A Numerical study on the hydrodynamic performance of an immersed foil: Uncertainty quantification of RANS and SPH methods

2019 ◽  
Vol 191 ◽  
pp. 104248
Author(s):  
M. Ayyildiz ◽  
A.Z. Saydam ◽  
M. Ozbulut
Keyword(s):  
Uncertainty Quantification ◽  
Numerical Study ◽  
Hydrodynamic Performance

Numerical Study on the Unsteady Hydrodynamic Performance of a Waterjet Impeller

2018 ◽  
Vol 341 ◽  
pp. 151-163 ◽  
Author(s):  
Jie Gong ◽  
Chun-Yu Guo ◽  
Tie-Cheng Wu ◽  
Ke-Wei Song
Keyword(s):  
Numerical Study ◽  
Hydrodynamic Performance

Hydrodynamic performance of an unconstrained flapping swimmer with flexible fin: A numerical study

2022 ◽  
Vol 34 (1) ◽  
pp. 011901
Author(s):  
Buchen Wu ◽  
Chang Shu ◽  
Minping Wan ◽  
Yan Wang ◽  
Shiyi Chen
Keyword(s):  
Numerical Study ◽  
Hydrodynamic Performance ◽  
Flexible Fin

Numerical study of the impact of water injection holes arrangement on cavitation flow control

2019 ◽  
Vol 103 (1) ◽  
pp. 003685041987774 ◽  
Author(s):  
Wei Wang ◽  
Qingdian Zhang ◽  
Tao Tang ◽  
Shengpeng Lu ◽  
Qi Yi ◽  
...  
Keyword(s):  
Flow Field ◽  
Numerical Study ◽  
Water Injection ◽  
Three Dimensional ◽  
Hydrodynamic Performance ◽  
Cavitation Flow ◽  
Suction Surface ◽  
Double Row ◽  
Suppression Effect ◽  
The Impact

A method of water injection to flow field using distributed holes on the suction surface of hydrofoil is presented in this article to control cavitation flow. Modified renormalization group k–ε turbulence model is coupled with full-cavitation model to calculate periodical cavitation patterns and the dynamic characteristics of the NACA66(MOD) hydrofoil. Water injection is found to be highly effective for cavitation suppression. The cavitation suppression effect of distributed regulation of jet holes and porosities along three-dimensional spanwise hydrofoil is also investigated. The appropriate porosities of single row spanwise jet holes and optimal jet position of double row jet holes are revealed for both cavitation suppression and good hydrodynamic performance. Double row jet holes setting in forward trapezoidal arrangement shows great potential for cavitation suppression and hydrodynamic performance. This research provides a method of water injection to flow field to actively control cavitation, which will facilitate development of engineering designs.

A 2.5D numerical study on open water hydrodynamic performance of a Voith-Schneider propeller

2019 ◽  
Vol 20 (6) ◽  
pp. 617
Author(s):  
Mohammad Bakhtiari ◽  
Hassan Ghassemi
Keyword(s):  
Numerical Method ◽  
Thrust Force ◽  
Numerical Study ◽  
Open Water ◽  
Hydrodynamic Performance ◽  
Maximum Efficiency ◽  
Water Efficiency ◽  
Blade Thickness ◽  
Unsteady Rans ◽  
Marine Vessels

Marine cycloidal propeller (MCP) is a special type of marine propulsors that provides high maneuverability for marine vessels. In a MCP, the propeller axis of rotation is perpendicular to the direction of thrust force. It consists of a number of lifting blade. Each blade rotates about the propeller axis and simultaneously pitches about its own axis. The magnitude and direction of thrust force can be adjusted by controlling the propeller pitch. Voith-Schneider propeller (VSP) is a low-pitch MCP with pure cycloidal blade motion allowing fast, accurate, and stepless control of thrust magnitude and direction. Generally, low-pitch cycloidal propellers are used in applications with low speed maneuvering requirements, such as tugboats, minesweepers, etc. In this study, a 2.5D numerical method based on unsteady RANS equations with SST k-ω turbulent model was implemented to predict the open water hydrodynamic performance of a VSP for different propeller pitches and blade thicknesses. The numerical method was validated against the experimental data before applying to VSP. The results showed that maximum open water efficiency of a VSP is enhanced by increasing the propeller pitch. Furthermore, the effect of blade thickness on open water efficiency is different at various advance coefficients, so that the maximum efficiency produced by the VSP decreases with increasing blade thickness at different propeller pitches.

