scholarly journals Propeller Performance Penalty of Biofouling: Computational Fluid Dynamics Prediction

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Soonseok Song ◽  
Yigit Kemal Demirel ◽  
Mehmet Atlar
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Characteristics ◽  
Open Water ◽  
Roughness Effect ◽  
Thrust Coefficient ◽  
Propulsion Performance ◽  
Negative Effect ◽  
Open Water Performance ◽  
Propeller Performance

Abstract The negative effect of biofouling on ship resistance has been investigated since the early days of naval architecture. However, for more precise prediction of fuel consumption of ships, understanding the effect of biofouling on ship propulsion performance is also important. In this study, computational fluid dynamics (CFD) simulations for the full-scale performance of KP505 propeller in open water, including the presence of marine biofouling, were conducted. To predict the effect of barnacle fouling on the propeller performance, experimentally obtained roughness functions of barnacle fouling were used in the wall-function of the CFD software. The roughness effect of barnacles of varying sizes and coverages on the propeller open water performance was predicted for advance coefficients ranging from 0.2 to 0.8. From the simulations, drastic effects of barnacle fouling on the propeller open water performance were found. The result suggests that the thrust coefficient decreases while the torque coefficient increases with increasing level of surface fouling, which leads to a reduction of the open water efficiency of the propeller. Using the obtained result, the penalty of propeller fouling on the required shaft power was predicted. Finally, further investigations were made into the roughness effect on the flow characteristics around the propeller and the results were in correspondence with the findings on the propeller open water performance.

An Investigation Into the Effect of Biofouling on Full-Scale Propeller Performance Using CFD

2019 ◽  
Author(s):  
Soonseok Song ◽  
Yigit Kemal Demirel ◽  
Mehmet Atlar
Keyword(s):  
Open Water ◽  
Full Scale ◽  
Roughness Effect ◽  
Thrust Coefficient ◽  
Propulsion Performance ◽  
Negative Effect ◽  
Precise Prediction ◽  
Torque Coefficient ◽  
Open Water Performance ◽  
Propeller Performance

Abstract The negative effect of biofouling on ship resistance has been investigated since the early days of naval architecture. However, for more precise prediction of fuel consumption of ships, understanding the effect of biofouling on ship propulsion performance is also important. In this study, CFD simulations for the full-scale performance of KP505 propeller in open water, including the presence of marine biofouling, were conducted. To predict the effect of barnacle fouling on the propeller performance, experimentally obtained roughness functions of barnacle fouling were employed in the wall-function of the CFD software. The roughness effect of barnacles of varying sizes and coverages on the propeller open water performance was predicted for advance coefficients ranging from 0.2 to 0.8. From the simulations, drastic effects of barnacle fouling on the propeller open water performance were found. The result suggests that the thrust coefficient decreases while the torque coefficient increases with increasing level of surface fouling, which leads to a reduction of the open water efficiency of the propeller. Further investigations into the roughness effect on the pressure and velocity field, surface pressure and wall shear stress, and propeller vortices were examined.

scholarly journals Prediction of Propeller Performance Using Computational Fluid Dynamics Approach

2019 ◽  
Vol 2 (2) ◽  
pp. 185-193
Author(s):  
Nur Amira Adam ◽  
Ahmad Fitriadhy ◽  
W. S. Kong ◽  
Faisal Mahmuddin ◽  
C. J. Quah
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Computational Simulation ◽  
Open Water ◽  
Water Model ◽  
Thrust Coefficient ◽  
Propeller Performance ◽  
Prediction Approach ◽  
Thrust And Torque

A reliable prediction approach to obtain a sufficient thrust and torque to propel the ship at desired forward speed is obviously required. To achieve this objective, the authors propose to predict the thrust coefficient (KT), torque coefficient (KQ) and efficiency (η) of the propeller in open-water model test condition using Computational Fluid Dynamics (CFD) simulation approach. The computational simulation presented in the various number of rotational speed (RPM) within the range of advance ratio J=0.1 up to 1.05. The higher value of J lead to decrease 10KQ and KT. While the η increased steadily at the lower value of J and decreased at the higher value of J. The results also showed that the propeller with 1048 rpm obtain a better efficiency at J=0.95 with η= 88.25%, 10KQ=0.1654 and KT= 0.0942. The computation result is very useful as preliminary data for propeller performance characteristics.

