• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.7
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• pp.19-28
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• 2004

This study is concerned with the method of equilibrium-pressure prediction from transient data. Pressure measurement system consisted of pressure sensor and pressure tube. The surface orifice where pressure is measured is connected to a pressure sensor by a tube. In case of high orifice pressure, the pressure sensor responds rapidly to the orifice pressure. But when the orifice pressure is low the pressure sensor does not respond rapidly to the orifice pressure and time lag occurs seriously. Various test conditions are applied to investigate the time lag and to assess the methods of equilibrium-pressure prediction. The test time of the low-pressure measurement can be reduced by the method of equilibrium-pressure prediction of the present study.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.5
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• pp.235-241
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• 2018

The internal pressure is a critical parameter for designing a pressure vessel. The static pressure that a pressure vessel must withstand is usually determined according to the various codes and standards with simple formula or numerical simulations considering the geometric parameters such as diameter and thickness of a vessel. However, there is no specific codes or technical standards we can use practically for designing of pressure vessels which have to endure the detonation pressure. Detonation pressure is a kind of dynamic pressure which causes an impulsive pressure on the vessel wall in a extremely short time duration. In addition, it is known that the magnitude of reflected pressure at the vessel wall due to the explosion can be over twice the incident pressure. Therefore, if we only consider the reflected pressure, the design of the pressure vessel can be too conservative from the economical point of view. In this study, we suggest a practical method to evaluate the magnitude of maximum allowable pressure that the pressure vessel can withstand against the detonation inside a vessel. As an example to validate the proposed method, we consider the pressure vessel containing hydrogen gas.

• Computational Structural Engineering
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• v.8 no.4
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• pp.189-198
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• 1995

The conventional finite element formulations for incompressible materials show pressure oscillations or pressure modes in four-node quadrilateral elements of commonly used displacement and pressure interpolations. The criterion for the stability in the pressure solution is the so-called Babugka-Brezzi stability condition, and the above elements do not satisfy this condition. In this study, a pressure continuity residual based on the pressure discontinuity at element interfaces is used to study the stabilization of pressure solutions in bilinear displacement-constant pressure four-node quadrilateral elements. This pressure residual is implemented in Q1P0 element derived from the conventional incompressible elasticity. The pressure solutions can be stable with the pressure residual though they exhibit sensitivity to the stabilization parameters. Parametric study for the solution stabilization is also discussed.

• Journal of the Korean Society of Propulsion Engineers
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• v.1 no.2
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• pp.1-11
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• 1997

During hydroproof test of composite pressure vessel, acoustic emission signal was measured and analyzed to evaluate structural integrity of composite motor case. When pressure was held for 1 min. at constant pressure from low pressure level to high pressure level, the pattern of hit rate of good composite pressure vessel is increased with higher value than that of bad composite pressure vessel. This report also presents detection possibility of burst location approximately in the range of 25∼36％ of burst pressure using energy rate. In case that it is difficult to detect burst location of composite motor case, it is possible to detect burst location, i.e. structurally weak location of composite pressure vessel with applying same pressure lower than maximum expected operating pressure(MEOP) repeatedly.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.1
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• pp.7-15
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• 2008

Pressure Sensitive Paint(PSP) means a reacting paint in pressure. The calibration of PSP and the wind tunnel test of PSP painted model are required to measure pressure by using PSP. Therefore, the post processing from these results shows the information and image of the pressure distribution. PSP can show the information of total pressure from the wind tunnel test and the calibration. In this study, equipments of PSP are composed, and experiment is accomplished by using PSP. The surface pressure distribution around the wall of nozzle is measured by PSP. The measured pressure has similar results to those of the CFD and pressure tap measurement.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.10
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• pp.645-651
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• 2016

Effects of pressure-side winglet width on the tip leakage flow and aerodynamic loss downstream of a turbine blade with a pressure-side squealer rim have been investigated for the tip gap-to-span ratio of h/s = 1.36%. The pressure-side squealer has a fixed height-to-span ratio of $h_p/s=3.75%$ and the pressure-side winglet, which is installed at an elevation of tip surface, has width-to-pitch ratios of w/p = 2.64%, 5.28%, 7.92% and 10.55%. The results show that with increasing w/p, aerodynamic loss in the passage vortex region decreases, whereas that in the leakage flow region increases. As a result, the mass-averaged loss coefficient all over the measurement plane tends to decrease minutely with the increment of w/p. It is concluded that the pressure-side winglet for the pressure-side squealer tip can hardly contribute to the tip-leakge loss reduction.

• Journal of the Korean Society for Railway
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• v.12 no.2
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• pp.309-314
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• 2009

When a train enters into a tunnel, a compression wave is generated by a front nose and a expansion wave is generated by a rear tail respectively. The interaction between pressure waves and the train makes the internal and external pressure of the train change dramatically. In this paper, we had measured the internal and external pressure variations of TTX and analyzed the pressure variations as the tunnel length. Also, the rate of internal pressure variations were investigated with the current airtight condition of TTX. In short tunnels, the internal and external pressure variation were not large because the superposition of pressure waves was not happened. In long tunnels, however, the rapid and large pressure variations were shown because of the superpositions between the same sort of pressure waves, such as expansion wave and expansion wave or compression wave and compression wave. In specific length tunnels, the pressure variation and the pressure variation rates were largely lessened because the compression wave and expansion wave were superposed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.4
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• pp.337-345
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• 2008

this study, three dimensional surface pressure distributions of SWIM whose main wing has NACA4412 airfoil with NACA0012 flaps were experimentally measured by pressure sensitive paint. Surface pressures on suction and pressure sides of the wing were measured by changing an angle of attack at a Reynolds number of 3.1x105 in KARI 1m subsonic wind tunnel. The experimental results showed that as an angle of attack increases minimum pressure region on a suction side moved from the wing root to the tip and low pressure region around trailing edge of the wing tip which causes wing tip vortex was observed. Although low pressure region at the tip still observed at an angle of attack 15 deg., other area on a suction side showed flat pressure distribution in a span-wise direction. It was also observed that the mean value of pressure coefficients was about 0.077 through a comparison between PSP and pressure taps at the same test conditions.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.4 no.2
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• pp.7-12
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• 2008

The purpose of this study is to present a methodology to estimate the capacity of the pressure relief valve which prevents overpressure of the pressure vessel in a cold state. In this methodology, the transient behavior of the flow rate through the pressure relief valve and the pressure inside the pressure vessel are considered. The result of this study shows the followings; The more the relief valve capacity is considered in excess, the more the initial relief flow rate and the initial pressure inside the pressure vessel are high and low respectively. When the relief valve capacity is determined properly, the pressure inside the pressure vessel maintains almost the same value, so the ASME code requirement will be met.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.7
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• pp.947-952
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• 2010

Components such as pressure vessel, hydraulic hose assembly, accumulator, hydraulic cylinder, hydraulic valve, pipe, etc., are tested under the impulse-pressure conditions prescribed in ISO and SAE standards. The impulse pressure test machine needs to have a high pressure, a precise control system and a long life. It should satisfy the requirements for fabrication of the impulse tester to generate ultra high pressure in the hydraulic system. In the impulse tester, a servo-valve control system is adopted; although the control application is convenient, it is expensive owing to the cost of developing the system. The type of the control system determines the pressure wave, which affects the components that are tested. In this study, the manufacturing process and the intensifier system design related to the flow, pressure, and the increasing rate of pressure are investigated. The results indicate the ultra high pressure waves in the system.