A Method to Resolve Simulation of Discontinuous Flow Field: a Valve Example From Full Closing to Re-Closure

Abstract In transient computational fluid dynamics (CFD) simulations, the continuity of the flow field is an essential prerequisite. However, continuous flows can be separated under certain conditions, such as the process from valve opening to re-closure. The current method often leaves a narrow gap to estimate the full closing status, which will introduce a deviation. To address this issue, a full closing numerical simulation method (FCNSM) is developed to solve the problem of simulation between discontinuous flow field (DFF) and continuous flow field (CFF). The matrix laboratory (MATLAB) program has been used to communicate Fluent as a server session to call the files Fluent and automatically execute text-based user interface (TUI) commands. The radial basis function (RBF) is used to construct the relationship between the variables of the flow field and the coordinates of mesh nodes, which can achieve the data transmission from a DFF to a CFF. Automatic stopping of transient calculations is achieved by passing variables among MATLAB program, scheme language, and user-defined functions (UDF) when a physical quantity reaches a set value. Based on this method, a transient simulation with a dynamic mesh of a 2-D model regarding a pressure relief valve (PRV) is performed to simulate the process of the valve from full closing to re-closure, the flow characteristics through the PRV are obtained using this method. This study makes it possible to use FCNSM for understanding dynamic characteristics from DFF to CFF.

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Research on Flow Characteristics of Aerostatic Circular Thrust Bearing with a Cone Cavity

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.308-310.189 ◽

2011 ◽

Vol 308-310 ◽

pp. 189-192

Author(s):

Long Xing Chen ◽

Wen Qi Ma ◽

He Chun Yu ◽

Hai Yan Liu ◽

Hong Wang Du

Keyword(s):

Numerical Simulation ◽

Flow Field ◽

Thrust Bearing ◽

Single Point ◽

Flow Characteristics ◽

Simulation Method ◽

Flow Passage ◽

Testing Method ◽

Measurement Results ◽

Simulation And Experiment

The aerostatic circular thrust bearing was taken as a study subject. The numerical simulation method was used to calculate the flow passage. Meanwhile, the single-point testing method was used to test the pressure distribution. The simulation and experiment measurement results were compared and analyzed. The results show that: The single-point testing method is effective to capture the change of flow characteristics. The overall results of simulation and testing coincide with each other well. In the range of cone cavity, the flow pattern for the gas is turbulent flow, and the flow field should be divided into different zones for simulation.

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Aerodynamic Simulation of Road Vehicle in Steady Crosswind

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.376.341 ◽

2013 ◽

Vol 376 ◽

pp. 341-344

Author(s):

Shan Ling Han ◽

Ru Xing Yu ◽

Yu Yue Wang ◽

Gui Shen Wang

Keyword(s):

Flow Field ◽

Wind Direction ◽

Motor Vehicle ◽

Aerodynamic Force ◽

Flow Characteristics ◽

Simulation Method ◽

Aerodynamic Characteristics ◽

External Flow ◽

Slant Angle ◽

Ahmed Body

Because crosswind affects drivers to control their vehicles safely, the research on flow characteristics in automotive crosswind has a great significance to improve the crosswind stability of the vehicle. By the steady state numerical simulation method, the aerodynamic characteristics of external flow field of Ahmed body in crosswind was investigated. The Ahmed body with 25° slant angle is built in UG NX. The external flow field of the Ahmed body in the wind direction of 0°, 15º, 30° angle is simulated in XFlow software. According to the map of the pressure and velocity distribution, the flow field both before and after, as well as left and right has significant change as the wind direction angle increased, and the trail turbulence intensity also changes. The changes of aerodynamic force and moment affect the driving stability of a motor vehicle.

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Study on the Flow Characteristics of the Monolithic Muffler in Train Air Conditioning Duct

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.462.300 ◽

2012 ◽

Vol 462 ◽

pp. 300-306

Author(s):

Xu Quan Li ◽

Dong Dong Dong ◽

Min Jie Gu ◽

Gang Wang ◽

Song Tao Hu

Keyword(s):

Flow Field ◽

Pressure Loss ◽

Air Conditioning ◽

Cfd Simulation ◽

Flow Characteristics ◽

Internal Flow ◽

Simulation Method ◽

Calculation Model ◽

Simulation Calculation ◽

Performance Research

After installing the monolithic muffler in the train air duct, noise is reduced, but meanwhile also increased the air duct resistance. In this paper, a monolithic muffler simulation calculation model is introduced in this paper. The pressure loss and internal flow field of the muffler are obtained by. CFD simulation. Experimental results validate the simulation method. It provides a basis for the silencer performance research of muffler.