scholarly journals Experimental and Numerical Study on Hydrodynamic Performance of an Underwater Glider

2018 ◽  
Vol 2018 ◽  
pp. 1-13
Author(s):  
Yanji Liu ◽  
Jie Ma ◽  
Ning Ma ◽  
Zhijian Huang
Keyword(s):  
Reynolds Number ◽  
Degrees Of Freedom ◽  
Numerical Study ◽  
Similarity Theory ◽  
Dynamics Simulation ◽  
Hydrodynamic Performance ◽  
Hull Design ◽  
Motion Characteristics ◽  
6 Degrees Of Freedom ◽  
Temperature Depth

The hydrodynamic coefficients are important parameters for predicting the motion of the glider and upgrading the hull design. In this paper, based on the Reynolds number similarity theory, 6 degrees of freedom (DOFs) of the fluid force and torque of a 1:1 full-scale glider model are measured. The present measurements were carried out at (2 - 14m/s) by varying attack angles and sideslip angles (-9 - 9°), respectively. The measurements were used to study the variation of the hydrodynamics of the glider, and the measurements have also been used to validate results obtained from a CFD code that uses RNG k-ε. The hydrodynamic force coefficients obtained from CFD accord well with the measurements. However, the torque coefficients difference is fairly large. Dynamics simulation results show that CFD results can be used to design and study the motion characteristics of gliders. In order to simplify the design process of gliders, we fit the empirical formula based on the experimental data and obtain a drag coefficient equation with Reynolds number. The influence of two kinds of appendages of the Conductance-Temperature-Depth (CTD) unit and thruster unit on the glider drag were studied by a contrast test. The analysis results can provide reference for design and the motion investigate of gliders.

scholarly journals Numerical study on the hydrodynamic performance of the semi-spade rudder and propeller

2019 ◽  
Vol 11 (1) ◽  
pp. 168781401882310 ◽  
Author(s):  
Xiao Yang ◽  
Yong Yin ◽  
Jing-Jing Lian
Keyword(s):  
Stokes Equations ◽  
Numerical Study ◽  
Turbulence Models ◽  
Suction Side ◽  
Hydrodynamic Performance ◽  
Computational Grids ◽  
Hydrodynamic Characteristics ◽  
Thrust Coefficient ◽  
Ship Maneuverability ◽  
Thrust And Torque

The semi-spade rudder and KP458 propeller of the KVLCC2 (KRISO very large crude carrier) model tanker are adopted by ITTC maneuvering technical committee in the comparative study of ship maneuverability. The incompressible viscous flow around semi-spade rudder and KP458 propeller is investigated using Reynolds-averaged Navier–Stokes equations, the computational grids are generated using ICEM software, and finite volume method is employed to discretize the governing equations. Combined with turbulence model, the hydrodynamic performance of semi-spade rudder is analyzed at different rudder angles, and the result provides a reference for the estimation of the hydrodynamic characteristics of semi-spade rudder. The multi-reference framework method is employed to carry out the numerical simulation of the flow field around the propeller. The thrust and torque of propeller under different turbulence models are calculated in the simulation. The thrust coefficient curve, torque coefficient curve, and efficiency curve are present. The pressure distributions of the pressure side and suction side of propeller blades are studied at different advance coefficient. Based on the study of the hydrodynamic performance of the semi-spade rudder and propeller, the propeller–rudder interaction is simulated and analyzed at different advance coefficient.

scholarly journals Uncertainty Quantification of Leakages in a Multistage Simulation and Comparison With Experiments

