In order to obtain the determining method of the installing angle and decrease the performance indices (cutting force and wearing rate) of the pick, the relationships among the installing angles (impact angle, inclina...In order to obtain the determining method of the installing angle and decrease the performance indices (cutting force and wearing rate) of the pick, the relationships among the installing angles (impact angle, inclination angle and the skew angle) were studied, and the static model of installing angles of the pick was built. The relationships among the impact angle, the tip angle of pick and the kinematics parameters of the pick were built, too. Moreover, the mechanic models of the maximum clearance angle and the wearing angle of the pick were set up. To research the relationships of the installing angles and the change law of the wearing angle along with the kinematics parameters, the simulation was done. In order to verify the correctness of the models, the cutting experiments were done by employing two picks with different pick tip angles. The results indicate that, the cutting force is the smallest when the direction of the resultant force of pick follows its axis, and the relationship derived among the installing angles should be satisfied. In addition, to decrease the cutting force and the wearing of the pick, the tip angle of pick should not be larger than the half of the difference between the minimum wearing angle and the impact angle of the pick, and the clearance angle must not be less than zero.展开更多
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
The patterns of wing rock motion at 52.5° angle of attack have already been investigated in detail （Rong, 2009; Wang, 2010）. These patterns are completely different from those at other angles of attack. This ph...The patterns of wing rock motion at 52.5° angle of attack have already been investigated in detail （Rong, 2009; Wang, 2010）. These patterns are completely different from those at other angles of attack. This phenomenon indicates that angle of attack affects wing rock motion. The present study alms to examine the different patterns of wing rock motion at different angles of attack. The flow mechanisms of the motion patterns are also revealed, especially the uncommanded lateral motions, including wing rock and lateral deflection, induced by regular asymmetric separated flow from wings at low angles of attack and fore- body asymmetric vortices at angles of attack of 27.5°〈 α 〈 70°. The test conditions, including the testing Reynolds number, wind tunnel, experimental techniques, and test model, are all the same as those used in a previous study at a = 52.5°. Finally, the experimental technique of rotating nose of the model to suppress the wing rock or lateral deflection, which is induced by forebody asymmetric vortex flow, is applied. The uncommanded lateral motions are successfully suppressed by this technique.展开更多
基金Project(51005232) supported by the National Natural Science Foundation of ChinaProject(20100481176) supported by the China Postdoctoral Science Foundation+1 种基金Project(201104583) supported by the China Postdoctoral Special FundProject(1101106c) supported by Jiangsu Postdoctoral Foundation, China
文摘In order to obtain the determining method of the installing angle and decrease the performance indices (cutting force and wearing rate) of the pick, the relationships among the installing angles (impact angle, inclination angle and the skew angle) were studied, and the static model of installing angles of the pick was built. The relationships among the impact angle, the tip angle of pick and the kinematics parameters of the pick were built, too. Moreover, the mechanic models of the maximum clearance angle and the wearing angle of the pick were set up. To research the relationships of the installing angles and the change law of the wearing angle along with the kinematics parameters, the simulation was done. In order to verify the correctness of the models, the cutting experiments were done by employing two picks with different pick tip angles. The results indicate that, the cutting force is the smallest when the direction of the resultant force of pick follows its axis, and the relationship derived among the installing angles should be satisfied. In addition, to decrease the cutting force and the wearing of the pick, the tip angle of pick should not be larger than the half of the difference between the minimum wearing angle and the impact angle of the pick, and the clearance angle must not be less than zero.
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.
基金supported by the National Natural Science Foundation of China(Grant Nos.11172030 and 11102012)
文摘The patterns of wing rock motion at 52.5° angle of attack have already been investigated in detail （Rong, 2009; Wang, 2010）. These patterns are completely different from those at other angles of attack. This phenomenon indicates that angle of attack affects wing rock motion. The present study alms to examine the different patterns of wing rock motion at different angles of attack. The flow mechanisms of the motion patterns are also revealed, especially the uncommanded lateral motions, including wing rock and lateral deflection, induced by regular asymmetric separated flow from wings at low angles of attack and fore- body asymmetric vortices at angles of attack of 27.5°〈 α 〈 70°. The test conditions, including the testing Reynolds number, wind tunnel, experimental techniques, and test model, are all the same as those used in a previous study at a = 52.5°. Finally, the experimental technique of rotating nose of the model to suppress the wing rock or lateral deflection, which is induced by forebody asymmetric vortex flow, is applied. The uncommanded lateral motions are successfully suppressed by this technique.
