One of the important phases of designing a craft is stability analysis and optimization of the drag force in cruise speed. In this research the longitudinal and lateral stability of a planing hull craft (DTMB 62 model...One of the important phases of designing a craft is stability analysis and optimization of the drag force in cruise speed. In this research the longitudinal and lateral stability of a planing hull craft (DTMB 62 model 4667-1) is investigated with some semi-empirical formulae and the effects of some important design parameters are investigated on the limit of stability region. Also on the basis of these empirical formulations and by using a genetic algorithm the drag force is optimized in each constant cruise speed with the stability criteria limits at a constant beam or projected area. Aspect ratio, the longitudinal position of the gravity center and deadrise angle are the optimization parameters. The results show that the aspect ratio and the longitudinal position of the gravity center are two important parameters in optimizing the drag force and for this planing vessel the drag force can be reduced by 22%.展开更多
The installation of plunger-type wave makers in experimental tanks will generally include a gap between the back of the wedge and the wall of the tank.In this study,we analyze the influence of this gap on the wave mak...The installation of plunger-type wave makers in experimental tanks will generally include a gap between the back of the wedge and the wall of the tank.In this study,we analyze the influence of this gap on the wave making performance of the plunger using two-dimensional(2 D)CFD calculations for a range of nearly linear wave conditions and compare the results with both experimental measurements and linear potential flow theory.Three wedge-shaped profiles,all with the same submerged volume,are considered.Moreover,the generated waves are compared with the predictions of linear potential flow theory.The calculations are made using the commercial ANSYS FLUENT finite-volume code with dynamic meshes to solve the Navier-Stokes equations and the volume of fluid scheme to capture the air-water interface.Furthermore,the linear potential flow solution of Wu(J Hydraul Res 26:481-493,1988)is extended to consider an arbitrary profile and serve as a reference solution.The amplitude ratios of the generated waves predicted by the CFD calculations compare well with the predictions of linear potential flow theory for a simple wedge,indicating that viscous effects do not influence this ratio for small-amplitude motions in 2 D.By contrast,significant higher harmonic components are produced by larger amplitude motions.Also,the simple wedge is found to produce the smallest spurious higher harmonic content in the far-field wave.展开更多
文摘One of the important phases of designing a craft is stability analysis and optimization of the drag force in cruise speed. In this research the longitudinal and lateral stability of a planing hull craft (DTMB 62 model 4667-1) is investigated with some semi-empirical formulae and the effects of some important design parameters are investigated on the limit of stability region. Also on the basis of these empirical formulations and by using a genetic algorithm the drag force is optimized in each constant cruise speed with the stability criteria limits at a constant beam or projected area. Aspect ratio, the longitudinal position of the gravity center and deadrise angle are the optimization parameters. The results show that the aspect ratio and the longitudinal position of the gravity center are two important parameters in optimizing the drag force and for this planing vessel the drag force can be reduced by 22%.
文摘The installation of plunger-type wave makers in experimental tanks will generally include a gap between the back of the wedge and the wall of the tank.In this study,we analyze the influence of this gap on the wave making performance of the plunger using two-dimensional(2 D)CFD calculations for a range of nearly linear wave conditions and compare the results with both experimental measurements and linear potential flow theory.Three wedge-shaped profiles,all with the same submerged volume,are considered.Moreover,the generated waves are compared with the predictions of linear potential flow theory.The calculations are made using the commercial ANSYS FLUENT finite-volume code with dynamic meshes to solve the Navier-Stokes equations and the volume of fluid scheme to capture the air-water interface.Furthermore,the linear potential flow solution of Wu(J Hydraul Res 26:481-493,1988)is extended to consider an arbitrary profile and serve as a reference solution.The amplitude ratios of the generated waves predicted by the CFD calculations compare well with the predictions of linear potential flow theory for a simple wedge,indicating that viscous effects do not influence this ratio for small-amplitude motions in 2 D.By contrast,significant higher harmonic components are produced by larger amplitude motions.Also,the simple wedge is found to produce the smallest spurious higher harmonic content in the far-field wave.
