• 설비공학논문집
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• 제25권2호
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• pp.94-100
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• 2013

A convergent-divergent nozzle or venturi nozzle has been used to accelerate the wind speed at its throat. The wind speed at the throat is inversely proportional to its area according to the continuity equation. In this numerical study, an airflow phenomena in the venturi system placed at a vertical structure was investigated to understand the vortex effect occurred at the rear-side of the vertical structure on the air speed increment at the throat of the venturi system. For this study, a venturi system sized by $20(m){\times}20(m){\times}6(m)$ was modelled and the area ratio(AR) of the model venturi was 2.86. To see the vortex effect on the air flow acceleration in the venturi throat, two different boundary conditions was defined From the study, it was found that the pressure coefficient(CP) of the venturi system with the vortex formed at the exit of the venturi was about 2.5times of the CP of the venturi system without the vortex effect. The velocity increment rate of the venturi system with the vortex was 61% but 9.5% only at the venturi system without the vortex. Conclusively, it can be said that the venturi system installed in a vertical structure has very positive effect on the flow acceleration at its throat due to the vortex formed at the rear-side of the vertical structure.

• 한국산업융합학회 논문집
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• 제22권2호
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• pp.173-181
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• 2019

This study was carried out numerically to investigate the flow characteristics in the Venturi tube with $90^{\circ}$ T-branch tube and the inflow of condensed water into the Venturi tube from the branch tube. In this study, the diameter of the branch tube(1, 2, 3mm) and the neck diameter of the Venturi tube(0.3, 0.9, 1.5mm) were varied. The flow rate of the water at the Venturi tube inlet is 80cc/min and the water temperature is 288K. The condensed water temperature at the branch tube inlet is 355K. It was found that the velocity and pressure of the fluid near the branch point in the Venturi tube were more dependent on the diameter of the Venturi tube than the diameter of the branch tube. The temperature of the mixed water at the exit of the Venturi tube was the highest when the Venturi tube's neck diameter is 0.9mm and the branch tube diameter is 2mm. This means that the condensed water is flowing well through the branch tube.

• Nuclear Engineering and Technology
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• 제45권2호
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• pp.203-210
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• 2013

The objective of this conducted research is to study the iodine removal efficiency in a self-priming venturi scrubber for submerged and non-submerged operating conditions experimentally and theoretically. The alkaline solution is used as an absorbent, which is prepared by dissolving sodium hydroxide (NaOH) and sodium thiosulphate ($Na2S_2O_3$) in water to remove the gaseous iodine ($I_2$) from the gas. Iodine removal efficiency is examined at various gas flow rates and inlet concentrations of iodine for submerged and non-submerged operating conditions. In the non-submerged venturi scrubber, only the droplets take part in iodine removal efficiency. However, in a submerged venturi scrubber condition, the iodine gas is absorbed from gas to droplets inside the venturi scrubber and from bubbles to surrounding liquid at the outlet of a venturi scrubber. Experimentally, it is observed that the iodine removal efficiency is greater in the submerged venturi scrubber as compare to a non-submerged venturi scrubber condition. The highest iodine removal efficiency of $0.99{\pm}0.001$ has been achieved in a submerged self-priming venturi scrubber condition. A mathematical correlation is used to predict the theoretical iodine removal efficiency in submerged and non-submerged conditions, and it is compared against the experimental results. The Wilkinson et al. correlation is used to predict the bubble diameter theoretically whereas the Nukiyama and Tanasawa correlation is used for droplet diameter. The mass transfer coefficient for the gas phase is calculated from the Steinberger and Treybal correlation. The calculated results for a submerged venturi scrubber agree well with experimental results but underpredicts in the case of the non-submerged venturi scrubber.

• Journal of Advanced Marine Engineering and Technology
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• 제35권7호
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• pp.914-920
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• 2011

For a hydro turbine electricity generation system in river or bay, a venturi system could be applied to accelerate flow speed at the inlet of the turbine system in a flow field. In this study, a steady flow simulation was conducted to understand the effect of venturi system on the acceleration of current speed at the inlet of a hydro turbine system. According to the continuity equation, the flow speed is inversely proportional to the cross-section area in a conduit flow; however, it would be different in an open region because the venturi system would be an obstruction in the flow region. As the throat area is 1/5 of the inlet area of the venturi, the flow velocity is accelerated up to 2.1 times of the inlet velocity. It is understood that the venturi system placed in an open flow region gives resistance to the upcoming flow and disperses the flow energy around the venturi system. The result of the study should be very important information for an optimum design of a hydro turbine electricity generation system.

• 한국추진공학회지
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• 제25권6호
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• pp.12-19
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• 2021

액체 추진제 공급 시, 하류의 압력변동과 무관하게 일정한 유량을 공급하기 위한 캐비테이션 벤츄리의 실험적 연구가 수행되었다. 캐비테이션 벤츄리의 성능을 파악하기 위해 벤츄리를 설계, 제작하여 후단의 형상, 전단압, 그리고 배압에 따른 유량과 벤츄리 전·후단 압력비를 관찰하였다. 일반적으로 캐비테이션 벤츄리의 구조적인 형상에만 종속하는 벤츄리 임계압력비는 실험결과, 후단의 형상 및 벤츄리 전단압과 관계없이 0.74로 일정함을 확인하였다.

