To realize the accurate control of water hammer in pipes by valve stroking, based on basic differential equations of water hammer subjected to initial and boundary conditions, the traveling solution of wave equations ...To realize the accurate control of water hammer in pipes by valve stroking, based on basic differential equations of water hammer subjected to initial and boundary conditions, the traveling solution of wave equations in finite region was applied to the linear water hammer problem. With the given velocity function at the valve and the introduction of curve integration independent of integral path, the exact analytic solution of dimensionless water hammer pressure was obtained in the course of valve closing. Based on the definition of eigen wave height, optimal eigen wave height and observation time, the control goal of water hammer pressure and the judgment rule of the optimal eigen wave height were determined, then the optimal velocity function in the calculated example was derived, which can reduce the water hammer pressure maximally. According to this function, a valve closing program was set, and the optimal control of water hammer could be realized.展开更多
A non-blasting mechanized mining experiment was carried out with a high-frequency impact hammer,and the daily mining performance was recorded to explore the applicability of the high-frequency impact hammer in deep ha...A non-blasting mechanized mining experiment was carried out with a high-frequency impact hammer,and the daily mining performance was recorded to explore the applicability of the high-frequency impact hammer in deep hard rock mines.Before the field application,the scope of the excavation damage zone was monitored,and rock samples were obtained from the ore body to be mined to carry out a series of laboratory experiments.Field application results show that the overall excavation efficiency reaches 50.6 t/h,and the efficiency of pillar excavation after excavating stress relief slot reaches 158.2 t/h.The results indicate that the non-blasting mechanized mining using high-frequency impact hammer has a good application in deep hard rock mines,and the stress relief slot is conducive to mechanical excavation.In addition,the high-frequency impact hammer also exhibits the advantages of high utilization rate of labor hours,small lumpiness of spalling ore,little dust,and little excavation damage.Finally,according to the field application and laboratory experiment results,a non-blasting mechanized mining method for hard rock mines based on high-frequency impact hammer is proposed.展开更多
基金Sponsored by the National Natural Science Foundation of China (Grant No. 50478025 and 50506009) the 46th China Postdoctoral Science Foundation(Grant No.20090460912)
文摘To realize the accurate control of water hammer in pipes by valve stroking, based on basic differential equations of water hammer subjected to initial and boundary conditions, the traveling solution of wave equations in finite region was applied to the linear water hammer problem. With the given velocity function at the valve and the introduction of curve integration independent of integral path, the exact analytic solution of dimensionless water hammer pressure was obtained in the course of valve closing. Based on the definition of eigen wave height, optimal eigen wave height and observation time, the control goal of water hammer pressure and the judgment rule of the optimal eigen wave height were determined, then the optimal velocity function in the calculated example was derived, which can reduce the water hammer pressure maximally. According to this function, a valve closing program was set, and the optimal control of water hammer could be realized.
基金supported by the National Natural Science Foundation of China (Nos. 52174099, 51904333)the Natural Science Foundation of Hunan Province, China (No. 2021JJ30842)
文摘A non-blasting mechanized mining experiment was carried out with a high-frequency impact hammer,and the daily mining performance was recorded to explore the applicability of the high-frequency impact hammer in deep hard rock mines.Before the field application,the scope of the excavation damage zone was monitored,and rock samples were obtained from the ore body to be mined to carry out a series of laboratory experiments.Field application results show that the overall excavation efficiency reaches 50.6 t/h,and the efficiency of pillar excavation after excavating stress relief slot reaches 158.2 t/h.The results indicate that the non-blasting mechanized mining using high-frequency impact hammer has a good application in deep hard rock mines,and the stress relief slot is conducive to mechanical excavation.In addition,the high-frequency impact hammer also exhibits the advantages of high utilization rate of labor hours,small lumpiness of spalling ore,little dust,and little excavation damage.Finally,according to the field application and laboratory experiment results,a non-blasting mechanized mining method for hard rock mines based on high-frequency impact hammer is proposed.
