• 제목/요약/키워드: Viscosity Force

검색결과 262건 처리시간 0.023초

스크롤 컴프레서 팁실의 마찰특성 (Friction Characteristics of the Tip Seal in a Scroll Compressor)

  • 정봉수
    • Tribology and Lubricants
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    • 제30권6호
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    • pp.370-377
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    • 2014
  • The basic elements in a rotary-type scroll compressor are two identical spiral scrolls containing refrigerant gas. The pressure variations in the compression pockets of a scroll compressor change the forces acting on the orbiting scroll, and these forces affect the dynamic behavior of the compression mechanism parts. To achieve high efficiency, using a self-sealing mechanism as a tip seal mechanism is very effective. Tip seals, which are placed on top of the scroll wraps, accomplish thrust sealing. This study calculates the friction force between the tip seal and the side plate of a scroll compressor using the numerical model considered in the Reynolds equation. The calculated friction force is verified by an experiment using a pin-on-disk apparatus. A hydraulic servo valve that controls the pressure of the oil hydraulic cylinder applies the normal load for the test, and a DC servo motor controls the sliding velocity of the disk. The friction force and normal load are measured by the force sensors attached to the supporting parts. The results show that the theoretical and experimental results are similar and that the friction is influenced by the viscosity of the oil and the sliding velocity of the scroll.

알칼리제가 밀가루의 리올로지와 국수의 성질에 미치는 영향 (Effects of Alkaline Reagent on the Rheological Properties of Wheat Flour and Noodle Property)

  • 김성곤;김흥래;방정범
    • 한국식품과학회지
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    • 제28권1호
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    • pp.58-65
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    • 1996
  • 탄산나트륨, 탄산칼륨과 이들의 혼합염(탄산나트륨/탄산칼륨=0.7-2.0)이 밀가루의 아밀로그래프에 의한 호화성질과 파리노그래프에 의한 반죽성질을 조사하였다. 알칼리제 혼합염(0.16%)이 국수의 성질에 미치는 영향도 아울러 검토하였다. 소금(0.17%)과 알칼리는 아밀로그래프의 호화개시 온도를 감소시켰고 최고점도를 증가시켰으며 그 효과는 탄산나트륨이 가장 현저하였다. 최고점도는 알칼리의 농도가 증가할수록 증가하였고 동일한 농도에서는 혼합비율에 따른 차이는 없었다. 파리노그래프의 흡수율은 소금에 의하여 감소되었고 알칼리제에는 영향을 받지 않았으나 소금과 알칼리제가 동시에 존재할 때는 소금의 효과가 감소하였다. 소금과 알칼리제는 반죽의 안정도를 크게 증가시켰으며 소금의 효과가 더욱 뚜렸하였다. 그러나 소금의 존재시 알칼리제 단독 또는 혼합 사용하였을 때는 농도에 관계없이 알밀로그람과 파리노그람 특성값은 큰 차이를 보이지 않았다. 알칼리제 혼합염의 첨가에 따라 건면의 황색도와 파쇄력이 증가하였고 파쇄력은 혼합비율 1.0에서 가장 큰 값을 보였다. 삶은 국수의 경우 무게와 부피증가 정도는 알칼리제 혼합염의 첨가에 따라 큰 변화가 없었으나 전단력과 압착력은 혼합비율 1.0에서 가장 높은 값을 보였다.

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진원형 정수압 베어링의 해석 (Analysis of Cylindrical Hydrostatic Bearing)

  • 문호지;한동철
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 1989년도 제10회 학술강연회초록집
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    • pp.94-99
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    • 1989
  • This paper analyzes file stiffness, damping coefficient, friction force and flow coefficient of externally pressurized oil journal beating, including the effect of journal rotation according to the Sommerfeld number. This paper assumed that the oil in the whole pocket has constant pressure, and that the oil in the whole bearing region has constant viscosity, temperature and density. Reynolds equation is derived from Nuvier - Stokes equation and continuity equation. And solved bearing pressure by ADI method for whole bearing region and fitted with out flow rate of pocket region. The model for numerical simulation is hydro - static oil journal bearing for high-speed, high-accuracy lathe spindle.

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정사각용기의 성형시 블랭크 홀더력에 관한 연구 (A STUDY ON THE ESTINMATION OF BLANK HOLDER FORCE IN SQUARE CUP DRAWING)

  • 김진무
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1999년도 춘계학술대회논문집
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    • pp.34-39
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    • 1999
  • IN this study when drawing a square cup blank holder pressure necessary for flange wrinkling prevention was experimentally studied. The materials used in the experiment were SPCC and SUS304 and drawing ratio was 1.62∼2.0 Two case for lubrication condition were experimented. One was without lubricant and the other was with lubrication of high viscosity.

