A study on the cause analysis for the wall thinning and. Comparative studies of drop impingement erosion and. Comparative studies of drop impingement erosion and cavitation erosion by john f. Integrated super computational prediction of liquid. In a power plant, pipe wall thinning by ldi is observed in steam piping systems. Water droplet erosion wde is defined as the progressive loss of original material from a solid surface due to continuous impingements of water droplets or jets. Mechanisms and laws of steel surface degradation during the.
The droplet impingement was photographed with a high speed cine camera to obtain. Single droplet and droplet train impingement pool cooling. Integrated super computational prediction of liquid droplet. Wall thinning of pipelines in power plants occurs mainly by flow acceleration corrosion fac, cavitation erosion ce, and liquid droplet impingement erosion lie. Mar 15, 2015 understanding wallthinning erosion of pipelines in nuclear or steam power plants is critically important for predicting and preventing human and material accidents. Numerical study on liquid droplet impingement erosion in bwrs. 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.
Standard test method for liquid impingement erosion using. In order to estimate life of the blade materials, it is essential to investigate the impingement factors such as diameter, frequency and velocity of droplets in erosion testing methods. The hydrodynamics of single droplet impingement on a heated surface was also studied in terms of the transition conditions. One of the most challenging tasks of computations of droplet impingement is to incorporate the wetting effects into the numerical models 2,3. Currently, there is no experimental or theoretical evidence that suggests which types of liquids exhibit the capillary energydominated impingement behavior. The impact pressure of a droplet is proportional to. Any equipment components directly exposed to fluid flow above a certain velocity can suffer impingement erosion. Assessing liquid droplet erosion potential in centrifugal. 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. In this study, the droplet was accelerated aerodynamically in a newly designed droplet wind tunnel.
Therefore, when the impact velocity becomes higher than 100 ms. China agricultural university, 2006 a thesis submitted in partial fulfillment of the requirements for the degree of master of science in the department of mechanical, materials and aerospace engineering. Effect of impingement angle on erosion of high strength low alloy steel shot peened, heat treated g. Experiments on liquid droplet impingement erosion on a. Electron microscopy and simulation methods are used to demonstrate that, at a given erosion stage, the surface degrades due to bubble cavitation accompanied by fatigue processes. The effect of liquid film on liquid droplet impingement erosion. The study of droplet impingement process has been an active research area in both experimental investigation and theoretical modeling for more than a century. Investigation of droplet path in a rain erosion tester.
This paper describes the recent development of researches on liquid. Erosion phenomenon caused by water droplet impingement and. Since ldie locally occurs, it is difficult to detect the damaged area. Liquid droplet impingement ldi erosion on a rough surface was studied experimentally in the initial stage of erosion using sprayjet impingement on various levels of sandpaper roughness and single groove roughness. Ripjen this research was jointly sponsored by the fluid dynamics branch of the office of naval research and the naval ship systems command general hydromechanics research program subproject sr 009 01 01. In the present study, an experimental investigation was conducted to examine the dynamics of water droplet impingement onto bioinspired surfaces with weber numbers rangingfrom 9. Prediction and numerical simulation of droplet impact. 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.
Droplet impingement on solid surfaces is of great importance to inkjet printing 1, spraycooling 2, 3, combustion 4, and coating processes5. Numerical analysis of liquid droplet impingement on rough. Read effect of impact angle on liquid droplet impingement erosion, wear on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Proceedings of the 2012 20th international conference on nuclear engineering and the asme 2012 power conference. 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. A liquid impingement erosion test is a technique for assessing the erosion resistance of certain materials. Importance of surface curvature in modelling droplet. Pdf parametric investigation on the effect factors for. Under steady conditions, the influence of variant bowed vane designs was compared based on the distribution. Oct 03, 20 droplet size range of 50 m elastic solid modeling. An erosion model has been used to analyze the erosion behavior of cocr alloy coated steam turbine blades of composite material. The physics of droplet impingement are related not only to fluid dynamics but also to the respective interfacial properties of the liquid and solid.
