Numerical Calculation of Hydrodynamic Interference Coefficients between Hull, Rudder and Propeller

2012 ◽  
Vol 591-593 ◽  
pp. 1949-1953 ◽  
Author(s):  
Xiao Wang ◽  
Ming Wu ◽  
Rong Rong Ying
Keyword(s):  
Numerical Simulation ◽  
Numerical Calculation ◽  
Flow Field ◽  
Interference Effect ◽  
Longitudinal Velocity ◽  
Transverse Force ◽  
Navier Stokes ◽  
Straight Line ◽  
Simulation Results ◽  
Viscous Flow Field

CFD developed rapidly in capability and practicality during past years. A lot of research works on numerical simulation of viscous flow field around ship were widely carried out in past decades. But the research of interference effect among the hull, rudder and propeller was rarely concerned. In this paper, based on an unsteady Reynolds Averaged Navier–Stokes method, the dynamic mesh methods(6DOF) are adopted to simulate straight line and oblique towing test of ship with twin propellers and twin rudders. And based on the simulation results, the interference coefficients, such as effective weak coefficient ωp, rudder’s effective longitudinal velocity uR, effective attack angle αR, rudder force’s modificatory factor αH for shiphandling derivational transverse force and its dimensionless distance to ship’s gravity point, are calculated. The computed results of this paper agree well with the experimental results carried out in the tower tank of ITTC. It shows that the methods on numerical calculation of Interference Coefficients between hull, rudder and propeller is successful.

Numerical Simulation of Muzzle Flow Field of Gun Based on CFD

2013 ◽  
Vol 291-294 ◽  
pp. 1981-1984
Author(s):  
Zhang Xia Guo ◽  
Yu Tian Pan ◽  
Yong Cun Wang ◽  
Hai Yan Zhang
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Stokes Equation ◽  
Wave Structure ◽  
Flow Fields ◽  
Single Equation ◽  
Navier Stokes ◽  
Turbulent Model ◽  
Navier Stokes Equation ◽  
Numerical Simulation Result

Gunpowder was released in an instant when the pill fly out of the shell during the firing, and then formed a complicated flow fields about the muzzle when the gas expanded sharply. Using the 2 d axisymmetric Navier-Stokes equation combined with single equation turbulent model to conduct the numerical simulation of the process of gunpowder gass evacuating out of the shell without muzzle regardless of the pill’s movement. The numerical simulation result was identical with the experimental. Then simulated the evacuating process of gunpowder gass of an artillery with muzzle brake. The result showed complicated wave structure of the flow fields with the muzzle brake and analysed the influence of muzzle brake to the gass flow field distribution.

Numerical Simulation of Powder Dispersion Performance by Different Mesh Types

2016 ◽  
Vol 680 ◽  
pp. 82-85
Author(s):  
Jian Cai ◽  
Lan Chen ◽  
Umezuruike Linus Opara
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Fine Particle ◽  
Particle Deposition ◽  
Tetrahedral Mesh ◽  
Computational Time ◽  
Kinetic Characteristics ◽  
Powder Dispersion ◽  
Simulation Results ◽  
Time Accuracy

OBJECTIVE To investigate the influence of mesh type on numerical simulating the dispersion performance of micro-powders through a home-made tube. METHODS With the computational fluid dynamics (CFD) method, a powder dispersion tube was meshed in three different types, namely, tetrahedral, unstructured hexahedral and prismatic-tetrahedral hybrid meshes. The inner flow field and the kinetic characteristics of the particles were investigated. Results of the numerical simulation were compared with literature evidences. RESULTS The results showed that using tetrahedral mesh had the highest computational efficiency, while employing the unstructured hexahedral mesh obtained more accurate outlet velocity. The simulation results of the inner flow field and the kinetic characteristics of the particles were slightly different among the three mesh types. The calculated particle velocity using the tetrahedral mesh had the best correlation with the changing trend of the fine particle mass in the first 4 stages of the new generation impactor (NGI) (R2 = 0.91 and 0.89 for powder A and B, respectively). Conclusions Mesh type affected computational time, accuracy of simulation results and the prediction abilities of fine particle deposition.

scholarly journals Slit Wall Effect on the Stability of Wavy Vortex Flow

2014 ◽  
Vol 6 ◽  
pp. 853069 ◽  
Author(s):  
Dong Liu ◽  
Ying-ze Wang ◽  
Hyoung-Bum Kim ◽  
Fang-neng Zhu ◽  
Chun-lin Wang
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Radial Velocity ◽  
Flow Regime ◽  
Experimental Measurement ◽  
Vortex Flow ◽  
Wall Effect ◽  
Taylor Vortices ◽  
Simulation Results ◽  
The Stability

