Ship resistance issues are related to fuel economy,speed,and cost efficiency.Air lubrication is a promising technique for lowering hull frictional resistance as it is supposed to modify the energy in the turbulent bou...Ship resistance issues are related to fuel economy,speed,and cost efficiency.Air lubrication is a promising technique for lowering hull frictional resistance as it is supposed to modify the energy in the turbulent boundary layer and thereby reduce hull friction.In this paper,the objective is to identify the optimum type of air lubrication using microbubble drag reduction(MBDR)and air layer drag reduction(ALDR)techniques to reduce the resistance of a 56-m Indonesian self-propelled barge(SPB).A model with the following dimensions was constructed:length L=2000 mm,breadth B=521.60 mm,and draft T=52.50 mm.The ship model was towed using standard towing tank experimental parameters.The speed was varied over the Froude number range 0.11–0.31.The air layer flow rate was varied at 80,85,and 90 standard liters per minute(SLPM)and the microbubble injection coefficient over the range 0.20–0.60.The results show that the ship model using the air layer had the highest drag reduction up to a maximum of 90%.Based on the characteristics of the SPB,which operates at low speed,the optimum air lubrication type to reduce resistance in this instance is ALDR.展开更多
Pentamaran,a vessel with five hulls,can be an alternative for high-speed vessels due to its advantages,for instance,its excellent stability and seakeeping performance and broader deck space than an equivalent monohull...Pentamaran,a vessel with five hulls,can be an alternative for high-speed vessels due to its advantages,for instance,its excellent stability and seakeeping performance and broader deck space than an equivalent monohull with the same displacement.The destructive interference between the system of waves produced by the vessel’s hulls might benefit the reduction of power consumption.This study investigated a Wigley hull form pentamaran model with five asymmetric and symmetric hull config-urations and three variations of hull separation.The ship model was towed in conditions of fixed towing and calm water with Froude numbers(Fr)ranging from 0.55 to 1.00.A resistance analysis had been carried out to ensure proper comparison between the asymmetric and symmetric hull configurations.Results showed that total resistance coefficient of the asymmetries created different properties from the symmetries,that is,symmetries produced steadier trends than asymmetries.The hull separation variation caused a slight alteration in the total resistant coefficient(in magnitude)under the same configuration.Although not a single configuration outperformed the others in the entire range of Fr,three configurations were noteworthy as optimum models based on their Fr range.Moreover,a configuration of asymmetric hull with S/L=0.22 could generate a constant destructive interference throughout the investigated Fr range.展开更多
文摘Ship resistance issues are related to fuel economy,speed,and cost efficiency.Air lubrication is a promising technique for lowering hull frictional resistance as it is supposed to modify the energy in the turbulent boundary layer and thereby reduce hull friction.In this paper,the objective is to identify the optimum type of air lubrication using microbubble drag reduction(MBDR)and air layer drag reduction(ALDR)techniques to reduce the resistance of a 56-m Indonesian self-propelled barge(SPB).A model with the following dimensions was constructed:length L=2000 mm,breadth B=521.60 mm,and draft T=52.50 mm.The ship model was towed using standard towing tank experimental parameters.The speed was varied over the Froude number range 0.11–0.31.The air layer flow rate was varied at 80,85,and 90 standard liters per minute(SLPM)and the microbubble injection coefficient over the range 0.20–0.60.The results show that the ship model using the air layer had the highest drag reduction up to a maximum of 90%.Based on the characteristics of the SPB,which operates at low speed,the optimum air lubrication type to reduce resistance in this instance is ALDR.
基金financially supported by the Hibah Q1Q2:NKB-0329/UN2.R3.1/HKp.05.00/2019
文摘Pentamaran,a vessel with five hulls,can be an alternative for high-speed vessels due to its advantages,for instance,its excellent stability and seakeeping performance and broader deck space than an equivalent monohull with the same displacement.The destructive interference between the system of waves produced by the vessel’s hulls might benefit the reduction of power consumption.This study investigated a Wigley hull form pentamaran model with five asymmetric and symmetric hull config-urations and three variations of hull separation.The ship model was towed in conditions of fixed towing and calm water with Froude numbers(Fr)ranging from 0.55 to 1.00.A resistance analysis had been carried out to ensure proper comparison between the asymmetric and symmetric hull configurations.Results showed that total resistance coefficient of the asymmetries created different properties from the symmetries,that is,symmetries produced steadier trends than asymmetries.The hull separation variation caused a slight alteration in the total resistant coefficient(in magnitude)under the same configuration.Although not a single configuration outperformed the others in the entire range of Fr,three configurations were noteworthy as optimum models based on their Fr range.Moreover,a configuration of asymmetric hull with S/L=0.22 could generate a constant destructive interference throughout the investigated Fr range.
