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 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.

scholarly journals Research on the Performance of Pumpjet Propulsor of Different Scales

2022 ◽  
Vol 10 (1) ◽  
pp. 78
Author(s):  
Jun Yang ◽  
Dakui Feng ◽  
Liwei Liu ◽  
Xianzhou Wang ◽  
Chaobang Yao
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Fluid Dynamic ◽  
Open Water ◽  
Small Scale ◽  
Thrust Coefficient ◽  
Total Thrust ◽  
Torque Coefficient ◽  
Open Water Performance ◽  
Thrust And Torque

This study presents a numerical research on the open-water performance of a pumpjet propulsor at different scales. Simulations were performed by an in-house viscous CFD (Computational Fluid Dynamic) code. The Reynolds-averaged Navier–Stokes (RANS) method with SST k-w turbulence model is employed. A dynamic overset grid is used to treat the relative motion between the rotor and other parts. The numerical results are compared with the model test data and they agree well. Comparisons for the open-water performance between the pumpjet propulsors with two scales are carried out. The results indicate that the total thrust coefficient of the large-scale pumpjet propulsor is greater than that of the small-scale one while the torque coefficient is smaller. Therefore, the efficiency of the large-scale pumpjet propulsor is about 8~10% higher than that of the small-scale pumpjet propulsor. The open-water performance of the rotor, pre-swirl stator and duct is obtained separately to estimate the discrepancies on the thrust and torque coefficients between different scales. To analyze the scale effect from different parts, the research on flow field and pressure distribution are carried out. The variation of total thrust and torque coefficient comes mainly from the rotor, which is caused by the flow field, influenced by the duct and stator.

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.

Screws Working in Behind and Prediction of the Performance of Full Ships

1990 ◽  
Vol 34 (04) ◽  
pp. 262-282
Author(s):  
Christopher Grigson
Keyword(s):  
Velocity Field ◽  
Scale Effect ◽  
Open Water ◽  
Full Scale ◽  
Constant Speed ◽  
Water Characteristics ◽  
Torque Coefficient ◽  
Ship Propeller

Constant speed propulsion tests of full models are investigated. The propulsion factors are found to vary with propeller speed, n. When the tests extend to idling conditions, the nominal wake fraction and the complete propeller-hull behind characteristics ϕ(u/nd) are determined. Fifteen designs of hull and screw are investigated. In some, the coupling between the velocity field of the hull and that of the screw is found to be strong. The behind characteristics depend both on the design of the screw and on the design of the hull. The same design of screw may efficiently power hulls of quite different form. A second kind of behind characteristic, ψ[(1 -ω)u/nd], is introduced. It is obtained from ϕ and it can be compared directly with the open-water characteristics. It is shown experimentally that in a full ship the open-water characteristics are not generally an accurate substitute for the behind ones. Therefore ϕ or ψ ought to be used when predicting ship propeller speed Ν and power. A condition for running the propulsion test is derived in which, after correction for the scale effect of blade friction on torque, the full-scale behind torque coefficient may be found from the model one. Furthermore, in this test condition Ν may be rigorously scaled from n, measured on the model. Thus full-scale performance is determined. Limited tests of the method appear accurate.

A CFD Research on the Effect of Pre-Swirl Stator Blades Number on a Pumpjet Propulsor

2021 ◽  
Author(s):  
Wang Guodong ◽  
Yang Jun ◽  
Yu Jiawei ◽  
Yang Wenjing ◽  
Feng Dakui
Keyword(s):  
Open Water ◽  
Rotor Blades ◽  
Navier Stokes ◽  
Structured Grids ◽  
Propulsion Efficiency ◽  
Computational Region ◽  
Shaft System ◽  
Negative Effect ◽  
Total Thrust ◽  
Open Water Performance

Abstract In this paper, effect of different pre-swirl stator number on open water performance of a pumpjet propulsor was studied. The pumpjet propulsor consists of shaft system, pre-swirl stator, rotor and duct. The numerical simulations were based on HUST-Ship, a series of inhouse codes, solving the Reynolds Averaged Navier-Stokes (RANS) equation. The computational region was discretized by structured grids and SST k-ω turbulence equations was discretized by finite difference method. The performances of rotor, pre-swirl stator and duct were monitored separately in order to understand the effect in the thrust and the torque. It was found that with the increase of the number of pre-swirl stator blades, the thrust produced by rotor blades increased. However, the number of pre-swirl stator blades influences the thrust of stator, and may have negative effect on the total thrust. In the meantime, thrust of duct also has a little increase. With the increase of the number of pre-swirl stator blades, the propulsion efficiency increases first and then decreases.

scholarly journals Experimental and computational investigation on interaction between nano rotor and aerodynamic rudder

2019 ◽  
Vol 11 ◽  
pp. 175682931986602
Author(s):  
Dong Yang ◽  
Zhen Liu ◽  
Chen Bu ◽  
Zhao Shanyong
Keyword(s):  
Flow Field ◽  
Deflection Angle ◽  
Aerodynamic Performance ◽  
Computational Investigation ◽  
Thrust Coefficient ◽  
Propulsive Performance ◽  
Propulsion Performance ◽  
Torque Coefficient ◽  
Left And Right ◽  
The Moment