Threedimensional simulation of impingement of a liquid. Since then, researches on the liquid droplet impingement erosion become active to prevent from such unexpected steamleakage problem in the pipeline astm g7398, 2005. Abstract one of the parameters influencing the liquid impingement erosion remarkably is droplet size. Single droplet and droplet train impingement pool cooling ajawara, c. Ldi erosion has been studied experimentally and theoretically with significant focus on single liquid droplet impingement on a solid wall, because this provides the fundamental mechanism of ldi erosion. Complete cavitation tests and limited impingement tests on the three astm materials are described together with test data on two other metals. This experiment allows the evaluation of erosion rate of solid materials due to the impingement of. These mechanisms induce wall thinning of the components and finally lead some components to be burst 1,2. Yamamoto 3 1 graduate school of mechanical engineering, tokyo university of science. Liquid droplet impingement erosion on groove roughness. Parametric investigation on the effect factors for liquid droplet impingement erosion. Impingement corrosion and cavitation are mechanically occurring degradations. The liquid droplet impingement erosion is one of the important causes of pipewall thinning in the aged nuclear power plants.
Effect of droplet diameter on liquid impingement erosion. To better understand liquidsolid interactions, the impact of single droplets on a healed surface was experimentally examined. An experimental approach to analysing rain droplet impingement on wind turbine blade materials craig siddons. Download fulltext pdf download fulltext pdf download fulltext pdf. Testing, mechanisms and improved representation hany kirols 1, mohammad s. Liquid droplet impingement ldi erosion on a rough surface was studied experimentally in the initial stage of erosion using sprayjet impingement on various levels of sandpaper roughness and. Study of the hydrodynamics of droplet impingement on a dry surface using lattice boltzmann method by xin gu b. Nonwetting of impinging droplets on textured surfaces. The 3d levelset method is employed to portray the droplet surface variation during its deformation. The effect of the contact angle on the droplet impingement process was studied using three contact angle models. The object of the work has been to investigate experimentally the mechanisms of erosion in metals and alloys under drop impingement attack. This impact wear phenomenon seen in highspeed moving. Ldie is the phenomenon that the material is damaged by the impact pressure when liquid droplets impinge on the material surface.
The droplet spreading factor and apex height were found to agree with the experimental results in the early spreading stage, but discrepancy were found in the receding stage. Growth of peak erosion rate in the early stage of erosion for the w groove was caused by the removal of groove top. Early studies on liquid droplet impingement erosion have been focused on the window materials of airplanes which fly in the rain, and for blades of low pressure steam turbines. An experimental approach to analysing rain droplet. Development of evaluation system of liquid droplet. Experimental study on liquid droplet impingement erosion by uniformly sprayed droplets. Droplet impingement on solid surfaces is of great importance to inkjet printing 1, spraycooling 2, 3, combustion 4, and coating processes 5. Impingement of cloud droplets on a cylinder and procedure for measuring liquidwater content and droplet sizes in supercooled clouds by rotating multicylinder method one of 1,423 reports in the series. 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.
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, university of bridgeport, bridgeport. Similarly, cavitation, as a special case of impingement corrosion, is caused by the collapse of gas bubbles in a liquid near a solid surface. Reduction in droplet size or particle diameter 39 4. 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. Analytical consideration of liquid droplet impingement on solid surfaces, scientific reports 2017. Building on the experimental results of droplet impingement on a solid surface, a further comprehensive understanding on the splashing criteria was given and a new correlation of splashing threshold was found. In order to estimate the erosion rate due to liquid droplet impingement ldi erosion, the erosion model has to be established. Only a limited comparison of cavitation and impingement erosion was possible with the data available.
