Water Hammer Characteristics of Glass Reinforced Plastic Oil Transportation Pipeline

2011 ◽  
Vol 204-210 ◽  
pp. 127-130 ◽  
Author(s):  
Chang Jun Li ◽  
Xia Wu ◽  
Wen Long Jia ◽  
Ke Xi Liao
Keyword(s):  
Pressure Fluctuation ◽  
Peak Pressure ◽  
Mathematic Model ◽  
Water Hammer ◽  
Steel Pipeline ◽  
Oil Transportation ◽  
Reinforced Plastic ◽  
Fluctuation Frequency ◽  
Simulation Results ◽  
Safety Operation

Glass reinforced plastic (GRP) pipeline has good characteristics of anti-corrosion, anti-scaling and it is widely used in the oil transportation pipeline. Analyze the water hammer characteristics of GRP pipeline is essential to ensure the safety operation of the pipeline. The water hammer mathematic model for GRP pipeline is built through combing the general water hammer mathematic model and prosperities of GRP pipeline. The solving method of the model is discussed based on the method of characteristic. Ultimately, the simulation results show the GRP pipeline can reduce the peak pressure and pressure fluctuation frequency as well as increase the low pressure caused by water hammer compared with steel pipeline. The GRP pipeline has a better capability to reduce the harms brought by water hammer than steel pipeline.

Model Building of Hydraulic Cylinder Exciting System Controlled by Wave Exciter

2012 ◽  
Vol 433-440 ◽  
pp. 2053-2058
Author(s):  
Zi Ming Kou ◽  
Xiu Ye Wei ◽  
Juan Wu ◽  
Hong Zhen Lian
Keyword(s):  
Pressure Fluctuation ◽  
Model Building ◽  
Excitation Frequency ◽  
Mathematic Model ◽  
Hydraulic Cylinder ◽  
Control Parameters ◽  
Cyclical Variation ◽  
Exciting System ◽  
Fluctuation Frequency ◽  
The Law

By analyzing exciting course of hydraulic cylinder exciting system controlled by wave-exciter, the pressure fluctuation law of hydraulic cylinder in exciting process has been gained, and the law presents a cyclical variation. The pressure fluctuation frequency is independently controlled by excitation frequency of wave exciter. And mathematic model of hydraulic cylinder exciting system controlled by wave-exciter, which contains three control parameters, has been built.

Modeling of Aluminum Extrusion Process Using Non-Orthogonal Block Structured Grids Based FVM

2011 ◽  
Vol 189-193 ◽  
pp. 1749-1752
Author(s):  
Rui Wang ◽  
Hong Zhong Li
Keyword(s):  
Mathematic Model ◽  
Extrusion Process ◽  
Special Treatment ◽  
Aluminum Extrusion ◽  
Rigid Plastic ◽  
Structured Grids ◽  
Simulation Results ◽  
Flow Theories ◽  
Volume Method ◽  
Die Extrusion

The mathematic model of 3D aluminum extrusion processes using finite volume method (FVM) was established in this paper. The basic theories and rigid-plastic flow theories of this model were researched and built. Non-orthogonal structured grids were used to match complex geometric boundaries and local refinement of grids was also realized. The collocated arrangement is used to discretize the governing equations on non-orthogonal grids directly, pressure oscillations bring by this arrangement and error caused by grid’s non-orthogonality is eliminated by special treatment. A pocket die extrusion process was simulated using the program developed in this paper. The simulation results were also compared with that simulated by FEM software Deform in the same process, material and die conditions. The feasibility and efficiency of the mathematic model built in this paper was demonstrated by the simulation results and the comparison.

Modeling and Testing of Linear Electric Servo System

2012 ◽  
Vol 241-244 ◽  
pp. 1411-1417
Author(s):  
Xue Jiao Zhao ◽  
Fan Lin
Keyword(s):  
Data Collection ◽  
Data Processing ◽  
Servo System ◽  
Mathematic Model ◽  
Simulation Results ◽  
Processing Steps

A mathematic model of the electric servo system was founded in this paper and several groups of data collection and data processing were executed to check up the model veracity. This paper described the data processing steps and analyzed the contrast of test and simulation results. This model is effectual to describe the performance of this kind of servo in respect that the results are mainly consentaneous.

scholarly journals Impact pressure on an orifice plate by a rising water column driven by an air pocket in a vertical riser

2020 ◽  
Vol 81 (5) ◽  
pp. 1029-1038 ◽  
Author(s):  
Yu Qian ◽  
David Z. Zhu
Keyword(s):  
Water Column ◽  
Peak Pressure ◽  
Current Model ◽  
Strong Relationship ◽  
Water Hammer ◽  
Orifice Plate ◽  
Minor Effect ◽  
Initial Water ◽  
Air Pocket ◽  
Riser Height

