• 한국유체기계학회 논문집
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• 제18권3호
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• pp.60-65
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• 2015

This paper deals with performance characteristics and efficiencies of Pelton turbine can be applied as one of ERDs (Energy Recovery Devices) of PRO (Pressure Retarded Osmosis) system for desalination. The objective of this study is experimentally estimating the performance of micro-scale Pelton turbine for PRO pilot plant. Especially the performance characteristics with variations of jet nozzle diameter of Pelton turbine are discussed in detail. In order to do this, lab scale test rig of Pelton turbine was made for performance test, which includes water tank, Pelton wheel with buckets, jet nozzle and torque brake and so on. The parameter effects related on Pelton turbine's efficiency were investigated and discussed on the influence of the variations of load and speed ratio.

• 한국분무공학회지
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• 제24권3호
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• pp.105-113
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• 2019

In this paper, a study of Urea-SCR System for Dosing Injector for responding to enhanced environmental regulations has been conducted. There is a limit to the experimental approach due to the structural characteristics of the injector. In order to overcome this problem, The analysis was performed assuming unsteady turbulent flow through computational fluid analysis and the internal flow characteristics of the injector were analyzed. By changing the nozzle shape of the injector, the performance factors of the swirl injector by shape were selected and compared. The design parameters were modified by changing the diameter of the nozzle at a constant ratio compared to the base model. Swirl coefficient, outlet mass flow, and sac volume were selected as performance parameters of the injector. The Conv. model to which the taper was applied showed the dominance in mass flow rate, discharge coefficient and swirl because of the smooth fluid flow by shape. Swirl coefficient, outlet mass flow, and sac volume were selected as performance parameters of the injector. As a result of the comparison coefficient derivation with those performance parameters for comparing the performance of the model-specific injector, the Conv-140 model with the nozzle diameter expanded by 140% showed the best value of the comparison coefficient.

• Journal of Biosystems Engineering
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• 제34권3호
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• pp.167-174
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• 2009

This study was conducted to develop an agaricus bisporus washing machine which uses compressed air to remove foreign materials attached on the surface of agaricus bisporus. A prototype of the washing machine was constructed, and performance of removing foreign materials was tested. Research results are as follows: 1. Several transferring methods including PE roller rotation, brush roller rotation, PE screw rotation, vibration plate, and belt conveyor were evaluated. Roller, screw, and vibration methods caused damages on the surface of the products, but belt conveyor method caused the least damages. 2. For air jet, a stationary nozzle type and a rotational type were evaluated. The best air jet nozzle was the jet-type nozzle, and the rotational type was more effective than stationary type nozzle. 3. With the conveyer belt, box type moving method and the rotational air jet nozzle, the washing machine showed the best performance when higher than 5.4${\times}$105 Pa of air jet pressure and lower than 0.047 m/s of moving speed was used. Working performance of the system was 650 kg/h, and the damaging rate was 1.2 %.

• 한국입자에어로졸학회지
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• 제8권2호
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• pp.55-68
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• 2012

Particulate matters (PM) which are collected into a diesel particulate filter (DPF) system have to be periodically removed by thermal oxidation. In this report, we fabricated an electrohydrodynamic-assisted pressure-swirl nozzle to spray diesel droplets finer. Atomization performance of the nozzle was evaluated using both experimental and numerical methods. Two types of nozzle designs, the charge induction type and the charge injection type, were tested. While the former generated diesel droplets of $400\;{\mu}m$ at an applied electric potential over 10 kV, the latter presented the droplets smaller than $23\;{\mu}m$ at an applied electric potential of 8 kV. The numerical simulation results showed that the reduced size of droplets caused higher evaporation of droplets and therefore the increased temperature, which would eventually increase the regeneration performance of the DPF system.

• 반도체디스플레이기술학회지
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• 제11권1호
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• pp.13-19
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• 2012

Thermal performance of an impinging cooling module for 150 W class high power LEDs have been investigated numerically and experimentally. Parametric studies were performed to compare the effect of several design parameters such as nozzle number, nozzle spacing, coolant flow rate, and impinging distance. The experiments were also carried out in order to validate the numerical results and the comparison between the experimental and numerical results showed good agreement. It is found that the overall thermal resistance of impinging cooling module strongly depends on the nozzle number, nozzle spacing, flow rate, and impinging distance. This results showed the optimized operating condition when number of nozzles is 25, nozzles spacing is 4mm, flow rate is 2.70 lpm, distance between nozzles and impinging surface is 2 mm.

