Time-Accurate Analysis of the Viscous Flow Around Puller Podded Drive Using Sliding Mesh Method

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Reza Shamsi ◽  
Hassan Ghassemi
Keyword(s):  
Experimental Data ◽  
Viscous Flow ◽  
Computational Method ◽  
Navier Stokes ◽  
Percentage Error ◽  
Accurate Analysis ◽  
Sliding Mesh ◽  
Mesh Method ◽  
Unsteady Viscous Flow ◽  
Thrust And Torque

In this paper a computational method is presented for predicting the unsteady hydrodynamic forces acting on podded drive components. These numerical simulations are performed with the aim of accurately studying the interaction between the propeller, the pod, and the strut. In order to simulate the unsteady viscous flow around a puller type podded drive, a Reynolds-Averaged Navier–Stokes (RANS) solver is used. The time-accurate calculations are made by applying the sliding mesh method. Structured and unstructured mesh techniques are used for the propeller and podded drive. The method is applied in the case of the straight condition. The unsteady propeller thrust and torque coefficient fluctuations are predicted for advance velocity ratios ranging from 0.2 to 1.0. The time averaged forces of the podded drive obtained by an unsteady analysis are compared to and verified by the steady result and the experimental data. Finally, discrepancies between the simulation results and the experimental data have been quantitatively evaluated in terms of the relative percentage error for the propulsive characteristics.

scholarly journals Numerical Analysis on Hydrodynamic Characteristics of Surface Piercing Propellers in Oblique Flow

Water ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2015
Author(s):  
Ren ◽  
Hua ◽  
Ji
Keyword(s):  
Experimental Data ◽  
Free Surface ◽  
Numerical Analysis ◽  
Navier Stokes ◽  
Hydrodynamic Characteristics ◽  
Planing Craft ◽  
Sliding Mesh ◽  
Oblique Flow ◽  
Thrust And Torque ◽  
Good Agreement

When a planing boat sails at the free surface, the posture changes drastically with time, so the surface piercing propellers usually work in oblique flow. In this paper, numerical simulations are performed to predict the performance of PSP-841B with Unsteady Reynolds Averaged Navier–Stokes (URANS) method coupling with sliding mesh and volume of fluid (VOF) method. The results show that the predicted thrust and torque coefficients of PSP-841B are in good agreement with the experimental data. It proves the present numerical schemes are feasible and validated. These schemes are applied in the simulations of SPP-1 that is installed to a planing craft. In oblique flow, the ventilation volume of SPP-1 increases dramatically, resulting in the postponed transition of vented status that changes from the fully dry to partially wetted; at the low advance ratios, the thrust and torque coefficients are less than that in the horizontal case. As the advance speed increases, the vented mode of SPP-1 varies from full ventilation to partially wet, and the forces and moments get closer to the results in the horizontal flow. In addition, the blockage effect of air cavity to the inflow in oblique flow is more significant than the results in the horizontal case.

URANS Studies of Effect of Eccentricity on Ship–Lock Interactions

2016 ◽  
Vol 13 (04) ◽  
pp. 1641012
Author(s):  
Qingjie Meng ◽  
Decheng Wan
Keyword(s):  
Viscous Flow ◽  
Hydrodynamic Interaction ◽  
Vertical Displacement ◽  
Navier Stokes ◽  
Test Case ◽  
The Third ◽  
Surface Pressure Distribution ◽  
Sst Turbulence Model ◽  
Unsteady Viscous Flow ◽  
Ship Lock

The unsteady viscous flow around a 12000TEU ship model entering the Third Set of Panama Locks with different eccentricity is simulated by solving the unsteady Reynolds averaged Navier–Stokes (RANS) equations in combination with the [Formula: see text]SST turbulence model. Overset grid technology is utilized to maintain grid orthogonality and the effects of the free surface are taken into account. The hydrodynamic forces, vertical displacement as well as surface pressure distribution are predicted and analyzed. First, a benchmark test case is designed to validate the capability of the present methods in the prediction of the viscous flow around the ship when maneuvering into the lock. The accumulation of water in front of the ship during entry into a lock is noticed. A set of systematic computations with different eccentricity are then carried out to examine the effect of eccentricity on the ship–lock hydrodynamic interaction.

