• Proceedings of the KSME Conference
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• 2000.04b
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• pp.580-585
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• 2000

Recently TEIS model, Two-zone model aid Stanitz equations are often used for off-design performance prediction of centrifugal compressor and pump. The prediction results often agree well with experimental data. However these models and equations have some important variables which have a great influence on overall performance prediction me. But no systematic study about these variables has been performed. So, in this paper, a systematic study about these variables influence on overall performance prediction owe is peformed. Finally the meaning of the variables and the research to be undertaken are discussed.

• International Journal of Air-Conditioning and Refrigeration
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• v.8 no.2
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• pp.108-118
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• 2000

This paper describes a design of the helium-recondensing system utilizing cascade Roebuck refrigerators. Superconducting generator or motor has the superconducting field wind-ing in its rotor that should be continuously cooled by cryogen. Since liquid helium transfer from the stationary system to the rotor is problematic, cumbersome, and inefficient, the novel concept of a rotating helium-recondensing system is contrived. The vaporized cold helium inside the rotor is isothermally compressed by centrifugal force and expanded sequentially in cascade refrigerators until the helium is recondensed at 4.2 K. There is no helium coupling between the rotor and the stationary liquid helium storage. Thermodynamic analysis of the cascade refrigeration system is performed to determine the key design parameters. The loss mechanisms are explained to identify entropy generation that degrades the performance of the system.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.323-323
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• 2003

Many recent development activities suggest the possibility of a high-speed turbo(centrifugal) compressor or blower for the industrial application of compressed air supplying system when used with the most advanced high-speed motor, inverter technology, and advanced bearing for high rotational speed. The problems to be overcome are of reliability, the application of mass production methods, cost effective manufacture and competitive running costs. This presentation is not focused on a specific technology advances but on an overall review of our recent experiences while we have developed the high pressure turbo blower for the commercial purpose.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.125-131
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• 2000

The turbo chiller uses centrifugal compressor, which operates at about 14500 rpm. Due to the high rpm of the impeller, the noise of chiller makes one of the serious problems. The possibility of the sound reduction by using absorbing material is studied in this paper. The generated sound propagates through the duct and then radiates to the outer field. So, the use of sound absorption material inside the duct is one of the effective methods. To study the effect of location of the material, we use Boundary Element Method to analyze the sound field inside the duct system. Numerical study shows the highest sound pressure region is near the elbow of curved duct. From the analysis, it is also shown that the elbow duct is the main radiator of noise and sound absorption treatment of this duct results noise reduction of the highest noise level at BPF and high frequency region.

• Journal of ILASS-Korea
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• v.24 no.3
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• pp.130-136
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• 2019

Spray visualization of a vaporizer fuel injection system of a micro turbo jet engine was experimentally studied. The fuel heating by combustion was simulated by the high pressure steam generator and combustor inlet air from the centrifugal compressor was simulated by compressed air stored in the high pressure air tank. Spray visualization was performed with single vaporizer, and then six vaporizers which are same number of micro turbojet engine were used. As a results, the spray characteristics of the vaporizer were understood with pressure difference of the combustor inlet air and the fuel supply pressure. Spray angles with three types of vaporizer configuration were measured. In the results, guide vane configuration has a wider spray angle than the straight tube and smooth curve tube with a swirler, so it is expected that the fuel will be effectively distributed inside the combustor flame tube.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.9
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• pp.56-62
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• 2022

This study analyzed the output precision of 3D printing methods. The inner impeller of the centrifugal compressor was printed in as a sheet with 100% packing density using two methods: field deposition modelling and stereolithography. Dimensional differences between the initial CAD and printed models were evaluated using a 3D scanner. To investigate the dimensional characteristics of the 3D printed impeller, 3D dimension analysis and point dimension analysis were performed. The point dimension analysis was divided into 3D and 2D for comparative analysis.

• Journal of the Korean Society of Propulsion Engineers
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• v.1 no.2
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• pp.84-90
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• 1997

The turboshaft engine with the free power turbine has been used for various purposes, for instance electric power generator, emergency power source, helicopter powerplant and so on. Steady-state simulation program was developed and experimental tests was carried out for comparing with computer simulation results. The test unit was composed of 1-stage centrifugal compressor, the can type combustor chamber, 1-stage radial type compressor turbine, and radial type free power turbine, and its output power is obtained from 3-phase AC generator. Main component characteristics which was used for the steady state simulation program, were obtained from the manufacturer of the test unit, and modified from experimental results of test unit. In comparison between computer simulation and experimental test results even though the test unit has the operational limit, deviation of component performance characteristics in simulation were within 6％ range of experimental results.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.834-840
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• 2001

Gear is general mechanical elements that used for power transmission between two shafts that interval is comparatively short. and it delivers big power as accurate ratio of speed. The profile of Spur gear which is the most basic factor is divided into Trochoidal fillet curve and Involute curve. Involute curve is used a lot of a shaped curve of machine parts such as a gear, a scroll compressor and a collar of centrifugal pump. However, It is poor to study the modeling of Trochoidal fillet curve and the three dimensions model shaped mathematical curve. This paper describes a mathematical model of profile shifted involute gear. and this model is based on Camus's theory. We draw three dimensions gear have accurate mathematical function using ADS, VisualLISP. and To check accuracy and perfection, we make a program of checking Interference. and use for this study.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.521-527
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• 2001

The dynamic performance analyses and tests for a 50kW turbo-generator (KIMM-TG50) were carried out. The operating concept of this machine is that it gets the initial driving force from the built-in motor-generator until it reaches its self-sustaining speed of 40,000 rpm, and then the driving mode is changed to self-operating mode by the combustor installed between the centrifugal compressor and the turbine. Due to winding mistake of motor-generator, the system could go only up to 22000 rpm by the motor so that high pressure air externally fed into the turbine was utilized to get the system to run up to 62,000 rpm thereafter. The vibration data collected during the tests revealed that the first bending critical speed is in near 5,600 rpm as predicted in the design stage of the rotor-bearing system, and that there were no other identifiable critical speeds up until 62,000 rpm due to high damping from the squeeze film damper-bearings supporting the rotor. This paper presented some of the experimental results along with dynamic performance predictions made in the design stage as a part of progress being made.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.877-880
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• 2017

Impeller blades in the centrifugal compressor are subjected to static loads due to the high-speed rotation and steady aerodynamic forces. At the same time, aerodynamic excitations by the interaction between the impeller and the diffuser vanes(DV) periodically excite the impeller blades in resonant conditions, which may lead to high cycle fatigue (HCF) and eventually result in failure of the blades. In order to predict the structural response accurately, the aerodynamic excitation and the major resonant conditions were predicted by performing the unsteady flow analysis and modal analysis using ANSYS. Next, a unidirectional forced vibration analysis was performed by using fluid-structure interaction (FSI) method, and the safety of HCF was evaluated based on the results.