• 제목/요약/키워드: Shape of Nozzle

검색결과 432건 처리시간 0.031초

Shape Effect of Inlet Nozzle and Draft Tube on the Performance and Internal Flow of Cross-Flow Hydro Turbine

  • Choi, Young-Do;Son, Sung-Woo
    • Journal of Advanced Marine Engineering and Technology
    • /
    • 제36권3호
    • /
    • pp.351-357
    • /
    • 2012
  • Small hydropower is a reliable energy technology to be considered for providing clean electricity generation. Producing electrical energy by small hydropower is the most efficient contribution to renewable energy. Cross-flow turbine is adopted primarily because of its simple structure and high possibility of applying to small hydropower. The purpose of this study is to investigate the effect of inlet nozzle shape on the performance and internal flow of a cross-flow turbine for small hydropower by CFD analysis. Moreover, the shape effect of draft tube has been investigated according to modified shapes of the length and the diffuse angle. The results show that relatively narrow and converging inlet nozzle shape gives better effect on the performance of the turbine.

소형 초음속 연소시험 장치를 위한 형상 천이 노즐 설계 (Design of a Shape Transition Nozzle for Lab-scale Supersonic Combustion Experimental Equipment)

  • 성부경;황원섭;최정열
    • 한국항공우주학회지
    • /
    • 제48권3호
    • /
    • pp.207-215
    • /
    • 2020
  • 소형 초음속 연소시험 장치 구축의 일부로서 형상 천이 노즐 설계 연구를 수행하였다. 원형의 연소식 공기가열기에 정사각형 단면의 초음속 연소기를 연결하기 위하여 MOC 설계기법을 이용하여 초음속 형상 천이 노즐의 면적변화를 산출하였다. 천이율을 조절하기 위하여 형상 천이 함수를 도입하였다. 3차원 전산유체 해석을 통한 경계층 보정과 함께 몇 가지 형상 천이 함수의 영향을 살펴보았다. 본 연구의 형상 천이 노즐에서는 일반적인 사각단면 노즐에서 모서리에 발생하는 압력구배에 의한 재순환영역과 이에 의한 노즐 벽 중심부의 경계층 발달이 비교적 작게 나타남을 확인하였다.

TIG용접에서 가스력을 이용한 비드형상제어를 위한 실드가스 노즐의 최적 형상에 관한 연구 (II) - 벤투리 노즐의 위보기 자세 용융금속제어 효과 - (A Study on Optimum Shape of Shield Gas Nozzle for Bead Shape Control in TIG Welding using Gas Force (II) - Effect of Molten Metal Control by Venturi Nozzle in Overhead Position -)

  • 함효식;서지석;최윤환;이연원;조상명
    • Journal of Welding and Joining
    • /
    • 제29권3호
    • /
    • pp.58-63
    • /
    • 2011
  • Bead shape control with gas force process has been developed to overcome the concave back bead in pipe orbital welding. However, It is impossible to make a convex back bead using the existing gas nozzle, because it has high gas-consuming and low gas force. The purpose of this paper, to develop optimum shape of nozzle which to reduce the consumption of gas, maximizing the shield gas force with low cost and high productivity coincide the Green welding. In this paper venturi-type nozzle was compared with existing CP-type nozzle by TIG pulse welding in overhead position. As a result, CP-type occurs the wormholes in the overhead position, but the Venturi-type without the pore and formed a good bead appearance.