A study on the effect of the rake angle on the performance of marine propellers

2011 ◽  
Vol 226 (4) ◽  
pp. 940-955 ◽  
Author(s):  
A N Hayati ◽  
S M Hashemi ◽  
M Shams
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Design Process ◽  
Flow Characteristics ◽  
Open Water ◽  
Rake Angle ◽  
Marine Propellers ◽  
Propeller Design ◽  
Open Water Performance ◽  
Dynamics Method

In this study, the open water performance of three propellers with diverse rake angles was investigated by computational fluid dynamics method. The objective of this study was to find out the influence of the rake angle on the performance of conventional screw propellers. For this purpose, first, the obtained results for three B-series propellers were validated against the empirical results and then by modifying the rake angle, different models were investigated by the same method. Flow characteristics were examined for the models and the evolvement of vortices on different planes around the propeller were compared. The results suggest that in case of conventional screw propellers with linear rake distribution, while the effect of the rake angle on the propeller efficiency is not significant, the augmentation of this parameter improves the propeller thrust, especially at high propeller loads, but at the same time, the required torque increases, which is not desirable for the propeller design process.

scholarly journals FULL SCALE PREDICTION OF HYDRODYNAMIC NOISE USING COMPUTATIONAL FLUID DYNAMICS

2019 ◽  
Author(s):  
E M Fay
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Marine Mammals ◽  
Bright Light ◽  
Open Water ◽  
Full Scale ◽  
Noise And Vibration ◽  
Vibration Data ◽  
Hydrodynamic Noise ◽  
Propeller Performance

The issues of noise and vibration related to the propulsion system of vessels shines a bright light over the present day operation of sea going vessels. Some of the principal issues coming to the front are not new and are concerned with passenger and crew comfort which has been a touchstone for a decade or more. The most recent, more ominous issue is transmission of noise from transiting vessels and how this noise affects marine mammals. The tools used to analyse and define the expected levels of vibration and noise in the design phase are becoming more and more robust. The paper describes the use of computational fluid dynamics to predict the noise and vibration generated by hydrodynamic flow over the hull and the propeller(s) of the vessel. The analysis is carried out using the program OpenFOAM comparing the operating propeller performance coefficients with the open water propeller coefficients. The paper also looks at the effects of cavitation, vessel trim and propeller loading on a 140 meter car ferry. The loading, noise and vibration data will be quantified and compared to full scale vessel data.

scholarly journals Analysis of a Converging, Annular, Isothermal Melt Blowing Jet Using Computational Fluid Dynamics

2005 ◽  
Vol os-14 (3) ◽  
pp. 1558925005os-14
Author(s):  
Eric M. Moore ◽  
Dimitrios V. Papavassiliou ◽  
Robert L. Shambaugh
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Kinetic Energy ◽  
Near Field ◽  
Flow Characteristics ◽  
Sectional Area ◽  
Melt Blowing ◽  
Mean Velocity ◽  
Cross Sectional ◽  
Computational Fluid Dynamics Cfd

An unconventional melt blowing die was analyzed using computational fluid dynamics (CFD). This die has an annular configuration wherein the jet inlet is tapered (the cross-sectional area decreases) as the air approaches the die face. It was found that the flow characteristics of this die are different from conventional slot and annular dies. In particular, for the tapered die the near-field normalized turbulent kinetic energy was found to be lower at shallow die angles. Also, it was found that the peak mean velocity behavior was intermediate between that of conventional annular and slot dies. The centerline turbulence profiles were found to be qualitatively similar to those of annular dies; quantitatively, higher values were present for tapered dies.

