Erosion caused by propeller jets in a low energy harbour basin

Mujal-Colilles, Anna; Gironella, X.; Sánchez‐Arcilla, Agustín; Puig-Polo, Càrol; Garcı́a-León, Manuel

doi:10.1080/00221686.2016.1252801

Cited by 25 publications

(18 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Actually, the depth of the scouring hole obtained at the end of the experiments is significantly larger when the two telegraph orders (ahead/astern) are combined. When [1] computed the maximum eroded depth using the formulas presented in the literature, they concluded that only two equations, [17,21], yielded feasible results, although they were twice the real value. The formulas were presented after experimental work using either a single propeller in forward continuous mode or a simple jet impacting a sediment bed, respectively.…”

Section: Discussionmentioning

confidence: 99%

“…The main problem is the change in bed morphology of the harbor: entrance channels suffer high rates of erosion and the changes on harbor basins seafloor combine both erosion and sedimentation. A recent field study of a particular harbor basin [1], showed that the erosion in these areas of the port can reach a depth up to the same order of magnitude as the stern propeller's diameter. The effects of the erosion are different depending on the location of the scouring hole.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Stern Twin-Propeller Effects on Harbor Infrastructures. Experimental Analysis

Mujal-Colilles

Castells

Marroig

et al. 2018

Water

Self Cite

View full text Add to dashboard Cite

The growth of marine traffic in harbors, and the subsequent increase in vessel and propulsion system sizes, produces three linked problems at the harbor basin area: (i) higher erosion rates damaging docking structures; (ii) sedimentation areas reducing the total depth; (iii) resuspension of contaminated materials deposited at the seabed. The published literature demonstrates that there are no formulations for twin stern propellers to compute the maximum scouring depth. Another important limitation is the fact that the formulations proposed only use one type of maneuvering during the experimental campaign, assuming that vessels are constantly being undocked. Trying to reproduce the real arrival and departure maneuvers, 24 different tests were conducted at an experimental laboratory in a medium-scale water tank using a twin propeller model to estimate the consequences and the maximum scouring depth produced by stern propellers during the backward/docking and forward/undocking scenarios. Results confirm that the combination of backward and forward scenario differs substantially from the experiments performed so far in the literature using only an accumulative forward scenario, yielding deeper scouring holes at the harbor basin area. The results presented in this paper can be used as guidelines to estimate the effects of regular vessels at their particular docking location. reducing its operability for larger draft vessels and the area has to be dredged often enough for safe navigation (with sufficient keel clearance). Moreover, an environmental problem can also arise from the scouring effects of stern twin propellers of the vessels, and the increase in marine traffic in ports is also increasing the accumulation of heavy contaminants in some areas of the harbor. One of the engineering solutions to improve the water quality of the harbor is to trap the contaminated sediment below a layer of coarser gravel [2]. However, as reported by [3,4], the action of stern propellers over the seafloor can negate the solution and free the contaminated sediment creating an important issue that correlates sediment resuspension of contaminants due to the stern propellers' effects and water quality requirements of the cruise shipping industry.Therefore, the growth of marine traffic in harbors and its subsequent increase in vessel and propulsion system sizes produces three linked problems at the seabed of the harbor basins: (i) higher erosion rates damaging docking structures; (ii) sedimentation areas reducing the total depth of the harbor basin and its operability; and (iii) resuspension of contaminated materials deposited at the seabed.The formulation published and used so far to investigate the erosion rates of ship's propellers is based on empirical equations with a dependent variable named efflux velocity, V 0 . Efflux velocity is defined as the average velocity of the flux nearby a single propeller in a plane parallel to the propeller blades. The first empirical equation for V 0 was developed by [5,6], and detailed the expression ...

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Stern Twin-Propeller Effects on Harbor Infrastructures. Experimental Analysis

Mujal-Colilles

Castells

Marroig

et al. 2018

Water

Self Cite

View full text Add to dashboard Cite

show abstract

“…Stewart [19] proposed the conversion of the small-scale laboratory works to predict the efflux velocity of full-scale single-propeller. Mujal-Colilles et al [29] and Tan & Yuksel [30] emphasised the importance of maximum scour depth without consideration of the time factors.…”

Section: Implementation Of Equations On Full-scale Vesselmentioning

confidence: 99%

“…The prediction from the proposed equations is compared with the previous works from Hamill [5], Hong et al [9], Yew [15], Mujal-Colilles et al [29], and Tan & Yuksel [30]. The case of twin-propeller TE-1 was used in the comparison and Table 6 shows the predicted scour depth and variations.…”

