• Title/Summary/Keyword: Cavitation damages

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Experimental Study for the Prevention of Cavitation Damage in the Diesel Fuel Injection Pumps (디젤엔진 연료분사펌프 캐비테이션 손상 방지를 위한 실험적 연구)

  • Kim, Dong-Hun;Park, Tae-Hyung;Heo, Jeong-Yun;Ryu, Seung-Hyup;Kang, Sang-Lip
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2011.10a
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    • pp.61-61
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    • 2011
  • Cavitation phenomena during the injection process of the conventional fuel injection pump for a medium-speed diesel engine can cause surface damage with material removal or round-off on the plunger and barrel port and may shorten their expected life time. An experiment of flow visualization was carried out to investigate the main cause of these cavitation damages and find the prevention method. Experimental results of flow visualization show that these damages are mainly affected by fountain-like cavitation and jet-type cavitation generated before and after the end of fuel delivery process and therefore the prevention method was designed to control these cavitation flows. From the visualization and endurance test, it was proved that this method can effectively prevent cavitation damages by controlling cavitation flows.

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Evaluation of Corrosion and the Anti-Cavitation Characteristics of Cu Alloy by Water Cavitation Peening (동합금의 워터캐비테이션피닝에 의한 내구성과 부식특성 평가)

  • Kim, Seong-Jong;Han, Min-Su;Kim, Min-Sung
    • Corrosion Science and Technology
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    • v.11 no.5
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    • pp.184-190
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    • 2012
  • Cu alloy is widely used for marine applications due to its excellent ductility and high resistance for corrosion as wells as cavitation. However, long term exposure of the material to marine environments may result in damages caused by cavitation and corrosion. Water cavitation peening has been introduced in order to improve resistance of Cu alloy to corrosion and cavitation. The technology induces compressive residual stress onto the surface, and thus enhances the fatigue strength and life. In this study, the characteristics of the material were investigated by using water cavitaiton peening technique, and results showed that 2 minutes of water cavitation peening indicated the considerable improvement in hardness. On the other hand, over 10 minutes of water cavitation peening accelerated damages to the surface. In the case of ALBC3, water cavitation peening in the range of 2 to 10 minutes has shown the excellent durability and corrosion resistance while minimizing surface damages.

Study on the Corrosion and Cavitation Erosion Control of Glass Flake Lining for Mild Steel in Marine Environment (해양환경 중에서 Glass Flake 라이닝 강재의 부식과 캐비테이션 침식 방지에 관한 연구)

  • Lim, Uh Joh;Kim, Seong Hoon
    • 유체기계공업학회:학술대회논문집
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    • 2000.12a
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    • pp.359-365
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    • 2000
  • Port facilities and marine structures used in marine environment were encountered to corrosion damages because of the influence of $Cl^-$. Generally, to protect these accidents, mainly applied anti-corrosion paint and epoxy coating. But it was still remained erosion-corrosion damage such as impingement erosion, cavitation erosion, deposit attack. There was needs to develope the new coating materials to protective those corrosion damages. This paper, polyester glass flake, vinylester glass flake lining and epoxy coating for SS were investigated electrochemical tests and cavitation erosion test for corrosion behaviour under sea water. The main results obtained are as follows, 1) Surface of epoxy coating appear erosion pin hole but surface of polyester glass flake and vinylester glass flake lining do not appear erosion pin hole after impingement-cavitation erosion test in sea water. 2) Weight loss of polyester glass flake and vinylester glass flake lining do not occur after impingement-cavitation erosion test in sea water. 3) Corrosion current density of polyester glass flake lining less drained than epoxy coating and substrate under corrosion potential.. 4) Corrosion current density of vinylester glass flake lining with three coating less drained than that of polyester glass flake lining with two coating.

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Electrochmical Characteristics by Water Cavitation Peening of Cu Alloy (워터캐비테이션피닝된 동합금의 전기화학적 특성평가)

  • Kim, Seong-Jong;Han, Min-Su;Kim, Min-Sung
    • Journal of Advanced Marine Engineering and Technology
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    • v.36 no.8
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    • pp.1083-1090
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    • 2012
  • Copper alloys are widely used for casting materials including ship's propellers and pump impellers as they provide high corrosion resistance. In addition, the demand for these alloys is increasing with rapid growth of offshore structures and exploitation of various substitute energy sources. However, they require regular maintenance because of erosion and cavitation damages induced by exposure to marine environment at high speed flows for a long period of time. Water cavitation peening have received attention as one of surface modifications for durability improvement of the copper alloys. This is a environment friendly technology without influence of heat and easily applicable to casting materials. In this research, water cavitation peening was employed in distilled water for copper alloy castings as a function of time and evaluation of corrosion resistance was followed in seawater for the modified surface by using electrochemical methods. The result suggests that the water cavitation peening for 2 minutes was found to be the optimal peening parameter in terms of durability and corrosion resistance.

Study on New Candidate Coating Materials to Challenge Rudder Cavitation Damage

  • Lee, H.I.;Han, M.S.;Baek, K.K.;Lee, C.H.;Shin, C.S.;Chung, M.K.
    • Corrosion Science and Technology
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    • v.7 no.5
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    • pp.274-282
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    • 2008
  • Ships' hull is typically protected by a combination of protective coating system and electrical cathodic protection system, which has been an economical and effective measure for ship's hull to date. However, ships' rudder and adjacent hull areas are known to be subjected to premature corrosion damages, which require more frequent coating repair than other hull areas. Conventional organic coating system for ship's hull has been known only to remain intact just for 2~3 months on the rudder and adjacent area, especially for the fast-going ships such as container carriers or naval vessels. In this study, special organic/inorganic coating materials, which are commercially available, were tested in terms of cavitation resistance as an alternative to existing rudder & hull protection system. Both standard ultrasonic tester and in-house developed ultra water jet test method were employed as a means to evaluate their performance against cavitation induced damages. Additionally, the overall cost evaluation and workability at actual shipyard were discussed.

