• Journal of Power System Engineering
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• v.11 no.4
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• pp.98-102
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• 2007

In this study, a measurement method of leakage flow-rate for pneumatic driving apparatus is proposed. The existing measurement methods of leakage flow-rate of air need disassemble the test component. Therefore, there is no effective method to measure the leakage flow-rate while operating pneumatic driving apparatus. In this study, the leakage flow-rate is measured from the pressure change in an isothermal chamber that can realize isothermal conditions by stuffing the steel wool into it. Therefore, a wide range of flow-rate could be measured only from the pressure response and the leakage flow-rate can be measured during operating pneumatic driving apparatus. The effectiveness of the proposed method is proved by experimental results.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.5
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• pp.751-757
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• 2011

The monitoring technique based on electrical conductivity (EC) can provide researchers with some advantages in maintenance management and is cost-effective as compared with existing CSOs monitoring. In this study, the flow rate estimation using EC data was executed in two sites where storm overflow chamber had installed. In the result of A-site, R2 of second order multinomial between dilution ratio of EC and observed flow rate was showed the range of 0.68 ~ 0.77. And $R^{2}$ of B-site was 0.62 ~ 0.81. On the other hand, cumulative frequency of A-site was 43.4 ~ 52.2% in the relative error level of under 20%. And B-site was 10.1 ~ 46.5%. The flow rate estimation formula was improved through consideration of some parameters including antecedent dry days and rainfall duration. And difference between estimated flow rate and observed flow rate in total rainfall event was very small.

• The KSFM Journal of Fluid Machinery
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• v.10 no.1 s.40
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• pp.49-55
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• 2007

An 'Y' strainer type automatic flow rate regulating valve, which functions are to remove impurities from hot water inside the pipe and to maintain a constant flow rate regardless of variations of the differential pressure between valve inlet and outlet at the same time, is developed for distributing hot water equally to several pipes with district heating or central heating system. Numerical analysis of the three dimensional turbulent flow field in a valve shape is carried out to confirm the flow field whether the designed regulator shape is acceptable or not. The final developed valve improves installation time and cost and maintenance ability comparing with set-up 'Y' strainer and regulator separately. Tolerance for the nominal flow rate is also satisfied within ${\pm}5%$.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.3
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• pp.109-115
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• 2019

The purpose of this study was to analyze and test the flow rate of a 1-inch ball valve used in a thermal power plant. To identify the flow-rate characteristics, numerical analysis was conducted and an experimental apparatus of the valve flow rate coefficient was used to compare the flow coefficient Cv values. To determine the internal pressure distribution, the sites of opening ball valves and flow fields were investigated. In particular, a smaller the valve opening resulted in a more complicated the flow field of the ball. The valve flow characteristic test showed that the Cv value and flow rate increased with increasing valve-opening rate and the secondary function was performed. The pressure drop increased as the valve opening rate decreased. In addition, the experimental results for the flow analysis are similar to the numerical analysis results.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.11
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• pp.1035-1042
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• 2005

In the present study, the principle of minimum energy is employed to configure the shape of rivulet flowing down an inclined surface. The profile of laminar rivulet is determined by numerical integration. The maximum center thickness, which corresponds to the minimum thickness of falling film, is found to exist regardless of liquid flow rate and is compared with the analytical and experimental data. At small liquid flow rate the center thickness of rivulet and its width increase almost linearly with flow rate. Once the center thickness of rivulet becomes very close to its maximum value, its growth rate retards abruptly. However the width of rivulet increases proportionally to the liquid flow rate and most part of its free surface is as flat as that of stable film. The growth rate of rivulet thickness with respect to liquid flow rate becomes larger at bigger contact angle. The width of rivulet increases rapidly with its flow rate especially at small contact angle, As the liquid-vapor interfacial shear stress increases, the center thickness of rivulet decreases with its flow rate, which is remarkable at small contact angle. However the effect of interfacial shear stress on the width of rivulet is almost negligible.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.2
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• pp.204-210
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• 2010

The inner structure of the triangular separate bar (TSB) was improved to enhance the productivity of the TSB flow meter by simplifying the machining process for making the flow meter. The cross section of upstream and downstream pressure chamber in the TSB was changed from triangle to circle, which make it possible to substitute the wire cutting by drilling in the process of machining the pressure chamber. The flow rate characteristics of the flow meters was calibrated with a laminar flow meter. Six kinds of flow meters whose diameters of pressure tap for measuring pressure of both upsteam and downstream pressure chamber were different one another were made. The effects of the pressure tap diameter on the flow rate characteristics of the TSB flow meter was little. The mass flow rate characteristics of the flow meters with increasing a non-dimensional parameter which includes the gas temperature, exhaust gas pressure and differential pressure at the flow meters and atmospheric pressure shows nearly linear relationship with a correlation coefficient of R=0.998.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.9 s.240
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• pp.971-978
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• 2005

Effects of inlet distorted flow on performance, stall and surge are experimentally investigated for a high-speed centrifugal compressor. Tested results for the distorted inlet flow cases are compared with the result of the undistorted one. The performance of compressor is slightly deteriorated due to the inlet distortion. The inlet distortion does not affect the number of stall cell and the propagation velocity. It also does not change stall inception flow rate. However, as the distortion increases, stall starts at the higher flow rate for low speed and at the lower flow rate for high speed. For 50,000 rpm stall occurrs as the flow rate decreases, however disappears fur the smaller flow rate. This is due to the interaction of surge and stall. After the stall and surge interact, the number of stall cell decreases.

• Transactions of The Korea Fluid Power Systems Society
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• v.8 no.2
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• pp.36-41
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• 2011

Analysis of two-dimensional flow in an involute gear pump has been done by using FLUENT. Analysis extended to the turbulent flow includes the mass flow rate with functions of pressure difference between inlet and outlet, rotational velocities of involute gear, and clearances between tip of gear and housing. In general mass flow rate decreases with decreasing rotational velocity, and with increasing clearance and pressure difference. The flow rate efficiency of gear pump, which is defined with the theoretical flow rate, has been presented in terms of the above parameters.

• Journal of Biosystems Engineering
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• v.21 no.2
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• pp.155-166
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• 1996

A direct injection sprayer was designed using the concepts of injection mixing and total flow control, flowrate-based system compensating for the variation of forwarding speed. A metered rate, proportionally to the actual diluent flow rate, of a tracer chemical was injected directly into the diluent stream. The injection of chemical may improve the precision and safety of chemical application process. The control system was evaluated for the variables of the control interval, tolerances and sensitivities of flow regulation valve and injection pump. Performance of the system was assessed as that the response time of flow rate, response time of injection rate, absolute steady state error, and the coefficient of variance(C.V.) of concentration were 8.5 and -0.53 seconds, 0.067 lpm(0.8%) and 3.15%, respectively, at optimal parameters of control interval of 1.0 sec, fast sensitivity of flow regulation valve, medium sensitivity of injection pump and medium tolerance of flow rate. Performance of the system can be improved by increasing the sensitivity of flow regulating valve and employing a high resolution velocimeter, such as Doppler radar.

• Tribology and Lubricants
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• v.22 no.1
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• pp.47-52
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• 2006

It is very important to control pressure and flow rate distribution on each component of engine lubrication network. Sometimes many kinds of orifice are used to control flow rate in the hydraulic lubrication field. In this study orifices were adopted on the lubrication network to control oil flow rate distribution. And unsteady transient flow network analysis was carried out to find out the effects of orifices on the engine oil circuit system.