To find a better way to estimate the lift force induced by an interceptor on a high-speed mono-hull ship,a series of high-speed mono-hull ship models are designed and investigated under different conditions.Different ...To find a better way to estimate the lift force induced by an interceptor on a high-speed mono-hull ship,a series of high-speed mono-hull ship models are designed and investigated under different conditions.Different lift forces are obtained by numerical calculations and validated by a model test in a towing tank.The factors that influence the force are the interceptor height,velocity,draft,and deadrise angle.The relationship between each factor and the induced lift force is investigated and obtained.We found that the induced lift mainly depends on the interceptor height and advancing velocity,and is proportional to the square of the interceptor height and velocity.The results also showed that the effects of the draft and deadrise angle are relatively less important,and the relationship between the induced lift and these two factors is generally linear.Based on the results,a formula including the combined effect of all factors used to estimate the lift force induced by the interceptor is developed based on systematic analysis.The proposed formula could be used to estimate the lift force induced by interceptors,especially under high-speed condition.展开更多
A new method improves prediction of the motion of a hybrid monohull in regular waves. Stem section hydrodynamic coefficients of a hybrid monohull with harmonic oscillation were computed using the Reynolds Averaged Nav...A new method improves prediction of the motion of a hybrid monohull in regular waves. Stem section hydrodynamic coefficients of a hybrid monohull with harmonic oscillation were computed using the Reynolds Averaged Navier-Stokes Equations （RANSE）. The governing equations were solved using the finite volume method. The VOF method was used for free surface treatment, and RNGK-ε turbulence model was employed in viscous flow calculation. The whole computational domain was divided into many blocks each with structured grids, and the dynamic process was treated with moving grids. Using a 2-D strip method and 2.5D theory with the correction hydrodynamic coefficients allows consideration of the viscous effect when predicting longitudinal motion of a hybrid monohull in regular waves. The method is effective at predicting motion of a hybrid monohull, showing that the viscous effect on a semi-submerged body cannot be ignored.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
A method Green function satisfying of three-dimensional time domain linear conditions at free surface and body surface boundary was employed to analyze the wave resistance and wave profile of a displacement multi-hull...A method Green function satisfying of three-dimensional time domain linear conditions at free surface and body surface boundary was employed to analyze the wave resistance and wave profile of a displacement multi-hull ship. The wave profile induced by a moving time domain point source was compared with those by a Havelock source, and satisfactory results were obtained. The panel method based on the time domain source distribution on the ship mean wetted hull surface was used to perform the wave making com- putations tbr mono-hull ships, catamaran and trimaran. Reasonable results were also obtained. Using the numerical method the wave profile simulations of multi-hull ships for a given Froude number were conducted.展开更多
基金financially supported by the National Key Research and Development Program of China(Grant No.2021YFC2800700)the National Natural Science Foundation of China(Grant Nos.52171330,52101379,52101380,51679053)+2 种基金the Project of Research and Development Plan in Key Areas of Guangdong Province(Grant No.2020B1111010002)the Foundation of Key Laboratory of Marine Environmental Survey Technology and Application,Ministry of Natural Resources(Grant No.MESTA-2021-B010)the Natural Science Foundation of Guangdong Province,China(Grant No.2021A1515012134)。
文摘To find a better way to estimate the lift force induced by an interceptor on a high-speed mono-hull ship,a series of high-speed mono-hull ship models are designed and investigated under different conditions.Different lift forces are obtained by numerical calculations and validated by a model test in a towing tank.The factors that influence the force are the interceptor height,velocity,draft,and deadrise angle.The relationship between each factor and the induced lift force is investigated and obtained.We found that the induced lift mainly depends on the interceptor height and advancing velocity,and is proportional to the square of the interceptor height and velocity.The results also showed that the effects of the draft and deadrise angle are relatively less important,and the relationship between the induced lift and these two factors is generally linear.Based on the results,a formula including the combined effect of all factors used to estimate the lift force induced by the interceptor is developed based on systematic analysis.The proposed formula could be used to estimate the lift force induced by interceptors,especially under high-speed condition.
文摘A new method improves prediction of the motion of a hybrid monohull in regular waves. Stem section hydrodynamic coefficients of a hybrid monohull with harmonic oscillation were computed using the Reynolds Averaged Navier-Stokes Equations （RANSE）. The governing equations were solved using the finite volume method. The VOF method was used for free surface treatment, and RNGK-ε turbulence model was employed in viscous flow calculation. The whole computational domain was divided into many blocks each with structured grids, and the dynamic process was treated with moving grids. Using a 2-D strip method and 2.5D theory with the correction hydrodynamic coefficients allows consideration of the viscous effect when predicting longitudinal motion of a hybrid monohull in regular waves. The method is effective at predicting motion of a hybrid monohull, showing that the viscous effect on a semi-submerged body cannot be ignored.
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.
基金Project supported by China Shipbuilding Indudustry Corporation (Grant No:J40.4.4).
文摘A method Green function satisfying of three-dimensional time domain linear conditions at free surface and body surface boundary was employed to analyze the wave resistance and wave profile of a displacement multi-hull ship. The wave profile induced by a moving time domain point source was compared with those by a Havelock source, and satisfactory results were obtained. The panel method based on the time domain source distribution on the ship mean wetted hull surface was used to perform the wave making com- putations tbr mono-hull ships, catamaran and trimaran. Reasonable results were also obtained. Using the numerical method the wave profile simulations of multi-hull ships for a given Froude number were conducted.
