• 대한조선학회지
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• 제26권3호
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• pp.29-40
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• 1989

고효율 및 캐비테이션 특성이 우수한 프로펠러 날개단면을 개발하기 위한 일련의 설계 제작 시험 및 해석과정을 기술하였다. 여러 날개단면의 양력-항력곡선과 캐비테이션 특징을 비교하기 위하여 11개의 2차원 날개 단면을 설계 제작 시험하였다. 개발된 단면(KH18 단면)은 양력-항력 곡선과 캐비티 초생 곡선에서 기존 단면에 비하여 폭이 넓기 때문에 불균일한 선미후류에서 작동하는 프로펠러의 날개 단면으로서 적합하리라 생각된다. 개방단면을 사용한 프로펠러 설계법을 제시하였다. 코오드 방향 부하분포 형상이 프로펠로 성능에 미치는 영향을 고찰하기 위하여 3가지 기준 부하 형상에 대한 프로펠러를 각각 설계하였다. 또한 날개단면이 프로펠러 성능에 미치는 영향을 비교하기 위하여 기존 날개단면만을 사용한 프로펠러를 2개 설계하였다.

• 한국수산과학회지
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• 제43권5호
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• pp.495-502
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• 2010

Pure lines were isolated from young gametophytic blades of pigmentation and morphological mutants in Porphyra tenera. Growth, blade-shape and photosynthetic pigment content of pure lines were compared with the wild type. Growth of blade length in the wild type (W, R-B), with round shape and brown color, was fastest at $5{\sim}10^{\circ}C$ and became slower as temperature increased. The blade-shape of the wild type changed from linear to round as temperature increased. The green type (R-G), with round shape and green color, showed slower growth, and the red type (R-R) 'with round shape and red color' showed faster growth than the wild type. The blade-shapes of the green and red types changed from elliptical or linear to round as temperature increased. The phycoerythrin (PE) / phycocyanin (PC) ratio of the green type was markedly lower and the PE/PC ratio of the red type was markedly higher than that of the wild type. The linear type (L-B), with liner shape and brown color, showed faster growth in blade length than the wild type at $10{\sim}20^{\circ}C$ and maintained its linear shape at $5{\sim}15^{\circ}C$. The content of photosynthetic pigments of the linear type was similar to that of the wild type. Each of the pure lines of pigmentation and morphological mutants that were isolated in the present study showed particular patterns in growth, blade-shape and photosynthetic pigment composition. Therefore, they are expected to be useful as new varieties by themselves and to be available for breeding and biotechnological studies.

• 대한기계학회논문집B
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• 제20권8호
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• pp.2707-2720
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• 1996

The aerodynamic design of the two-stages of centrifugal compressors in an 1.2MW industrial gas turbine is completed with the application of numerical analyses. The final shape of an intake, the axial guide vanes and a return channel is determined using several interactions between design and two-dimensional turbulent flow analysis, focused on the minimum loss of internal flows. The one-dimensional turbulent flow analysis, focused on the minimum loss of internal flows. The one-dimensional design and prediction of aerodynamic performances for the compressors are performed by two different methods; one is a method with conventional loss models, and the other a method with the two-zone model. The combination methods of the Betzier curves generate three-dimensional geometric shapes of impeller blades which are to be checked with a careful change of aerodynamic blade loadings. The impeller design is finally completed by the applications of three-dimensional compressible turbulent flow solvers, and the effect of minor change of design of the second-stage channel diffuser is also studied. All the aerodynamic design results are soon to the verified by component performance tests of prototype centrifugal compressors.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 춘계학술대회논문집
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• pp.232-238
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• 2009

The objective of this study is to investigate the suitable design for a domestic CWP pump, which is used in cooling-water intakes for the unit 3 and 4 of Yeonggwang nuclear power plant. All the simulations are performed, using CFD method with a commercial code STAR-CCM+ version 3.02. After modeling a present design of the pump, the flow around the rotating blade was calculated by using quasi-static method and sliding mesh method with the almost same condition as an actual state. Based on fundamental simulations with various depth of sea water, the reference pressure for the boundary condition of the present study was decided. To verify the reliability of the calculation results, the suction flow rate of the data was compared with that of the experimental data. As a result of this comparison, it is confirmed that two results are fairly consistent. For the improvement of the suction flow rate, computational analysis was done by changing a flow channel and blade shapes. It is shown that the suction flow rate of the new pump was improved.