• 대한기계학회논문집B
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• 제40권10호
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• pp.667-672
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• 2016

본 연구는 다공성 재질의 목을 가진 벤츄리관 공기방울 발생장치의 설계를 위해 수행되었다. 주어진 공급 유량 조건 하에서 다공성 재질을 통해 공급되는 공기방울의 공급 성능 최대화를 위한 벤츄리관의 길이와 직경을 결정하기 위해 2상 전산유동해석에 기초한 최적화 설계를 수행하였다. 이러한 일련의 연구 수행 결과를 통해 다공성 재질을 통해 공급되는 공기방울의 공급 성능 최대화를 위한 공급유량과 이들 설계변수들 관계를 규명하였다.

• Nuclear Engineering and Technology
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• 제53권1호
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• pp.69-78
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• 2021

Venturi meter is frequently used in feed water flow control system in a nuclear power plant. Its accurate measurement plays a vital role in the safe operation of the plant. This paper firstly investigates the influence of the length of each section of pipeline, the throat inner diameter of Venturi and the flow characteristics in a single-phase flow on the accuracy of Venturi measurement by numerical calculation. Then the flow and the accuracy are discussed in a multi-phase flow. Numerical results show that the geometrical parameters and the characteristics of complex turbulent flow in the single-phase flow have little impact on the accuracy of Venturi flow rate measurement. In the multi-phase flow, the calculated flow rate of Venturi deviated from the actual flow rate and this deviation value is closely related to the amount of steam in the pipeline and increases sharply with the increase of the amount of steam. The over-reading of Venturi flow rate is present.

• 한국가시화정보학회지
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• 제21권1호
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• pp.57-66
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• 2023

In this study, we investigate the effects of a single roughness element on Venturi cavitation. The single roughness element of hemispherical shape is installed at the throat inlet of a Venturi tube. Since the wake behind the roughness element induces an additional pressure drop, cavitation inception occurs at a higher Cavitation number for the Venturi model with the single roughness element than for the Venturi model with no roughness. Cavitation bubbles form along the wake of the roughness element and lengthen in the streamwise direction as the Cavitation number decreases, forming a longitudinal cavitation. With a further decrease in the Cavitation number, the longitudinal cavitation bubble merges with the sheet cavitation initiated from the exit edge of the Venturi tube throat, followed by the shedding of cloud cavitation. The merging of the longitudinal cavitation and sheet cavitation is accompanied by a sudden decrease in the discharge coefficient and an increase in the pressure loss coefficient as it chokes the flow inside the Venturi tube.

• 드라이브 ㆍ 컨트롤
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• 제20권4호
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• pp.123-132
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• 2023

In disaster situations, to facilitate rapid drainage, electric underwater pumps are installed manually. This poses a high risk of electric shock accidents due to a short circuit, and a lot of time is required for hose connection and installation of electrical devices. To solve these problems, a Venturi pump using the venturi effect without external power is used. However, Venturi pumps that operate without external power make it difficult to install flow sensors such as electric devices; consequently, it is difficult to check the real-time flow rate. This paper proposes a flow estimation logic to replace the function of the flow sensor for the venturi pump . To develop the flow estimation logic, the flow characteristics of the venturi pump, according to the operating conditions, were checked. After that, the relationship with the flow rate of the venturi pump was defined using a pressure sensor corresponding to a low-cost sensor. Finally, an analysis of the estimation error was performed using the developed flow estimation logic.

• Nuclear Engineering and Technology
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• 제56권3호
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• pp.1081-1090
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• 2024

The liquid Lead-bismuth eutectic is used as the coolant for Gen-IV reactor concepts. However, due to its strong corrosive and high operating temperature, it is difficult to accurately measure the flow rate in long-term operating conditions. Venturi flowmeter is a simple structured flowmeter, which plays a very important role in the flow measurement of high-temperature liquid metals, especially since the existing flowmeters are difficult to be competent. It has the advantages of easy maintenance and stable operation. Therefore, it is necessary to study the operating conditions of the venturi flowmeter under high-temperature conditions. This work performs a series of simulations of the fluid-solid interaction between the flow liquid metal and venturi flowmeter with COMSOL software, including the dimensional sensitivity analysis of the venturi flowmeter to explore the most suitable structure and parameters for liquid heavy metal, the sensitivity analysis of the geometric parameters of the venturi tube on the varying conditions. It shows that when the contraction angle of the venturi flowmeter is 33°, the diffusion angle is 13°, the diameter of the throat is 8 mm, and the temperature of the lead-bismuth eutectic is 733.15 K, it is most suitable for the measurement in the lead-bismuth circuit.