scholarly journals Approach for a breastshot waterwheel numerical simulation methodology using six degrees of freedom

2020 ◽  
Vol 6 ◽  
pp. 611-616
Author(s):  
Warjito ◽  
Aji Putro Prakoso ◽  
Dendy Adanta ◽  
Budiarso ◽  
Ridho Irwansyah
Keyword(s):  
Numerical Simulation ◽  
Degrees Of Freedom ◽  
Simulation Methodology ◽  
Six Degrees Of Freedom

Nonlinear system controllability analysis and autopilot design for bank-to-turn aircraft with two flaps

2018 ◽  
Vol 233 (5) ◽  
pp. 1772-1783 ◽  
Author(s):  
Jinlu Dong ◽  
Di Zhou ◽  
Chuntao Shao ◽  
Shikai Wu
Keyword(s):  
Numerical Simulation ◽  
Control System ◽  
Nonlinear System ◽  
Feedback Linearization ◽  
Degrees Of Freedom ◽  
Lyapunov Stability Theory ◽  
Zero Dynamics ◽  
Controlled System ◽  
Linearization Technique ◽  
Six Degrees Of Freedom

In this study, the six-degrees-of-freedom flight motion of a tail-controlled bank-to-turn aircraft with two flaps is described as a nonlinear control system. The controllability of this flap-controlled system is analyzed based on nonlinear controllability theory and the system is proved to be weakly controllable. By choosing the angle-of-attack and roll angle as the outputs of this control system, the zero dynamics of the system are analyzed using Lyapunov stability theory, and are proved to be stable under some conditions given by an inequality. Then an autopilot is designed for this system using the feedback linearization technique. Results of the numerical simulation for this control system show the effectiveness of the controllability analysis and autopilot design.

Numerical Simulation of Ship-Ship Interactions in Waves

2019 ◽  
Author(s):  
Xueshen Xie ◽  
Yuxiang Wan ◽  
Qing Wang ◽  
Hao Liu ◽  
Dakui Feng
Keyword(s):  
Numerical Simulation ◽  
Degrees Of Freedom ◽  
Simulation Analysis ◽  
Turbulence Models ◽  
Body Motion ◽  
Structured Grid ◽  
Six Degrees Of Freedom ◽  
Unsteady Rans ◽  
Small Ship ◽  
The Impact

Abstract A numerical simulation of the hydrodynamic interaction and attitude of a ship and two ships of different sizes navigating in parallel in waves were carried out in this paper. The study of the two ships navigating in parallel is of great significance in marine replenishment. This paper used in house computational fluid dynamics (CFD) code to solve unsteady RANS equation coupled with six degrees of freedom (6DOF) solid body motion equations. URANS equations are solved by finite difference method and PISO algorithm. Structured grid with overset technology have been used to make computations. Turbulence models used the Shear Stress Transport (SST) k-ω model. The method used for free surface simulation is single phase level set. In this paper, two DTMB 5415 with different scales are selected for simulation analysis. This paper analyzed the impact of the big ship on the small ship when the two ships were navigating in parallel. This paper also analyzed the relationship between interaction and velocity between hulls, which has certain guiding significance for the ship’s encounter on the sea.

Numerical Simulation of Submarine Surfacing With Six Degrees of Freedom in Regular Waves

2016 ◽  
Author(s):  
Weijian Jiang ◽  
Zhilin Wang ◽  
Ran He ◽  
Xianzhou Wang ◽  
Dakui Feng
Keyword(s):  
Numerical Simulation ◽  
Wave Height ◽  
Velocity Fluctuation ◽  
Degrees Of Freedom ◽  
Wave Length ◽  
Roll Angle ◽  
Regular Waves ◽  
Rolling Moment ◽  
Six Degrees Of Freedom ◽  
Calm Water

Submarine surfacing in waves is three dimensional unsteady motion and includes complex coupling between force and motion. This paper uses computational fluid dynamics (CFD) to solve RANS equation with coupled six degrees of freedom solid body motion equations. RANS equations are solved by finite difference method and PISO arithmetic. Level-set method is used to simulate the free surface. Computations were performed for the standard DARPA SUBOFF model. The structured dynamic overset grid is applied to the numerical simulation of submarine surfacing (no forward speed) in regular waves and computation cases include surfacing in the calm water, transverse regular waves with different ratio of wave height and submarine length (h/L = 0.01, 0.02, 0.03, 0.04) and transverse regular waves with different ratio of wave length and submarine length (λ/L = 0.5, 1, 1.5). The asymmetric vortices in the process of submarine surfacing can be captured. It proves that roll instability is caused by the destabilizing hydrodynamic rolling moment overcoming the static righting moment both under the water and in regular waves. Relations among maximum roll angle, surfacing velocity fluctuation and wave parameters are concluded by comparison with variation trend of submarine motion attitude and velocity of surfacing in different wave conditions. Simulation results confirm that wave height h/L = 0.04 and wave length λ/L = 1.5 lead to surfacing velocity fluctuation significantly. Maximum roll angle increases with the increase of wave height and wave length. Especially the law presents approximate linear relationship. Maximum roll angle with wave height (h/L = 0.04) can reach to 7.29° while maximum roll angle with wave length (λ/L = 1.5) can reach to 5.79° by contrast with 0.85° in calm water. According to the above conclusions, maneuverability can be guided in the process of submarine surfacing in waves in order to avoid potential safety hazard.