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Cosimo Maria Mazzoni ◽  
Richard Ahlfeld ◽  
Budimir Rosic ◽  
Francesco Montomoli
Keyword(s):  
Uncertainty Quantification ◽  
Numerical Study ◽  
Turbine Blades ◽  
Industrial Practice ◽  
Turbine Efficiency ◽  
Simulation Based ◽  
Multistage Turbine ◽  
Computational Fluid Dynamics Cfd ◽  
Yaw Angle ◽  
The Impact

This paper presents a numerical study of the impact of tip gap uncertainties in a multistage turbine. It is well known that the rotor gap can change the gas turbine efficiency, but the impact of the random variation of the clearance height has not been investigated before. In this paper, the radial seals clearance of a datum shroud geometry, representative of steam turbine industrial practice, was systematically varied and numerically tested by means of unsteady computational fluid dynamics (CFD). By using a nonintrusive uncertainty quantification (UQ) simulation based on a sparse arbitrary moment-based approach, it is possible to predict the radial distribution of uncertainty in stagnation pressure and yaw angle at the exit of the turbine blades. This work shows that the impact of gap uncertainties propagates radially from the tip toward the hub of the turbine, and the complete span is affected by a variation of the rotor tip gap. This amplification of the uncertainty is mainly due to the low-aspect ratio of the turbine, and a similar behavior is expected in high pressure (HP) turbines.

scholarly journals Performance of Porous Breakwaters: Application of the BOUSS-2D Model

2012 ◽  
Vol 9 (1) ◽  
pp. 11
Author(s):  
R Balaji
Keyword(s):  
Reflection Coefficient ◽  
Transmission Coefficient ◽  
Numerical Study ◽  
Hydrodynamic Performance ◽  
Transmission Characteristics ◽  
Regular Waves ◽  
Reflection And Transmission ◽  
Wave Elevation ◽  
Time Histories ◽  
Model Setup

 The hydrodynamic performance of porous breakwaters was studied by numerical analysis to assess reflection and transmission characteristics. The finite-difference method on BOUSS-2D was used to test the efficiency of porous breakwaters. The effects of porosity on reflection and transmission characteristics under the action of regular waves were investigated. The wave elevation time histories obtained from the numerical study were compared to those measured during an experimental study, on the leeward and seaward sides of the porous breakwater and were found to be in close agreement. The reflection coefficient increases, whereas the transmission coefficient decreases with a decrease in the porosity. A model with a porosity of 5.9% showed a maximum reflection coefficient of about 0.7 and a minimum transmission coefficient of 0.3. The details of the numerical method, physical model, model setup and results are discussed in this paper. 

scholarly journals NUMERICAL STUDY OF ACOUSTIC CHARACTERISTICS OF A DTMB 4119 PROPELLER DUE TO TIP RAKE

2019 ◽  
Author(s):  
Danio Joe ◽  
Vijit Misra ◽  
R Vijayakumar
Keyword(s):  
Marine Mammals ◽  
Numerical Study ◽  
Hydrodynamic Performance ◽  
Hydrodynamic Characteristics ◽  
Acoustic Characteristics ◽  
Radiated Noise ◽  
Propeller Noise ◽  
Disk Plane ◽  
Propeller Geometry ◽  
The Impact

The impact of increased Underwater Radiated Noise (URN) over the past two decades on marine mammals has resulted in the pressing requirement to reduce it. Shipping contributes immensely to the URN. Propeller noise is a major source of URN. The reduction in Propeller noise can hence significantly help in the reduction of URN. With the sole objective of improving the hydrodynamic performance of propellers ways to prevent cavitation are being developed. However, the reduction of non cavitating noise produced by the propeller would still remain a challenge. The change in the propeller geometry can modify the acoustic characteristics. In this present study, effect of modifying the tip of DTMB4119 propeller on the acoustic and hydrodynamic characteristics is presented. The change in the flow pattern at the tip due to introduction of tip rake is also discussed. The SPL has been calculated by using the two-step Ffowcs William and Hawkings (FW-H) equations from the pressure distribution at various points around the propeller. SPL at various points in the downstream and propeller disk plane are numerically predicted and discussed.

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