• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.1
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• pp.89-95
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• 2015

A surge phenomenon cause noise and pulsations in a turbo compressor, which is an unstable operating regime. Because surge protection ensures a safe compressor operation, it is important to understand the physics of the surge phenomenon. In this study, the surge characteristics of a 250-hp class turbo-compressor were evaluated experimentally. The experimental parameters were the rotational speed, opening angles of the inlet guide vane and exit valve, and inlet pipe diameter and flow rates of the inlet gases. The results showed that the compressor surge was very sensitive to the gas flow rates, exit pressure, rotational speed, and bypass flow rates.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.181.2-181.2
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• 2005

• Plant Journal
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• v.15 no.4
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• pp.36-42
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• 2019

In recent, according to the tightening of environment regulation policy, the height of the site of the power plant is increased and the length of the cooling water pipe is increased. This has a serious impact on the stability of the plant. This study analyzes the transient phenomenon using LIQT 7.2, an unsteady state one-dimensional analysis software, to secure the stability of 1,000 MW high-capacity coal-fired power plant cooling water system with high head. To prevent water hammer, The effects on performance characteristics were predicted by individual and combination application. The surge pressure of the cooling water which occurs when the pump was stopped without installing the anti-surge devices was the largest at the pump outlet side. The most effective and simple way to reduce surge pressure in these cooling water systems is to combine a vacuum breaker with a hydraulic non-return valve, which is an essential device for pump protection.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.5
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• pp.111-118
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• 1998

Surge pressure problem at the oil return line of the hydraulic circuit of an active suspension system for passenger cars was investigated by experiments and numerical analyses. In the numerical analyses, the method of characteristics was used for simulating unsteady flow in the hydraulic system and gas discrete model was adopted for estimating gas volume variation in separated liquid column. In the experiments and analyses, effects of the physical parameters of the accumlator on smoothing surge pressure was elucidated.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.3
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• pp.1-8
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• 2009

This thesis has analyzed the effect of the surge happening in flight on the engine performance, especially on the PW4000 turbofan engine. It is to be judged that the flight surge can occur more often at the time of takeoff than it does en route due to the fact that the engine parameters are prone to fluctuate. EPR is judged to be the most highly sensitive parameter responding when surge occurs. Both Engine rpm and Wf decrease almost simultaneously just like an EPR. During the take-off rolling, N1 vibration is more sensitive than the N2 vibration. Consequently, the surge can be detected by EGT increase, while the other parameters (EPR, rpm, Wf, etc) decrease.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.236-239
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• 2008

This thesis has analyzed the effect of the surge happening in flight on the engine performance of the PW4000 turbofan engine. EPR is judged to be the most highly sensitive parameter responding when surge occurs. Both N1 rpm and N2 rpm decreases almost simultaneously just like an EPR. During the take-off rolling, the N1 vibration is more sensitive than the N2 vibration. Consequently, the surge can be detected by EGT increase, while the other parameters decrease.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.6
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• pp.2428-2434
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• 2012

This paper describes the control of a solenoid valve of ESC(Electronic Stability Control) with hydraulic modulator in braking system. ESC ECU(Electronic Control Unit) to control the high-frequency control and slope control method was applied, the surge pressure and EMI(electromagnetic interference) reduction characteristics were studied. The stage of ECU output was added the slope shaping function to reduce electromagnetic emission at higher frequencies. Measurements show that this high frequency ECU manages to reduce the surge pressure and electromagnetic emission by the control of solenoid valve. In conclusion, by using the results of this study for the high frequency ECU control, we could expect enhancement of braking system performance.

• Journal of the Korea Society for Simulation
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• v.22 no.3
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• pp.81-87
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• 2013

This paper is about study how to decrese surge pressure that is occurred in excavator driving motor. We used computer simulation program SimulationX. It is also about the way finding design problem and approaching a solution through interpreting shape design sensitivity analysis. Programmes are below. First of all, finding shape fault by analyzing dynamic behavior of valves installed in hydraulic driving motor which is designed now. And drawing variable which is considered sensitive to improve dynamic efficiency among a lot of shape variables. Then, targeting that variable and examining dynamic efficiency stabilization tendency with controlling it. Finally, suggesting the most effective tuning method through variable combination as there are a lot of sensitive variables.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.1
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• pp.124-134
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• 1996

In this paper the pressures and flowrate distributions in the loading/unloading piping system of LNG carrier have been investigated in the case of unsteady flow state as well as steady one. Under emergency situation the main cargo pumps are forced to fail, and the ESD(Emergency Shut Down) valves and Stop valves are closed within set-time. The surge pressures according to the variations of valve closing time have been computed to recognize the surge phenomenon due to sudden decrease of flowrate. By means of these analysis results, the most important factors on the in-pipe surge phenomenon of cargo loading/unloading piping system of LNG Carrier are the type of ESD and Stop valves, valve closing time, and the pipe arrangements.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.2
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• pp.18-24
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• 2004

A fuel spiking test was performed to measure the surge margin of the compressor in a gas turbine engine. During the test, fuel spiking signal is superposed on the engine controller demand signals and the combined signals are used to control a fuel control valve. For the superposition, a subsystem composed of a fuel controller and a function generator is used. The real engine test was performed at the Altitude Engine Test Facility (AETF) in Korea Aerospace Research Institute (KARI). In the preliminary test, the fuel spiking signals are in good agreement with the dynamic pressure at the fuel line and at the compressor discharge point. After the preliminary test, a fuel spiking test to measure the surge point at a specific engine speed was performed. The test results show that the fuel spiking test is very effective in the measurement of surge.