In the present study, an experimental investigation of the decay of the maximum velocity and its turbulent characteristics behind a ship propeller, in ＂bollard pull＂ condition （zero speed of advance）, is reported....In the present study, an experimental investigation of the decay of the maximum velocity and its turbulent characteristics behind a ship propeller, in ＂bollard pull＂ condition （zero speed of advance）, is reported. Velocity measurements were performed in laboratory by use of a Laser Doppler Anemometry （LDA） measurement system. Earlier researchers described that the maximum axial velocity is constant at the initial stage of a ship＇s propeller jet （Fuehrer and Romisch, 1977; Blaauw and van de Kaa, 1978; Berger et al, 1981; Verhey, 1983） as reported in a pure water jet （Albertson et al., 1950; Lee et al., 2002; Dai, 2005）, but a number of researchers disagreed with the constant velocity assumption. The present study found that the maximum axial velocity decays in the zone of flow establishment and the zone of established flow with different rates. The investigation provides an insight into the decays of both the maximum velocity and the maximum turbulent fluctuation in axial, tangential and radial components and the decay of the maximum turbulent kinetic energy. Empirical equations are proposed to allow coastal engineers to estimate the jet characteristics from a ship＇s propeller.展开更多
When fuel efficiency is at stake,along with the reduction of the environmental foot print of air pollution,a need is presented to estimate a ship’s fuel consumption for a forthcoming voyage,and means for decision mak...When fuel efficiency is at stake,along with the reduction of the environmental foot print of air pollution,a need is presented to estimate a ship’s fuel consumption for a forthcoming voyage,and means for decision making and for cost saving.This paper suggests an operational approach for obtaining an accurate fuel consumption and speed curve,on the basis of major factors affecting it,namely,ship’s draft and displacement,weather force and direction,hull and propeller roughness.A statistical analysis on 418 noon reports of a Pure Car and Truck Carrier case ship is carried out and the influence of the above factors is calculated.As expected,stronger wind and head weather increases the fuel consumption,and the difference between several weather conditions could be quantified.A simple and accurate algorithm is proposed in order for ship owners,managers and operators to be in a position to apply the suggested method on their fleet.Finally,applications of the structured algorithm are introduced with examples,in estimating the fuel consumption of the case ship for a future voyage,and also the same for a sister ship.Furthermore,voyage planning in several scenarios is proposed in order to assist the stakeholders with decision making aimed to fuel saving and environmental friendliness of their ships.展开更多
基金supported by SPUR Studentship from Queen's University Belfastsupported by the National Natural Science Foundation of China (Grant No. 51006019)Petro China Innovation Foundation from China National Petroleum Corporation (Grant No. 2010D-5006-0208)
文摘In the present study, an experimental investigation of the decay of the maximum velocity and its turbulent characteristics behind a ship propeller, in ＂bollard pull＂ condition （zero speed of advance）, is reported. Velocity measurements were performed in laboratory by use of a Laser Doppler Anemometry （LDA） measurement system. Earlier researchers described that the maximum axial velocity is constant at the initial stage of a ship＇s propeller jet （Fuehrer and Romisch, 1977; Blaauw and van de Kaa, 1978; Berger et al, 1981; Verhey, 1983） as reported in a pure water jet （Albertson et al., 1950; Lee et al., 2002; Dai, 2005）, but a number of researchers disagreed with the constant velocity assumption. The present study found that the maximum axial velocity decays in the zone of flow establishment and the zone of established flow with different rates. The investigation provides an insight into the decays of both the maximum velocity and the maximum turbulent fluctuation in axial, tangential and radial components and the decay of the maximum turbulent kinetic energy. Empirical equations are proposed to allow coastal engineers to estimate the jet characteristics from a ship＇s propeller.
文摘When fuel efficiency is at stake,along with the reduction of the environmental foot print of air pollution,a need is presented to estimate a ship’s fuel consumption for a forthcoming voyage,and means for decision making and for cost saving.This paper suggests an operational approach for obtaining an accurate fuel consumption and speed curve,on the basis of major factors affecting it,namely,ship’s draft and displacement,weather force and direction,hull and propeller roughness.A statistical analysis on 418 noon reports of a Pure Car and Truck Carrier case ship is carried out and the influence of the above factors is calculated.As expected,stronger wind and head weather increases the fuel consumption,and the difference between several weather conditions could be quantified.A simple and accurate algorithm is proposed in order for ship owners,managers and operators to be in a position to apply the suggested method on their fleet.Finally,applications of the structured algorithm are introduced with examples,in estimating the fuel consumption of the case ship for a future voyage,and also the same for a sister ship.Furthermore,voyage planning in several scenarios is proposed in order to assist the stakeholders with decision making aimed to fuel saving and environmental friendliness of their ships.
