Impact of biofilm on the ship propulsion characteristics and the speed reduction

Abstract

Ship fuel consumption and the greenhouse gas emissions in the service are affected by various factors, including waves, wind, biofouling, corrosion, confined water. One of the operational measures for the reduction of the fuel consumption is the optimization of the maintenance schedule, but lack of information related to the potential benefits of the application of this measure represents an important barrier. Therefore, the prediction of the impact of biofouling on ship hydrodynamic characteristics is important. In this paper, a numerical model based on Reynolds Averaged Navier-Stokes (RANS) equations, which allows the prediction of the impact of biofilm on the ship propulsion characteristics is proposed. Roughness function models representing surface conditions of biofilm fouling were employed within the wall function of the CFD software. Thereafter, a detail analysis of the impact of biofilm on the propulsion characteristics and the flow around full-scale containership is presented. This study has demonstrated that the occurrence of biofilm should not be ignored and that the presence of biofilm can cause extremely detrimental effects on ship hydrodynamic characteristics. Thus, it is shown that the biofilm can cause a significant increase in delivered power and consequently an increase in fuel consumption or a decrease in ship speed, contradicting the often ignoring of the biofilm presence on the ship hull.

Propeller Performance Penalty of Biofouling: Computational Fluid Dynamics Prediction

“…The adverse effects of biofouling on ship performance have been reported from the earliest times [1]. Accordingly, a large number of studies have been devoted to the roughness effect on ship resistance [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. According to the literature, the impact of calcareous (hard shell) fouling is particularly critical and highly dependent on the fouling type and coverage [2,3,9,10].…”

“…More recently, there have been studies utilising 3D printed artificial calcareous fouling models, e.g. barnacles, oysters or tubeworms [14,[17][18][19][20][21]. They observed significant increases in skin friction according to the sizes and coverage densities of the artificial fouling models.…”

Impact of Hard Fouling on the Ship Performance of Different Ship Forms

“…An explanation of the approach for the determination of the impact of biofilm on the ship resistance and propulsion characteristics is presented in [8,18] and is applied within this study. Firstly, an experimental study related to towing tank measurements of fouled flat plates was carried out within [12].…”

Investigating the Effect of Heterogeneous Hull Roughness on Ship Resistance Using CFD

“…Furthermore, the CFD method is not only limited to ship hulls, but it can be applied for an arbitrary object in fluid. Accordingly, the CFD method has been used for investigating the roughness effect on ship resistance, e.g., [16][17][18], propeller performance, e.g., [19,20], and ship self-propulsion performance, e.g., [21,22], as well as the tidal turbine performance, e.g., [23].…”