Abstract Occurrences of storm geyser events have attracted significant attention in recent years. Previous studies suggest that using an orifice plate can reduce the intensity of a geyser event but may induce a water-hammer type of pressure on the orifice plate. This study was conducted to explore the factors that influence the pressure transients when an orifice plate was installed in a vertical riser. A novel model was developed to simulated the movement of a rising water column driven by an air pocket in a vertical riser with an orifice plate on the top. Water-hammer type of pressure occurs when the water column reaches the orifice plate. The current model accurately simulates the dynamics of the water column considering its mass loss due to the flow along the wall of the riser (film flow) and the existence of the orifice plate. It was found that the initial water column length and the driving pressure, as well as the riser material, have a strong relationship with the peak pressure. The riser diameter and riser height have minor effect on the peak pressure. The water-hammer induced peak pressure reaches the maximum when the orifice opening is around 0.2 times the diameter of the vertical riser.

Pressure and Flow Rate Fluctuations in Single- and Two-Blade Pumps

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Andreas Pesch ◽  
Steffen Melzer ◽  
Stephan Schepeler ◽  
Tobias Kalkkuhl ◽  
Romuald Skoda
Keyword(s):  
Flow Rate ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Electromagnetic Flowmeter ◽  
Flow Region ◽  
Mean Values ◽  
Wall Pressure Fluctuations ◽  
Simulation Results ◽  
Blade Pump

Abstract A comparative study on the highly unsteady flow field in single- and two-blade pumps is performed. Stationary pump characteristics, as well as pressure and flow rate fluctuations, are presented. Wall pressure fluctuations were measured in the suction and pressure pipe as well as at several locations within the volute casing by piezoresistive transducers. Flow rate fluctuations were evaluated by a recently presented measurement system based on an electromagnetic flowmeter (Melzer et al. 2020, “A System for Time-Fluctuating Flow Rate Measurements in a Single-Blade Pump Circuit,” Flow Meas. Instrum., 71, p. 101675). Measurements were accompanied by three-dimensional (3D) flow simulations with the open-source cfd software foam-extend. A thorough grid study and validation of the simulation were performed. By a complementary analysis of measurement and simulation results, distinctive differences between both pump types were observed, e.g., flow rate and pressure fluctuation magnitudes are significantly higher in the single-blade pump. In relation to the respective mean values, flow rate fluctuation magnitudes are one order lower than pressure fluctuation magnitudes for both pumps. For the two-blade pump, fluctuations attenuate toward overload irrespective of the particular pump circuit, while they rise for the single-blade pump. 3D simulation results yield detailed insight into the spatially and temporally resolved impeller–volute interaction and reveal that the single-blade impeller pushes a high-pressure flow region forward in a way as a positive displacement pump, resulting in an inherently fluctuating velocity and pressure distribution within the volute.

Study on Directly Driven Wind Turbine with Permanent Magnet Synchronous Generators (D-PMSG)

2011 ◽  
Vol 383-390 ◽  
pp. 3528-3534 ◽  
Author(s):  
Zhong Yao Du ◽  
Rong Ju
Keyword(s):  
Wind Turbine ◽  
Wind Power ◽  
Mathematic Model ◽  
Module Structure ◽  
Synchronous Generators ◽  
Simulation Research ◽  
Permanent Magnet Synchronous Generators ◽  
Speed Modulation ◽  
Simulation Results ◽  
Turbine Speed

Recently, the wind power develops rapidly. In this paper, the mathematic model and vector control of D-PMSG are studied. This thesis involves in simulation research of wind turbine, speed modulation, coordinate transformation, SVPWM waves, main loop and the whole system based on module structure under the environment of MATLAB/SIMULINK. The simulation results indicate that PMSM has perfect characteristic and gives practical meanings for the studies of wind power.

Genetic Based Reinforcement Learning Load Control for Smart Grids

2013 ◽  
Vol 860-863 ◽  
pp. 2423-2426
Author(s):  
Xin Li ◽  
Dan Yu ◽  
Chuan Zhi Zang
Keyword(s):  
Reinforcement Learning ◽  
Electric Charge ◽  
Smart Grids ◽  
Mathematic Model ◽  
Customer Participation ◽  
Load Control ◽  
Demand Side ◽  
Energy Usage ◽  
Take The Best ◽  
Simulation Results

As the improvement of smart grids, the customer participation has reinvigorated interest in demand-side features such as load control for domestic users. A genetic based reinforcement learning (RL) load controller is proposed. The genetic is used to adjust the parameters of the controller. The RL algorithm, which is independent of the mathematic model, shows the particular superiority in load control. By means of learning procedures, the proposed controller can learn to take the best actions to regulate the energy usage for equipments with the features of high comfortable for energy usage and low electric charge meanwhile. Simulation results show that the proposed load controller can promote the performance energy usage in smart grids.