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Unsteady Simulation on Flow Characteristics of Steam Jet Condensed Into Subcooled Water

ASME 2019 Power Conference ◽

10.1115/power2019-1889 ◽

2019 ◽

Author(s):

Shilin Song ◽

Daotong Chong ◽

Quanbin Zhao ◽

Weixiong Chen ◽

Junjie Yan

Keyword(s):

Flow Field ◽

Dynamic Process ◽

Nuclear Reactor ◽

Pressure Pulse ◽

Flow Characteristics ◽

Simulation Method ◽

Sonic Nozzle ◽

Subcooled Water ◽

Unsteady Simulation ◽

Good Agreement

Abstract Steam jet condensation through sonic nozzle in quiescent subcooled water pool is important for the safety of nuclear reactor system. In this study, the dynamic process of stable condensation jet steam plume is obtained by numerical simulation method. The simulation results are in good agreement with the experimental results. The flow field results indicate that two typical fluctuation regimes exist in the dynamic process of steam plume. Simultaneous analysis of pressure and flow field indicates that two fluctuation regimes produce different pressure pulses. When the detachment phenomenon occurs during the fluctuation of the steam plume, a pressure pulse which value is clearly greater than 220 kPa is generated. When the plume sharply contracts without obvious detachment phenomenon during the fluctuation process, a pressure pulse which value is almost lower than 120 kPa is generated.

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Comparative Study on Flow Characteristics of Pipeline System Based on CFD

E3S Web of Conferences ◽

10.1051/e3sconf/202125202053 ◽

2021 ◽

Vol 252 ◽

pp. 02053

Author(s):

Hou Yingzhe ◽

Wu Hao ◽

Yan Xiaozhe ◽

Zhu Haoqiang ◽

Gao Haitao ◽

...

Keyword(s):

Flow Field ◽

Flow Rate ◽

Flow Characteristics ◽

Internal Flow ◽

Simulation Method ◽

Hot Water ◽

Pipeline System ◽

Uniformity Coefficient ◽

Study Results ◽

Pipeline Vibration

Based on the CFD numerical simulation method, this paper established a pipeline model to study the internal flow characteristics of three different combinations of hot water pipeline systems and thus obtained the flow field information such as pressure, flow rate, and flow rate inside the pipeline. The study results showed that the smoother the pipeline transition, the smaller the velocity uniformity coefficient; the higher the uniformity of the flow field, the smaller the pressure and velocity fluctuations, the smaller the resulting pipeline vibration. Besides, the flow characteristics have been greatly improved.

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Optimization of Nonlinear Pressure-flow Characteristics of a Spring- Loaded Pressure Relief Valve Based on CFD Simulation

Journal of Pressure Vessel Technology ◽

10.1115/1.4050933 ◽

2021 ◽

Author(s):

Chengshuo Wu ◽

Shiyang Li ◽

Qianqian Li ◽

Peng Wu ◽

Bin Huang ◽

...

Keyword(s):

Flow Characteristic ◽

Characteristic Curve ◽

Flow Characteristics ◽

Internal Flow ◽

Relief Valve ◽

Pressure Flow ◽

Hydraulic Force ◽

Middle Chamber ◽

Valve Opening ◽

Cfd Method

Abstract In this study, the nonlinear pressure-flow characteristics of a spring-loaded pressure relief valve (PRV) which is used in the automotive fuel supply system for pressure control is analyzed, and its characteristics are improved by means of geometrical modifications of the valve structure. Given the complexity of the coupling mechanism between the valve internal flow characteristics and spring system, a quasi-steady computational fluid dynamics (CFD) method is introduced to predict the nonlinear pressure-flow characteristic curve of the valve and the accuracy is validated by experimental data. The total hydraulic force on the valve spool and diaphragm are divided into three parts according to the position of action and the correlation between the internal flow characteristics, hydraulic force, and pressure-flow characteristics of the valve are explained by CFD analysis and visualization. The result shows that the quasi-steady CFD method can accurately predict the trends of the valve nonlinear pressure-flow characteristic curve which is mainly determined by the hydraulic force produced in the middle chamber of the valve, when the valve opening reaches a certain value, a main vortex would be formulated in the middle chamber and lead to the sudden increase of hydraulic force which causes the fluctuation of the pressure-flow characteristic curve of the valve. It was also found that by increasing the round corner size, the valve opening value of flow pattern change will be promoted and the valve pressure-flow characteristic can be optimized.

