• Title/Summary/Keyword: Pressure field

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A proposed model of the pressure field in a downburst

  • Tang, Z.;Lu, L.Y.
    • Wind and Structures
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    • v.17 no.2
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    • pp.123-133
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    • 2013
  • Pressure field and velocity profiles in a thunderstorm downburst are significantly different from that of an atmospheric boundary layer wind. A model of the pressure field in a downburst is presented in accordance with the experimental and numerical results. Large eddy simulation method is employed to investigate transient pressure field on impingement ground of a downburst. In addition, velocity profiles of the downburst are studied, and good agreement is achieved between the present results and the data obtained from empirical models.

A numerical approach for assessing internal pressure capacity at liner failure in the expanded free-field of the prestressed concrete containment vessel

  • Woo-Min Cho;Seong-Kug Ha;SaeHanSol Kang;Yoon-Suk Chang
    • Nuclear Engineering and Technology
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    • v.55 no.10
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    • pp.3677-3691
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    • 2023
  • Since containment building is the major shielding structure to ensure safety of nuclear power plant, the structural behavior and ultimate pressure capacity of containments must be studied in depth. This paper addresses ambiguous issue of determining free-field position for liner failure by suggesting an expanded free-field region and comparing internal pressure capacities obtained by test data, conservative assumption and suggested free-field region. For this purpose, a practical approach to determine the free-field position for the evaluation of liner tearing is carried out. The maximum principal strain histories versus internal pressure capacities among different free-field positions at various azimuths and elevations are compared with those at the equipment hatch as a conservative assumption. The comparison shows that there are considerable differences in the internal pressure capacity at liner failure within the expanded free-field region compared to the vicinity of the equipment hatch. Additionally, this study proposes an approximate correlation with conservative factors by considering the expanded free-field ranges and material characteristics to determine realistic failure criteria for liner. The applicability of the proposed correlation is demonstrated by comparing the internal pressure capacities of full-scale containment buildings following liner failure criteria according to RG 1.216 and an approximate correlation.

A New Control Volume Finite Element Method for Three Dimensional Analysis of Polymer Flow (고분자 유동의 3차원 해석을 위한 새로운 검사 체적 유한 요소법)

  • 이석원;윤재륜
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.05a
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    • pp.461-464
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    • 2003
  • A new control volume finite element method is proposed for three dimensional analysis of polymer flow. Tetrahedral finite element is employed and co-located interpolation procedure for pressure and velocity is implemented. Inclusion of pressure gradient term in the velocity shape functions prevents the checkerboard pressure field from being developed. Vectorial nature of pressure gradient is considered in the velocity shape function so that velocity profile in the limit of very small Reynolds number becomes physically meaningful. The proposed method was verified through three dimensional simulation of pipe flow problem for Newtonian and power-law fluid. Calculated pressure and velocity field showed an excellent agreement with analytic solutions for pressure and velocity. Driven-cavity problem, which is reported to yield checkerboard pressure filed when conventional finite element method is applied, could be solved without yielding checkerboard pressure field when the proposed control volume finite element method was applied. The proposed method could be successfully applied to the three dimensional mold filling problem.

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Pressure Fluctuation Induced by Propeller Sheet Cavitation with Consideration of the Near Field Effect (근접장 효과를 고려한 추진기 얇은 층 캐비테이션에 의해 유기되는 변동압력에 관한 연구)

  • Seol, Han-Shin;Moon, Il-Sung
    • Journal of the Society of Naval Architects of Korea
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    • v.46 no.2
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    • pp.105-113
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    • 2009
  • A theoretical study on the pressure fluctuation induced by a propeller was carried out in this study. The main objective of this study is to analyze the source mechanism of the pressure fluctuation induced by propeller sheet cavitation. To analyze the pressure fluctuation induced by propeller sheet cavitation, modern acoustic theory was applied. Governing equation of pressure fluctuation induced by sheet cavitation was derived using Ffowcs Williams proposed time domain acoustic approaches. Several factors affecting pressure fluctuation were analyzed based on the derived governing equation. Pressure fluctuation result was represented by combined results of the far field term and near field term. Finally, the physical mechanism of pressure fluctuation at the blade rate frequency was analyzed using numerically generated cavitation volume variation.

Comparison between CFD analysis and experiments according to various PEMFC flow-field designs (유로 형상 변화에 따른 CFD 해석 결과와 PEM 연료전지 성능 비교)

  • Lee, Kang-In;Park, Min-Soo;Lee, Se-Won;Chu, Chong-Nam
    • 한국신재생에너지학회:학술대회논문집
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    • 2008.05a
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    • pp.572-575
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    • 2008
  • Flow-field design has much influence over the performance of proton exchange membrane fuel cell (PEMFC) because it affects the pressure magnitude and distribution of the reactant gases. To obtain the pressure magnitude and distribution of reactant gases in four kinds of flow-field designs without additional measurement equipment, computational fluid dynamics (CFD) analysis was performed. After the CFD analysis, the performance values of PEMFC according to the flow-field configurations were measured via a single cell test. As expected, the pressure differences due to different flow-field configurations were related to the PEMFC performance because the actual performance results showed the same tendency as the results of the CFD analysis. A large pressure drop resulted in high PEMFC performance. So, the single serpentine configuration gave the highest performance. On the other hand, the parallel flow-field configuration gave the lowest performance because the pressure difference between inlet and outlet was the lowest.