The interference effect between the nano rotor and aerodynamic rudder was studied experimentally and computationally. Propulsive performance of nano rotor and aerodynamic performance of aerodynamic rudder were achieved experimentally. The disturbed flow field of nano rotor was also analyzed computationally to disclose the flow mechanics of the interaction. Results showed that the nano rotor has a great effect on the aerodynamic performance of aerodynamic rudder. The moment of aerodynamic rudder fluctuated with the rotor-to-rudder spacing and achieved the smallest value at the spacing of 0.5R. And the moment of aerodynamic rudder varied with deflection angle linearly. Aerodynamic rudder influenced the propulsion performance of the nano rotor slightly. The thrust coefficient and torque coefficient increased a little with spacing but changed slightly with the deflection angle. Numerical simulation showed that aerodynamic rudder blocked the flow field of the nano rotor and the counterclockwise rotation of the rotor drives the flow in the downstream rotating in a counterclockwise direction resulting in the different angle of attack between left and right rudder surface.

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.

Full Scale Thruster-Hull Interaction Improvement Revealed With CFD Analysis

2013 ◽  
Author(s):  
Norbert Bulten ◽  
Petra Stoltenkamp
Keyword(s):  
Open Water ◽  
Full Scale ◽  
Full Potential ◽  
Cfd Analysis ◽  
Calculation Methods ◽  
Pronounced Difference ◽  
Shaft Line ◽  
Comparable Performance ◽  
Improved Performance ◽  
Open Water Performance

The performance of two steerable thruster configurations has been compared: a more conventional straight unit and a tilted-shaft-line unit. Based on a theoretical approach, it has been shown that the full scale bollard pull performance of both units is close to the realistic optimum. The open water performance of the units revealed comparable performance at bollard pull for the straight and tilted unit. A more pronounced difference in favor of the straight unit is found in free sailing condition. When the thruster-hull interaction effects are taken into account, the trends change however. Some typical cases have been analyzed in detail with RANS-CFD numerical analysis methods: a drill ship in free sailing and bollard pull condition and a drill rig in bollard pull condition. The thrust-deduction factors are reduced significantly for all analyzed cases when the tilted unit is compared to the straight unit. This leads to improved performance of the complete vessel. In order to capture the full potential of the tilted-shaft line thruster units, a detailed review of the currently used DP-capability calculation methods needs to be made. Besides the reduced thrust-deduction factors due to hull interaction, also the forbidden-zones due to thruster-thruster interaction need to be reviewed. The downward deflection of the jet in case of tilted units will reduce the zones of interaction with other thrusters. Based on the currently presented research, it should be clear that the tilted thruster concept has a large potential for drill ships and drill rigs. A very good DP-capability will be achieved with the currently installed powers.

Influence of Finite Tip Clearance on the Tip Flow Characteristics of Ducted Propeller

2014 ◽  
Vol 889-890 ◽  
pp. 374-379
Author(s):  
Hao Liang Ni ◽  
Jun Wei Zhou ◽  
Da Zheng Wang
Keyword(s):  
Flow Characteristics ◽  
Open Water ◽  
Tip Clearance ◽  
Blade Surface ◽  
Tip Leakage ◽  
Cavitation Performance ◽  
Ducted Propeller ◽  
Torque Coefficient ◽  
Open Water Performance ◽  
Thrust And Torque

The influence of finite tip clearances on the tip flow characteristics, as well as pressure distribution on blade surface near the tip and open water performance of ducted propeller 19A/Ka4-55 model is studied in this paper. It is discovered that tip leakage vortex (TLV for short) disappears when clearance size reduces to a certain extent (0.08% of the propeller radius in this model). The decreasing of tip clearance size also leads to increasing efficiency and better cavitation performance. Besides, variation of thrust and torque coefficient with clearance size show stepped shape instead of linear.

The Research of Hydrodynamic Performance for Ducted Propeller with PBCF

2015 ◽  
Vol 733 ◽  
pp. 578-582
Author(s):  
Zhen Qiu Yao ◽  
Xin Gu ◽  
Yun Shen
Keyword(s):  
Energy Saving ◽  
Open Water ◽  
Hydrodynamic Performance ◽  
Thrust Coefficient ◽  
Rotation Direction ◽  
Ducted Propeller ◽  
Efficiency Increase ◽  
Good Energy ◽  
Torque Coefficient ◽  
Saving Effect

The Propeller Boss Cap Fins (PBCF) is often used to ordinary propeller, a good energy-saving effect being obtained. In order to study the energy-saving mechanism of ducted propeller with PBCF, in this paper, the FLUENT has been taken to simulate the distribution of thrust coefficient, torque coefficient, blade pressure and velocity vector of hub surface at different advance coefficients. By contrasting the results of numerical simulation of hydrodynamic performance of ducted propeller between with fins and without fins, we know that at the low advance coefficient, the ducted propeller with fins will increase the thrust coefficient and decrease the torque coefficient; rising the open water propeller efficiency, improving the efficiency under the premise of the efficiency increase by duct. The existence of fins has changed velocity distribution of water around the hub and made the water that flowed around the propeller hub with propeller rotation direction flow to propeller tail along the fins not gather in the cub, so it weakened the hub vortex.

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