages. Any equipment components directly exposed to fluid flow above a certain velocity can suffer impingement erosion. One of the parameters influencing the liquid impingement erosion remarkably is droplet size. Pdf the bent pipe wall thinning phenomenon has been often found at the. The effect of droplet size has been studied since 1927.
Formation of the erosive wear of austenitic steel under multicycle droplet impingement impact has been studied. The ordering of the materials and their shields as to the erosion resistance may vary depending on the impact velocity and droplet diameter variation. Critical consideration on wall thinning rate by liquid droplet. The advantages of a liquid impingement test are that droplet or jet sizes and impact velocities can be selected and it can simulate more closely a specific liquid impingement environment. Liquid droplet erosion is one of major concerns in the design of modern large fossil steam turbines because it causes serious operational problems such as performance degradation and reduction of service life. Liquid impingement erosion1 friction, lubrication, and. Droplet diameter measurements for the prediction of liquid. Liquid droplet surface impact interactions droplet and target shockwave behavior.
Droplet impingement on solid surfaces is of great importance to inkjet printing 1, spraycooling 2, 3, combustion 4, and coating processes 5. One of the main causes of pipe wall thinning phenomenon of power generation facilities is the liquid droplet impingement erosion ldie. Effect of droplet diameter on liquid impingement erosion. In the present paper, liquid droplet impingement erosion is studied by using a highspeed spray. It has been shown that, with an existing relief on the steel surface, the bubble cavitation becomes the predominant wear factor under dropletimpingement erosion. Erosion model the nondimensional erosion rate vm due to the liquid droplet impingement erosion for pure aluminum can be formulated by the following equation considering the in. The characteristics of liquid droplet diameter are investigated for the prediction of liquid droplet impingement erosion ldi occurring in a power plant. Understanding wallthinning erosion of pipelines in nuclear or steam power plants is critically important for predicting and preventing human and material accidents. Pdf numerical study on liquid droplet impingement erosion. Erosion liquid droplet surface impact interactions droplet and target shockwave behavior cavitation erosion model dularet al, 2006 collapse of cavitation cloud. Flashing, liquid droplet impingement, and solid particle erosion in nuclear power plant piping systems. Liquid impingement erosion has been defined as progressive loss of original material from a solid surface due to continued exposure to impacts by liquid drops or jets.
Formation of the erosive wear of austenitic steel under multicycle dropletimpingement impact has been studied. The release of the droplet was detected by placing an optical interrupter approximately 5 mm. Condensate recovery piping in particular can be susceptible to erosion from improperly handled flash steam that occurs in the discharge stream. Liquid droplet impingement ldi erosion is closely related to the pipe wall thinning by aged deterioration in actual work of the nuclear power plant. Water droplet erosion of stainless steel steam turbine blades. The flow rate was low enough to allow a drop let to form at the needfe tip and detach under its own weight. In august 2008, the header pipe in the high pressure feedwater heater vent system leaked at a korean nuclear power plant. However, most of the published research on this wear. Pdf on nov 3, 2009, rui li and others published numerical study on liquid droplet impingement erosion in bwrs find, read and cite all the research you need on researchgate. Nasa techaical manordum 83352 a comprehensive analysis of cavitation and liquid impingement erosion data uasala83352 a ccflprebiieife pispli5is cf rezzbc30 cavflaiicr abd liquic iceiegepebl eicsici lata basa 18 p rc boze ac 1 cscl 1lf uncl ae 6326 c7ttl p. This technique has been instrumental in developing understanding of wde and used successfully for over 50 years 4, 7. Impingement corrosion and cavitation are mechanically occurring degradations. Numerical study on liquid droplet impingement erosion in bwrs article pdf available in transactions of the american nuclear society 101. An erosion model has been used to analyze the erosion behavior of cocr alloy coated steam turbine blades of composite material.
Attenuation of wallthinning rate in deep erosion by liquid droplet impingement droplet generation during liquid jet impingement onto a horizontal plate effective parameters for erosion caused by water droplet impingement and applications to surface treatment technology. Experiments on liquid droplet impingement erosion on a rough. In this study, the effect of droplet size on liquid impingement erosion was studied for pure aluminum and lowcarbon steel s15c. Most of what is known about liquid drop impacts with a solid surface has been derived from highspeed photographs,l 2 fig. Reduction in droplet size or particle diameter 39 4. The effect of liquid film on liquid droplet impingement. Using fullfield measurements to improve understanding of water droplet erosion of aeroengine fan blades c. Peak erosion rate was found at small relative groove roughness.
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