The wavy vortex flow in the plain model was studied by experimental measurement; the preliminary feature of wavy vortex flow was obtained. This flow field in the plain model was also studied by numerical simulation. The reliability of numerical simulation was verified by comparing with the experimental and numerical simulation results. To study the slit wall effect on the wavy vortex flow regime, another two models with different slit number were considered; the slit number was 6 and 12. By comparing the wavy vortex flow field in different models, the axial fluctuation of Taylor vortices was found to be different, which was increased with the increasing of slit number. The maximum radial velocity from the inner cylinder to the outer one in the 6-slit number was increased by 12.7% compared to that of plain model. From the results of different circumferential position in the same slit model, it can be found that the maximum radial velocity in slit plane is significantly greater than that in other planes. The size of Taylor vortices in different models was also calculated, which was found to be increased in the 6-slit model but was not changed as the slit number increased further.

Study on flow field of gas–solid two-phase pulsed jet

2019 ◽  
Vol 33 (24) ◽  
pp. 1950279
Author(s):  
Xinhua Song ◽  
Xiaojie Li ◽  
Yang Wang ◽  
Honghao Yan
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Particle Distribution ◽  
Starch Granule ◽  
Injection Pressure ◽  
Two Phase ◽  
Particle Injection ◽  
Pulsed Jet ◽  
Simulation Based ◽  
Simulation Results

In this paper, a computational fluid dynamics–discrete element method (CFD–DEM) coupling method is established to simulate the starch granule injection by coupling CFD and DEM. Then a gas–solid two-phase pulsed jet system is designed to capture the flow field trajectory of particle injection (colored starch with a mean diameter of 10.67 [Formula: see text]m), and the image is processed by color moment and histogram. Finally, the simulation results are compared with the experimental results, and the following conclusions are drawn. The numerical simulation results show that with the increase of injection pressure, the injection height increases gradually. When the injection pressure reaches above 0.4 MPa, the increase of injection height decreases. The experimental images show that the larger the pressure (i.e., the greater the initial velocity), the faster the velocity of particle distribution in the space, and the injection heights with the injection pressures of 0.4 MPa and 0.5 MPa are close, which is consistent with the result from the FLUENT numerical simulation based on CFD–DEM.

Numerical Simulation of Partial Cavitating Flow of 2-D Hydrofoil in Viscous Flow

2012 ◽  
Vol 214 ◽  
pp. 102-107
Author(s):  
Xiao Hui He ◽  
Lei Gao ◽  
Hong Bing Liu ◽  
Zhi Gang Li
Keyword(s):  
Numerical Simulation ◽  
Numerical Calculation ◽  
Flow Field ◽  
Viscous Flow ◽  
Reynolds Equation ◽  
Cavitating Flow ◽  
Partial Cavitation ◽  
Calculation Results ◽  
Control Equation ◽  
Precise Degree

This paper has studied the partial cavitation of 2-D hydrofoil based on the theory of viscous flow. The numerical calculation sets forth from the complete N-S equation and adopts the two-equation turbulence model closed Reynolds equation. As the basic control equation, the cavitating flow adopts the Rayleigh plesset model and calculates the zero angle of attack. At the same time, it calculates the influences of different ship speeds on the hydrofoil partial cavitating flow and analyzes the flow field of the hydrofoil. In addition, it makes comparisons on the calculation results and the published test conclusions. The results have shown that the calculation method in this paper has relatively good calculation precise degree.

scholarly journals Numerical Simulation of Mutual Influence in 470 Sailing Hull and Rudder at Different Hull Speeds

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 134
Author(s):  
Shijie Lin ◽  
Yong Ma ◽  
Weitao Zheng ◽  
Zhengye Pan
Keyword(s):  
Numerical Simulation ◽  
Stokes Equations ◽  
Mutual Influence ◽  
Effective Area ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Stall Angle ◽  
The Stability ◽  
Viscous Flow Field ◽  
Reducing Energy

A 470 sailing race requires effective cooperation between athletes to optimize the hull position and the correct heading. To understand the effect of the hull on the maneuverability of the rudder and the influence of the rudder on the stability and rapidity of the hull at different ship speeds, requires numerical 3D simulation and research on the viscous flow field of 470 sailing based on Reynolds-averaged Navier-Stokes equations. The results show that the rudder can reduce the wave making characteristics of the hull, reducing energy loss and thus improving the hull’s rapidity when the speed is greater than 6 m/s, as the effective area of rudder decrease and increases the stall angle, which reduces the manipulatable performance of the rudder to some extent. This study could quantify the performance of the hull and rudder at different speeds. Moreover, this study might provide strategies for the athletes to effectively control the rudder and hull at different speeds.

