Numerical Study of the Behaviors of Ventilated Supercavities in a Periodic Gust Flow

Abstract We conducted a numerical simulation of ventilated supercavitation from a forward-facing cavitator in unsteady flows generated by a gust generator under different gust angles of attack and gust frequencies. The numerical method is validated through the experimental results under specific steady and unsteady conditions. It is shown that the simulation can capture the degree of cavity shape fluctuation and internal pressure variation in a gust cycle. Specifically, the cavity centerline shows periodic wavelike undulation with a maximum amplitude matching that of the incoming flow perturbation. The cavity internal pressure also fluctuates periodically, causing the corresponding change of difference between internal and external pressure across the closure that leads to the closure mode change in a gust cycle. In addition, the simulation captures the variation of cavity internal flow, particularly the development internal flow boundary layer along the cavitator mounting strut, upon the incoming flow perturbation, correlating with cavity deformation and closure mode variation. With increasing angle of attack, the cavity exhibits augmented wavelike undulation and pressure fluctuation. As the wavelength of the flow perturbation approaches the cavity length with increasing gust frequency, the cavity experiences stronger wavelike undulation and internal pressure fluctuation but reduced cavitation number variation.

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An Experimental and Numerical Study of Regulating Performance and Flow Loss in a V-Port Ball Valve

Journal of Fluids Engineering ◽

10.1115/1.4044986 ◽

2019 ◽

Vol 142 (2) ◽

Cited By ~ 20

Author(s):

Junyu Tao ◽

Zhe Lin ◽

Chuanjing Ma ◽

Jiahui Ye ◽

Zuchao Zhu ◽

...

Keyword(s):

Pressure Fluctuation ◽

Fluid Transport ◽

Numerical Study ◽

Internal Flow ◽

External Pressure ◽

Ball Valve ◽

Flow Coefficient ◽

Design And Optimization ◽

Stable Position ◽

Valve Opening

Abstract Process valves are responsible for regulating and controlling the rate and direction of flow in pipeline systems. The V-port ball valve is one kind of process valve with a regulating performance influenced by V-angle. In this article, a DN50 V-port ball valve is taken as the research object. This work therefore aims to investigate the effect of and relationship between the V-angle on valve performance and internal flow properties via experiments and numerical simulations. Results indicate that an increase in either V-angle or valve opening causes a large-pressure fluctuation near the valve outlet, thus leading to a long pressure-stable distance. Meanwhile, the flow coefficient increases exponentially with valve opening, and the value of the exponent remains at 2.5 for different V-angles. Furthermore, the stable position of internal energy loss along the downstream pipe is well-matched with the stable position of external pressure fluctuation. This inspires a new method for controlling the pressure stability downstream from the valve. These results may facilitate improvements in the design and optimization of the process valve, thus benefiting the development of fluid transport techniques in energy industries.

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Numerical Study of Pipeline-Riser Slugging in an Open Source Way

Volume 2: CFD and VIV ◽

10.1115/omae2016-54085 ◽

2016 ◽

Author(s):

Xiangyin Meng ◽

Longbin Tao

Keyword(s):

Open Source ◽

Mesh Generation ◽

Pressure Fluctuation ◽

Numerical Study ◽

Internal Flow ◽

Post Process ◽

System Pressure ◽

Fluid Properties ◽

Gas Liquid Flow ◽

First Time

This paper describes an open source numerical investigation into slugging flow in a typical two-dimensional pipeline-riser for the first time. CFD tools Gmsh, OpenFOAM and ParaView are employed for mesh generation, numerical simulation and post process respectively. Original OpenFOAM solver ‘twoPhaseEulerFoam’ is used to simulate the gas-liquid flow in the system consisting of inclined pipeline and vertical riser. By comparing the numerical results of slugging phenomena and pressure fluctuation periods to previous experimental observations, it can be confirmed that it is possible to carry out such simulations in a complete open source way. Based on case studies, pressure fluctuation features in a typical single slugging cycle is also discussed in details. Furthermore, temperature variation of the internal flow due to air compressibility is found to have similar fluctuation period as that of pressure. In the end, the impacts of fluid properties on system pressure variations are discussed too. To future numerical investigations of subsea pipeline-riser induced slugging, present work is a basis for further open source solvers development.

