• Tribology and Lubricants
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• v.36 no.2
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• pp.75-81
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• 2020

In this paper, we present an experimental investigation of the leakage and endurance performances of mechanical face seals in a 75-tonf turbopump for the Korea Space Launch Vehicle II first-stage engine. A mechanical face seal is used between the fuel pump and turbine to prevent mixing of the fuel and turbine gas. However, excessive leakage occurs through the carbon attached to the mechanical face seal bellows. To reduce this leakage, we redesign the mechanical face seal such that the contact area between the fuel and carbon is reduced, height of the carbon nose is reduced, and stiffness of the bellows is increased. Then, we conduct static and dynamic leakage tests and endurance tests to compare the performances of the original and modified mechanical face seals. The investigation of the leakage of the old and new mechanical face seals confirms that the leakage performance is significantly improved, by 80%, in the new design in comparison with the old design. The endurance tests demonstrate that the average wear rate of carbon in the new mechanical face seal is 0.1094 ㎛/s. The service lifetime is predicted to be 4,200 s, which is 28 times greater than the requirement. Finally, we present a new mechanical face seal in a 75-tonf turbopump, and perform a validation test in the real-propellant test facility at the NARO Space Center. Based on the test results, we can confirm that the modified mechanical face seal works well under real operating conditions.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.5
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• pp.95-101
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• 2012

An electric water pump for engine cooling system has an advantage which particularly in the cold start, the use of the electric water pump saves fuel and leads to a corresponding reduction in emissions. The canned type electric water pump without mechanical sealing elements was selected to meet the requirements for operational reliability and life. However, the electric water pump for internal combustion engine generates much more heat loss than for hybrid electric vehicle since it is operated by the electric power of high current and low voltage. In this study, the fluid flow and thermal characteristics of the canned type electric water pump as an inverter integrated water pump has been investigated under the effects of heat generation. The analysis conditions such as outdoor air temperature of $125^{\circ}C$, water pump speed of 6000 rpm, coolant temperature of $106^{\circ}C$ and coolant flow rate of 120 L/min was used as a standard condition. Therefore, flow fields and temperature distribution inside the water pump were obtained. Also, we checked the feasibility of the canned type for the electric water pump in comparison with the mechanical seal type.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.533-539
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• 1997

Pressure ripple of hydraulic vane pump results form flow ripple due to pump geometry and reverse flow through the discharge port due to compressibility of fluid and result in vibration and noise of connected hydraulic elements. In a ba;anced type vane pump, cam ring curve is important factor to influence the flow ripple. Therefore, to reduce the now ripple, it has been required that optimal selection of seal region by proper design of cam ring and each port position, and notches for preventing the excessive reverse flow. This paper has been performed analytical study of compression characteristics with major design parameter in side plate and cam ring, and examined into the role of notch and radius reduction ratio.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.1
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• pp.87-93
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• 1998

Pressure ripples of hydraulic vane pump results from flow ripples due to pump geometry and reverse flow through the discharge port due to compressibility of fluid and result in vibration and noise of connected hydraulic elements. In a balanced type vane pump, cam ring curve is important factor to influence the flow ripples. Therefore, to reduce the flow ripple, it has been required that optimal selection of seal region by proper design of cam ring and each port position, and notches for preventing the excessive reverse flow. This paper has been performed analytical study of compression characteristics with major design parameter in side plate and cam ring. and examined into the role of notch and radius reduction ratio.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.2
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• pp.376-381
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• 2004

A rig was constructed to test the performance characteristics and compare the hydraulic forces exerted on a centrifugal type artificial heart impeller. A conventional shaft. seal and bearing system. while driven by a small electric motor. supported the impeller which was separated from the pump casing by a six degree of freedom force transducer (JR3 Ine). Radial (x. y) and axial (z) hydraulic forces were recorded and compared. At physiological operating conditions. the results indicate that the double entry/exit centrifugal pump encounters a smaller radial force and significantly reduced axial thrust. These experimental results are valuable in the design of a magnetic bearing system to suspend the impeller of a centrifugal artificial heart pump. This experimental technique may also be applied to evaluate the required capacity and predict the lifetime of contact bearings in marine pumps.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.12
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• pp.30-37
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• 1995

The mechanical seals, which are installed in rotating machines like pump and compressor, are gengrally used as sealing devices in the many fields of industries. The failure of mechanical seals such as leakage,fast and severe wear, excessive torque, and squeaking results in big problems. To monitor the failure of mechanical seals and to propose the proper monitoring techniques with artificial neural network, sliding wear experiments were conducted. Torque and temperature of the mechanical seals were measured during experiments. Optical microstructure was observed for the wear processing after every 10 minute sliding at rotation speed of 1750 rpm and scanning electron microscopy was also observed. During the experiment, the variation of torque and temperature that meant an abnormal phenomenon, was observed. That experimental data recorded were applied to the developed monitoring system with artificial neural network. This study concludes that torque and temperature of mechanical seals wil be used to identify and to monitor the condition of sliding motion of mechanical seals. An availability to monitor the mechanical seal failure with artificial neural network was confirmed.

• The KSFM Journal of Fluid Machinery
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• v.15 no.6
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• pp.46-50
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• 2012

A high-speed centrifugal pump requires more attention to the control of its axial thrust due to the high discharge pressure than a conventional industrial pump. Vanes employed toward the rear cavity of the impeller can be an effective device to control the axial thrust of the pump. The vanes disturb circumferential flow of the cavity and it can modify the axial force acting on the impeller. In this paper, three types of vanes are installed in the high-speed centrifugal pump for liquid rocket engines and the thrust of the pump is measured with an additional thrust measurement unit. According to the results, shapes of cavity vanes have effects on the axial thrust of the pump. As the height of vanes increases, the outlet pressure of the rear floating ring seal decreases which results in a decrease of the thrust. On the other hand, head of the pump is almost same regardless of cavity vanes. Also, the pressure drop of the bypass pipeline increases when vanes are removed.

• Journal of the Korean Institute of Gas
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• v.9 no.1 s.26
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• pp.26-32
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• 2005

This paper presents the design safety of metal seals in pressure vessels. For a high-pressure vessel, a metal seal is usually used as a primary sealing, and an elastomeric rubber O-ring is adopted as a secondary sealing unit. The FEM computed results show that an aluminium material for sealing a gas leakage is superior to a steel one because of the thermal expansion rate. The deformation and stress distributions on the metal seal and pressure vessel structures are mainly dominated by transferred temperature compared to those of the gas pressure in which is supplied by an external pump. Thus, the temperature of a metal seal material should be restricted to under $200^{\circ}C$.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.709-711
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• 2011

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.756-757
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• 2012