Study on the Principle of Yarn Splicing of Pneumatic Splicer Using Numerical Simulation

2012 ◽  
Vol 588-589 ◽  
pp. 1355-1358
Author(s):  
Xiao Xing ◽  
Guo Ming Ye
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Three Dimensional ◽  
Numerical Results ◽  
Simulation Results

During the splicing process of pneumatic splicer, the principle of yarn splicing is closely related to the flow field inside the splicing chamber. This paper presents a numerical simulation of the flow char-acteristics inside the splicing chamber of the pneumatic splicer. A three-dimensional grid and the realizable tur¬bulence model are used in this simulation. The numerical results of veloc¬ity vectors distribution inside the chamber are shown. Streamlines starting from the two air injectors are also acquired. Based on the simulation, the principle of yarn splicing of the pneumatic splicer is discussed. The airflow in the splicing chamber can be divided into three regions. In addition, the simulation results have well sup¬ported the principle of yarn splicing of pneumatic splicer claimed by the splicing chamber makers.

Numerical Simulation of the Flow Field in Cavitations Nozzle for Impinging Streams Reactor

2010 ◽  
Vol 139-141 ◽  
pp. 1048-1051 ◽  
Author(s):  
Qin Li ◽  
Hui Lin Wang ◽  
Fu Bao Li
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Surrounding Medium ◽  
Analytical Calculation ◽  
Simple Algorithm ◽  
Shear Effect ◽  
Outlet Pressure ◽  
Pressure Distributions ◽  
Strong Shear ◽  
Simulation Results

The pressure distributions in cavitations nozzle of three different structures were studied by Hydromechanics theory, the models and mashes were completed by using Gambit software, for the conditions of the inlet pressure to 20MPa and the outlet pressure to 0.1MPa, the flow field within cavitations nozzles is simulated based on the standard k-ε model and the SIMPLE algorithm with Fluent. The result of numerical simulation is consistent with that of analytical calculation. Simulation results show that the flow has a strong shear effect with the surrounding medium in the diffuser, resulting in significant negative pressure, which is conducive to the formation of cavitations bubbles. The angle nozzle is best selected for impinging streams cavitations reactor on this basis in the paper.

Numerical Simulation of Flow Field of Inflation Pressure for Large Complex Sulfide Mineral of Low-Tin Flotation Machine

2013 ◽  
Vol 341-342 ◽  
pp. 333-336
Author(s):  
Ming Zhen Hu ◽  
Bo Zeng Wu ◽  
Jin Quan Chen ◽  
Ji Shu Zeng
Keyword(s):  
Fluid Dynamics ◽  
Numerical Simulation ◽  
Flow Field ◽  
Sulfide Mineral ◽  
Inflation Pressure ◽  
Flotation Machine ◽  
Complex Sulfide ◽  
Flow Field Characteristics ◽  
Machine Simulation ◽  
Simulation Results

For flotation characteristics of complex sulfide mineral of low-tin in Guangxi Dachang mine, fluid dynamics software FLUENT was applied to simulate the turbulence intensity of slurry fluid in flotation machine at different inflation pressures. The effect of flow field characteristics was gotten for flotation machine. Simulation results show that the best inflation pressure was 120000 Pa.

scholarly journals Robust Observer-Based H∞ Controller Design for Motorcycle Lateral Dynamics

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
A. Ferjani ◽  
I. Zaidi ◽  
M. Chaabane
Keyword(s):  
Numerical Simulation ◽  
Convex Optimization ◽  
Optimization Problem ◽  
Controller Design ◽  
Longitudinal Velocity ◽  
Robust Controller ◽  
Convex Optimization Problem ◽  
Lateral Dynamics ◽  
Robust Observer ◽  
Simulation Results

The present work deals with the design problem of a robust observer-based controller for a motorcycle system using LPV approach. The designed model is specifically uncertain and disturbed one, whose uncertainties are related to variations of both the cornering stiffness and the longitudinal velocity. The nonlinear motorcycle model is firstly transformed on an uncertain LPV model with two vertices; then an observer-based H∞ robust controller is designed. Both the controller and observer gain matrices are computed by solving a unified convex optimization problem under LMI constraints using YALMIP solver. Numerical simulation results are given to illustrate the effectiveness of the designed method.

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