충돌 제트에서 Rod 형상 변화에 따른 주변 유동 특성연구 (A Study on The Flow Characteristics according to Changes of Rod Shape on Impinging Jet)

  • 손승우;이상범;강도훈;송민근;주은선
    • 대한기계학회:학술대회논문집
    • /
    • 대한기계학회 2002년도 학술대회지
    • /
    • pp.525-528
    • /
    • 2002
  • The objective of this study is to investigate characteristics of flow by the Rod shape and the choice of the turbulent intensity enhancement section. The Rod was setup vertically to the way of a nozzle exit flow and nozzle diameter is 17mm. Rod height is 5mm and its shapes are square, triangle, and circle. Characteristics of fluid such as velocity vector distribution, kinetic energy, turbulent intensity, and etc. were visualized, observed, and considered at 3 kinds of Re No. such as 2000, 3000, and 4000. The characteristics of flow field were investigated in each case of the distance rate from the nozzle exit to impinging plate(H/B=8, 10). The temperature of water is $20^{\circ}E$ and the measurement region divided by 3 sections(I, II, III). The nozzle diameter is 17mm. As the experimental result by PIV measurement, scale of the vector profile showed a tendency to an unbalance parabola distribution as increasing of the Re No. When the impinging plates such as square, triangle, and circle shape are installed respectively in front of the flow accelerated, rod shape of the highest velocity vector is circle shape and rod shape of the highest turbulent Intensity is square shape.

  • PDF

Effect of Guide Nozzle Shape on the Performance Improvement of a Very Low Head Cross Flow Turbine

  • Chen, Zhenmu;Singh, Patrick Mark;Choi, Young-Do
    • 한국유체기계학회 논문집
    • /
    • 제17권5호
    • /
    • pp.19-26
    • /
    • 2014
  • The cross flow turbine attracts more and more attention for its relatively wide operating range and simple structure. In this study, a novel type of micro cross flow turbine is developed for application to a step in an irrigational channel. The head of the turbine is only H=4.3m and the turbine inlet channel is open ducted type, which has barely been studied. The efficiency of the turbine with inlet open duct channel is relatively low. Therefore, a guide nozzle on the turbine inlet is attached to improve the performance of the turbine. The guide nozzle shapes are investigated to find the best shape for the turbine. The guide nozzle plays an important role on directing flow at the runner entry, and it also decreases the negative torque loss by reducing the pressure difference in Region 1. There is 12.5% of efficiency improvement by attaching a well shaped guide nozzle on the turbine inlet.

폴리우레탄 발포 노즐 형상이 혼합 성능에 미치는 영향 (Influences of Polyurethane Nozzle Shape on Mixing Efficiency)

  • 김도연;이태경;정해도;김형재
    • 한국정밀공학회지
    • /
    • 제33권1호
    • /
    • pp.31-35
    • /
    • 2016
  • For reaction injection molding (RIM) polyurethane was mixed in the mixing head by impingement mixing, injected into the mold, and cured quickly, as soon as the mold is filled. The shape of the nozzle in the mixing head is critical to improve the quality of polyurethane. To achieve homogeneous mixing, an intensive turbulence energy in the mixing nozzle is essential. In this study, a mixing nozzle for RIM was designed, and mixing efficiency was investigated based on experiment. Experiments were conducted with different combinations of nozzle tips and exit diameter to measure the mixing efficiency by measuring jet force and investigating mixing image with high speed camera. Jet force increased gradually and reaches steady state conditions. The jet force depended on shape of nozzle tip and outlet sizes. These results suggest that optimized nozzle configurations are necessary for high efficiency mixing with RIM.

이중판 노즐형 지지격자 스프링의 지지 강성감소를 위한 형상 개선 (Shape Modification for Decreasing the Spring Stiffness of Double-plated Nozzle Type Spacer Grid Spring)

  • 강흥석;송기남;이재호;이강희
    • 대한기계학회:학술대회논문집
    • /
    • 대한기계학회 2001년도 추계학술대회논문집A
    • /
    • pp.400-405
    • /
    • 2001
  • Nozzle of the double-plated grid plays the role of the spring to support a fuel rod as well as to provide the coolant path in grid. The nozzle was known to be necessary to reduce the spring stiffness for supporting performance. In this study the contact analysis between the fuel rod and the nozzle type spacer grid was performed by using ABAQUS standard to propose the preferable shape in tenn of spring performance. Two small cuts at the upper and lower part of the nozzle appeared to have a minor effect in decreasing the nozzle stiffness. A long slot at the center of the nozzle was turned out not only to decrease the spring constant as desired but also to increase the elastic displacement.

