Wave-piercing design is a revolution in hull design for small high-speed boats to operate in adverse sea conditions. To study hydrodynamics of the small high speed wave piercing monohull craft systematically, four typ...Wave-piercing design is a revolution in hull design for small high-speed boats to operate in adverse sea conditions. To study hydrodynamics of the small high speed wave piercing monohull craft systematically, four typical small high-speed wave-piercing monohull crafts were developed, and validated CFD methods were adopted to calculate hull resistances and motions. The resistances and hull motions of these high-speed wave piercing monohull crafts in calm water and waves were obtained and compared. Obvious operating differences can be observed. High-speed wave piercing monohull crafts with slender and twisted planing hulls have smaller resistance at high speed, but the dynamic effects increase as sea conditions worsen. The high-speed wave-piercing monohull craft with a slim multi-chine hull maintains in waves for softer hull motions but suffers the disadvantages of larger resistance. The high-speed wave piercing monohull craft with a triangular hull shows no obvious advantages compared with the other types.展开更多
The progress of economic globalization,the rapid growth of international trade,and the maritime transportation has played an increasingly significant role in the international supply chain.As a result,worldwide seapor...The progress of economic globalization,the rapid growth of international trade,and the maritime transportation has played an increasingly significant role in the international supply chain.As a result,worldwide seaports have suffered from a central problem,which appears in the form of massive amounts of fuel consumed and exhaust gas fumes emitted from the ships while berthed.Many ports have taken the necessary precautions to overcome this problem,while others still suffer due to the presence of technical and financial constraints.In this paper,the barriers,interconnection standards,rules,regulations,power sources,and economic and environmental analysis related to ships,shore-side power were studied in efforts to find a solution to overcome his problem.As a case study,this paper investigates the practicability,costs and benefits of switching from onboard ship auxiliary engines to shore-side power connection for high-speed crafts called Alkahera while berthed at the port of Safaga,Egypt.The results provide the national electricity grid concept as the best economical selection with 49.03 percent of annual cost saving.Moreover,environmentally,it could achieve an annual reduction in exhaust gas emissions of CO2,CO,NOx,P.M,and SO2by 276,2.32,18.87,0.825 and 3.84 tons,respectively.展开更多
A proper characterization of catamarans performance in relation to demi-hull separation ratio (Sc/L) is imperative for optimal design and applications. Resistance, propulsion and good sea-keeping characteristics for v...A proper characterization of catamarans performance in relation to demi-hull separation ratio (Sc/L) is imperative for optimal design and applications. Resistance, propulsion and good sea-keeping characteristics for various demi-hull separation ratios at different operating conditions are prime considerations. This work evaluates the Resistance and Propulsion (RAP) characteristics of a 72 m long catamaran for various values of Sc/L (0.3, 0.4 and 0.5). Both physical models and numerical methods are implemented for the analysis. The analysis shows that the frictional resistance (RF) of catamaran is parabolic and slightly higher than those of monohulls. However, catamarans have superior sea-keeping performance. The RF of catamaran dominates the total resistance (RT) at low speeds;however, at high Froude number (Fn > 0.25), wave-making resistance (Rw) becomes dominant, especially during humps. Consequently, the RT-curve and the effective power PE-curve oscillate in rhythm with the Rw-curve as the velocity increases. Again, the effect of residuary resistance interference due to demi-hulls separation ratio is marginal, except during humps. Also, four speed-regimes are identified such as: 1) Low-speed (Fn st hump (0.23 nd hump, high-speed (Fn > 0.60). The catamaran PE for Fn > 0.6 is very high and uneconomical. Therefore, for optimal performance, catamarans should have service speed limits not exceeding Fn = 0.6.展开更多
文摘Wave-piercing design is a revolution in hull design for small high-speed boats to operate in adverse sea conditions. To study hydrodynamics of the small high speed wave piercing monohull craft systematically, four typical small high-speed wave-piercing monohull crafts were developed, and validated CFD methods were adopted to calculate hull resistances and motions. The resistances and hull motions of these high-speed wave piercing monohull crafts in calm water and waves were obtained and compared. Obvious operating differences can be observed. High-speed wave piercing monohull crafts with slender and twisted planing hulls have smaller resistance at high speed, but the dynamic effects increase as sea conditions worsen. The high-speed wave-piercing monohull craft with a slim multi-chine hull maintains in waves for softer hull motions but suffers the disadvantages of larger resistance. The high-speed wave piercing monohull craft with a triangular hull shows no obvious advantages compared with the other types.
文摘The progress of economic globalization,the rapid growth of international trade,and the maritime transportation has played an increasingly significant role in the international supply chain.As a result,worldwide seaports have suffered from a central problem,which appears in the form of massive amounts of fuel consumed and exhaust gas fumes emitted from the ships while berthed.Many ports have taken the necessary precautions to overcome this problem,while others still suffer due to the presence of technical and financial constraints.In this paper,the barriers,interconnection standards,rules,regulations,power sources,and economic and environmental analysis related to ships,shore-side power were studied in efforts to find a solution to overcome his problem.As a case study,this paper investigates the practicability,costs and benefits of switching from onboard ship auxiliary engines to shore-side power connection for high-speed crafts called Alkahera while berthed at the port of Safaga,Egypt.The results provide the national electricity grid concept as the best economical selection with 49.03 percent of annual cost saving.Moreover,environmentally,it could achieve an annual reduction in exhaust gas emissions of CO2,CO,NOx,P.M,and SO2by 276,2.32,18.87,0.825 and 3.84 tons,respectively.
文摘A proper characterization of catamarans performance in relation to demi-hull separation ratio (Sc/L) is imperative for optimal design and applications. Resistance, propulsion and good sea-keeping characteristics for various demi-hull separation ratios at different operating conditions are prime considerations. This work evaluates the Resistance and Propulsion (RAP) characteristics of a 72 m long catamaran for various values of Sc/L (0.3, 0.4 and 0.5). Both physical models and numerical methods are implemented for the analysis. The analysis shows that the frictional resistance (RF) of catamaran is parabolic and slightly higher than those of monohulls. However, catamarans have superior sea-keeping performance. The RF of catamaran dominates the total resistance (RT) at low speeds;however, at high Froude number (Fn > 0.25), wave-making resistance (Rw) becomes dominant, especially during humps. Consequently, the RT-curve and the effective power PE-curve oscillate in rhythm with the Rw-curve as the velocity increases. Again, the effect of residuary resistance interference due to demi-hulls separation ratio is marginal, except during humps. Also, four speed-regimes are identified such as: 1) Low-speed (Fn st hump (0.23 nd hump, high-speed (Fn > 0.60). The catamaran PE for Fn > 0.6 is very high and uneconomical. Therefore, for optimal performance, catamarans should have service speed limits not exceeding Fn = 0.6.
