• Proceedings of the KSME Conference
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• 2001.11b
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• pp.688-692
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• 2001

Three-dimensional experimental analyses were conducted in the pulverizer simplified isothermal model. The experimental model was constructed on a 1/3.5 scale of 500MW pulverized coal boiler. The purpose of this study is to investigate the characteristics of coal particle separator and the pressure loss in the pulverizer models with dynamic classifier. Without regards a shape of separator top, the results showed that the increase of dynamic classifier rpm was induced in finer coal particle. But the capacity of total mass per minute was reduced. Also, the increase of dynamic classifier rpm had no effect on total pressure loss, but an increase of inlet velocity was induced that the rise of total pressure loss in the pulverizer models with dynamic classifier.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.11
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• pp.3022-3030
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• 1995

The irreversibility of condensation process in the supersonic flow of steam turbine cascade causes the entropy to increase and the total pressure loss to be generated. In the present study, in order to investigate the moist air flow in two dimensional steam turbine cascade made as the configuration of the last stage tip section of the actual steam turbine moving blade, the static and total pressures along suction side of the blade are measured by pressure taps and Pitot tube. The flow field is visualized by a Schlieren system. The effects of stagnation temperature and the degree of supersaturation on energy loss and entropy change in the flow are clearly identified.

• Journal of Environmental Health Sciences
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• v.31 no.5 s.86
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• pp.372-378
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• 2005

To enhance educational effect for exhaust ventilation system, more instructive educational engineering such as experimental system should be needed. This study was performed to 1) manufacture the basic experimental system for local exhaust ventilation, 2) experiment with this system and 3) develop methodology of exhaust ventilation education. With this system, three pressures (static pressure(SP), velocity pressure(VP) and total pressure(TP)) were measured and illustrated and the graphic shapes agreed to theoretical ones relatively. Entry loss factor ($F_h$) of each hood was found to be different with hood shape, duct velocity and flow rate. This result implies that precise $F_h$ should be determined case by case and a industrial hygienist should not be dependent on the existing values. Pressure loss using velocity pressure method and characteristics of air movement near hoods using fume were grasped with this system. But larger system should be recommended to produce more precise experimental results.

• Journal of Drive and Control
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• v.9 no.2
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• pp.8-14
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• 2012

Electro-hydraulic spring return actuator(ESRA) is utilized for air conditioning facilities in a nuclear power plant. It features self-contained, hydraulic power that is integrally coupled to a single acting hydraulic cylinder and provides efficient and precise linear control of valves as well as return of the actuator to the de-energized position upon loss of power. In this paper, the algebraic equations of ESRA at steady-state have been developed for the analysis of static characteristics that includes control pressure and valve displacement of pressure reducing valve, flow force on flapper as well as its displacement over the entire operating range. Also, the effect of external load on piston deviation is investigated in terms of linear system analysis. The results of static characteristics show the unique feature of force balance mechanism and can be applied to the stable self-controlled mechanical system design of ESAR.

• International Journal of Fluid Machinery and Systems
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• v.2 no.1
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• pp.13-20
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• 2009

The effects of positively bowed blade on the aerodynamic performance of annular compressor cascades with large camber angle were experimentally investigated under different incidences. The distributions of the exit total pressure loss and secondary flow vectors of compressor cascades were analyzed. The static pressure was measured by tapping on the cascade surfaces, and the ink-trace flow visualizations were conducted. The results show that the value of the optimum bowed angle and optimum bowed height decrease because of the increased losses at the mid-span with the increase of the caber angle. The C-shape static pressure distribution along the radial direction exists on the suction surface of the straight cascade with large r camber angles. When bowed blade is applied, the larger bowed angle and larger bowed height will further enhance the accumulation of the low-energy fluid at the mid-span, thus deteriorate the flow behavior. Under $60^{\circ}$ camber angle, flow behavior near the end-wall region of some bowed cascades even deteriorates instead of improving because the blockage of the separated flow near the mid-span keeps the low-energy fluid near the end-walls from moving towards the mid-span region, and as a result, a rapid augmentation of the total loss is easy to take place under large bowed angle. With the increase of camber angle, the choice range of bowed angle corresponding to the best performance in different incidences become narrower.

• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.259-264
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• 2000

The functions of the plug valve are the control of flow rate as well closing and opening pipe lines. Analyses on the flow characteristics in plug valve port are required to improve the performance and safety at severe operating conditions such as high-pressure and high-temperature. In this study, numerical analyses are carried out with varying the opening rate (fraction of the full open to close) of the valve and the shapes of valve Uk: straight, convex, concave and mixed shapes. The parameters influencing the flow characteristics in the valve are the discharge coefficient( $C_v$) and the resistance coefficient( K). Therefore, the distributions of static pressure, velocity vector and stream lines are investigated, and $C_v$ and K are calculated in each opening rate and shape. In case of full open, the static pressure passed through the valve port has almost been recovered. However, in case of other opening rates, the pressure does not permanently regained due to pressure drop leading to loss. This phenomenon in each shape of the valve shows the different behaviors. Calculation results show that the mixed shape has the best flow attribute.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.1
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• pp.81-88
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• 2011

The triple eccentric butterfly valve has metal sheet and this study about butterfly valve ceiling is an innovative approach. But it is affected by the static pressure as well as cross-current. The damage at the valve on the pipe resulted from the reflux is due to valve leakage. This study is investigated on the triple eccentric disk and it is applied with angle and the static pressure in all cases to develop cross-current triple eccentric butterfly valves. The disc with the diameter of 300A is valve against flow velocity. The entrance pressure by flow characteristics is performed with numerical analysis. As the result, valve torque production is reduced more than the conventional triple eccentric valve and entrance pressure is decreased on the increase of valve open angle. And flow coefficient can be known to be increased.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.195-201
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• 2008

In the jet engines on the aircrafts cruising at high altitude over 20 km and subsonic speed, the Reynolds number in terms of the compressor blades becomes very low. In such an operating condition with low Reynolds number, it is widely reported that total pressure loss of the air flow through the compressor cascades increases dramatically due to separation of the boundary layer and the secondary-flow. But the detail of flow mechanisms causes the total pressure loss has not been fully understood yet. In the present study, two series of numerical investigations were conducted to study the effects of Reynolds number on the aerodynamic characteristics of compressor cascades. At first, the incompressible flow fields in the two-dimensional compressor cascade composed of C4 airfoils were numerically simulated with various values of Reynolds number. Compared with the corresponding experimental data, the numerically estimated trend of total pressure loss as a function of Reynolds number showed good agreement with that of experiment. From the visualized numerical results, the thickness of boundary layer and wake were found to increase with the decrease of Reynolds number. Especially at very low Reynolds number, the separation of boundary layer and vortex shedding were observed. The other series, as the preparatory investigation, the flow fields in the transonic compressor, NASA Rotor 37, were simulated under the several conditions, which corresponded to the operation at sea level static and at 10 km of altitude with low density and temperature. It was found that, in the case of operation at high altitude, the separation region on the blade surface became lager, and that the radial and reverse flow around the trailing edge become stronger than those under sea level static condition.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.807-812
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• 2001

The effects of casing shapes on the interaction of the impeller and volute in a small-size turbo-compressor are investigated. Numerical analysis is conducted for the compressor with circular and single volute casings from inlet to discharge nozzle. In order to predict the flow pattern inside the entire impeller, vaneless diffuser, and casing, calculations with a multiple frame of reference method between the rotating and stationery parts of the domain are carried out. For incompressible turbulent flow fields, the continuity and three-dimensional time-averaged Navier-Stokes equations are employed. To predict the performance of two types of casings, the static pressure and loss coefficients are obtained with various flow rates. Also, static pressure distributions around casings are studied for different casing shapes, which are very important to predict the distribution of radial load.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.2171-2180
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• 1991

An analysis model for off-design performance of radial inflow turbines with or without variable area guide vane is developed, where two important factors in loss models, total pressure ratio between variable area guide vane exit and scroll casing inlet and rotor loss coefficient are determined without experimental data. The analysis results show that the predicted trends with or without variable area guide vane are consistent with the experimental observations. The comparison of present method with the well-known NASA off-design performance analysis program shows that the mass flow rate and static efficiency by present analysis are in good agreement with those by the NASA program. Therefore, this method can be used to predict off-design performance of radial inflow turbines with validity of the loss models used by present analysis.