• Title/Summary/Keyword: hydraulic model test

Search Result 546, Processing Time 0.024 seconds

Investigation of thermal hydraulic behavior of the High Temperature Test Facility's lower plenum via large eddy simulation

  • Hyeongi Moon ;Sujong Yoon;Mauricio Tano-Retamale ;Aaron Epiney ;Minseop Song;Jae-Ho Jeong
    • Nuclear Engineering and Technology
    • /
    • v.55 no.10
    • /
    • pp.3874-3897
    • /
    • 2023
  • A high-fidelity computational fluid dynamics (CFD) analysis was performed using the Large Eddy Simulation (LES) model for the lower plenum of the High-Temperature Test Facility (HTTF), a ¼ scale test facility of the modular high temperature gas-cooled reactor (MHTGR) managed by Oregon State University. In most next-generation nuclear reactors, thermal stress due to thermal striping is one of the risks to be curiously considered. This is also true for HTGRs, especially since the exhaust helium gas temperature is high. In order to evaluate these risks and performance, organizations in the United States led by the OECD NEA are conducting a thermal hydraulic code benchmark for HTGR, and the test facility used for this benchmark is HTTF. HTTF can perform experiments in both normal and accident situations and provide high-quality experimental data. However, it is difficult to provide sufficient data for benchmarking through experiments, and there is a problem with the reliability of CFD analysis results based on Reynolds-averaged Navier-Stokes to analyze thermal hydraulic behavior without verification. To solve this problem, high-fidelity 3-D CFD analysis was performed using the LES model for HTTF. It was also verified that the LES model can properly simulate this jet mixing phenomenon via a unit cell test that provides experimental information. As a result of CFD analysis, the lower the dependency of the sub-grid scale model, the closer to the actual analysis result. In the case of unit cell test CFD analysis and HTTF CFD analysis, the volume-averaged sub-grid scale model dependency was calculated to be 13.0% and 9.16%, respectively. As a result of HTTF analysis, quantitative data of the fluid inside the HTTF lower plenum was provided in this paper. As a result of qualitative analysis, the temperature was highest at the center of the lower plenum, while the temperature fluctuation was highest near the edge of the lower plenum wall. The power spectral density of temperature was analyzed via fast Fourier transform (FFT) for specific points on the center and side of the lower plenum. FFT results did not reveal specific frequency-dominant temperature fluctuations in the center part. It was confirmed that the temperature power spectral density (PSD) at the top increased from the center to the wake. The vortex was visualized using the well-known scalar Q-criterion, and as a result, the closer to the outlet duct, the greater the influence of the mainstream, so that the inflow jet vortex was dissipated and mixed at the top of the lower plenum. Additionally, FFT analysis was performed on the support structure near the corner of the lower plenum with large temperature fluctuations, and as a result, it was confirmed that the temperature fluctuation of the flow did not have a significant effect near the corner wall. In addition, the vortices generated from the lower plenum to the outlet duct were identified in this paper. It is considered that the quantitative and qualitative results presented in this paper will serve as reference data for the benchmark.

Comparison of MCC and SSC Models Based on Numerical Analysis of Consolidation Test (압밀시험의 수치해석에 의한 MCC 모델과 SSC 모델 비교)

  • Kwon, Byenghae;Eam, Sunghoon
    • Journal of The Korean Society of Agricultural Engineers
    • /
    • v.66 no.2
    • /
    • pp.1-12
    • /
    • 2024
  • In order to integrate two consolidation theories of Terzaghi's consolidation theory and Mesri's secondary compression theory and to identify a model suitable for analyzing stress-strain behavior over time, numerical analysis on consolidation tests were conducted using a modified cam-clay model and a soft soil creep model and the following conclusions were obtained. The results of numerical analysis applying the theory that a linear proportional relationship is established between the void ratio at logarithmic scale and the permeability coefficient at logarithmic scale is better agreement with the result of oedometer test than the results of applying constant hydraulic conductivity. The modified cam-clay model is a model that does not include secondary compression, but the slope of the normal consolidation line corresponding to the compression index of the standard consolidation test includes secondary compression, so the actual settlement curve over time is lower than the predicted value through numerical analysis. It always gets smaller. Other previous studies that applied Terzaghi's consolidation theory to consolidation test analysis showed the same results and were cross-confirmed. The soft soil creep model, which includes secondary compression in the theory, showed good agreement in all sections including secondary compression in the consolidation test results. It was judged appropriate to use a soft soil creep model when performing numerical analysis of soft clay ground.

