• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.3
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• pp.201-209
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• 2001

Some passenger cars with sunroofs open at tilted positions experience reverse flows into cabin rooms and wind noises much louder compared to other cars. In this study, flows around open sunroofs are numerically studied with the variations of body leakage. The effects of body leakage on ventilation and wind noise of a sun roof are examined, in particular. Furthermore, flow visualization, pressure, and noise measured from wind tunnel and road tests are presented. The results show that too small body leakage results in poor performance of ventilation and generates high wind noise around a sunroof. It is therefore very important to secure an adequate body leakage from the early design stage to achieve better performance of a sunroof as well as passengers' comfort related to HVAC(Heating, Ventilation, and Airconditioning).

• Journal of Drive and Control
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• v.21 no.4
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• pp.145-151
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• 2024

Most papers related to hydraulic breakers are studies on structural analysis and performance. This study was conducted on the correlation between gap leakage and performance to identify areas to be designed more carefully when designing actual models. The hydraulic breaker has a supply line, which is the hydraulic fluid inlet, and a return line through which the used fluid is discharged. Both the theoretical implementation of no fluid outflow and the part where gap leakage is expected to affect actual performance were reflected in the modeling. Through this, the difference in performance was confirmed by comparing and analyzing the ideal hydraulic breaker with minimal gap leakage, and the resulting value was obtained for areas to be noted during design.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.4
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• pp.795-802
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• 1992

A numerical analysis is performed on the turbulent flow in the plain seal with injection. The parameters used in this study are as follows : Reynolds number, rotation speed, injection speed, clearance ratio, injection angle, and axial injection location. Flow pattern and leakage performance due to the variation of parameters are investigated. SIMPLER algorithm is used to solve the Navier-Stokes equation governing steady, incompressible turbulent flow and standard K- .epsilon. turbulent model is used to consider the turbulence effects. The leakage performance is significantly enhanced with injection. The increases of the injection flow rate and be rotation speed of the shaft cause the leakage performance to the increased. With the increase of the Reynolds number the leakage performance is diminished. At the injection angle of 90deg, the leakage coefficient has a minimum value. The pressure drop has a maximum value at axial center location but the injection location has little effect on the pressure drop. Clearance ratio has a significant effect on the pressure drop.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.63-68
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• 2002

ADC(Automatic Discharge Connector) is commonly used for the easy maintenance of the submersible pumps. However, the small gap between the flange of the base plate and that of the pipe due to the head rise, the flow momentum change and the mis-installation makes leakage flow that may be a great loss to the pumping system. In this study, the performance degradation was predicted with the simple leakage flow model through the gap. The newly developed ADC was tested and the leakage performance was compared with the old one and also no-leakage piping system. The newly developed ADC reduced the leakage flow in a satisfactory way in comparison with the old model.

• The KSFM Journal of Fluid Machinery
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• v.6 no.2 s.19
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• pp.23-28
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• 2003

ADC (Automatic Discharge Connector) is commonly used for the easy maintenance of the submersible pumps. However, the small gap between the flange of the base plate and that of the pipe due to the head rise, the flow momentum change and the mis-installation make a leakage flow that may be a great loss to the pumping system. In this study, the performance degradation was predicted with the simple leakage flow model through the gap. The newly developed ADC was tested, and the leakage performance was compared with the old one and also no-leakage piping system. The newly developed ADC reduced the leakage flow in a satisfactory way in comparison with the old model.

• Earthquakes and Structures
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• v.16 no.6
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• pp.727-741
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• 2019

A reinforced concrete water tank is a typical functional liquid storage structure and cracks are the greatest threat to the liquid storage structure. Tanks are readily cracked due to seismic activity, thereby leading to the leakage of the stored liquid and a loss of function. In order to study the effect of cracks on liquid storage tanks, self-healing and leakage tests for bending cracks and through cracks in the walls of a reinforced concrete water tank were conducted. Material performance tests were also performed. The self-healing performance of bending cracks in a lentic environment and through cracks in a lotic environment were tested, thereby the self-healing width of bending micro-cracks in the lentic environment in the short term were determined. The through cracks had the capacity for self-healing in the lotic environment was found. The leakage characteristics of the bending cracks and through cracks were tested with the actual water head on the crack. The effects on liquid leakage of the width of bending cracks, the depth of the compression zone, and the acting head were determined. The relationships between the leakage rate and time with the height of the water head were analyzed. Based on the tests, the relationships between the crack characteristics and self-healing as well as the leakage were obtained. Thereby the references for water tank structure design and grading earthquake damage were provided.

• Tribology and Lubricants
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• v.25 no.3
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• pp.187-191
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• 2009

A leakage performance test and an endurance performance test of a 75 ton class turbopump mechanical face seal are performed using water under high speed and high temperature environment. A prototype mechanical face seal is manufactured for the purpose of sealing of fuel between a fuel pump and turbine. By simulating operating condition experimentally, the leakage rate and seal carbon wear rate are obtained to evaluate the performance of the prototype mechanical face seal. The test results show the acceptable leakage performance and reasonable wear tendency as well.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.10
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• pp.1339-1349
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• 1997

A numerical method of calculating the performance of a scroll compressor for refrigerant R-22 and R-134a is presented in this paper. A series of involute curves are employed for the scroll wrap design and the compression volume is investigated geometrically. The radial leakage flow rate through tip clearance is calculated by the two-dimensional compressible flow. On the basis of the results, quasi one-dimensional leakage modeling can be applied to the performance analysis of a scroll compressor, more effectively. Furthermore, the heat transfer effect between scroll wrap and working fluid in compression chamber is considered for the performance analysis. As the results of this study, the effects of the radial and tangential leakage flow rate and heat transfer on the scroll compressor performance are derived precisely. These results may provide the guideline for the design and development of a real scroll compressor.

• Tribology and Lubricants
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• v.20 no.4
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• pp.204-208
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• 2004

This paper presents the oil leakage characteristics of the valve stem system in gasoline engines. For the oil leakage investigation, four study models have been prepared as functions of used poppet valve and used valve stem seal, used poppet valve and unused valve stem seal, unused poppet valve and used valve stem seal, and unused poppet valve and unused valve stem seal. With four models, the experimental study on the oil leakage has been investigated for the oil temperature, intake pressure, and camshaft speed. The experimental results show that the sealing performance of the valve stem seal plays an important role on the leakage of the valve stem system. And the appropriate replacement of a stem seal with used poppet valve shows good sealing performance in oil leakage in compared with a new valve system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.10
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• pp.843-851
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• 2003

The present paper studies the leakage flow model used in the performance prediction of a scroll compressor. Two leakage flow models, isentropic and Fanno flow model, are studied in detail. Their predictions are also compared with CFD solutions to check the validity as a leakage flow model. Comparison with CFD solutions shows that the isentropic flow model predicts excessive leakage flow rate, while the Fanno flow model shows acceptable agreement with CFD solutions. The excessive leakage flow rate by isentropic flow model results in under-prediction of the overall performance of a scroll compressor.