CFD-Based Hydrodynamic Analysis of High Performance Racing Yachts

2009 ◽  
Author(s):  
Len Imas ◽  
Bryan Baker ◽  
Britton Ward ◽  
Gregory Buley
Keyword(s):  
High Performance ◽  
Large Scale ◽  
Rigid Body Dynamics ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Cfd Simulations ◽  
Hydrodynamic Analysis ◽  
Efficient Performance ◽  
Body Dynamics ◽  
Free Surface Capturing

Recent development in Navier-Stokes solver technology and meshing techniques have furthered the ability of naval architects and hydrodynamicists to analyze intricate flow simulations of high performance racing yachts. The effect of this development has contributed to enlarging the bounds of the design space aiding in comprehension and optimization of high performance yachts. This paper will present selected examples from a research study based around tow tank tests and CFD simulations of a canonical high-performance racing yacht. The geometry configurations studied were fully appended with rudders, keel/bulb and a dagger-board. Simulations were performed with various operating conditions covering both lifting and non-lifting flow regimes. Topics covered will address (i) validation against tow tank measurements; (ii) efficient performance of large-scale computations; and (iii) numerical issues related to (a) mesh generation, (b) solution, discretization, and free surface capturing algorithms, (c) turbulence modelling, (d) rigid body dynamics and sail force models.

High-loaded sub-6 nm Pt1Co1 intermetallic compounds with high-efficient performance expression in PEMFCs

2021 ◽  
Author(s):  
Qingqing Cheng ◽  
Shuai Yang ◽  
Cehuang Fu ◽  
Liang-Liang Zou ◽  
Zhi-Qing Zou ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Intermetallic Compounds ◽  
High Performance ◽  
Reduction Reaction ◽  
Operating Conditions ◽  
Practical Application ◽  
Efficient Performance ◽  
High Efficient ◽  
High Metal

High-loaded oxygen reduction reaction (ORR) Pt intermetallic compounds with high performance expression under PEMFC operating conditions are prerequisite for practical application. Nevertheless, high metal-loading would lead to the severe agglomeration...

Experimental Measurements and Computational Solutions for Aerodynamic Forces on an Ahmed Body at Various Ground Clearances

2003 ◽  
Author(s):  
Ilhan Bayraktar ◽  
Drew Landman ◽  
Tuba Bayraktar
Keyword(s):  
Large Scale ◽  
Bluff Body ◽  
Ground Plane ◽  
Computational Simulation ◽  
Simulation Method ◽  
Full Scale ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Ground Clearance ◽  
Ahmed Body

Reliable computer solutions to external aerodynamic flow fields on road vehicles are extremely desirable to road vehicle designers. In a previous publication a study was performed to validate a Reynolds-averaged unsteady Navier-stokes solution for the aerodynamic characterization of a large-scale bluff body. In the present study, the external aerodynamics of this body as a function of ground clearance are explored. Experimental force measurements are obtained in a full-scale wind tunnel using an Ahmed body model and test conditions representative of full-scale operating conditions. A Reynolds averaged Navier-Stokes solver is employed for computational simulation of the external flowfield at the same conditions. Experimental and computational force coefficients versus vehicle ground clearance are presented for fixed ground, moving ground, and suction slot road simulations. Experimental results using boundary layer suction are compared to computational results with a moving ground plane in order to better understand the effect of a road simulation method.

Steady and Unsteady Modeling for Heat Transfer Predictions of High Pressure Turbine Blade Internal Cooling

2012 ◽  
Author(s):  
Rémy Fransen ◽  
Nicolas Gourdain ◽  
Laurent Y. M. Gicquel
Keyword(s):  
Heat Transfer ◽  
Large Scale ◽  
Cooling System ◽  
Transfer Problem ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Wall Region ◽  
Internal Cooling ◽  
Computational Domain ◽  
Complex Flow

This work focuses on numerical simulations of flows in blade internal cooling system. Large Eddy Simulation (LES) and Reynolds-Averaged Navier Stokes (RANS) approaches are compared in a typical blade cooling related problem. The case is a straight rib-roughened channel with high blockage ratio, computed and compared for both a periodic and full spatial domains. The configuration was measured at the Von Karman Institute (VKI) using Particle Image Velocimetry (PIV) in near gas turbine operating conditions. Results show that RANS models used fail to predict the full evolution of the flow within the channels where massive separation and large scale unsteady features are evidenced. In contrast LES succeeds in reproducing these complex flow motions and both mean and fluctuating components are clearly improved in the channels and in the near wall region. Periodic computations are gauged against the spatial computational domain and results on the heat transfer problem are addressed.

Projective Jacobi and Gauss-Seidel on the GPU for Non-Smooth Multi-Body Systems

2014 ◽  
Author(s):  
Gabriel Nützi ◽  
Adrian Schweizer ◽  
Michael Möller ◽  
Christoph Glocker
Keyword(s):  
Granular Media ◽  
Large Scale ◽  
Contact Problems ◽  
Rigid Body Dynamics ◽  
Contact Dynamics ◽  
Problem Size ◽  
Body Dynamics ◽  
Smooth Contact ◽  
Multi Body ◽  
Speedup Factor

Large-scale contact problems with impacts and Coulomb friction arise in the simulation of rigid body dynamics treated within the non-smooth contact dynamics approach using set-valued force and impact laws. In this paper the parallelization of two popular numerical methods for solving such contact problems on the GPU, being the projected over-relaxed Jacobi (JOR Prox) and projected Gauss-Seidel iteration (SOR Prox), is studied in detail. Performance tests for the parallel JOR and SOR Prox iterations are conducted and a speedup factor of up to 16, depending on the problem size, can be achieved compared to a sequential implementation. This work forms the stepping stone to the simulation of granular media on a computer cluster.

