• Title/Summary/Keyword: supersonic jet impingement

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Numerical Analysis on the Characteristics of Supersonic Steam Jet Impingement Load (초음속 증기제트의 충돌하중 특성에 대한 수치해석 연구)

  • Oh, Se-Hong;Choi, Dae Kyung;Park, Won Man;Kim, Won Tae;Chang, Yoon-Suk;Choi, Choengryul
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.14 no.2
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    • pp.1-10
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    • 2018
  • Structures, systems and components of nuclear power plants should be able to maintain safety even in the event of design-basis accidents such as high-energy line breaks. The high-pressure steam jet ejected from the broken pipe may cause damage to the adjacent structures. The ANSI/ANS 58.2 code has been adopted as a technical standard for evaluating the jet impingement load. Recently, the U.S. NRC pointed out the non-conservativeness of the ANSI/ANS 58.2, because it does not take into account the blast wave effect, dynamic behavior of the jet, and oversimplifies the shape and load characteristics of the supersonic steam jet. Therefore, it is necessary to improve the evaluation method for the high-energy line break accident. In order to evaluate the behavior of supersonic steam jet, an appropriate numerical analysis technique considering compressible flow effect is needed. In this study, numerical analysis methodology for evaluating supersonic jet impingement load was developed and verified. In addition, the conservativeness of the ANSI/ANS 58.2 model was investigated using the numerical analysis methodology. It is estimated that the ANSI jet model does not sufficiently reflect the physical behavior of under-expanded supersonic steam jet and evaluates the jet impingement load lower than CFD analysis result at certain positions.

Numerical Analysis on the Transient Load Characteristics of Supersonic Steam Impinging Jet using LES Turbulence Model (LES 난류모델을 이용한 초음속 증기 충돌제트의 과도하중 특성에 대한 수치해석 연구)

  • Oh, Se-Hong;Choi, Dae Kyung;Park, Won Man;Kim, Won Tae;Chang, Yoon-Suk;Choi, Choengryul
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.14 no.2
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    • pp.77-87
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    • 2018
  • In the case of high-energy line breaks in nuclear power plants, supersonic steam jet is formed due to the rapid depressurization. The steam jet can cause impingement load on the adjacent structures, piping systems and components. In order to secure the design integrity of the nuclear power plant, it is necessary to evaluate the load characteristics of the steam jet generated by high-energy pipe rupture. In the design process of nuclear power plant, jet impingement load evaluation was usually performed based on ANSI/ANS 58.2. However, U.S. NRC recently pointed out that ANSI/ANS 58.2 oversimplifies the jet behavior and that some assumptions are non-conservative. In addition, it is recommended that dynamic analysis techniques should be applied to consider transient load characteristics. Therefore, it is necessary to establish an evaluation methodology that can analyze the dynamic load characteristics of steam jet ejected when high energy pipe breaks. This research group has developed and validated the CFD analysis methodology to evaluate the transient behavior of supersonic impinging jet in the previous study. In this study, numerical study on the transient load characteristics of supersonic steam jet impingement was carried out and amplitude and frequency analysis of transient jet load was performed.

Prediction of Supersonic Jet Impingement on Flat Plate and Its Application (초음속 충돌제트에 대한 수치적 연구와 응용)

  • Lee K. S.;Hong S. K.;Park S. O.;Bae Y. S.
    • Proceedings of the KSME Conference
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    • 2002.08a
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    • pp.225-228
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    • 2002
  • Supersonic jet impingement on a flat plate has been investigated to show the flow physics for different jet heights and to demonstrate the adequacy of the characteristics-based flux-difference Wavier-Stokes code Current study also compares the steady-state solutions obtained with variable CFL number for different grid spacing with the time-accurate unsteady solutions using the inner iterations, displaying a good agreement between the two sets of numerical solutions. The unsteady nature of wall fluctuations due to bouncing of the plate shock is also uncovered for high pressure ratios. The methodology is then applied to a complex vertical launcher system where the jet plume hits the bottom wail, deflects into the plenum and eventually exits through the vertical uptake. Flow structures within vertical launcher system are captured and solutions are partially verified against the flight test data. Present jet impingement study thus shows the usefulness of CFD in designing a complex structure and predicting flow behavior within such a system.

