• 대한기계학회논문집B
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• 제32권4호
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• pp.317-326
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• 2008

The main purpose of the present study is to perform shape optimizations of transonic compressor blade in order to enhance its performance. In this study, the Latin hypercube sampling of design of experiments and the weighted average surrogate model with the help of a gradient based optimization algorithm are used within design space by the lower and upper limits of each design variable and for finding optimum designs, respectively. 3-D Reynolds-averaged Navier-Stokes solver is used to evaluate the objective functions of adiabatic efficiency and pressure ratio. Six variables from lean and airfoil thickness profile are selected as design variables. The results show that the adiabatic efficiency is enhanced by 1.43% by efficiency optimization while the pressure ratio is increased very small, and pressure ratio is increased by 0.24% by pressure ratio optimization.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2005년도 연구개발 발표회 논문집
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• pp.525-532
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• 2005

Shape optimization of a transonic axial compressor rotor operating at the design flow condition has been performed using response surface method and three-dimensional Navier-Stokes analysis. Three design variables of blade sweep. lean and skew are introduced to optimize the three-dimensional stacking line of the rotor blade. The object function of the shape optimization is selected as an adiabatic efficiency. Throughout the shape optimization of the rotor. the adiabatic efficiency is increased by reducing the tub comer and tip losses. Separation line due to the interference between a passage shock and surface boundary layer on the blade suction surface is moved downstream for the optimized blade compared to the reference one.

• 대한기계학회논문집
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• 제14권5호
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• pp.1356-1364
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• 1990

본 연구에서는 단열해석에 재생기효율을 고려함으로써 보다 합리적인 예비설 계조건을 도출하고자 함이다. 스터링기관용 재생기의 특성검토를 통하여 예비설계에 적합한 재생기효율을 정립하며, 기 발표된 단열모델에 대한 해석적 근사해에 적용하는 방법으로 접근한다. 재생기효율이 고려될 경우 기관의 기본형태와 연관된 위상각, 행정체적비, 불용체적비, 압축비등 설계인자의 최적조건에 관하여 취급하며 온도비, 비열비등 부여조건의 변화에 따른 영향을 검토한다.

• 한국유체기계학회 논문집
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• 제14권5호
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• pp.31-38
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• 2011

Optimization using a hybrid multi-objective evolutionary algorithm coupled with response surface approximation has been performed to improve the performance of a transonic axial compressor with circumferential casing grooves. In order to optimize the operating stability and peak adiabatic efficiency of the compressor with circumferential casing grooves, tip clearance, angle distribution at blade tip and the depth of the circumferential casing grooves are selected as design variables. Three-dimensional Reynolds-averaged Navier-Stokes equations with the shear stress transport turbulence model are discretized by finite volume approximations. The trade-off between two objectives with the interaction of blade and casing treatment is determined and discussed with respect to the representative clusters in the Pareto-optimal solutions compared to the axial compressor without the casing treatment.

• ETRI Journal
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• 제24권3호
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• pp.255-258
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• 2002

We created a new design for an Nd-doped clad-pumped silica fiber laser to enhance the pump absorption and lasing efficiency for a butt-coupled, end-pumped scheme. Two concatenated adiabatic tapers formed within the laser cavity simultaneously removed higher order modes and were spliced to conventional single mode fibers. We theoretically analyzed mode propagation along the composite cavity and experimentally achieved continuous wave oscillation in the $LP_{01}$ mode at $1.06\;{\mu}m$ and a laser output power of over 820 mW with a slope efficiency of 27%.

• Steel and Composite Structures
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• 제43권5호
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• pp.523-532
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• 2022

Turbocharger technology is one of the ways to survive in a competitive market that is facing increasing demand for fuel and improving the efficiency of vehicle engines. Turbocharging allows the engine to operate at close to its maximum power, thereby reducing the relative friction losses. One way to optimally understand the behavior of a turbocharger is to better understand the heat flow. In this paper, a 1.7 liter, 4 cylinder and 16 air valve gasoline engine turbocharger with compressible, viscous and 3D flow was investigated. The purpose of this paper is numerical investigation of the number of heat transfer in gasoline engines turbochargers under 3D flow and to examine the effect of different types of coatings on its performance; To do this, modeling of snail chamber and turbine blades in CATIA and simulation in ANSYS-FLUENT software have been used to compare the results of turbine with experimental results in both adiabatic and non-adiabatic (heat transfer) conditions. It should be noted that the turbine blades are modeled using multiple rotational coordinate methods. In the experimental section, we simulated our model without coating in two states of adiabatic and non-adiabatic. Then we matched our results with the experimental results to prove the validation of the model. Comparison of numerical and experimental results showed a difference of 8-10%, which indicates the accuracy and precision of numerical results. Also, in our studies, we concluded that the highest effective power of the turbocharged engine is achieved in the adiabatic state. We also used three types of SiO₂, Sic and Si₃N₄ ceramic coatings to investigate the effect of insulating coatings on turbine shells to prevent heat transfer. The results showed that SiO₂ has better results than the other two coatings due to its lower heat transfer coefficient.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.74.2-74.2
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• 2005

• 한국자동차공학회논문집
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• 제8권2호
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• pp.72-80
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• 2000

This study aims at the optimal design of the screw rotor, its performance analysis, and development of a small screw supercharger which has a low noise compared with the root type supercharger. The basic theoretical equations and the basic design of the screw supercharger have been established. The optical design of the screw rotor's shape has been also performed theoretically. Also, the performance analysis technique of the designed screw rotor has been developed.

• Journal of Advanced Marine Engineering and Technology
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• 제33권8호
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• pp.1144-1151
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• 2009

냉동기는 비단열모세관을 채택하여 사용함으로써 사이클의 효율을 향상시킬 수 있다. 비단열모세관은 모세관과 흡입관을 접합함으로써 둘 사이에 열전달이 일어날 수 있도록 한 장치로서 SLHX 라고 부른다. 두 관을 접합하는 방법은 다양하며 이는 사이클의 성능에 영향을 미칠 수 있다. 본 연구에서는 가장 널리 사용되는 두 가지 접합방법이 냉동사이클에 미치는 영향을 해석하였다. 실험결과 용접형 SLHX의 열저항이 테이프형 SLHX의 열저항 보다 크게 작은 것으로 나타났다. 이를 이용한 사이클해석 결과 용접형 SLHX는 COP 와 냉동능력을 5.09%와 14.77% 향상시키고 테이프형 SLHX는 각각 5.05%와 14.75% 향상시켜 둘 사이의 차이는 매우 작은 것으로 나타났다.

• 한국디지털건축인테리어학회논문집
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• 제11권1호
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• pp.33-42
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• 2011

As the development of construction technology and new materials, building requirements has been varied gadually. Comfortable environment and serviceability of production activity and energy conservation are being dealt with very seriously. Recently localization of engineering technology of Power Plant, however, construction materials and domestic technology are being developed forcingly. According to above topics this thes is going to study roof waterproofing, thermal insulation and evaluate adiabatic performance and evaluation of properties of waterproofing materials and energy conservation. The results of studying and evaluating of roof waterproofing, thermal insulation and adiabatic performance of Power Plant are as follows. 1. Sheet waterproofing method is better than that of asphalt waterproofing method in that adaptability of wearhertight, thermal resistant, contraction and expansion. 2. It is required to replace polyurethane or ethylene used as thermal insulation with rock wool which is noncombustible materials. 3. It is recommended to usd outer insulation method than inner insulation method due to superioty of outer insulation method. Efficiency of insulation materials used in power plant is generally good except perlite mortar used in the power plant(YGN 1-2, GRI 1-2).