CFD Transonic Trajectory Predictions of Three-Store Ripple Release Using Chimera Method

2014 ◽  
Vol 513-517 ◽  
pp. 4490-4493 ◽  
Author(s):  
Ke Xi ◽  
Chao Yan
Keyword(s):  
Moving Boundary ◽  
Stokes Equations ◽  
Unsteady Flows ◽  
Rigid Body Dynamics ◽  
Navier Stokes ◽  
Separation Problem ◽  
Navier Stokes Equations ◽  
Body Dynamics ◽  
Multi Body ◽  
Good Agreement

The complicated unsteady flows with moving boundary were simulated numerically by coupling solving unsteady compressible Navier-Stokes equations and 6DOF rigid-body dynamics equations. The Chimera grid technology was used to handle the relative motion. The three-store ripple release of the wing-store configuration was simulated using this method. The computational results are in good agreement with data from other literature, showing that the method used has a strong applicability to complex multi-body separation problem.

2116 Large-scale rigid-body dynamics simulation of cluster of water molecules under external electric field

2012 ◽  
Vol 2012.25 (0) ◽  
pp. 204-205
Author(s):  
Yohei NIWA ◽  
Yasuhiro KAJIMA ◽  
Shuji OGATA ◽  
Miyabi HIYAMA ◽  
Ryo KOBAYASHI ◽  
...  
Keyword(s):  
Electric Field ◽  
Rigid Body ◽  
External Electric Field ◽  
Large Scale ◽  
Rigid Body Dynamics ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Body Dynamics

Design of Rigid Body Dynamics for Pitch Regulation Mechanism to Maximize Energy Capture by Wind Turbine

2020 ◽  
pp. 48-51
Author(s):  
S. A. Ahmad ◽  
M. Y. Javaid ◽  
M. Abubakar
Keyword(s):  
Wind Turbine ◽  
Large Scale ◽  
Rigid Body Dynamics ◽  
Maximum Power ◽  
Regulation Mechanism ◽  
Energy Capture ◽  
Wind Speeds ◽  
Depth Analysis ◽  
Body Dynamics ◽  
Pitch Regulation

Wind turbines are generally designed for specific wind speeds and at below or above these speeds wind turbine could not give the expected maximum power. To obtain the maximum power at different wind speeds, pitching mechanism of the blades introduced. Mostly active pitching is used on large scale but the study gives detail advantages, design and analysis of passive pitching which is free of electronics. The study suggested the design that through centrifugal masses the rotor is able to changes the pitch angles through 10 degrees which are enough for wind speed ranges from 4-20 m/s which maintain the optimum angle of attack maximizing the power output. This report includes an in- depth analysis of design process, detailed components and assembly, recommendations, and conclusions.

Scaling of Turbine Blade Roughness for Model Studies

2003 ◽  
Author(s):  
Hugh M. McIlroy ◽  
Ralph S. Budwig ◽  
Donald M. McEligot
Keyword(s):  
Turbine Blade ◽  
High Performance ◽  
Large Scale ◽  
Turbine Rotor ◽  
Operating Conditions ◽  
Detailed Knowledge ◽  
Model Studies ◽  
Surface Data ◽  
Scale Experiment ◽  
Parameter Ranges

The purpose of this note is to provide an approach to scaling turbine blade roughness so a large-scale experiment will yield useful results despite lack of detailed knowledge about the application. In the process, an apparently new approach for scaling of actual turbine blade roughness on an experimental model of a rough turbine blade is presented. Rough surface data from a first-stage high-pressure turbine rotor, estimates of engine operating conditions representative of high-performance aircraft, and assumed matches of the Reynolds number and acceleration parameter ranges are used. A scaling factor is determined by estimating and matching the nondimensional roughness (in wall coordinates) of a typical airfoil for a model.

scholarly journals Posing Multibody Dynamics With Friction and Contact as a Differential Complementarity Problem

2017 ◽  
Vol 13 (1) ◽  
Author(s):  
Dan Negrut ◽  
Radu Serban ◽  
Alessandro Tasora
Keyword(s):  
Rigid Body ◽  
Multibody Dynamics ◽  
Complementarity Problem ◽  
Large Scale ◽  
Differential Algebraic Equations ◽  
Rigid Body Dynamics ◽  
Quadratic Program ◽  
Body Dynamics ◽  
Complementarity Approach ◽  
Matrix Free

This technical brief revisits the method outlined in Tasora and Anitescu 2011 [“A Matrix-Free Cone Complementarity Approach for Solving Large-Scale, Nonsmooth, Rigid Body Dynamics,” Comput. Methods Appl. Mech. Eng., 200(5–8), pp. 439–453], which was introduced to solve the rigid multibody dynamics problem in the presence of friction and contact. The discretized equations of motion obtained here are identical to the ones in Tasora and Anitescu 2011 [“A Matrix-Free Cone Complementarity Approach for Solving Large-Scale, Nonsmooth, Rigid Body Dynamics,” Comput. Methods Appl. Mech. Eng., 200(5–8), pp. 439–453]; what is different is the process of obtaining these equations. Instead of using maximum dissipation conditions as the basis for the Coulomb friction model, the approach detailed uses complementarity conditions that combine with contact unilateral constraints to augment the classical index-3 differential algebraic equations of multibody dynamics. The resulting set of differential, algebraic, and complementarity equations is relaxed after time discretization to a cone complementarity problem (CCP) whose solution represents the first-order optimality condition of a quadratic program with conic constraints. The method discussed herein has proven reliable in handling large frictional contact problems. Recently, it has been used with promising results in fluid–solid interaction applications. Alas, this solution is not perfect, and it is hoped that the detailed account provided herein will serve as a starting point for future improvements.

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