• The KSFM Journal of Fluid Machinery
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• v.6 no.4 s.21
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• pp.50-57
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• 2003

The hydraulic performance analysis of a turbopump with an inducer for a liquid rocket engine was performed using three-dimensional Navier-Stokes equations. A simple mixing-plane method and a full interaction method were used to simulate inducer/impeller interaction. Two methods show almost similar results due to the weak interaction between the inducer and impeller since the inducer outlet blade angle is lather small. But, when the inducer and the impeller are closely spaced near the shroud region, flow angles at the impeller inlet show different results between two methods. Thus, the full interaction method predicts about $2\%$ higher pump performance than the mixing-plane method. And the effects of prewhirl at the impeller inlet are also investigated. As the inlet flow angle is increased, the head rise and the efficiency are decreased. The computational results are compared with measured ones. The computational results at the design point show good agreements with experimental data, however under-predicts the head rise at high mass flow rates compared to the experiment.

• Tribology and Lubricants
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• v.14 no.1
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• pp.7-13
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• 1998

The static characteristics of a five-pad tilting pad journal bearing of load on pad (LOP) type have been investigated experimentally under the different values of bearing load and shaft speed. The diameter and length of the bearing are 300.91 mrn and 149.8 mm, reslx;ctively. Circumferential distribution of the film pressure, film thickness, journal surface temperature and beating surface temperature are measured. A noticeable inlet pressure rise is observed at the entrance of each pad, especially the bottom pad. The inlet pressure is increased by the increase of shaft speed as well as bearing load. In the five-pad tilting pad joumal bearing of LOP type, almost all of beating load is being carried only by the bottom pad. The maximum bearing surface temperature is observed at near the minimum film thickness. It is observed that the metal temperature of the mid-plane is higher than that of the edge at the inlet region, while the metal temperature of the edge is higher than that of the mid-plane at the outlet region.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.5 s.176
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• pp.1314-1322
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• 2000

The acoustic property of reactive type single expansion chamber can be analyzed by traditional plane wave theory. This theory can be applied in low frequency range and has good performance. But this theory can't include higher order modes, therefore another method is essential to analyze acoustic filter in high frequency range. Many researcher suggested the method that can concern higher order modes, and their methods are using mode matching technique. But there is no method that can be applied to the analysis of single expansion chamber with arbitrary inlet/outlet duct position and numbers of higher order modes of inlet/outlet duct and middle chamber. In this paper, the method which can analyze single expansion chamber with arbitrary inlet/outlet duct position and numbers of higher order modes of inlet/outlet duct and middle chamber using fundamental mode matching technique, was suggested and the predictions by this method was compared with those by the finite element method, and the influence of inlet/outlet location to acoustic performance of single expansion chamber is investigated and explained by higher order mode effects.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.10 s.181
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• pp.2487-2495
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• 2000

The acoustic characteristics of expansion chamber will be changed with the variation of inlet/outlet location due to the higher order acoustic mode in a high frequency in which the plane wave theory is not available. In this paper, the acoustic performance of reactive type expansion chamber with circular cross-section is analyzed by using the modified mode matching theory. The sensitivity analysis of four-pole parameters with respect to the location of inlet and outlet is also suggested to increase the acoustic performance. The acoustic power transmission coefficient is used as cost function, and the location of inlet and outlet is used as design variables. The steepest descent method and SUMT algorithm are used for optimization technique. Several results showed that the expansion chamber with optimally located inlet/outlet had better acoustic performance than concentric expansion chamber.