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정사각용기의 성형시 블랭크 홀더력에 관한 연구 (A Study on the Estimation of Blank Holder Force in Square Cup Drawing)

  • 김진무;송영배
    • 소성∙가공
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    • 제9권4호
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    • pp.356-361
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    • 2000
  • In this study, when a square cup is under drawing, blank holder pressure necessary for flange wrinkling prevention was experimentally studied. The materials used in the experiment were SPCC steel and SUS304 and the drawing ratio was 1.62∼2.0. Two cases for lubricantion condition were investigated. One was without lubricant and the other was with lubricant of high viscosity.

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크랭크 프레스 주축 저널 베어링의 최적 설계 (Optimal Design of the Crank Press Main Journal Bearings)

  • 심현해;김창호;권오관
    • Tribology and Lubricants
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    • 제5권1호
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    • pp.69-75
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    • 1989
  • The mobility method of dynamically loaded journal bearings was applied to optimize the lubrication of the main journal bearing of the crank press. The effects of oil viscosity, temperature bearing clearance, length, the existence of the circumferential groove, peak press force, and crank rpm were examined. From the results of the minimum film thickness and the maximum film pressure, some of the factors could be optimized, and the degrees of the beneficial and detrimental effects of the others could be estimated.

A Visual Simulation of Volcanic Eruption in the Use of Particle System

  • Yamashita, Yusuke;Namae, Takuya;Makino, Mitsunori
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2002년도 ITC-CSCC -3
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    • pp.1503-1506
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    • 2002
  • In this paper, a modified particle system is proposed for volcanic eruption with lava, ashes and smoke. In the proposed method each eruptive material consists of particles. The movement of particles is determined by the external force and interaction (attraction: repulsion and viscosity) only in neighbor region. Since the method can be executed in combination with the geographic information, the proposed method may also be useful for disaster prevention.

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Non-Newtonian thermal Effects in Elastohydrodynamic Lubrication between the Two Rolling Systems

  • Kim, Joon-Hyun;Kim, Joo-Hyun
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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    • pp.87-88
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    • 2002
  • To analyze complicated phenomena on the fluid hydrodynamic and the elastic deformation between sliding body surfaces, an analysis to the elastohydrodynamic lubrication of sliding contacts has been developed taking into account the thermal and non-Newtonian effects. The computational technique handled the simultaneous solution of the non-Newtonian hydrodynamic effects, elasticity, the load, the viscosity variation, and temperatures rise. The results included the lubricant pressure profile, film thickness, velocity, shear stress, and temperature distribution, and the sliding frictional force on the surface at various slip conditions. These factors showed a great influence on the behavior resulted in the film shape and pressure distribution. Especially, Non-Newtonian effects and temperature rise by the sliding friction force acted as important roles in the lubrication performance.

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자성 유체를 이용한 1자유도 계의 공진멸소에 관한 실험적 연구 (An experimental study on resonance reduction of system with one degree of freedom by magneticfluid)

  • 전운학;이봉규;황승식;이희상;김중
    • 한국자동차공학회논문집
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    • 제7권9호
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    • pp.131-137
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    • 1999
  • Under magnetism , as the magneticfluid is being itself magnetized, increase the apparent viscosity because of its body force and has the magnetic characteristics in response ot magnetism, the magnetic fluid is getting attention in various field. The magnetic fluid has the fluidity, which is a special characteristics of fluid and the magneticism , which is a special one of solid. Using this characteristics, this study has been proceeded to show the basic data for developing of a viscous damper with magnetism fluid as hydraulic fluid. Experimental study shows that the application of magnetic field is effective reducing the resonance characteristics of the spring-mass system.

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터빈유량계의 3차원 유동에 관한 수치적 연구 (Numerical Study of Three-dimensional Flow Through a Turbine Flow Meter)

  • 김진범;고성호
    • 한국유체기계학회 논문집
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    • 제6권1호
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    • pp.44-50
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    • 2003
  • Flow through a turbine flow meter is simulated by solving the incompressible Navier-Stokes equations. The solution method is based on the pseudo-compressibility approach and uses an implicit-upwind differencing scheme together with the Gauss-Seidel line relaxation method. The equations are solved steadily in rotating reference frames, and the centrifugal force and the Coriolis force are added to the equation of motion. The standard $k-{\epsilon}$model is employed to evaluate turbulent viscosity. Computational results yield quantitative as well as qualitative information on the design of turbine flow meters by showing the distributions of pressure and velocity around the turbine blades.