• 대한기계학회논문집B
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• 제37권4호
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• pp.423-429
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• 2013

수직축 풍력발전기의 발전 전력을 유동해석을 이용하여 예측하였다. 해석은 블레이드 회전 속도를 고정하고 그 회전 속도에서 토크를 반력으로 추출하였다. 여러 경우의 블레이드의 회전 속도에 대해 토크를 구하고 발전 용량을 계산하였다. 회전 속도에 따른 발전 토크와 발전 용량을 계산함으로써 최적의 발전기와 그 때의 회전 속도를 선정할 수 있었다. 또한, 블레이드의 개수와 블레이드의 형상에 대해 해석을 수행하여 그 영향을 분석하였다. 마지막으로 실험을 수행하여 그 결과를 비교하였다.

• 한국전산유체공학회지
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• 제8권4호
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• pp.16-25
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• 2003

The design method for transonic turbine blades has been developed based on Wavier-Stokes equations. The present computing process is done on the four separate steps, i.e., determination of the blade profile, generation of the computational grids, cascade flow simulation and analysis of the computed results in the sense of the aerodynamic performance. The blade shapes are designed using the cubic polynomials under the control of the design parameters. Numerical methods for the flow equations are based on Van-Leer's FVS with an upwind TVD scheme on the finite volume. In the present study, numerical simulation has been done to investigate the effects of the design parameters on the aerodynamic peformance of the axial-flow turbine blades. Applications are made to the VKI transonic rotor blades. Computed results are analyzed with respect to four parameters and compared with the experimental data.

• Journal of Advanced Marine Engineering and Technology
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• 제31권6호
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• pp.768-776
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• 2007

In this study, axial vibration analysis has been conducted on a propulsion and lift shafting system for an air cushion vehicle using ANSYS code. The shafting system is totally flexible multi-elements system including wood composite material of air propeller. aluminum alloy of lift fan and thin walled shaft with flexible coupling. The analysis calculated the axial natural frequencies and mode shapes of the shafting system taking into account an equivalent mass-elastic model for shafting system as well as the three-dimensional models for propeller blade and fan impeller. Such a flexible shafting system has very intricate vibrating characteristics and especially, axial natural frequencies of flexible components such as propeller blade and impeller of lift fan can be lower to the extent that causes a resonance in the range of operating revolution. The results for axial vibration analysis are presented and compared with the results of axial vibration test for lift fan conducted during Sea Trial.

• 동력기계공학회지
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• 제11권3호
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• pp.47-52
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• 2007

Punching, blanking, trimming and slitting are widely used in shearing processes in sheet metal forming of automotive parts. In this paper the effects of clearance, cutting angle and tool sharpness on the formation of burr were investigated by experimental method in shearing processes of steel sheets, SPCEN and SPRC35E. The amount of burr and the shapes of burr were different between two kinds of steel sheets. It has been shown that the cutting angle of the shearing blade had no effects on the height of burr when the clearance was below the 10% of the steel sheet thickness, and also that the height and shape of burr were not affected by the cutting angle when the wear of shearing blade was below the 10% of the steel sheet thickness. It was known that there had been existing the critical clearance of 10 to 15% for the tested steel sheet, SPCEN and SPRC35E.

• 소음진동
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• 제8권5호
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• pp.870-878
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• 1998

The cross-flow fan which constitutes a fan-duct system with a stabilizer and a scroll casing is widely used in many air-ventilating and air-conditioning devices. Its ooperating points of high efficiency and loading conditions frequently induce a annoying sharp tonal component of discrete frequency on the noise spectrum, which is open called as a BPF(Blade-Passing-Frequency) noise and degrades the sound quality of the devices. this BPF tone has been one of the defects of the cross-flow fan. This study proposes two methods in order to reduce this tonal noise component, which are the random distributions of the fan blades and the skewed shapes of the stabilizer. The proposed methods are verified by a simple analytical model and are applied in manufacturing the cross-flow fan and the stabilizer samples. Some experiments are carried out to verify the reduction capability of BPF tones of above two schemes and the experimental results are analyzed. The comparison between two method is also carried out.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.380-387
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• 2000

In this paper, a successful result of modification of an axial flow fan and a shroud for noise reduction of a window type air conditioner is presented especially in order to verify the importance of blade shape improvement and the searching for the optimal shape of shrouds. Effective ways to work out the result as mentioned above are to make the tip of the blade varied in thickness and to have special shapes. From the viewpoint of the shape in a shroud, several cases were examined and the particular value of a design parameter of the shroud was acquired to get the best noise reduction of an air conditioner. Through the application of the methods, the air conditioner became less noisy by 4.5 dB(A) in terms of air-borne noise produced only by the axial flow fan and consumed less energy by 20.9% compared to the current one.