We present the results of theoretical and experimental studies of flow processes of extended axisymmetric cavitators during motion near a free surface taking into account a considerable effect of fluid weightiness. Th...We present the results of theoretical and experimental studies of flow processes of extended axisymmetric cavitators during motion near a free surface taking into account a considerable effect of fluid weightiness. The main objective of work is to study ways of reduction of fluid weightiness effect using lift at cavitator and other body （hull） elements within a cavity, in order to apply this way of drag reduction for a range of considerably lower motion speeds.展开更多
In order to understand the laws of motion for supercavitating vehicle better, simplified equations for longitudinal motion of supercavitating vehicle were derived. Then the corresponding simulation software for trajec...In order to understand the laws of motion for supercavitating vehicle better, simplified equations for longitudinal motion of supercavitating vehicle were derived. Then the corresponding simulation software for trajectory of supereavitating vehicle was programmed, by which the theoretical predicted trajectories of the supercavitating vehicle at different velocities were obtained. It was found that the predicted trajectories at low speed and without cavitation on the vehicle in theory agreed well with those in experiments, and the theoretical predicted trajectories at high speed and with supercavity on the vehicle correctly reflected the motion laws of the supercavitating vehicle. The influences of various parameters of eavitator and rudder on the underwater trajectory were compared and analyzed, which can provide a guide for the design of hydrodynamic distribution and gross parameters of the supereavitating weapons.展开更多
A class of dynamic cavitations is examined for an isotropic incompressible hyperelastic circular sheet under a pre-strained state caused by an initially applied finite radial tension.The solutions that describe the ra...A class of dynamic cavitations is examined for an isotropic incompressible hyperelastic circular sheet under a pre-strained state caused by an initially applied finite radial tension.The solutions that describe the radially symmetric motion of the pre-strained sheet are obtained.The conditions of cavitated bifurcation that describe cavity formation and motion with time at the axial line of the pre-strained sheet are proposed,that is to say,a circular cavity will form if the suddenly applied radial tensile load exceeds a certain critical value;dynamically,it is proved that the formed cavity will present a nonlinearly periodic oscillation,which is essentially different from the singular periodic oscillation of the formed cavity in an incompressible hyperelastic solid sphere.Numerical simulations show the effects of prescribed radial tension,material parameter and tensile load on critical ten-sile load describing cavity formation and periodic oscillation of the pre-strained circular sheet.展开更多
文摘We present the results of theoretical and experimental studies of flow processes of extended axisymmetric cavitators during motion near a free surface taking into account a considerable effect of fluid weightiness. The main objective of work is to study ways of reduction of fluid weightiness effect using lift at cavitator and other body （hull） elements within a cavity, in order to apply this way of drag reduction for a range of considerably lower motion speeds.
文摘In order to understand the laws of motion for supercavitating vehicle better, simplified equations for longitudinal motion of supercavitating vehicle were derived. Then the corresponding simulation software for trajectory of supereavitating vehicle was programmed, by which the theoretical predicted trajectories of the supercavitating vehicle at different velocities were obtained. It was found that the predicted trajectories at low speed and without cavitation on the vehicle in theory agreed well with those in experiments, and the theoretical predicted trajectories at high speed and with supercavity on the vehicle correctly reflected the motion laws of the supercavitating vehicle. The influences of various parameters of eavitator and rudder on the underwater trajectory were compared and analyzed, which can provide a guide for the design of hydrodynamic distribution and gross parameters of the supereavitating weapons.
基金supported by the National Natural Science Foundation of China (Grant Nos.10872045, 10721062)the Program for New Century Excellent Talents in University (Grant No.NCET-09-0096)the Fundamental Research Funds for Central Universities (Grant No.DC10030104)
文摘A class of dynamic cavitations is examined for an isotropic incompressible hyperelastic circular sheet under a pre-strained state caused by an initially applied finite radial tension.The solutions that describe the radially symmetric motion of the pre-strained sheet are obtained.The conditions of cavitated bifurcation that describe cavity formation and motion with time at the axial line of the pre-strained sheet are proposed,that is to say,a circular cavity will form if the suddenly applied radial tensile load exceeds a certain critical value;dynamically,it is proved that the formed cavity will present a nonlinearly periodic oscillation,which is essentially different from the singular periodic oscillation of the formed cavity in an incompressible hyperelastic solid sphere.Numerical simulations show the effects of prescribed radial tension,material parameter and tensile load on critical ten-sile load describing cavity formation and periodic oscillation of the pre-strained circular sheet.