Cavitation and Electrochemical Characteristics Using Hydrogen Overpotential Method for ALBC3 Alloy (ALBC3 합금의 수소과전압 현상을 이용한 캐비테이션과 전기화학적 특성)

  • Park, Jae-Cheul;Lee, Seung-Jun;Kim, Seong-Jong
    • Journal of the Korean institute of surface engineering
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    • v.44 no.6
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    • pp.277-283
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    • 2011
  • In this study, the cavitation test and electrochemical experiments were conducted for ALBC3(Cu-Al) alloy that has an excellent corrosion resistance and cavitation characteristic in sea water. Based on the ASTMG32 regulation, the cavitation test was performed with the cavitation and cavitation erosion tester using piezoelectric effect. The electrochemical characteristics are evaluated with potentiostatic experiments in activation polarization potential range. As a result, cavitation damage is increased proportionally to temperature and time at $30{\mu}m$ amplitude. It is appeared that acceleration period in weight loss presented over 6 hours under the cavitation environment in sea water. In addition, corrosion damages were observed at the potential range of -3.2~-1.4 V as the result of potensiostatic experiments during 12 hours in activation polarization potential range.

Cavitation Damage Behavior of Inconel 625 Coating Layer by Arc Thermal Spraying Method in Sea Water (아크 용사법을 이용한 Inconel 625 코팅 층의 해수 내 캐비테이션 손상 거동)

  • Park, Il-Cho;Kim, Seong-Jong
    • Journal of the Korean institute of surface engineering
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    • v.48 no.6
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    • pp.349-353
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    • 2015
  • In this paper, arc thermal spray coating was conducted onto the SS400 steel using Inconel 625 wires in order to improve the durability of marine steel structures, and then investigated cavitation damage behavior of Inconel 625 coating layer in sea water. For the Inconel 625 coating layer, surface hardness appeared similar to that of existing high velocity oxy-fuel coating technology with 380~480 HV, but the porosity of about 6 % was larger relatively. During the cavitation experiment, pit damages were originated and grown at the rough surface and pore defect area of Inconel 625 coating layer. And, after the 72 hours of experimental time, weight loss of Inconel 625 coating layer exhibited gradually increasing tendency due to surface damage effect of the undercut.

Effect of Solution Temperature on the Cavitation Degradation Properties of Epoxy Coatings for Seawater Piping

  • Jeon, J.M.;Yoo, Y.R.;Jeong, M.J.;Kim, Y.C.;Kim, Y.S.
    • Corrosion Science and Technology
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    • v.20 no.6
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    • pp.335-346
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    • 2021
  • Since epoxy resin coating shows excellent properties in formability, adhesion, and corrosion resistance, they have been extensively used in many industries. However, various types of damages in the epoxy coated tube within a relative short time have been reported due to cavitation erosion, liquid impingement, variation of temperature and pressure. Nevertheless, there has been little research on the effect of temperature on the cavitation degradation of epoxy coatings. Therefore, this work used an ultrasonic cavitation tester to focus on the effect of solution temperature on the cavitation properties of 3 kinds of epoxy coatings in 3.5% NaCl. The cavitation properties were discussed basis on the material properties and environmental aspects. As the solution temperature increased, even though with large fluctuation, the cavitation degradation rates of A and B coatings were reduced rapidly, but the rate of C coating was decreased gradually. In addition to the cushioning effect, the reason that the cavitation degradation rate reduced with solution temperature was partly related to the brittle fracture and water absorptivity of the epoxy coatings, and the water density, but was little related to the shape and composition of the compound in the coatings or the phase transition of the epoxy coating.

An Experimental Research on Gap Cavitation Erosion of Semi-spade Rudder (혼-타의 간극 캐비테이션 침식 저감을 위한 실험적 연구)

  • Kim, Sung-Pyo;Park, Jae-Jun;Kim, Yong-Soo;Jang, Young-Hun;Choi, Young-Bok;Paik, Bu-Geun
    • Journal of the Society of Naval Architects of Korea
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    • v.43 no.5 s.149
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    • pp.578-585
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    • 2006
  • Cavitation related erosion damages on semi-spade rudder generally occur at around leading edge of lower-face and behind gap of lower pintle. To get the idea of gap entrance profile for the latter case, a series of tests with large models has been carried out at MOERI. In the tests, the flow pattern around lower pintle have been investigated and visualized by high speed camera. Additionally, cavitation inception tests and pressure measurements have also been conducted for better comparison. As a result a new model (F rudder) has been developed. The new model turned out to have stable pressure distribution along the surface and so the cavitation inception speeds within ${\pm}5^{\circ}$ of rudder angle were delayed approx. 4 knots in average.

Optical Observation of Cavitation Phenomena in Diesel Fuel Injection Pumps (디젤 엔진 연료 분사 펌프 캐비테이션 현상의 가시화 연구)

  • Ryu, Seung-Hyup;Kim, Dong-Hun;Kim, Byung-Seok;Park, Tae-Hyung
    • Journal of Advanced Marine Engineering and Technology
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    • v.35 no.4
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    • pp.460-467
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    • 2011
  • Cavitation phenomena during the spill process of the Bosch type fuel injection pump for medium-speed diesel engine were investigated by optical observations. Typically, these phenomena can cause a surface damage with material removal or round-off at the plunger and barrel port etc., and may shorten their expected life time. The images, which were recorded with high speed CCD camera and borescope, show that the plunger damage is mainly affected by fountain-like cavitation generated before the end of delivery. And the damages of barrel port and deflector are caused by jet-type cavitation generated after end of delivery.