Computed tomography angiography as an adjunct to computational fluid dynamics for prediction of oxygenator thrombus formation

Perfusion ◽  
2020 ◽  
pp. 026765912094410
Author(s):  
Robert G Conway ◽  
Jiafeng Zhang ◽  
Jean Jeudy ◽  
Charles Evans ◽  
Tieluo Li ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computed Tomography ◽  
Computational Fluid Dynamics ◽  
Computed Tomography Angiography ◽  
Thrombus Formation ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Region Of Interest ◽  
Computational Fluid Dynamics Analysis ◽  
Clot Burden

Introduction: Extracorporeal membrane oxygenation circuit performance can be compromised by oxygenator thrombosis. Stagnant blood flow in the oxygenator can increase the risk of thrombus formation. To minimize thrombogenic potential, computational fluid dynamics is frequently applied for identification of stagnant flow conditions. We investigate the use of computed tomography angiography to identify flow patterns associated with thrombus formation. Methods: A computed tomography angiography was performed on a Quadrox D oxygenator, and video densitometric parameters associated with flow stagnation were measured from the acquired videos. Computational fluid dynamics analysis of the same oxygenator was performed to establish computational fluid dynamics–based flow characteristics. Forty-one Quadrox D oxygenators were sectioned following completion of clinical use. Section images were analyzed with software to determine oxygenator clot burden. Linear regression was used to correlate clot burden to computed tomography angiography and computational fluid dynamics–based flow characteristics. Results: Clot burden from the explanted oxygenators demonstrated a well-defined pattern, with the largest clot burden at the corner opposite the blood inlet and outlet. The regression model predicted clot burden by region of interest as a function of time to first opacification on computed tomography angiography (R2 = 0.55). The explanted oxygenator clot burden map agreed well with the computed tomography angiography predicted clot burden map. The computational fluid dynamics parameter of residence time, when summed in the Z-direction, was partially predictive of clot burden (R2 = 0.35). Conclusion: In the studied oxygenator, clot burden follows a pattern consistent with clinical observations. Computed tomography angiography–based flow analysis provides a useful adjunct to computational fluid dynamics–based flow analysis in understanding oxygenator thrombus formation.

scholarly journals Modelling river history and evolution

2012 ◽  
Vol 370 (1966) ◽  
pp. 2123-2142 ◽  
Author(s):  
T. J. Coulthard ◽  
M. J. Van De Wiel
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Landscape Evolution ◽  
Numerical Models ◽  
Flow Characteristics ◽  
Sedimentary Facies ◽  
Cellular Models ◽  
Depositional Processes ◽  
Alluvial Architecture ◽  
Dynamics Models

Over the last few decades, a suite of numerical models has been developed for studying river history and evolution that is almost as diverse as the subject of river history itself. A distinction can be made between landscape evolution models (LEMs), alluvial architecture models, meander models, cellular models and computational fluid dynamics models. Although these models share some similarities, there also are notable differences between them, which make them more or less suitable for simulating particular aspects of river history and evolution. LEMs embrace entire drainage basins at the price of detail; alluvial architecture models simulate sedimentary facies but oversimplify flow characteristics; and computational fluid dynamics models have to assume a fixed channel form. While all these models have helped us to predict erosion and depositional processes as well as fluvial landscape evolution, some areas of prediction are likely to remain limited and short-term owing to the often nonlinear response of fluvial systems. Nevertheless, progress in model algorithms, computing and field data capture will lead to greater integration between these approaches and thus the ability to interpret river history more comprehensively.

The Flow Characteristics of Nanometer Microspheres in the Vessel

2013 ◽  
Vol 404 ◽  
pp. 167-170
Author(s):  
Yong Bo Yang ◽  
Li Min Qiao ◽  
Rui Gu ◽  
Xue Shan Liu ◽  
Guang Sen Zhou
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Computational Result ◽  
Blood Viscosity ◽  
Drug Carrier ◽  
Flow Characteristics ◽  
Diffusion Flow ◽  
Curative Effect ◽  
Flow Phenomenon ◽  
Biotechnology Research

The application of the nanoparticle technology is more and more popular currently. For the excellent abilities, nanoparticle technology is widely used in the biotechnology research. Nanometer microspheres can be used as a drug carrier. But the blood viscosity has relatively greater influence on its flow performance. The flow characteristics of nanometer microspheres in the vessel is very important to the curative effect. In order to resolve this problem, a length of vessel is introduced. By the CFD(computational fluid dynamics) software, the diffusion flow phenomenon is studied. The computational result and the analysis show that the nanometer microspheres would mix rapidly around the corner of the vessel. The results may provide technical reference of the further research.

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