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Numerical Analysis on Feedback Mechanism of Supersonic Impinging Jet using LES (LES를 이용한 초음속 충돌제트의 피드백 메커니즘에 대한 수치해석 연구)

  • Oh, Se-Hong;Choi, Dae Kyung;Kim, Won Tae;Chang, Yoon-Suk;Choi, Choengryul
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.13 no.2
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    • pp.51-59
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    • 2017
  • Steam jets ejected from a rupture zone of high energy pipes may cause damage to adjacent structures. This event could lead to more serious accidents in nuclear power plants. Therefore, to prevent serious accidents, high energy pipes of nuclear power plants are designed according to the ANSI / ANS 58.2 technical standard. However, the US Nuclear Regulatory Commission (USNRC) has recently pointed out non-conservatism in existing high energy pipe fracture evaluation methods, and required the assessment of the unsteady load of the jet caused by a potential feedback mechanism as well as the impact range of steam jet, the jet impact loads and the blast wave effects at the initial breakage stage. The potential feedback mechanism refers to a phenomenon in which a vortex formed by impingement jets amplifies vortex itself and induces jet vibration in a shear layer. In this study, CFD methodology using the LES turbulence model is established and numerical analysis is carried out to evaluate the dynamic behavior of impingement jets and the potential feedback mechanism during jet impingement. Obtained results have been compared with an empirical correlation and experiment.

NUMERICAL INVESTIGATIONS OF SUPERSONIC JET IMPINGEMENT ON A FLAT WALL IN A CONFINED PLENUM (화염배출 출구면적 변화에 대한 수직발사관 내부 초음속 충돌유동의 수치적 해석)

  • Lee K. S.;Hong S. K.;Ahan C. S.
    • 한국전산유체공학회:학술대회논문집
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    • 2005.10a
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    • pp.281-285
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    • 2005
  • Viscous solutions of supersonic jet impinging on a flat wall in a confined plenum are simulated using three-dimensional Navier-Stokes solver. A confined plenum was designed for simulating the missile launch and analyzing the behavior of the exhaust plume, which were accompanied by complex flow interactions with shock and boundary layer. Concerns of this paper are to show accurate simulation of internal flow in confined plenum and to demonstrate the jet flow structure when the jet interacts with a small opening on the side. Objectives of this numerical simulation are to understand the effect of changing the plume exit area of the plenum. Pressure and temperature rise at certain position in the plenum are traced and compared with test data.

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Jet Flow Interactions in the Practical Airframe Design

  • Hong, Seung-Kyu;Lee, Kwang-Seop
    • 한국전산유체공학회:학술대회논문집
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    • 2006.10a
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    • pp.20-21
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    • 2006
  • Three kinds of jet flows encountered in the practical airframe design phase are discussed in this paper. Firstly, the side jet effect on the cavity flow over the flat plate was investigated. Secondly, the aerodynamic modeling of side jet influence on body-tail configuration was presented. Computational study of the similarity parameters was done to minimize the wind tunnel test. Lastly, supersonic jet impingement on a flat plate surrounded by solid walls was simulated numerically for both axi-symmetric and three-dimensional calculations with moving body method.

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A Numerical Analysis of Supersonic Impinging Jet Flows on Curved Surfaces using Upwind Wavier-Stokes Method (Upwind Navier-Stokes 방법을 이용한 굴곡면에 충돌하는 초음속 제트유동의 수치 해석적 연구)

  • Seo Jeong Il;Song Dong Joo
    • Proceedings of the KSME Conference
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    • 2002.08a
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    • pp.229-232
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    • 2002
  • For the purpose of Thermal Protection Material design problem, a numerical analysis of axisymmetric high temperature supersonic impinging jet flows of exhaust gas from combustor on curved surfaces has been accomplished. A modifed CSCM Upwind Navier-Stokes method which is able to cure the carbuncle Phenomena has been developed to study strong shock wave structure and thermodynamic wall properties such as pressure and heat transfer rate on various curved surfaces. The results show that the maximum heat transfer rate which is the most important parameter affecting thermo-chemical surface ablation on the plate did not occur at the center of jet impingement, but rather on a circle slightly away from the center of impingement and the shear stress distribution alone the wall is similar to the wall heat transfer late distribution.