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A deep learning framework for wind pressure super-resolution reconstruction

  • Xiao Chen;Xinhui Dong;Pengfei Lin;Fei Ding;Bubryur Kim;Jie Song;Yiqing Xiao;Gang Hu
    • Wind and Structures
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    • v.36 no.6
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    • pp.405-421
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    • 2023
  • Strong wind is the main factors of wind-damage of high-rise buildings, which often creates largely economical losses and casualties. Wind pressure plays a critical role in wind effects on buildings. To obtain the high-resolution wind pressure field, it often requires massive pressure taps. In this study, two traditional methods, including bilinear and bicubic interpolation, and two deep learning techniques including Residual Networks (ResNet) and Generative Adversarial Networks (GANs), are employed to reconstruct wind pressure filed from limited pressure taps on the surface of an ideal building from TPU database. It was found that the GANs model exhibits the best performance in reconstructing the wind pressure field. Meanwhile, it was confirmed that k-means clustering based retained pressure taps as model input can significantly improve the reconstruction ability of GANs model. Finally, the generalization ability of k-means clustering based GANs model in reconstructing wind pressure field is verified by an actual engineering structure. Importantly, the k-means clustering based GANs model can achieve satisfactory reconstruction in wind pressure field under the inputs processing by k-means clustering, even the 20% of pressure taps. Therefore, it is expected to save a huge number of pressure taps under the field reconstruction and achieve timely and accurately reconstruction of wind pressure field under k-means clustering based GANs model.

Rock mechanics and wellbore stability in Dongfang 1-1 Gas Field in South China Sea

  • Yan, Chuanliang;Deng, Jingen;Cheng, Yuanfang;Yan, Xinjiang;Yuan, Junliang;Deng, Fucheng
    • Geomechanics and Engineering
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    • v.12 no.3
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    • pp.465-481
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    • 2017
  • Thermal effect has great influence on wellbore stability in Dongfang 1-1 (DF 1-1) gas field, a reservoir with high-temperature and high-pressure. In order to analyze the wellbore stability in DF1-1 gas field, the variation of temperature field after drilling was analyzed. In addition, the effect of temperature changing on formation strength and the thermal expansion coefficients of formation were tested. On this basis, a wellbore stability model considering thermal effect was developed and the thermal effect on fracture pressure and collapse pressure was analyzed. One of the main challenges in this gas field is the decreasing temperature of the wellbore will reduce fracture pressure substantially, resulting in the drilling fluid leakage. If the drilling fluid density was reduced, kick or blowout may happen. Therefore, the key of safe drilling in DF1-1 gas field is to predict the fracture pressure accurately.

Unsteady Pressure Measurement of Fan Stator Vane Using Pressure Sensitive Paint

  • Sakamoto, Kazuyuki;Tsuchiya, Naoki;Yamamoto, Masahiko;Hamano, Yasunori;Fujii, Kozo
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2004.03a
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    • pp.789-794
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    • 2004
  • The pressure sensitive paint (PSP) technique has been well established in external flow field. However, there are still unresolved issues in internal flow field. This work was focused on the application to unsteady pressure measurement of fan flow field. The PSP measurement system was established and the image processing software was developed. First, the performance of PSP was investigated at the static cell. Then the unsteady PSP measurement was carried out at fan test facility. PSP data images were acquired from the suction and pressure surface of stator vanes. Pressure distributions on the surface of the stator vane were detected non-intrusively. The issues of image acquisition and image processing were clarified through the practical PSP application to fan flow field.

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Estimation of Degree of Consolidation in Soft Ground Using Field Measurements and Rheology Model (현장 계측치와 유변학적 모형을 이용한 연약지반의 압밀도 추정)

  • Lee, Dal-Won;Yoon, Hyun-Jung
    • Journal of The Korean Society of Agricultural Engineers
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    • v.47 no.2
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    • pp.87-96
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    • 2005
  • In this research, an attempt is made to derive the practical estimation of the degree of consolidation in soft clay from field measurements under embankments. For the practical estimation of pore water pressure in soft clay, the elasto-viscous rheological model was proposed, with a transform of parameters and a field geotechnical measurements in southern Korea. By using the rheological properties of soft clays and the dissipation of excess pore water pressure behaviour during step loading, a degree of consolidation or pore water pressure estimation in the future can be performed, and are shown to be generally close to the field measurements of pore water pressure. Finally, a pore water pressure behaviour in soft clay can be explained through measured data in field and the excess pore water pressure data can also be used to estimate settlement.

Pressure equalization of rainscreen facades: Analysis of the field data in the frequency domain

  • Kumar, K. Suresh;Wisse, J.A.
    • Wind and Structures
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    • v.4 no.2
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    • pp.101-118
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    • 2001
  • This paper reports the field measurements concerning pressure equalization of rainscreen facades carried out at the Technical University of Eindhoven (TUE) in the Netherlands. The field facility including the details of test panel, meteorological tower, instrumentation, data collection and analysis is presented. Results of investigations into cavity response for various leakage and venting configurations are discussed. Frequency domain techniques have been utilized to show the influence of wind as well as facade characteristics on the pressure equalization performance. Further, this paper presents an early attempt to synthesize the experimental results into existing building codes.