Numerical analysis of unsteady hydrodynamic performance of pump-jet propulsor in oblique flow

A numerical analysis on the factors affecting the hydrodynamic performance for parallel surfaces with microtextures is presented in this paper. The semianalytical method and fast Fourier transform technique are implemented in the analysis. The numerical procedure is validated by comparing the results from the present model with the analytical solutions for the lubrication problem in an infinitewide sliding bearing with step-shaped textures. The numerical results show that the hydrodynamic performance can be greatly affected by the factors, such as the boundary conditions, cavitation pressure, microtextures, surface deformation, etc. This study can be of a great help for better understanding the mechanism of hydrodynamic pressure generated between parallel surfaces and realistically evaluating the improvement of tribological performance caused by textures.

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Calculations of the Hydrodynamic Characteristics of a Ducted Propeller Operating in Oblique Flow

Ciencia y tecnología de buques ◽

10.25043/19098642.147 ◽

2017 ◽

Vol 10 (20) ◽

pp. 31

Author(s):

Hassan Ghassemi ◽

Sohrab Majdfar ◽

Hamid Forouzan

Keyword(s):

Stokes Equations ◽

Open Water ◽

Hydrodynamic Performance ◽

Numerical Code ◽

Navier Stokes ◽

Hydrodynamic Characteristics ◽

Navier Stokes Equations ◽

Oblique Flow ◽

Ducted Propeller ◽

Acceptable Agreement

The purpose of this paper is to calculate the hydrodynamic performance of a ducted propeller (hereafter Duct_P) at oblique flows. e numerical code based on the solution of the Reynolds-averaged Navier– Stokes equations (RANSE) applies to the Kaplan propeller with 19A duct. e shear-stress transport (SST)-k-ω turbulence model is used for the present results. Open-water hydrodynamic results are compared with experimental data showing a relatively acceptable agreement. Two oblique flow angles selected to analyze in this paper are 10 and 20 degrees. Numerical results of the pressure distribution and hydrodynamic performance are presented and discussed.

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Numerical analysis of a leading edge tubercle hydrofoil in turbulent regime

Journal of Fluid Mechanics ◽

10.1017/jfm.2019.611 ◽

2019 ◽

Vol 878 ◽

pp. 292-305 ◽

Cited By ~ 1

Author(s):

Blanca Pena ◽

Ema Muk-Pavic ◽

Giles Thomas ◽

Patrick Fitzsimmons

Keyword(s):

Numerical Analysis ◽

Turbulent Flow ◽

Flow Regime ◽

Leading Edge ◽

Reynolds Numbers ◽

Main Flow ◽

Hydrodynamic Performance ◽

Turbulent Regime ◽

Transitional Regime ◽

Turbulent Flow Regime

This paper presents a numerical performance evaluation of the leading edge tubercles hydrofoil with particular focus on a fully turbulent flow regime. Efforts were focused on the setting up of an appropriate numerical approach required for an in-depth analysis of this phenomenon, being able to predict the main flow features and the hydrodynamic performance of the foil when operating at high Reynolds numbers. The numerical analysis was conducted using an improved delayed detached eddy simulation for Reynolds numbers corresponding to the transitional and fully turbulent flow regimes at different angles of attack for the pre-stall and post-stall regimes. The results show that tubercles operating in turbulent flow improve the hydrodynamic performance of the foil when compared to a transitional flow regime. Flow separation was identified behind the tubercle troughs, but was significantly reduced when operating in a turbulent regime and for which we have identified the main flow mechanisms. This finding confirms that the tubercle effect identified in a transitional regime is not lost in a turbulent flow. Furthermore, when the hydrofoil operates in the turbulent flow regime, the transition to a turbulent regime takes place further upstream. This phenomenon suppresses a formation of a laminar separation bubble and therefore the hydrofoil exhibits a superior hydrodynamic performance when compared to the same foil in the transitional regime.

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Influence of Central Platform on Hydrodynamic Performance of Semi-Submerged Multi-Buoy Wave Energy Converter

Journal of Marine Science and Engineering ◽

10.3390/jmse8010012 ◽

2019 ◽

Vol 8 (1) ◽

pp. 12

Author(s):

Yuan Hu ◽

Shaohui Yang ◽

Hongzhou He ◽

Hu Chen

Keyword(s):

Numerical Analysis ◽

Wave Energy ◽

Wave Energy Converter ◽

Hydrodynamic Performance ◽

Theoretical Research ◽

Width Ratio ◽

Energy Converter ◽

Wave Condition ◽

Energy Capture ◽

Central Platform

The influence of the central platform on hydrodynamic performance of a wave energy converter (WEC) has remained elusive. To approach this dearth of relevant theoretical research, this paper presents a semi-submerged multi-buoy WEC and the results of the numerical analysis at different dimension parameters of the central platform of the WEC. The WEC consists of three oscillating buoys hinged with a central platform through multiple actuating arms. Numerical analysis revealed that there exists a relationship between the hydrodynamic performance of device and the geometry of the central platform. At the given wave condition, different central platform size would obviously affect the hydrodynamic performance and wave energy capture width ratio of the semi-submerged multi-buoy WEC. Additionally, appropriately increasing central platform draft would help to improve the wave energy capture capability of the oscillating buoys.

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The Research of Moonpool Size Effect on the Hydrodynamic Performance of FDPSO

Volume 1: Offshore Technology; Polar and Arctic Sciences and Technology ◽

10.1115/omae2011-49586 ◽

2011 ◽

Cited By ~ 3

Author(s):

Yuefeng Wei ◽

Jianmin Yang ◽

Gang Chen ◽

Zhiqiang Hu

Keyword(s):

Numerical Analysis ◽

Size Effect ◽

White Noise ◽

Natural Frequency ◽

Model Test ◽

Hydrodynamic Performance ◽

Ocean Engineering ◽

Floating Platform ◽

Paper Making ◽

Reliable Model

FDPSO is a multifunction floating platform, which has the combined function of drilling, production, storage and offloading oil. The moonpool is necessary for drilling operation and the moonpool size effect will play a role on the hydrodynamic performance of FDPSO. A study of the moonpool size effect on such performance of FDPSO hull is presented in this paper, making use of numerical analysis and model tests techniques. The code WADAM is used for the hydrodynamic performance analysis. A model test aiming to validate the accuracy of the numerical analysis results was conducted in the Ocean Engineering basin in the State Key Laboratory of Ocean Engineering in the Shanghai Jiao Tong University. The model test included decaying test and white noise test. The decaying tests are performed in still water for heave, roll and pitch. White noise tests were carried out to obtain the RAO of FDPSO, with the wave incoming direction of 180° and 135°. The numerical results show a good agreement with the model test results, indicating a reliable model. The “piston” motion of the water inside the moonpool is significant, affecting the hydrodynamic performance of the FDPSO. The effect of moonpool size on the hydrodynamic performance of the FDPSO is analyzed through a numerical method. The relationship between the piston natural frequency of the water column inside the moonpool and its diameter and draft, are studied. An empirical formula of the “piston” natural frequency is proposed, and its validity is assessed.

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