Because ldi usually occurs very locally and is difficult to detect, prediction of ldi location is required for the safety of the plant. The conditions leading to the appearance of bubble. Based on computational fluid dynamics and the finite volume method, water droplet erosion in the last stage of an industrial steam turbine was researched and the trajectories of the water droplets were traced by using the lagrange method. Experimental study of the impingement process of a liquid. Request pdf liquid droplet impingement erosion on groove roughness a study of erosion mechanism during the liquid droplet impingement ldi on a rough surface was conducted using both. Impingement of cloud droplets on a cylinder and procedure. Analytical consideration of liquid droplet impingement on. Liquid droplet impingement erosion was studied on rough surface with top and bottom elements. The bent pipe wall thinning phenomenon has been often found at the elbow of pipelines in the power engineering industry. When a liquid droplet impinges on a wall the shape of the droplet quickly deforms, typically within a timescale on the order of microseconds, which results in the generation of. Simulation of droplet impingement on a solid surface by the level set method j. Time dependence of solidparticle impingement erosion of.
A pioneering method for reducing water droplet erosion. Xiong3 1department of mechanical engineering, university of bridgeport, bridgeport, ct, usa. Corrosionpedia what is a liquid impingement erosion test. In both, the damage is associated with repeated, smallscale, highintensity pressure pulses acting on the solid surface. The impingement of liquid fuels on surfaces in ic engines affects performance and emissions. Influence of impact speed on water droplet erosion of tial. Liquid impingement erosion1 friction, lubrication, and. When a droplet impinges on a solid surface, its kinetic energy is mainly converted to capillary energy and viscous dissipation energy, the ratio of which depends on the wettability of the target surface and the liquid properties. Understanding wallthinning erosion of pipelines in nuclear or steam power plants is critically important for predicting and preventing human and material accidents. To better understand liquid solid interactions, the impact of single droplets on a healed surface was experimentally examined. In this study, the effect of droplet size on liquid impingement erosion was.
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. Effect of impact angle on liquid droplet impingement erosion. Zhou fm global, norwood, ma, usa abstract a water transport model is one of the key components in fire modelling of sprinkler protection of solid combustible commodities. May 24, 2017 new theory describes liquid droplet behavior on solid surfaces. The influence of material hardness on liquid droplet. An experimental investigation on unsteady heat transfer and. Simulation of droplet impingement on a solid surface by. In this study, the effect of droplet size on liquid impingement erosion was studied for pure aluminum and lowcarbon steel s15c. Numerical study on liquid droplet impingement erosion in bwrs article pdf available in transactions of the american nuclear society 101.
To model the impingement of a highspeed water droplet on a surface, researchers have frequently assumed the droplet is a perfectly spherical, b impinging perpendicularly, on a c smooth, flat. An experimental study on the dynamics of water droplets. Response to the impact pressure generated by the droplet impingement resolving the stress components in the solid substrate in elastic mode compare the peak stress component with critical material threshold 4. In the present paper, the pipewall thinning due to liquid droplet impingement erosion is studied experimentally by using a highspeed conical spray under the influences of liquid film on the. Water droplet erosion wde is a result of repetitive highspeed water droplet impacts on solid surfaces which generate impulsive pressure 1. Effect of impingement angle on erosion of high strength. Thus, erosion is very widespread and of great economic importance. Liquid droplet impingement ldi erosion is generally the result of high impact pressure p on the wall material at droplet impact. The erosion model selected is used to calculate a threshold velocity that represents the limit for the onset of erosion damage. F082003 study on liquid droplet impingement erosion ldi. The parameters used in the model include the liquid phase density and viscosity, impeller geometry, shaft rotational speed, impeller material hardness, maximum droplet diameter size, and sonic velocity of the liquid phase.
Department of mechanical and aerospace engineering, university of strathclyde, 75 montrose street, glasgow, g1. Time dependence of solidparticle impingement erosion of an. Characterization of impingement dynamics of single droplet. Effects of contact angle on the dynamics of water droplet.
Water droplet impingement erosion has been a severe problem of low pressure steam turbine blade materials in energy generation system. Experimental study on liquid droplet impingement erosion. Experiments on liquid droplet impingement erosion on a rough. The features inherent to the degradation of austenitic steel are investigated under cyclic droplet impingement when a developed erosion relief exists on a surface.