  • PDF

극간절연회복성능 향상을 위한 초고압GCB의 노즐형상설계 (Design of Nozzle Shape for UHV GCB to Improve the Dielectric Recovery Characteristics between Electrodes)

  • 송기동;박경엽;신영준;권기영;송원표
    • 대한전기학회:학술대회논문집
    • /
    • 대한전기학회 1995년도 추계학술대회 논문집 학회본부
    • /
    • pp.479-481
    • /
    • 1995
  • This paper presents a method witch tan improve the dielectric recovery characteristics of UHV class gas circuit breakers by changing the nozzle shape. To calculate the dielectric recovery voltage between electrodes, the flow field and electric field analysis in a 362kV model interrupter has been performed with the commercial programs, RAMPANT and FLUX2D, respectively. As a result, we found that the nozzle shape affects the characteristics of dielectric recovery between electrodes and obtained great improvement of it by the changing the downstream nozzle shape.

  • PDF

유입부 비대칭 노즐의 성능연구 (Performance Study of Supersonic Nozzle with Asymmetric Entrance Shape)

  • 이지형;김중근;이도형
    • 한국추진공학회:학술대회논문집
    • /
    • 한국추진공학회 2005년도 제25회 추계학술대회논문집
    • /
    • pp.40-45
    • /
    • 2005
  • 현재까지 적용되고 있는 추력제어 장치로는 크게 노즐의 확대부에 장착되어 화염의 방향을 조종하는 제트베인(jet vane), 제트탭(jet tab)방식과 노즐자체를 회전하는 방식인 볼/소켓형(ball & socket) 노즐, 플렉시블 씰형 (flexible seal)노즐로 구분된다. 본 연구는 노즐자체를 회전하여 추력방향을 제어하는 볼/소켓형(ball & socket) 노즐이 회전할 경우 발생되는 유입부의 비대칭성이 노즐 성능에 미치는 영향을 예측하기 위하여 수행한 3차원 수치해석결과와 공압시험 결과를 수록하였다. 유동해석 결과 유입부의 비대칭성이 유동에 미치는 영향은 노즐 목까지 점차적으로 줄어들고 하류 유동에 미치는 영향이 미비하였으며 해석된 주 추력의 크기는 시험에서 측정된 추력과 비슷한 경향을 나타내었으나 측 추력의 경우 시험 값보다 낮게 나타났다.

  • PDF

유입부 비대칭 노즐의 성능연구 (Performance Study of Supersonic Nozzle with Asymmetric Entrance Shape)

  • 이지형;김중근;이도형
    • 한국추진공학회지
    • /
    • 제10권2호
    • /
    • pp.46-52
    • /
    • 2006
  • 현재까지 적용되고 있는 추력제어 장치로는 크게 노즐의 확대부에 장착되어 화염의 방향을 조종하는 제트베인(jet vane), 제트탭(jet tab)방식과 노즐자체를 회전하는 방식인 볼/소켓형(ball & socket) 노즐, 플렉시블 씰형 (flexible seal)노즐로 구분된다. 본 연구는 노즐자체를 회전하여 추력방향을 제어하는 볼/소켓형(ball & socket) 노즐이 회전할 경우 발생되는 유입부의 비대칭성이 노즐 성능에 미치는 영향을 예측하기 위하여 수행한 3차원 수치해석결과와 공압시험 결과를 수록하였다. 유동해석 결과 유입부의 비대칭성이 유동에 미치는 영향은 노즐 목을 지나면서 현저히 줄어들고 하류 유동에 미치는 영향이 미비하였으며 해석된 주 추력의 크기는 시험에서 측정된 추력과 비슷한 경향을 나타내었으나 측 추력의 경우 시험 값보다 낮게 나타났다. 또한 시험의 결과 기하학적으로 회전된 회전각에 의한 추력방향과 측정된 추력의 방향이 일치하지 않음을 알 수 있었다.