• Title/Summary/Keyword: 디퓨져/노즐

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Improvement of Starting Performance in Supersonic Exhaust Diffuser with Second Throat for High Altitude Simulation (2차목에 의한 고고도 모사용 초음속 디퓨져 시동성능 향상)

  • Park, Sung-Hyun;Park, Byung-Hoon;Lim, Ji-Hwan;Yoon, Woong-Sup
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.05a
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    • pp.321-327
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    • 2008
  • Performance characteristics of the axi-symmetric supersonic exhaust diffuser (SED) with a second throat are numerically investigated. Computational strategy repeats those for a straight exhaust diffuser with zero-secondary flows. Renolds-Average Navier-Stokes equations with a standard ${\kappa}-{\varepsilon}$ turbulence model incorporated with standard wall function are solved to simulate the diffusing evolutions of the nozzle plume. The methodology is validated with accuracy. To predict the improvement of starting performance by second throat diffuser, diffuser characteristic curve due to the SED equipped with the second throat is speculated with respect to that of a straight area type as a function of nozzle stagnation pressure. Principal physics caused by the of the second throst is also addressed in terms of a second throat area ratio.

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Analysis of Characteristics of Second Throat Exhaust Diffuser for Simulating High-Altitude of Liquid Rocket Engine by Using Computational Fluid Dynamics (CFD를 이용한 액체로켓엔진 고고도 모사용 2차목 초음속 디퓨져 특성 해석)

  • Moon, Yoon-Wan;Lee, Eun-Seok
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2011.11a
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    • pp.968-969
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    • 2011
  • The characteristics of second throat exhaust diffuser were investigated by using CFD. Because the second throat exhaust diffuser(STED) is known as the effective device for simulating high-altitude circumstance more than a cylindrical supersonic diffuser STED was analyzed. The back pressure around nozzle was reduced by entrance size of STED and it was observed that the initial strong shock was the weak oblique shock along the diffuser. Therefore the static pressure at nozzle exit was recovered as the ambient pressure and the STED worked well.

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Study on Design- and Operating- Parameters of Supersonic Exhaust Diffusers Simulating high Altitude (고고도 모사용 초음속 디퓨져의 설계인자 및 작동인자에 대한 연구)

  • Yoon, Sang-Kyu;Kim, Jin-Kon;Sung, Hong-Gye;Kim, Yong-Wook;Oh, Seung-Hyup
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2007.04a
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    • pp.303-306
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    • 2007
  • A engineering analysis has been conducted to study operating characteristics of a supersonic exhaust diffuser simulating high altitude atmosphere from a flow-developing point of view. Emphasis is placed in the detail flow structure resulting from several design- and operating- parameters of the diffuser such as the area ratios of a exhaust nozzle to the diffuser, the vacuum chamber size, and jet pressure.

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디퓨져의 확대각이 임계노즐 유동에 미치는 영향

  • 김재형;김희동
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2002.04a
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    • pp.31-32
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    • 2002
  • 임계노즐(critical nozzle)은 유동을 유로 최소단면부에서 초크시켜, 질량유량을 계측하기 위한 일종의 유체기구로, 최근 다양한 분야에서 널리 활용되고 있다. 압축성 기체역학의 관계식에 의하면, 임계노즐을 통하는 기체유동의 이론적인 질량유량은 노즐 목의 직경, 노즐 상류의 온도와 압력 그리고 기체의 비열비 등의 함수로 주어진다 그러나 실제 유동에서는 점성과 열전달 등의 초과로 인하여, 이론적 질량 유량과 실제유량의 비 즉 유출계수(discharge coefficient)의 값은 1.0으로 되지 않는다.