Section: Comparisonmentioning

confidence: 99%

Temporal Model for Ship Twin-Propeller Jet Induced Sandbed Scour

Cui

Lam

Zhang

et al. 2019

JMSE

View full text Add to dashboard Cite

This research paper proposes the use of empirical equations to estimate the temporal maximum scour that is induced by twin-propeller ( ε t w i n = Ω t [ l n ( t ) ] Γ t ) when acting over non-cohesive bed materials. A purpose built experimental apparatus is used to obtain the measurement data required for the calculation of the empirical constants. The output from rigorous experimental investigations demonstrates that the maximum scour depth produced from the operation of twin-propeller ( ε t w i n ), within the confines of a harbour basin, varies as a logarithmic function of time. A dimensional analysis of the standard single propeller configuration is used as the foundation upon which the scour equation is postulated. This is extended to include the influence of the operating distance between the twin-propeller configurations for the first time. The division of scours by twin-propeller and single-propeller ( ε twin / ε m ) enables the establishment of mathematical relation to calculate C1, C2, A, and B. The constants are C 1 = 366.11, C 2 = 0.3376, A = 0.859, and B = 0.1571. The proposed scour equation is more reliable within the time zone up to two hours based on the experimental data.

show abstract

“…In the sea, near densely populated areas, further possibly harmful pollutants could accumulate as a consequence of human activity. Harmful bacteria like E. coli, heavy metals like copper and pesticides are likely to be deposited in the seabed sediment which poses a threat to both human and animal life at sea, especially if dredging or seabed erosion resuspends them again [5][6][7][8]. Stagnant seawater regularly is characterized by a reduction in dissolved oxygen, which favors the growth of harmful algal blooms and afterward could further compromise the marine ecosystem [9,10].…”

Section: Introductionmentioning

confidence: 99%

The Flow Generator Relations for Water Renewal through the Flushing Culverts in Marinas

Bartolić

Lončar

Bujak

et al. 2018

Water

View full text Add to dashboard Cite

An understanding of the relationship between the flow generators and harbor design could result in an acceptable seawater renewal into an enclosed basin. The flushing culverts located in the breakwater are the most cost-effective technique for improving water renewal in port engineering. The aim of the paper was to identify and quantify the relation between flow generators and culvert flow to propose an optimal position for the flushing culverts. Mentioned relations are important for designing and positioning the flushing culverts in marinas to achieve optimal sea exchange in the marina basin. Field measurements in the marina Opatija were performed and the data served for calibrating a 3D circulation model and a wave generation/propagation model. The absolute volume of the flow through the culverts caused by wind waves has the more important contribution to the water renewal in the marina basin than the coastal springs have. The optimal flow rates through the culverts are performed by positioning the flushing culvert axis at the mean sea level in accordance with the main incident direction of the propagating waves.Water 2018, 10, 936 2 of 22 discharge, etc.). An understanding of the relationship between the flow generators and harbor design could result in an acceptable seawater renewal with the purpose of reducing pollution concentrations introduced into an enclosed basin [13].Previous scientific research offers mathematical procedures to compute the seawater renewal efficiency of a semi-enclosed basin, frequently grounded either on hydrodynamic or morphological features. Most approaches for seawater renewal estimation are fundamentally built around tidal oscillations as the dominant generator of water circulation inside enclosed basins [14][15][16].The structural features such as the planform geometry of a port, inlet width, water depth, bed slope and so forth, also influence the water renewal efficiency [15][16][17][18]. In regions where the tidal oscillation range is considerably small like the Mediterranean and the Adriatic Sea, the water renewal is also consequently reduced substantially. In these areas, it is widespread to use openings or flushing culverts (pipes or rectangular openings in a breakwater) with the aim of improving the water exchange capacity of the basin [19,20]. Flushing culverts are regarded as the most cost-effective technique for improving water renewal in port engineering. Its purpose is to improve the water renewal within an enclosed basin harnessing also other flow generators like wind and waves, without allowing undesirable wave energy to come into and disturb the port basin. Optimal opening layouts design can be achieved by taking into account two basic yet contradicting criteria, i.e., the water renewal and the wave energy penetration into the harbor [21].Wind action and waves have also been identified to have a significant influence on the seawater renewal. Research making use of numerical models, established to study the Venice lagoon seawater circulation, demonstrated a valuable...

show abstract

Erosion caused by propeller jets in a low energy harbour basin

Cited by 25 publications

References 10 publications

Stern Twin-Propeller Effects on Harbor Infrastructures. Experimental Analysis

Stern Twin-Propeller Effects on Harbor Infrastructures. Experimental Analysis

Temporal Model for Ship Twin-Propeller Jet Induced Sandbed Scour

The Flow Generator Relations for Water Renewal through the Flushing Culverts in Marinas

Contact Info

Product

Resources

About