Analysis of River Levee Failure Mechanism by Piping and Remediation Method Evaluation (파이핑에 의한 하천제방 붕괴 메카니즘 분석 및 대책공법 평가)

  • Kim, Jin-Man;Moon, In-Jong
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.18 no.3
    • /
    • pp.600-608
    • /
    • 2017
  • The presence of piping in a levee body allows water seepage to occur by producing a large cavity or water tunnel within it, ultimately resulting in the failure of the river levee and differential settlement. In order to properly cope with river levee failure due to piping and establish a proper remediation method for this problem, it is necessary to analyze the failure mechanism of the river levee due to piping. Therefore, this study analyzed the shape and mechanism of river levee failure due to piping through small-scale and large-scale models and evaluated the seepage pressure distribution characteristics in the hydraulic well, which has been suggested as a remediation method for piping. According to the results of this study, as the safety factor for the piping in the river levee decreased, the river levee failure shape was more clearly shown through the small-scale model test. In the large-scale model test, the type of local damage to the levee due to the piping was identified and the evaluation showed that the hydraulic well had the largest effect on the inhibition of piping below the center of the well. A follow-up study is needed to confirm the reliability of the results. However, it is thought that this study can be utilized as the baseline data for research into the piping-induced river levee failure mechanism and for the preparation of a remediation method.

NEW MODELING AND CONTROL OF AN ASYMMETRIC HYDRAULIC ACTIVE SUSPENSION SYSTEM

  • Kim, Wanil;Sangchul Won
    • 제어로봇시스템학회:학술대회논문집
    • /
    • 1998.10a
    • /
    • pp.490-495
    • /
    • 1998
  • In this paper an asymmetric hydraulic actuator which consists of single acting cylinder and servo valve is modeled for a quarter car active suspension system. This model regards the force as an internal state rather than a control input. The control input of the model is the sum of oil flows that pass through the valve's orifices. The resulting dynamic equation in the state space ap-pears a feedback connection of a nominal linear time in-variant term with a nonlinear bounded uncertain block. Since this model makes it possible to eliminate the force control phase, analysis and controller design are made straightforward and simple. Well known LQR method is then applied. Simulation and test rig experiment show the effectiveness of this approach in modeling and control.

  • PDF

Hydraulic model test for corrugated artificial reef stability (수리실험을 통한 요철형 인공어초 안정성 검토)

  • Baek, Seung Hwa;Shin, Bum-Shick;Kim, Kyu-Han
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.15 no.8
    • /
    • pp.5327-5332
    • /
    • 2014
  • In Korea, the quantitative growth rate of artificial reef construction is supposed to reach the peak point. Therefore, new approach is needed to the point of artificial reefs business. Functional reefs, such as shellfish reefs, recreational reefs, seaweed reefs, and fish reefs, are beneficial alternatives. This study conducted hydraulic testing to assess the stability of corrugated artificial reefs (ARs) that were constructed to promote the growth of shellfish and seaweed. The results of this study showed that some dimensionless design parameters affected the stability of corrugated artificial reefs under a range of wave and water depth conditions in a fixed bed condition. The findings also highlight the importance of hydraulic experiments in solving the problems that have emerged in the design and construction of artificial reefs.

Development and Performance Test of the Kick Motor Igniter (킥모터 점화기 개발 및 성능 시험)

  • Koh, Hyeon-Seok;Kil, Gyoung-Sub;Kim, Byung-Hun;Cho, In-Hyun
    • Aerospace Engineering and Technology
    • /
    • v.6 no.1
    • /
    • pp.190-200
    • /
    • 2007
  • A pyrogen type igniter was designed to satisfy the requirements of KSLV-I Kick Motor system. To insure the reliability of the igniter before the production of the flight model, we have been performed the structure, environmental, combustion tests. The hydraulic test was carried out to confirm the strength of the components of the igniter. The shock and vibration tests were considered to check whether the igniter operates normally under the severe environmental condition. The combustion tests were also performed to understand the ignition characteristics with the variation of initial condition. Finally, we confirmed that the igniter could provide the acceptable energy to ignite the propellant of kick motor at the ground test.