Numerical simulation of h-adaptive immersed boundary method for freely falling disks

2018 ◽  
Vol 32 (12n13) ◽  
pp. 1840002
Author(s):  
Pan Zhang ◽  
Zhenhua Xia ◽  
Qingdong Cai
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Aspect Ratio ◽  
Immersed Boundary Method ◽  
Adaptive Mesh Refinement ◽  
Degrees Of Freedom ◽  
Adaptive Mesh ◽  
Immersed Boundary ◽  
Six Degrees Of Freedom ◽  
Boundary Method

In this work, a freely falling disk with aspect ratio 1/10 is directly simulated by using an adaptive numerical model implemented on a parallel computation framework JASMIN. The adaptive numerical model is a combination of the h-adaptive mesh refinement technique and the implicit immersed boundary method (IBM). Our numerical results agree well with the experimental results in all of the six degrees of freedom of the disk. Furthermore, very similar vortex structures observed in the experiment were also obtained.

Numerical Simulation of Projectile Accelerating Process in Aftereffect Period

2012 ◽  
Vol 236-237 ◽  
pp. 576-580
Author(s):  
Yang Zhong ◽  
Liang Ming Wang
Keyword(s):  
Numerical Simulation ◽  
Initial Velocity ◽  
Degrees Of Freedom ◽  
Large Scale ◽  
Six Degrees Of Freedom ◽  
After Effect ◽  
Rigid Model ◽  
Peak Value

The initial velocity of a projectile has great effects on the weapon performances and it influences firing accuracy. It is meaningful to know the motion of projectiles in after-effect period. This article studies the motion of the projectile by using a Six Degrees-of-Freedom rigid model and chimera method, which is suitble to simulate large-scale deplacemengt of projectiles. The results of the simulation show that the velocity of the projectile increases rapidly first and decreases slowly after reaching the peak value.

scholarly journals Numerical Simulation of Ship Oil Spill in Arctic Icy Waters

2020 ◽  
Vol 10 (4) ◽  
pp. 1394
Author(s):  
Wei Li ◽  
Xiao Liang ◽  
Jianguo Lin ◽  
Ping Guo ◽  
Qiang Ma ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Oil Spill ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Oil Film ◽  
Six Degrees Of Freedom ◽  
Oil Dispersant ◽  
Surface Method ◽  
Water Conditions ◽  
Ice Floes

This paper presents a three-dimensional numerical simulation model of an oil spill for application in emergency treatment methods under icy water conditions. The combined effects of wind, wave, current and ice implemented in our model correspond to Arctic Ocean conditions. A discrete element method combined with an overset grid was adopted to track the trajectory movements of oil film with medium-density ice floes and simulate the flow field of moving ice of large displacement in six degrees of freedom (6DOF). The probability of oil spill area extensions were estimated by a response surface method (RSM). Results showed reduced risk of pollution in icy water conditions and greater drift action of oil film. Accordingly, the spraying location and quantity of oil-dispersant could be rapidly specified.

Control of processing at multi-tool two-support setup

2020 ◽  
pp. 67-73
Author(s):  
N.D. YUsubov ◽  
G.M. Abbasova
Keyword(s):  
Degrees Of Freedom ◽  
Factor Model ◽  
Angular Displacement ◽  
Factor Models ◽  
Technological System ◽  
Displacement Control ◽  
Model Accuracy ◽  
Six Degrees Of Freedom ◽  
Angular Displacements ◽  
And Control

The accuracy of two-tool machining on automatic lathes is analyzed. Full-factor models of distortions and scattering fields of the performed dimensions, taking into account the flexibility of the technological system on six degrees of freedom, i. e. angular displacements in the technological system, were used in the research. Possibilities of design and control of two-tool adjustment are considered. Keywords turning processing, cutting mode, two-tool setup, full-factor model, accuracy, angular displacement, control, calculation [email protected]

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