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Numerical Analysis about the Flow Characteristics for Different Figures of Inlet and Outlet in Diffuser/Nozzle based on Piezoelectric Micropump (디퓨져/노즐을 이용한 압전형 마이크로 펌프의 입 . 출구 형상 차이에 따른 유동특성에 관한 수치해석적 연구)

  • Kim, Chang-Nyung;Kim, Chin-Uck
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.3104-3109
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    • 2007
  • The present study has been carried out to investigate the pumping characteristics for different figures of inlet and outlet in diffuser/nozzle based on piezoelectric micropump. Piezoelectric micropump system consists of several parts like a pumping chamber, diffuser/nozzle, piezoelectric element and tubes. Parts of the micropump connected with diffuser/nozzle and tubes have been analyzed.. The magnified parts have been classified into two different models based on their resistance. These models have been further classified into six models with each one having three different angles at the magnified parts. Each model has been compared and analyzed using the simulation tool, namely, CFD-ACE depending on their flow rates and characteristics.

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Investigation concerning Design Method of the Diffuser Expansion Ratio Commanding a Starting of the Second Throat Exhaust Diffuser for High Altitude Simulation (고도모사용 2차목 디퓨져 시동을 위한 디퓨져 팽창비 설계기법에 관한 연구)

  • Park, Sung-Hyun;Park, Byung-Hoon;Lim, Ji-Hwan;Yoon, Woong-Sup
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.11a
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    • pp.299-304
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    • 2008
  • Starting characteristics of the axi-symmetric second throat exhaust diffuser (STED) with zero-secondary flows are numerically investigated. Renolds-Average Navier-Stokes equations with a standard ${\kappa}-{\varepsilon}$ turbulence model incorporated with enhanced wall treatment are solved to simulate the diffusing evolutions of the nozzle plume. Minimum (optimum) starting pressure difference of 20$\sim$25% between 1-D theory and the measured data validated from previous results[5] is also applied to predict the range of an effective diffuser expansion ratio (Ad/At) in this system.

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CFD Analysis on the Flow Characteristics of Diffuser/Nozzles for Micro-pumps (마이크로 펌프용 디퓨져/노즐의 유동 특성에 관한 CFD 해석)

  • Kim Donghwan;Han Dong-Seok;Jeong Siyoung;Hur Nahmkeon;Yoon Seok-Jin
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.17 no.6
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    • pp.544-551
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    • 2005
  • The flow characteristics have been numerically investigated for various shapes of the diffuser/nozzles which are used for a valveless micro-pump. The important parameters considered in this study are the throat width ($15\~120\mu$m), the taper angle ($3.15\~25.2^{\circ}$), and the diffuser length ( $600\~4,800\mu$m), and the size of the middle chamber ($1\~16mm^2$). To find the optimal values for these parameters, steady state calculations have been performed assuming the constant pressure difference between the inlet and exit of the flow For the taper angle and the throat width, it is found that there exists an optimum at which the net flow rate is the greatest. The optimal taper angle is in the range of $10\~20^{\circ}$ for all the pressure differences; and the throat width indicates an optimal value near $75\mu$m for the case of 35 kPa pressure difference. The net flow rate is also influenced by the size of the middle chamber. With decreasing chamber size, the net flow rate is reduced because of the interference between two streams flowing into the middle chamber. The unsteady pulsating flow characteristics for a micro-pump with a given diffuser/nozzle shape have been also investigated to show the validity of the steady state parametric study.

Concept Design of High Altitude Simulation Test Facility (고공환경모사 시험설비 구축을 위한 개념설계)

  • Kim, Sang-Heon;Kim, Yong-Wook;Lee, Jung-Ho;Yu, Byung-Il;Cho, Sang-Yeon;Oh, Seung-Hyub
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2006.11a
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    • pp.75-81
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    • 2006
  • The propulsion system of KSLV-I second stage is engine with high expansion ratio and its starting altitude is high. To verify the performance of engine before the launch in the ground, high altitude test facility to simulate its operating condition is necessary. This material is about the concept design of high altitude simulation test facility for second stage engine. And it will be the basis for the construction of test facility and the test of engine.

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