• Elastomers and Composites
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• 제55권3호
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• pp.222-228
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• 2020

Rubber materials, used in nuclear power plants, need high heat-oxidation resistance to curing or cracking under a heat aging environment. This is because they are applied to environments with high temperature, high humidity, and radiation exposure. Nuclear radiation causes additional hardening or degradation, therefore, rubber materials need radiation resistance that satisfies the general and any accidental conditions produced in the power plant. Therefore, in this study, we developed a rubber material with excellent heat and radiation resistance for the diaphragm seal of a nuclear steam generator nozzle dam. The rubber material greatly improved the reliability of the steam generator nozzle dam. In addition, 30 inch and 42 inch diaphragm seals were manufactured using the developed rubber material. A nozzle dam was installed in a nuclear power plant and tested under the same conditions as a steam generator to evaluate safety and reliability. In the future, the performance and safety of diaphragm seals developed through field tests of nuclear power plants will be evaluated and applied to currently operating and new nuclear power plants.

• 대한조선학회논문집
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• 제59권2호
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• pp.80-88
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• 2022

A systematic experimental study is carried out for the fire fighting monitor nozzle of 65A diameter to design and manufacture a new nozzle with better water spray performance than available domestic nozzles. The nozzle inlet pressure, flow rate and reach for the discharged water from the nozzle are measured by utilizing the experimental facility consisting of two pumps and piping system with a flow meter and pressure gauges. It was found that the baffle position and baffle head chamfering were the most sensitive design factors to be remarkably changed in the flow rate of the discharged water. Also, It was confirmed that the baffle position and the water exit area had the significant effect on the change in reach distance. The results obtained from this study are expected to be used effectively to design new nozzles with excellent spray performances and also to validate numerical analysis results for evaluating the water spray performance of fire fighting monitor nozzles.

• 한국추진공학회지
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• 제26권5호
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• pp.11-23
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• 2022

길이를 단축한 ED(Expansion Deflection) 노즐의 설계를 위해 길이 단축 방안에 따른 ED 노즐의 수치적 연구를 수행하였다. 첫 번째 방안은 80% 벨 노즐 길이를 갖는 ED 노즐의 확장부 길이를 10%, 20%와 30%씩 단축하는 것이다. 두 번째 방안은 노즐 목 각도를 증가시켜 확장부 길이를 단축하는 것이다. 길이 단축에 따른 윤곽선의 곡률 증가로 인해 80% 벨 노즐 길이인 ED 노즐과 첫 번째 방안의 ED 노즐의 출구 유동 속도의 감소폭이 줄어들어 추력이 유사해졌다. 두 번째 방안의 ED 노즐은 80% 벨 노즐 길이인 ED 노즐보다 출구 유동 속도가 증가하여 추력이 증가하였다.

• 한국항공우주학회지
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• 제45권10호
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• pp.844-854
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• 2017

E-D 노즐은 고도에 따라 노즐 내의 유효 면적을 변화시켜 고도 보정 효과를 통해 성능 이득을 가지는 노즐이다. E-D 노즐은 노즐의 길이를 절감시켜 발사체의 탑재중량이득을 얻을 수 있다고 알려져 있는데, 이러한 E-D 노즐의 장점과 잠재적인 가능성 때문에 영국, 독일, 호주, 유럽 등에서 관련된 연구가 수행되었다. 영국의 경우 E-D 노즐의 유동 특성과 고도 보정 노즐 중 듀얼 벨 노즐과의 성능 비교 연구를 수행하였고, DLR에서는 E-D 노즐의 천이 특성을 파악하기 위해 노즐 압력비 변화에 따른 천이 특성을 중점적으로 분석하였다. 유럽에서는 실제 발사체 Ariane 5 ESC-B 상단에 E-D 노즐 개념을 적용한 수치적 연구를 수행하여 노즐 길이 절감에 따른 탑재중량이득 가능성을 확인하였다. 본 논문에서는 국외에서 수행한 E-D 노즐의 연구 동향을 특징 별로 분류 및 분석하였고, 향후 E-D 노즐 연구의 기초 자료로 활용하고자 한다.

• 한국항공우주학회지
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• 제46권8호
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• pp.662-670
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• 2018

고도보정 노즐은 모든 고도에서 최적의 성능을 발휘할 수 있도록 고안된 노즐이다. 발사체의 비추력을 향상시키기 위한 방법으로는 연소실만의 특성인 특성배기속도를 향상시키는 방법과 노즐만의 특성인 추력계수를 향상시키는 방법이 있다. 고도보정 노즐은 동일한 연소기에서 노즐의 성능 개선을 통해 발사체의 성능향상을 가능하게 한다. 고도보정 노즐에 대한 연구는 독일 DLR에서 활발하게 진행되고 있으며, 미국, 러시아, 영국, 호주, 일본 등 항공우주선진국에서도 진행되고 있다. 본 논문에서는 고도보정 노즐에 대한 기술 현황 및 특허 동향에 대해 조사하였다. 이를 바탕으로 고도보정 노즐의 기술흐름을 파악하고 발사체 성능향상 연구에 기초자료로 활용하고자 한다.