• Journal of Power System Engineering
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• v.16 no.4
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• pp.51-59
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• 2012

The computational flow analysis using LES technique was carried out to investigate the flow characteristics of a sirocco fan under the maximum flowrate condition. The commercial SC/Tetra software was used for this unsteady and three-dimensional numerical analysis. In consequence, because a flow is unstable within the range of about 50% of a housing depth from a bellmouth around the cutoff region, the passing flow through the blade cascade occurred on the X-Y plane is a slow or a reverse with approaching to the housing inlet. Also, the secondary flow shows on the radial plane of a housing, and its vortex center exists within about 33% of a housing depth from a bellmouth except the cutoff region. Moreover, the flow occurring on the exit plane of a sirocco fan shows a complex secondary flow.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.4
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• pp.401-409
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• 2018

A numerical investigation has been conducted to find the effects of pressure losses by struts and rakes, and averaging methods on the performance of a multi-stage axial fan and a multi-stage axial compressor. Struts and rakes which produce pressure losses are installed upstream of the aerodynamic inlet plane in the fan and the compressor rigs. Some of normal stator vanes are substituted with thick vanes with total pressure probes to measure total pressure between stages. Three-dimensional Reynolds-averaged Navier- Stokes equations with $k-{\omega}$ SST turbulence model were applied to analyze the pressure losses by the struts, inlet rakes, and thick instrumented vanes. The hexahedral grids were used to construct computational domain. Inlet pressure losses were evaluated for the compressor as a function of Mach number. The passage pressure losses due to the instrumented vanes were evaluated at the two speed lines in the fan. Total properties, such as pressure and temperature, were evaluated at the exit of the fan and the compressor with two different averaging methods which are area-averaging and mass-averaging, respectively.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.2
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• pp.42-53
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• 2009

Gas turbine engine simulation program has been developed. In compressor and turbine, 2-D NS implicit code is used with k-$\omega$ SST turbulent model. In combustor, 0-D lumped method chemical equilibrium code is adopted under the limitations, the products are only 10 species of molecular and air-fuel is perfectly mixed state with 100% combustion efficiency at constant pressure. Fluid properties are shared on interfaces between engine components. The outlet conditions of compressor have been used as the inlet condition of combustor. The inlet condition of turbine comes from the compressor The back pressure in compressor outlet is transferred by the inlet pressure of turbine. Unsteady phenomena at rotor-stator in compressor and turbine is covered by mixing-plane method. The state of engine can be determined only by given inlet condition of compressor, outlet condition of turbine, equivalence ratio and rotating speed.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.6
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• pp.748-754
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• 1999

The acoustic performance of reactive type single expansion chamber can be calculated theoretically by plane wave theory. But higher order modes should be considered to widen the frequency range. Munjal has suggested the method for analyzing the acoustic properties of simple expansion chamber with taking into consideration of higher order mode of inlet/outlet. But his method cannot predict the acoustic properties exactly when the dimensions of inlet/outlet and expansion chamber have not integer multiples. In this paper the new method was suggested to overcome the shortcomings of Munjal's method The predictions by this method were also compared with those by the finite element method.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.753-762
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• 2004

Conceptual studies of a combined-cycle engine have been conducted. Herein, the results are presented. The engine is composed of ejector-jet, ramjet, scramjet and rocket modes, and will be mounted on the Single-Stage-to-Orbit aerospace plane. Propellants are hydrogen and oxygen. Calculated engine thrust performances and cooling requirement of the engine are presented. Pitching moment of the plane with the engine will be balanced even in the vacuum condition. The experimental results of the inlet and the ejector-jet, ramjet and scramjet modes are presented. The effect of the airframe configuration on the engine performance and the thermal environment in the in-side of the plane are also presented. Through the investigations, possibilities of the combined-cycle engine and the aerospace plane are being made clear now.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.271-275
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• 2001

Three dimensional flow characteristics in a liquid fuel ramjet combustor are investigated using PIV method. The combustors have two rectangular inlets that form 90 degree each other. Three guide vane is installed in each rectangular inlet to improve the flow stability. We made three cases of test combustors in which those inlet angles are 30 degree, 45 degree and 60 degree. Each combustor easily changes the size of combustor's recirculation zone with the replacement of combustors dome. The experiments are performed in the water tunnel test with the same Reynolds number in the case of Mach 0.3 at inlet. PIV software is developed to measure the flow field in the combustor and the accuracy of developed PIV program is verified with rotating disk experiment and standard data. The experimental results show that the two main streams from rectangular inlet collide near the plane of symmetry and generate two large longitudinal vortex, A large and complex three-dimensional recirculating flow is measured in the recirculation zone.