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On the Assessment of Compressibility Effects of Two-Equation Turbulence Models for Supersonic Transition Flow with Flow Separation

  • Sung, Hong-Gye;Kim, Seong-Jin;Yeom, Hyo-Won;Heo, Jun-Young
    • International Journal of Aeronautical and Space Sciences
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    • v.14 no.4
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    • pp.387-397
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    • 2013
  • An assessment of two-equation turbulence models, the low Reynolds k-${\varepsilon}$ and k-${\omega}$ SST models, with the compressibility corrections proposed by Sarkar and Wilcox, has been performed. The compressibility models are evaluated by investigating transonic or supersonic flows, including the arc-bump, transonic diffuser, supersonic jet impingement, and unsteady supersonic diffuser. A unified implicit finite volume scheme, consisting of mass, momentum, and energy conservation equations, is used, and the results are compared with experimental data. The model accuracy is found to depend strongly on the flow separation behavior. An MPI (Message Passing Interface) parallel computing scheme is implemented.

Characteristics of Supersonic Nozzle and Jet Impingement (초음속 노즐과 벽면 충돌제트의 유동특성)

  • Hong, Seung-Kyu;Lee, Kwang-Seop;Sung, Woong-Je
    • Journal of the Korea Institute of Military Science and Technology
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    • v.4 no.2
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    • pp.256-262
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    • 2001
  • Viscous solutions of supersonic side jet nozzle and supersonic jet impinging on a flat plate are simulated using three-dimensional Navier-Stokes solver. For rapid and abrupt control of a missile in supersonic flight, side jet on a missile body is found to be a useful devise as evidenced by recent missile development at several nations. The magnitude of the side jet and the duration of it decide the level of control of such a missile system. The aerodynamic characteristics of the side jet devise itself are examined in terms of key parameters such as the side jet nozzle geometry, the chamber pressure and temperature. On the other hand, the jet impinging flow structure exhibits such complex nature as shock shell, plate shock and Mach disk depending on the flow parameters. Among others, the dominant parameters are the ratio of the nozzle exit pressure to the ambient pressure and the distance between the nozzle exit plane and the impinging plane. As the plate is placed close to the nozzle, the computed wall pressure at or near the jet center oscillates with large amplitude with respect to the mean value. The amplitude of wall pressure fluctuations subsides as the plate/nozzle distance increases, and the frequency of the wall pressure is estimated on the order of 10.0 KHz. Objectives of this paper are to show accurate simulation of nozzle flow itself and to demonstrate the jet flow structure when the jet interacts with a wall at a close range.

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Spray Characterization and Flow Visualization of the Supersonic Liquid Jet by a Projectile Impingement (발사체 충돌에 의한 초음속 액체 제트의 분사 특성 및 유동 가시화)

  • Shin, Jeung-Hwan;Lee, In-Chul;Koo, Ja-Ye;Kim, Heuy-Dong
    • Journal of the Korean Society of Visualization
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    • v.9 no.2
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    • pp.27-33
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    • 2011
  • Supersonic liquid jet discharged from a nozzle has been investigated by using a ballistic range which is composed of high-pressure tube, pump tube, launch tube and liquid storage nozzle. High-speed Schlieren optical method was used to visualize the supersonic liquid jet flow field containing shock wave system, and spray droplet diameter was measured by the laser diffraction method. Experiment was performed with various types of nozzle to investigate the major characteristics of the supersonic liquid jet operating at the range of total pressure of 0.8 from 2.14 GPa. The results obtained shows that shock wave considerably affects the detailed atomization process of the liquid jet and as the nozzle diameter decreases, the shock wave angle and the averaged SMD of spray droplet tends to decrease.