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Numerical Study on Sloshing Characteristics with Reynolds Number Variation in a Rectangular Tank

Computation ◽

10.3390/computation6040053 ◽

2018 ◽

Vol 6 (4) ◽

pp. 53 ◽

Cited By ~ 3

Author(s):

Hyunjong Kim ◽

Mohan Dey ◽

Nobuyuki Oshima ◽

Yeon Lee

Keyword(s):

Reynolds Number ◽

Pressure Fluctuation ◽

Numerical Study ◽

Amplitude Spectrum ◽

Linear Solution ◽

Rectangular Tank ◽

Large Pressure ◽

Pressure Cycle ◽

Number Variation ◽

The Impact

A study on sloshing characteristics in a rectangular tank, which is horizontally excited with a specific range of the Reynolds number, is approached numerically. The nonlinearity of sloshing flow is confirmed by comparing it with the linear solution based on the potential theory, and the time series results of the sloshing pressure are analyzed by Fast Fourier Transform (FFT) algorithm. Then, the pressure fluctuation phenomena are mainly observed and the magnitude of the amplitude spectrum is compared. The results show that, when the impact pressure is generated, large pressure fluctuation in a pressure cycle is observed, and the effects of the frequencies of integral multiples when the fundamental frequency appears dominantly in the sloshing flow.

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Unsteady Turbulent Simulation and Analysis of Pressure Fluctuation for High Temperature and High Pressure Centrifugal Pump

ASME-JSME-KSME 2011 Joint Fluids Engineering Conference: Volume 1, Symposia – Parts A, B, C, and D ◽

10.1115/ajk2011-22053 ◽

2011 ◽

Author(s):

Shuhong Liu ◽

Yujun Sha ◽

Yulin Wu ◽

Baogang Wang

Keyword(s):

High Pressure ◽

High Temperature ◽

Centrifugal Pump ◽

Pressure Fluctuation ◽

Maximum Amplitude ◽

Internal Flow ◽

Dominant Frequency ◽

Reference Points ◽

Flow Passage ◽

Key Factor

The pressure fluctuation in the internal flow passage of centrifugal pump is a key factor affecting the stability of the hydraulic system, especially working at conditions of high temperature and pressure. In this paper, RNG k–ε turbulent model is adopted to simulate the unsteady flow through the whole flow passage of centrifugal pump working at temperature T = 300 °C and high pressure P = 280 bar. The pressure fluctuation is calculated at the predefined reference points in the different planes. By analyzing the results, it is found that: 1) the rotor-stator interaction between impeller and diffuser is the main cause for pressure fluctuation; 2) the dominant frequency of pressure fluctuation in the flow passage of impeller is the diffuser passing frequency; 3) the dominant frequency at the points of casing wall is almost the same, and the maximum amplitude is relatively small.

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A numerical study of the hydrodynamics of bubbling fluidized beds using pressure fluctuation signals

Proceeding of THMT-15. Proceedings of the Eighth International Symposium On Turbulence Heat and Mass Transfer ◽

10.1615/ichmt.2015.thmt-15.1370 ◽

2015 ◽

Author(s):

Mohammad Reza Haghgoo ◽

Donald J. Bergstrom ◽

Raymond J. Spiteri

Keyword(s):

Pressure Fluctuation ◽

Fluidized Beds ◽

Numerical Study

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NUMERICAL STUDY OF POROUS BLUNT NOSECONE TRANSPIRATION COOLING UNDER SUPERSONIC INCOMING FLOW

Journal of Porous Media ◽

10.1615/jpormedia.v20.i7.30 ◽

2017 ◽

Vol 20 (7) ◽

pp. 607-618 ◽

Cited By ~ 3

Author(s):

Yifei Wu ◽

Zhengping Zou ◽

Chao Fu ◽

Weihao Zhang

Keyword(s):

Numerical Study ◽

Transpiration Cooling ◽

Incoming Flow

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Fitness for Service Assessments of Bulging and Out-of-Round Structures

Fitness for Service, Life Extension, Remediation, Repair, and Erosion/Corrosion Issues for Pressure Vessels and Components ◽

10.1115/pvp2004-2244 ◽

2004 ◽

Author(s):

Peter Carter ◽

D. L. Marriott ◽

M. J. Swindeman

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Internal Pressure ◽

Structural Model ◽

External Pressure ◽

Element Analysis ◽

Structural Imperfection ◽

Level 2

This paper examines techniques for the evaluation of two kinds of structural imperfection, namely bulging subject to internal pressure, and out-of-round imperfections subject to external pressure, with and without creep. Comparisons between comprehensive finite element analysis and API 579 Level 2 techniques are made. It is recommended that structural, as opposed to material, failures such as these should be assessed with a structural model that explicitly represents the defect.