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Analysis and Research on Flow Characteristics of Hot Water Pipeline System

E3S Web of Conferences ◽

10.1051/e3sconf/202125203041 ◽

2021 ◽

Vol 252 ◽

pp. 03041

Author(s):

Hou Yingzhe ◽

Wu Hao ◽

Yan Xiaozhe ◽

Zhu Haoqiang ◽

Gao Haitao ◽

...

Keyword(s):

Flow Field ◽

Flow Characteristics ◽

Internal Flow ◽

Simulation Method ◽

Hot Water ◽

Pipeline System ◽

Pipe System ◽

Uniformity Coefficient ◽

Pipe Model ◽

Pipeline Vibration

Based on the CFD numerical simulation method, a pipe model was established to study the internal flow characteristics of two different specifications of hot water pipe system, and the related information of the flow field was obtained, such as the internal pressure, flow velocity and flow rate. The results showed that the smoother the pipeline transition was, the smaller the velocity uniformity coefficient would be, and the higher flow field uniformity means the smaller pressure and velocity fluctuations. Therefore, the pipeline vibration will be smaller, and the flow characteristics are greatly improved.

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Numerical Study on Mechanical Characteristics of Steam Turbine Valve Disc

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.572.319 ◽

2013 ◽

Vol 572 ◽

pp. 319-322

Author(s):

Dong Yue Qu ◽

Zhong Yuan Guo ◽

Chong Liu

Keyword(s):

Flow Field ◽

Axial Force ◽

Numerical Study ◽

Pressure Ratio ◽

Flow Characteristics ◽

Control Valve ◽

Internal Flow ◽

Simulation Method ◽

Complex Flow ◽

Valve Stem

The instability flow in the control valve often lead to abnormal vibration, the valve wear and the valve stem destruction, also lead to pressure loss. The flow in the control valve show complex flow regime distribution and variation, it is a typical unsteady flow. Therefore, it is necessary to theoretical calculation and qualitative analyses the flow field of valve by the numerical simulation method. In this paper, we study on the axial force of valve stem that caused by the fluid pulsation pressure. Establishing the flow field model of the control valve, generating the computational grid through the pre-processor, using the CFD software to do discretized and solved, getting visualization graphics of the internal flow field. Study the changes of the flow characteristics according to different pressure ratio, getting the variation characteristic of axial force. Provide the basis for subsequent optimization and design of the low vibration control valve.

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Analysis of Flow Characteristics and Effects of Turbulence Models for the Butterfly Valve

Applied Sciences ◽

10.3390/app11146319 ◽

2021 ◽

Vol 11 (14) ◽

pp. 6319

Author(s):

Sung-Woong Choi ◽

Hyoung-Seock Seo ◽

Han-Sang Kim

Keyword(s):

Turbulence Model ◽

Dissipation Rate ◽

Flow Characteristics ◽

Turbulence Models ◽

Flow Properties ◽

Nominal Diameter ◽

Large Pressure ◽

Sst Model ◽

Turbulence Effect ◽

Valve Opening

In the present study, the flow characteristics of butterfly valves with different sizes DN 80 (nominal diameter: 76.2 mm), DN 262 (nominal diameter: 254 mm), DN 400 (nominal diameter: 406 mm) were numerically investigated under different valve opening percentages. Representative two-equation turbulence models of two-equation k-epsilon model of Launder and Sharma, two-equation k-omega model of Wilcox, and two-equation k-omega SST model of Menter were selected. Flow characteristics of butterfly valves were examined to determine turbulence model effects. It was determined that increasing turbulence effect could cause many discrepancies between turbulence models, especially in areas with large pressure drop and velocity increase. In addition, sensitivity analysis of flow properties was conducted to determine the effect of constants used in each turbulence model. It was observed that the most sensitive flow properties were turbulence dissipation rate (Epsilon) for the k-epsilon turbulence model and turbulence specific dissipation rate (Omega) for the k-omega turbulence model.

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