  • PDF

Development of a Concrete Pump Truck's Core Pump Model and Its Validation (콘크리트 펌프트럭의 코어펌프 해석모델개발 및 신뢰성 검토)

  • Park, Sung Su;Noh, Dae Kyung;Lee, Geun Ho;Lee, Dae Hee;Jang, Ju Sup
    • Journal of Drive and Control
    • /
    • v.15 no.2
    • /
    • pp.1-8
    • /
    • 2018
  • This study is a first step toward reducing surge pressure, and it has another purpose, which is to developing an analysis model which can closely analyze a hydraulic circuit and be used in design. For development of analysis model, SimulationX, a commercial program, is used. The study progress methods are as follows. By analyzing the structure and operating mechanisms of each part of the hydraulic system of the pump truck and referring its parameters, develop a single component model. Assemble the developed single component model, and make an overall analysis the model. By comparing the similarities between the developed model and the actual system's test results, validate the reliability of the analysis model.

Study of a Model Turbine Design Case Via Application of Spiral Case and Draft Tube Shape in Hydraulic Power Plant Modernization (수력 현대화 개·대체 시 스파이럴 케이스와 흡출관 형상에 따른 모델수차 설계 적용사례 연구)

  • Park, Nohyun;Kim, Jin-Hyuk;Kim, Seung-Jun;Hyun, Jungjae;Choi, Jongwoong;Cho, Yong
    • New & Renewable Energy
    • /
    • v.16 no.2
    • /
    • pp.35-46
    • /
    • 2020
  • Recently, turbines operating in hydro power plants are required to undergo renovation and modernization due to their age exceeding 30 years. In the process of renovation or modernization, a performance test of the scaled-down model is necessary to verify the performance of the real-size model. This model test method, with criteria that is similar to that of a real turbine, is the most economical and important method. Furthermore, the shapes of the runner and guide vane can be modified or replaced easily. However, during the process of modernization, the components with the spiral casing and draft tube are impossible to repair or replace because of the buried ground. Thus, in this study, numerical analysis is conducted to investigate the hydraulic performance based on the difference between the two-dimensional computer-aided design (CAD) shape and the real three-dimensional scan shape of the spiral casing and draft tube.

A Study on the Approximate model of the Flow rate Characteristics in External Gear pump for EHPS (전기 유압식 동력 조향시스템용 외접형 기어펌프의 유량특성 근사식에 관한 연구)

  • Kim, Ji-Hye;Kim, Sung-Gaun
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.14 no.2
    • /
    • pp.548-553
    • /
    • 2013
  • EHPS(Electro-Hydraulic Power Steering) is a system to generate the steering operation force from the electric motor connected directly to the oil pump. To optimize the manufacturing cost and efficiency of the performance of the steering system is very important. Until now, the development of the hydraulic system is implemented by the field test which needs a significant time and cost. In this paper, flow measurement of an external gear pump is performed. Then using the experimental results, an approximate model expressed by flow rate characteristics is proposed to calculate the discharge flow rate. Proposed approximate model is verified by comparing with the experimental data and AMESim results. As the experimental data and AMESim results agree well, the approximate model data can be used as an alternative to highly cost experimental procedure.

Hydraulic Experiments on Reflection Coefficients for Perforated Wall Caisson with Rock Fill (유수실을 사석으로 채운 유공 케이슨에 대한 반사계수 실험)

  • Kim, Young-Taek;Lee, Jong-In
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.31 no.6
    • /
    • pp.403-408
    • /
    • 2019
  • In general, the caisson having the perforated wall is used to for the purpose of reducing the wave reflection and wave overtopping. In this study, the hydraulic characteristics (reflection coefficient) of the perforated wall caisson chamber filled with aggregates (rocks) were investigated with hydraulic model tests. When the perforated wall chambers were filled with aggregates, the reflection coefficients would increase. However, it was confirmed that the rock filling method into the perforated wall chamber could secure the stability of the structures and satisfy the hydraulic characteristics at a certain level.