• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.50-55
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• 2015

This study examined the relationship between the shape of the inside of the PRV and the cavitation of the water supply system of an apartment house. In this paper, nine types of PRV with different gaps and shapes were analyzed numerically using a 3D model embedded in the commercial code, ANSYS-CFX. The lowest pressure and the maximum velocity occurred at the narrow gap, which is located at the between the stem and the disk. When the gap size was increased, the vapor volume fraction was always greater than 0, but the vapor volume fraction of the type of expansion pipe approached 0. These results indicate that the cavitation of PRV can be reduced by a shape change to the type of expansion pipe.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.10
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• pp.865-871
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• 2014

This study was conducted with the aim of developing a venturi-type air supply system for a microbubble generator. In order to determine the influence of the varying geometry of the venturi tube on the flow characteristics, a computational fluid dynamics (CFD) simulation was performed using the commercial CFD software ANSYS CFX-15. Furthermore, in order to elucidate the effects of variation in major design dimensions such as the air supply hole size, position of holes, and number of holes on the air supply characteristics, two-phase multiflow CFD analysis was performed. The analysis results showed that the starting point of expansion on the venturi tube with 0.75 is the best hole position and that the air supply hole size and the number of holes are linearly proportional to the amount of air.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.10
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• pp.961-969
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• 2013

In this study, the numerical analysis of a turbulent flow around both a staggered and an inline tube bundle was conducted using ANSYS CFX V.13, a commercial CFD software. The flow was assumed to be steady, incompressible, and isothermal. According to the CFD Best Practice Guideline, the sensitivity study for grid size, accuracy of the discretization scheme for convection term, and turbulence model was conducted, and its result was compared with the experimental data to estimate the applicability of the CFD Best Practice Guideline. It was concluded that the CFD Best Practice Guideline did not always guarantee an improvement in the prediction performance of the commercial CFD software in the field of tube bundle flow.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.5
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• pp.329-339
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• 2017

Impingement jets have been applied in a wide variety of fields as they provide significantly high heat transfer on the impingement-jet stagnation zone. However, the crossflow in an impingement chamber developed by spent wall jets can disrupt and deflect the downstream jets in the array, leading to a decrease in the cooling performance of an array of impingement jets. A numerical analysis is made of the fluid flow and heat transfer characteristics in a corrugated structure that traps the spent air in the corrugations between impingement jets and reduces crossflow effects on downstream jets. All computations are performed by considering a three-dimensional, steady, and incompressible flow by using the ANSYS-CFX 15.0 code. The effects of the configuration parameters of the corrugated structure on crossflow reduction of the array of impingement jets are presented and discussed.

• Journal of the Korea Organic Resources Recycling Association
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• v.21 no.3
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• pp.74-81
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• 2013

In this study, the separation efficiency of wind power selector (the direction of the air flow of the air to perform gravity separation method) of municipal solid waste which was landfilled was investigated to reduce amount of waste that is designed to increase the recycling rate of wastes for the ANSYS CFX Program's numerical methods with wind through the separator. When a suction device designed to suction 1000mL of a plastic bag, the separation efficiency was 100% and when the wind speed was 0.9 m /sec or more and when the wind speed was 1.6 m / sec or more, the efficiency of plastic bottles in a mixture of 500mL and 1500mL plastic bottle waste was 100% and the aluminum screening efficiency of 250mL aluminum can was 100 % when the wind speed was 2.3 m / sec. In the last, 5mm thick compressed aluminum can efficiency was 90 % when the wind speed was 2.4 m / sec.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6412-6418
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• 2014

This paper performed a numerical study of an air-liquid ejector. An ejector is a fluid-transportation device that spouts high-pressure fluid from driving pipes using the kinetic energy of the spouted fluid and increases the pressure through the exchange of momentum with the surrounding gases of the lower pressure. The air-liquid ejector was investigated through steady three-dimensional multiphase CFD analysis using commercial software ANSYS-CFX 14.0. Water as the primary fluid is driven through the driving nozzle and air is ejected as the second gas instead of ozone in real applications. The difference in performance according to the shape of the diffuser of the ejector was examined. The results provide deep insight into the influence of various factors on the performance of the air-liquid ejector. The proposed numerical model will be very helpful for further design optimization of the air-liquid ejectors.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.2
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• pp.246-252
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• 2016

In this study, conceptual design of the fore-body hull form of catamaran type dredging vessel was performed that can effectively remove the contaminated sediments in coastal seabed. The hull form was simpled for the easy hull construction and the resistance performance was investigated to find out the effect of hull form parameters between variation of waterline and angle of entrance, etc. The relation between resistance performance and characteristics of free surface flows according to variation of bow forms was investigated by model testing in the circulating water channel and using Ansys CFX. The improvement of ship resistance performance to the wave resistance decrease due to improved wave pattern has been verified according to move the stem and the volume of the shoulder to the fore part of the vessel.

• Journal of the Korean Applied Science and Technology
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• v.36 no.4
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• pp.1410-1419
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• 2019

In this research, it is to find a method that frost does not form on the outdoor unit to develop a heat pump capable of heating in cold regions. For this reason, we produced an incubator capable of creating an environment of -25℃, and constructed an experimental apparatus so that experiments in the room were possible. However, it is necessary to grasp the characteristics of the air reaching the front of the heat pump outdoor unit installed in the experimental apparatus, and flow analysis was performed using ANSYS CFX, which is general-purpose software. As a result, the flow velocity of the air reaching the front of the outdoor unit in the outdoor unit chamber in the entire region of the simulation conditions (5.0 to 7.5 m/s) has many differences in the upper and lower portions, resulting in a natural state. It turned out that the condition can not be satisfied. Therefore, it is determined that it is necessary to additionally install a frequency divider at the front of the outdoor unit to make the flow velocity constant.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.11
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• pp.903-910
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• 2014

Electric fans, which consist of axial blades, are operated by the induction motor. In this paper, the objective of this study is the performance improvement of the base model fan using the design optimization. In order to aerodynamic analysis, computational simulations are performed using commercial tool ANSYS-CFX ver. 14.5. And k-${\omega}$ SST turbulence model is used for the CFD analysis. The design variables are set up as sweep and lean angles. Volumetric flow rate and torque of the fan blades are fixed to objective function. The optimized model is shown the increment of the volumetric flow rate and the reduction of the torque compared with the base model. The experimental procedure is followed KS C 9301. CFD results and experimental results are fairly well matched.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.2
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• pp.83-93
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• 2017

A numerical analysis is made of the fluid flow and heat transfer characteristics in the corrugated structure that traps the spent air in the corrugations between impinging jets to reduce crossflow effects on downstream jets in the array. All computations are performed by considering three-dimensional, steady state, and incompressible flow by using the ANSYS-CFX 15.0 code. Averaged jet Reynolds number is 10,000. The oblique angles of impingement jets on the spanwise section are $70^{\circ}$, $80^{\circ}$, $90^{\circ}$, and the oblique angles of impingement jets on the streamwise section are $70^{\circ}$, $90^{\circ}$, $110^{\circ}$. The investigation focuses on the oblique angle influence of impinging jet array on the fluid flow and heat transfer characteristics of a corrugated structure.