Simulation of the Gap Resonance Between Two Rectangular Barges in Regular Waves by a Free Surface Viscous Flow Solver

2013 ◽  
Author(s):  
B. Elie ◽  
G. Reliquet ◽  
P.-E. Guillerm ◽  
O. Thilleul ◽  
P. Ferrant ◽  
...  
Keyword(s):  
Experimental Data ◽  
Free Surface ◽  
Viscous Flow ◽  
Stokes Equations ◽  
Resonance Phenomenon ◽  
Navier Stokes ◽  
Regular Waves ◽  
Navier Stokes Equations ◽  
Flow Solver ◽  
Gap Resonance

This paper compares numerical and experimental results in the study of the resonance phenomenon which appears between two side-by-side fixed barges for different sea-states. Simulations were performed using SWENSE (Spectral Wave Explicit Navier-Stokes Equations) approach and results are compared with experimental data on two fixed barges with different headings and bilges. Numerical results, obtained using the SWENSE approach, are able to predict both the frequency and the magnitude of the RAO functions.

scholarly journals Compressible, Turbulent, Viscous Flow Computations for Blade Aerodynamic and Heat Transfer

1996 ◽  
Author(s):  
A. A. Boretti
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Reynolds Number ◽  
Partial Differential Equations ◽  
Differential Equations ◽  
Viscous Flow ◽  
Three Dimensional ◽  
Time Dependent ◽  
Navier Stokes ◽  
Partial Differential

The paper presents a computer code for steady and unsteady, three-dimensional, compressible, turbulent, viscous flow simulations. The mathematical model is based on the Favre-averaged Navier-Stokes conservation equations, closed by a statistical model of turbulence. Turbulence effects are represented by using a low Reynolds number K-ω model. The numerical model makes use of a finite difference approximation in generalized coordinates for space discretization. The solution of time-dependent, three-dimensional, non-homogeneous, partial differential equations is obtained by solving, in a prescribed, symmetric pattern, three time-dependent, one-dimensional, homogeneous partial differential equations, representing convection and diffusion along each generalized coordinate direction, and one ordinary differential equation, representing generation and destruction. An explicit, multi-step, dissipative, Runge-Kutta scheme is finally adopted for time discretization. The code is applied to simulate the flow through a linear cascade of turbine rotor blades, where detailed experimental data are available. Blade aerodynamic and heat transfer are computed, at variable Reynolds and Mach numbers and turbulence levels, and compared with experimental data. While the aerodynamic prediction is relatively unaffected by the properties of both mathematical and numerical models, the heat transfer prediction proves to be extremely sensitive to models details. Low Reynolds number K-ω turbulence models theoretically reproduce laminar, turbulent and transitional boundary layers. However, their practical use in a Navier-Stokes code does not allow to entirely capture the effects of turbulence intensity and Mach and Reynolds numbers on blade heat transfer.

Study of Aerodynamic Interactions of Dual Flapping Airfoils in Tandem Configurations

2012 ◽  
Vol 160 ◽  
pp. 301-306
Author(s):  
Bao Li Zhu ◽  
Hui Pen Wu ◽  
Tian Hang Xiao
Keyword(s):  
Viscous Flow ◽  
Great Influence ◽  
Aerodynamic Performance ◽  
Navier Stokes ◽  
Propulsive Efficiency ◽  
Motion Models ◽  
Hybrid Meshes ◽  
Thrust Generation ◽  
Unsteady Viscous Flow ◽  
Flapping Airfoil

The unsteady viscous flow fields of dual flapping airfoils in tandem configurations are simulated by a Navier-Stokes Solver based on dynamic deformable hybrid meshes. Aerodynamic interactions of three motion models are studied including flapping fore airfoil with fixed aft airfoil, two airfoils flapping in phase and out-of-phase. The results indicate that the aft airfoil in the wake of the flapping fore airfoil has great influence on the aerodynamic performance. When the fore airfoil flaps with a fixed aft airfoil, the thrust generation and thrust propulsive efficiency were enhanced by 65% and 44% respectively, compared to that of single flapping airfoil. When the two airfoils stoke in phase, the thrust generation is twice over that of single flapping airfoil. However the out-of-phase stroking has relatively much lower thrust.