Comprehensive analysis cavitation and liquid impingement. Liquid droplet impingement erosion ldi is defined as an erosion phenomenon caused by highspeed droplet attack in a steam flow. Experimental droplet impingement on four bodies of. Ti64 substrate isotropic material response to the impact pressure generated by the droplet impingement resolving the stress components in the solid substrate in elastic mode compare the peak stress component with critical material threshold 4. The surface roughening of fan blade leadingedges on large civil aeroengines, due to water droplet erosion wde, can lead to a decrease in engine performance and increase the risk of flutter. The erosion rate in the terminal stage of liquid droplet impingement erosion is evaluated from the experimental data.
Liquid droplet impingement ldi erosion could be regarded as one of the major causes and is a significant issue of the thermal hydraulics and structural integrity in aging and life extension for nuclear power plant safety. This is most beneficial to service environments wherein solid areas are subjected to repetitive impacts by jets or liquid drops. Some researchers found a strong increase in erosion with droplet size and the others found a weak dependence. Results regarding velocity distribution, local impingement characteristics, and correlation. Drop impingement erosion of metals proceedings of the. This impact wear phenomenon seen in highspeed moving components in environments containing water droplets has always been a challenge, as it may decrease their service life. Hydrodynamics of droplet impingement on a heated surface. The effect of droplet size has been studied since 1927. Liquid droplet sprays and jet impingement cooling have been widely used in the metal manufacturing industry and have been shown capable of high heat removal rates. Department of mechanical engineering university of california, riverside riverside, ca 92521 usa abstract the cooling behavior of an impacting single droplet and train of droplets on a heated substrate t 60oc for. Computational fluid dynamics study of liquid droplet.
In the present paper, liquid droplet impingement erosion is studied by using a highspeed spray. Fujisawa, nobuyuki, hayashi, kanto, hama, daichi, yamagata, takayuki, and takano, tsuyoshi. For this purpose an apparatus of the wheel and jet type has been used to erode aluminium, copper, iron, cobalt and alloys of these metals. Study of the hydrodynamics of droplet impingement on a. An experiment was conducted to obtain the rate and area of cloud droplet impingement on four bodies of revolution was conducted in the icing tunnel with a dyetracer technique. Liquid droplet impingement ldi erosion is closely related to the pipe wall thinning by aged deterioration in actual work of the nuclear power plant. The factors affecting liquid droplet impingement erosion include flow velocity, droplet size, impact angle and so on.
This chapter will discuss tests for the major forms of erosion, solid particle, slurry, droplet. Further descriptive material on details for impingement testing is also included. Study of fluidstructure interaction in liquid droplet impingement phenomena 151 4. Evaluation of erosion by liquid droplet impingement for. One of the main causes of pipe wall thinning phenomenon of power generation facilities is the liquid droplet impingement erosion ldie. The droplet path is recorded using a fastcamapx rs high speed camera. New theory describes liquid droplet behavior on solid surfaces. Mechanical components such as steam turbine blades may experience heavy damage when subjected to repeated impingement of liquid droplets. The analysis of pipe wall thinning phenomenon is a critical issue for the safety and to increase the operation rate of power plants. High erosion rate occurred in earlier stages of erosion on the w groove than that in the v groove. 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. 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 occurs at the elbows in steam pipes where droplets impinge at high speed. Experimental study of the impingement process of a liquid droplet upon a corrugated cardboard surface x.
The damages are closely related to fluid such as water or wet steam inside the compo. 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. Jan 24, 2005 the hydrodynamics and heat transfer phenomena of a liquid droplet impacting upon a hot flat surface are analyzed based on threedimensional 3d numerical simulation considering filmboiling behavior. 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. Moreover, it is observed that the leak occurred at the reattachment point of the vortex flow in the downstream side of the orifice. Liquid droplet impingement ldi erosion could be regarded to be one of the major causes of unexpected troubles occasionally occurred in the inner bent pipe surface. Title analytical consideration of liquid droplet impingement. Nasatp233919840023279 paper i 2339 august 1984 empirical relations for cavitation and liquid impingement erosion processes p. Simulation of droplet impingement on a solid surface by the. 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. The physics of droplet impingement are related not. The effect of liquid film on liquid droplet impingement.
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