Dynamic Analysis of Flapper/Nozzle Electrohydraulic Servovalve Considering the Influence of the First-Stage Parameters

2014 ◽  
Vol 687-691 ◽  
pp. 316-321
Author(s):  
Wei Zhang ◽  
Song Jing Li
Keyword(s):  
Dynamic Response ◽  
Dynamic Analysis ◽  
Simulation Model ◽  
Discharge Coefficient ◽  
Mathematic Model ◽  
Viscous Damping ◽  
Response Characteristics ◽  
The Past ◽  
Simulation Results ◽  
Dynamic Response Characteristics

The mathematic model of flapper/nozzle electrohydraulic servovalves is rearranged, many factors are reconsidered which have been omitted in the past analysis which are for the purposes of convenience or on the assumption that they are of no particular significance. According to the rearranged mathematic model, the simulation model of the servovalve is established using the Matlab/simulink software, dynamic response characteristics of the servovalve is simulated when the parameters of the discharge coefficient of nozzles and the viscous damping constant of torque motor and flapper are changed. Simulation results show that the change of the parameters influence the dynamic response of the spool displacement.

Large-Eddy Simulation and Passive Control of Flows for a Low Pressure Turbine Cascade

2009 ◽  
Author(s):  
Jibing Lan ◽  
Yonghui Xie ◽  
Di Zhang ◽  
Jing Shu
Keyword(s):  
Pressure Fluctuation ◽  
Passive Control ◽  
Static Pressure ◽  
Separation Bubble ◽  
Suction Surface ◽  
Surface Separation ◽  
Low Pressure Turbine ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Fluctuation Frequency

A rectangular bar which just likes a forward-backward facing step was designed to passive control of the Low-Pressure Turbine (LPT) PakB cascade suction surface separation. Large-eddy simulation (LES) was adopted to analyze the separated-transition flows for the PakB cascade with and without the rectangular bar at Re (Reynolds number based on inlet condition and axial chord) of 86,000 and the freestream turbulence intensity of 1%. Computed results of uncontrolled condition agree well with the experimental data of Lake et al.[6, 7]. And the LES results shown that the rectangular bar control device was successful to control the LPT cascade suction surface separation and provides about 10% kinetic loss coefficient reduction from the uncontrolled one. Unsteady flow structures were also investigated in detail. Static pressure fluctuation frequency at six locations, ranging from 0.56Cx to 0.95Cx axial chord location and with a constant wall normal distance y/h = 1.0, was the same to the separation bubble vortex shedding frequency. Unsteady fluctuation velocity was examined too, which confirmed that the separation bubble vortex frequency was the same to the suction surface static pressure fluctuation frequency.

Parametric Research on Micro-Zigzag Slot Mechanism in OICW

2011 ◽  
Vol 483 ◽  
pp. 699-704 ◽  
Author(s):  
Chuan Qin Liu ◽  
Wen Zhong Lou ◽  
Long Fei Zhang ◽  
Yong Jia Lv
Keyword(s):  
Mathematic Model ◽  
Rectangular Pulse ◽  
Structural Parameter ◽  
Delayed Effect ◽  
Linear Dynamic ◽  
Simulation Results ◽  
Motion Characteristics ◽  
Acceleration Signals ◽  
Theoretical Results ◽  
Simulation Condition

This paper describes the delayed effect on the motion characteristics of the slider in the S&A mechanism resulting from the micro-zigzag slot used in OICW (Objective Individual Combat Weapon) and studies its influence on the ability of filtering transient acceleration signals. Firstly, we established the mathematic model of the slider when the S&A mechanism was loaded by the rectangular pulse acceleration according to the Rigid Dynamic Mechanics Theory and got its analytical solution by using MATLAB. Secondly, to verify the feasibility of this micro-zigzag slot mechanism, we adopted two different kinds of acceleration loading curves, after the non-linear dynamic mechanics simulation on it by using ANSYS/LS-DYNA, displacement and velocity curves of the slider were calculated. Then, to find which structural parameter playing more important role in affecting the characteristics of micro-zigzag slot, we adopted Single-variable Method to study its structural parameter under the same simulation condition. The simulation results we got were almost consistent with the theoretical results. The parametric research of the micro-zigzag slot lays certain a foundation on the research of MEMS system.

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