scholarly journals Computational hydrodynamic analysis of a highly skewed marine propeller

2019 ◽  
Vol 16 (1) ◽  
pp. 21-32
Author(s):  
Houari Hussein ◽  
Kadda Boumediene ◽  
Samir Belhenniche ◽  
Omar Imine ◽  
Mohamed Bouzit
Keyword(s):  
Open Water ◽  
Navier Stokes ◽  
Marine Propeller ◽  
Navier Stokes Equation ◽  
Ansys Fluent ◽  
Ship Wake ◽  
Sliding Mesh ◽  
Wide Range ◽  
Volume Method ◽  
Thrust And Torque

 The objective of the current paper is to study the flow around Seiun Maru Highly Skewed (HSP) marine propeller by assessment of blade forces and moments under non-cavitating case. The calculations are performed in open water (steady case) and non-uniform ship wake (Unsteady case). The governing equations based on Reynolds Averaged Navier-Stokes Equation (RANSE) are solved using Finite Volume Method. Ansys Fluent 14.0 is used to implement the simulation. For the steady case, Moving Reference Frame (MRF) is selected while sliding mesh technique is adopted for the unsteady case. Calculated open water performances in terms of thrust and torque coefficients fit very well with experimental data for a wide range of advance ratio. In the unsteady calculations, axial velocities, deduced from the nominal wake, are introduced in the Ansys fluent code. To locate suitably the non-uniform wake in the propeller front plane, three positions of inlet wake have been taken into account to determine their effects on the accuracy of the results. Obtained results show that computed performances are improved compared to panel method when the inlet is close to the propeller.  

Numerical Simulation of the 3D Viscous Flow in the Exhaust Casing of a Low-Pressure Steam Turbine

2001 ◽  
Author(s):  
X. Xu ◽  
S. Kang ◽  
Ch. Hirsch
Keyword(s):  
Experimental Data ◽  
Viscous Flow ◽  
Steam Turbine ◽  
Low Pressure ◽  
Navier Stokes ◽  
Computational Results ◽  
Vortex System ◽  
Passage Vortex ◽  
Pressure Steam ◽  
Good Agreement

Numerical results of the 3D viscous flow in a downward exhaust casing of a low-pressure steam turbine, obtained with the 3D Navier-Stokes solver Fine/TURBO, is presented. Comprehensive comparisons of the computational results with the available experimental data, such as velocity, static and total pressure coefficients, are given. A good agreement with the experimental data is obtained. The computational results reveal a complex vortex system, including a passage vortex, a secondary vortex, an endwall vortex and a separation vortex, within the casing model. It is found that of all the vortices, most portion of energy losses within the casing is contributed from the passage vortex.

Viscous Flow Computations on a Smooth Cylinders: A Detailed Numerical Study With Validation

2007 ◽  
Author(s):  
Guilherme Vaz ◽  
Christophe Mabilat ◽  
Remmelt van der Wal ◽  
Paul Gallagher
Keyword(s):  
Experimental Data ◽  
Viscous Flow ◽  
Numerical Study ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Time Step ◽  
Drag Forces

The objective of this paper is to investigate several numerical and modelling features that the CFD community is currently using to compute the flow around a fixed smooth circular cylinder. Two high Reynolds numbers, 9 × 104 and 5 × 105, are chosen which are in the so called drag-crisis region. Using a viscous flow solver, these features are assessed in terms of quality by comparing the numerical results with experimental data. The study involves grid sensitivity, time step sensitivity, the use of different turbulence models, three-dimensional effects, and a RANS/DES (Reynolds Averaged Navier Stokes, Detached Eddy Simulation) comparison. The resulting drag forces and Strouhal numbers are compared with experimental data of different sources. Major flow features such as velocity and vorticity fields are presented. One of the main conclusions of the present study is that all models predict forces which are far from the experimental values, particularly for the higher Reynolds numbers in the drag-crisis region. Three-dimensional and unsteadiness effects are present, but are only fully captured by sophisticated turbulence models or by DES. DES seems to be the key to better solve the flow problem and obtain better agreement with experimental data. However, its considerable computational demands still do not allow to use it for engineering design purposes.

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