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Numerical study of the aerodynamic and power characteristics of the cycloidal rotor, under incoming flow

Вычислительные технологии ◽

10.25743/ict.2018.23.6.004 ◽

2019 ◽

pp. 25-34

Author(s):

Александр Анатольевич Дектерев ◽

Артем Александрович Дектерев ◽

Юрий Николаевич Горюнов

Keyword(s):

Flow Velocity ◽

Numerical Study ◽

Lift Coefficient ◽

Simulation Method ◽

Aerodynamic Characteristics ◽

Incoming Flow ◽

Ansys Fluent ◽

Energy Characteristics ◽

Power Characteristics ◽

Calculation Results

Исследование направлено на разработку и апробацию методики численного моделирования аэродинамических и энергетических характеристик циклоидального ротора. За основу взята конфигурация ротора IAT21 L3. Для нее с использованием CFD-пакета ANSYS Fluent построена математическая модель и выполнен расчет. Проанализировано влияние скорости набегающего потока воздуха на движущийся ротор. Математическая модель и полученные результаты исследования могут быть использованы при создании летательных аппаратов с движителями роторного типа. This article addresses the study of the aerodynamic and energy characteristics of a cycloidal rotor subject to the influence of the incoming flow. Cycloidal rotor is one of the perspective devices that provide movement of aircrafts. Despite the fact that the concept of a cycloidal rotor arose in the early twentieth century, the model of a full-scale aircraft has not been yet realized. Foreign scientists have developed models of aircraft ranging in weight from 0.06 to 100 kg. The method of numerical calculation of the cycloidal rotor from the article [1] is considered and realized in this study. The purpose of study was the development and testing of a numerical simulation method for the cycloidal rotor and study aerodynamic and energy characteristics of the rotor in the hovering mode and under the influence of the oncoming flow. The aerodynamic and energy characteristics of the cycloidal rotor, rotating at a speed of 1000 rpm with incoming flow on it with velocities of 20-80 km/h, were calculated. The calculation results showed a directly proportional increase of thrust with an increase of the incoming on the rotor flow velocity, but the power consumed by the rotor was also increased. Increase of the incoming flow velocity leads to the proportional increasing of the lift coefficient and the coefficient of drag. Up to a speed of 80 km/h, an increase in thrust and power is observed; at higher speeds, there is a predominance of nonstationary effects and difficulties in estimating the aerodynamic characteristics of the rotor. In the future, it is planned to consider the 3D formulation of the problem combined with possibility of the flow coming from other sides.

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Numerical Simulation of a Jumper Conveying Slurry for Deep-Sea Mining

10.1115/omae2021-62356 ◽

2021 ◽

Author(s):

Marcio Yamamoto ◽

Tomo Fujiwara ◽

Joji Yamamoto ◽

Sotaro Masanobu

Keyword(s):

Experimental Data ◽

Pressure Drop ◽

Dynamic Analysis ◽

Internal Pressure ◽

Deep Sea ◽

Petroleum Industry ◽

Vertical Direction ◽

Internal Flow ◽

Horizontal Direction ◽

Viscous Pressure

Abstract One key technology for Deep-Sea Mining is the riser system. The riser is already a field-proven technology in the Petroleum Industry. However, several differences exist between a petroleum production riser and a riser for Deep-Sea Mining, mainly related to the internal flow. The ore-slurry has a larger density than the hydrocarbons and shall be pumped with a much higher flowrate. The current software tools for riser’s dynamic analysis may include the internal fluid hydrostatic pressure and the centrifugal and Coriolis forces imposed by the bent pipe’s internal flow. However, the internal pressure drop is not calculated. The internal pressure alters the pipe’s effective tension and can alter the pipe’s bending moment changing its mechanical behavior. This article describes a computational script’s development to run embedded in a commercial software for riser’s dynamic analysis. Our script calculates the internal viscous pressure drop along with the jumper. This pressure is then converted into wall axial tension (buckling) and imposed on each node of the jumper’s numerical model. Each simulation case was calculated twice with and without the internal flow viscous pressure drop. The comparison with experimental data revealed that the jumper’s average position has a good agreement among all cases. However, the amplitude caused by the top oscillation showed some discrepancies. Experimental data has the highest amplitude in the horizontal direction, while the simulation without viscous pressure calculation had the smallest. The simulation with our embedded script had intermediary amplitude in the horizontal direction. The vertical direction amplitudes have the same behavior for all cases, but the experimental data showed the highest amplitude.

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