Determination of the efflux velocity from a ship's propeller

Hamill, Gerard; McGarvey, J.A.; Hughes, David

doi:10.1680/maen.2004.157.2.83

Cited by 23 publications

(15 citation statements)

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“…x/D p = 20.0 4 Radial profile of mean axial velocity 0.5R and 0.7R [9]. The results here appear to lie approximately in this zone and are similar to those described by Petersson et al [15], where a three-bladed mixer operated in weak co-flow at 1,800 rpm.…”

Section: Radial Profile Of the Mean Axial Velocitysupporting

confidence: 84%

“…Studies based on detailed experiments have been published on the near field propeller flow using high temporal and spatial resolution [2,3]. Hamill and Hughes [4] proposed that the efflux velocity (maximum velocity on the propeller plane) is proportional to the revolution speed, propeller tip diameter, and parameters related to thrust coefficient, propeller blade area ratio, and hub diameter ratio. Liu [5] conducted a numerical study and investigated the effect of marine propeller geometry under different loading conditions and the model of a far field wake, while Ikehata [6] looked at a numerical model of thrust generation at the near field wake.…”

Section: Nearmentioning

confidence: 99%

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Experimental study of the concentration field of discharge from a boat propeller

2010

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Engines in boats and ships using total loss lubrication deposit a significant proportion of their lubricant and fuel directly into the water. Their impact on the Australian coastline and marine ecosystems is of great concern. The purpose of this study was to document the velocity and concentration field characteristics of a submerged swirling water jet emanating from a propeller in order to provide information on its fundamental characteristics. The properties of the jet were examined far enough downstream to be relevant to the eventual modelling of the mixing problem. Measurements of the velocity and concentration field were performed in a turbulent jet generated by a model boat propeller (0.02 m diameter) within a 0.4 m-wide and 0.15 m-deep flume, operating at 1,500 and 3,000 rpm in a weak co-flow of 0.04 m/s. The measurements were carried out in the Zone of Established Flow up to 50 propeller diameters downstream of the propeller. Results pertaining to radial distribution, self-similarity, standard deviation growth, maximum value decay and integral fluxes of velocity and concentration fitted with empirical correlations. Furthermore, propeller-induced mixing and pollutant source concentration from a two-stroke engine were estimated.

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Section: Radial Profile Of the Mean Axial Velocitysupporting

confidence: 84%

Section: Nearmentioning

confidence: 99%

Experimental study of the concentration field of discharge from a boat propeller

2010

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“…Hamill et al (2004) found the core assumptions of this theory inadequately described the process involved. More recently Lam et al (2012a) described semi-empirical methods for predicting the efflux velocity of the main axial component of the flow, based on a range of experiments with one test propeller, while Lam et al (2012b) extended the discussion by including measurements of turbulence intensity.…”

Section: Introductionmentioning

confidence: 99%

“…Prosser (1986) suggested the maximum velocity in the jet occurred at approximately 60% of the blade radius from the propeller centreline, due to the low blade velocities at the hub, which produce less thrust. Work by Hamill et al (2004) found the axial velocity distribution to increase from the propeller hub to a distance of approximately 0·7R p along the blade before decreasing towards the blade tips.…”

mentioning

confidence: 99%

Three-dimension efflux velocity characteristics of marine propeller jets

Hamill¹,

Ryan²,

Kee³

2015

Proceedings of the ICE - Maritime Engineering

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Determining the efflux velocity in a ship's propeller jet is the key to calculating the velocity at any other location within the diffusing jet. Current semi-empirical equations used to calculate the magnitude of the efflux velocity have been based on studies that employed a limited range of propeller characteristics. This paper reports on the findings of an experimental investigation into the magnitude of the efflux velocities of the jets produced by four different propellers, where the characteristic of the blade geometry has been chosen to extend the range of applicability of the outcomes. Measurements of velocity have been made using a three-dimensional laser Doppler anemometry system, with the test propellers operating at a range of rotational speeds that bound typical operational values.Comparisons are made with current predictive theories and, to aid engineers in the design of marine infrastructure, methods are presented by which the three-dimensional efflux velocity components, as well as the resultant efflux value, can be more accurately determined.

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“…The comparison is made using several different relationships taken from the literature and recent physical modelling experiments. The relative magnitude of the two types of wave loading is then assessed using climatological and tsunami risk information for the Mediterranean Sea.In recent issues we have featured several papers that have looked at the issue of propeller scour (Hamill et al, 2004(Hamill et al, , 2009Ryan and Hamill, 2011). This series of papers presents the theoretical background and experimental results that lead to some design equations for the maximum depth of erosion in the presence of a quay wall and the time-dependent development of the maximum depth of erosion within the scour pit.…”

mentioning

confidence: 99%

Editorial

Townend¹

2012

Proceedings of the Institution of Civil Engineers - Maritime En

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The briefing article (Gouldby, 2012) and the first two papers in this issue (Chen and Alani, 2012;Cihan, 2012) relate to various aspects of risk assessment. This reflects the progressive move to risk-based techniques in both design and planning over the past few decades. Such techniques, in the form of reliability analysis, saw significant advance for the design of offshore platforms to extract North Sea oil and gas in the 1970s and 1980s (ThoftChristensen and Baker, 1982). At about this time, exploratory applications were also under way for the design of coastal defences, notably in the US and Netherlands (CUR/TAW, 1990;Dover and Bea, 1980). During the 1990s and early 2000s the focus shifted from individual structures to applying risk-based assessment at a large scale to whole systems (e.g. entire catchments, or coastal cells). This was enabled by advances in computing capability, in conjunction with the development of large databases containing details of defences, land levels, property and so on, alongside long-term records of the key drivers such as sea level, storm surge and waves. Such systematic analysis of sea defence reliability and flood risk is now becoming common practice and being applied in vulnerable locations around the world (Pender and Faulkner, 2010;Reeve, 2010).The ability to undertake risk analysis at a regional, or national, scale can be particularly valuable for both planning and policy formulation. A good example of the former is the TE2100 project, where regional analysis of flood risk in the Thames helped identify the most vulnerable areas and hence prioritise investment needs (Lavery and Donovan, 2005). The value of the latter has underpinned the formulation of strategic investment planning for flood defences in the UK (EA, 2009) and more recently has provided a robust foundation for an important aspect of the UK's first climate change risk assessment (CCRA) (Defra, 2012). The CCRA also starts to provide a much broader context, considering socio-economic change alongside climate change and trying to relate the biophysical impacts caused by climate change (notably sea level rise, flooding and drought) to impacts on health, transport, biodiversity and business, as well as the direct impacts on domestic and industrial properties. The more detailed advances presented in this issue all contribute to developing a richer understanding of the complex risk landscape that needs to be assessed to inform policy and enable robust decision making.A while ago we announced that we were seeking to start two new initiatives in Maritime Engineering. One was to have short briefing articles about historical papers that retain a contemporary relevance or interest. We hope that the first of these will appear shortly. The second initiative was to include a briefing article that links to a paper we are publishing, to provide a broader context and some explanation of the article. The aim is to provide an introduction for non-specialists and, for very theoretical papers, to highlight the potential applications o...

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Determination of the efflux velocity from a ship's propeller

Cited by 23 publications

References 1 publication

Experimental study of the concentration field of discharge from a boat propeller

Experimental study of the concentration field of discharge from a boat propeller

Three-dimension efflux velocity characteristics of marine propeller jets

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