Electrical capacitance tomography (ECT) was applied to dense-phase pneumatic conveying of pulverized coal, including the visualization of gas-solid flows in a horizontal pipeline.The pressure of experimental setup was...Electrical capacitance tomography (ECT) was applied to dense-phase pneumatic conveying of pulverized coal, including the visualization of gas-solid flows in a horizontal pipeline.The pressure of experimental setup was up to 4.0 MPa, the solid-gas ratio was up to 11.73 kg·kg-1, and the diameter of conveying pipeline was 10 mm.The pipeline thickness of 8-electrode ECT system was 5 mm.An improved AC-based capacitance measuring circuit was developed.Single channel capacitance measuring circuit was adopted to simplify the ECT hardware.Landweber algorithm was used to reconstruct image.The flow characteristics of dense-phase pneumatic conveying was investigated with the method of ECT experiment.Finally, the serial ECT image was compared with the result of Fluent simulation to validate the reliability.展开更多
A thermal-mechanical and micro-macro coupled finite element（FE） model for the hot extrusion process of large-scale thick-walled Inconel 625 pipe was developed based on the DEFORM-2D platform.Then,the influence rules...A thermal-mechanical and micro-macro coupled finite element（FE） model for the hot extrusion process of large-scale thick-walled Inconel 625 pipe was developed based on the DEFORM-2D platform.Then,the influence rules of the key extrusion parameters on the average grain size and grain uniformity of the extruded pipe were revealed.The results show that with the increase of initial billet temperature,extrusion speed and friction coefficient,the grain uniformity is firstly improved and then deteriorated.Larger extrusion ratio leads to more uniform grain distribution.With the increase of initial billet temperature,the average grain size of the pipe first decreases and then increases.Additionally,larger extrusion ratio can bring smaller average grain size.The extrusion speed and friction coefficient have slight effects on the average grain size of the extruded pipe.展开更多
In order to explore drum instability problems of thinning spinning ultra thin-walled tubes with large diameter-to-hickness ratio, experiments of thinning spinning ultra thin-walled tubes with different clearances betw...In order to explore drum instability problems of thinning spinning ultra thin-walled tubes with large diameter-to-hickness ratio, experiments of thinning spinning ultra thin-walled tubes with different clearances between the mandrel and the tube were carried out. The phenomena of drum instability were analyzed. Drum instability mechanism was studied. The important influence of the mandrel-locked ring on stable thinning spinning was found. Besides, two important parameters, namely drum ratio and drum stiffness, were proposed to characterize the drum instability of spinning ultra thin-walled tubes with large diameter-to-thickness ratio. What's more, numerical simulations were applied to explore the influences of different clearance ratios and diameter-to-thickness ratios on the drum instability. As a result, it is found that the mandrel-locked ring is the key to the stability and precision of spinning; drum ratio can reflect the degree of the deformation of the tubes; drum stiffness is a comprehensive index to measure the influences of the tube's own parameters on the spinning instability; both the clearance ratio and diameter-thickness ratio have significant influences on the drum ratio and drum stiffness.展开更多
The principle and method for measuring the wall thickness of transparent tube are presented.The measurement is based on total-refection vanishing light. The transmittance of transparent tube in the parallel light is s...The principle and method for measuring the wall thickness of transparent tube are presented.The measurement is based on total-refection vanishing light. The transmittance of transparent tube in the parallel light is studied. The critical conditions of total--reflection are discussed.展开更多
文摘Electrical capacitance tomography (ECT) was applied to dense-phase pneumatic conveying of pulverized coal, including the visualization of gas-solid flows in a horizontal pipeline.The pressure of experimental setup was up to 4.0 MPa, the solid-gas ratio was up to 11.73 kg·kg-1, and the diameter of conveying pipeline was 10 mm.The pipeline thickness of 8-electrode ECT system was 5 mm.An improved AC-based capacitance measuring circuit was developed.Single channel capacitance measuring circuit was adopted to simplify the ECT hardware.Landweber algorithm was used to reconstruct image.The flow characteristics of dense-phase pneumatic conveying was investigated with the method of ECT experiment.Finally, the serial ECT image was compared with the result of Fluent simulation to validate the reliability.
基金Project(2009ZX04005-031-11)supported by the Major National Science and Technology Special Project of ChinaProject(KP200911)supported by the Research Fund of State Key Laboratory of Solidification Processing of ChinaProject(B08040)supported by the"111"Project of China
文摘A thermal-mechanical and micro-macro coupled finite element（FE） model for the hot extrusion process of large-scale thick-walled Inconel 625 pipe was developed based on the DEFORM-2D platform.Then,the influence rules of the key extrusion parameters on the average grain size and grain uniformity of the extruded pipe were revealed.The results show that with the increase of initial billet temperature,extrusion speed and friction coefficient,the grain uniformity is firstly improved and then deteriorated.Larger extrusion ratio leads to more uniform grain distribution.With the increase of initial billet temperature,the average grain size of the pipe first decreases and then increases.Additionally,larger extrusion ratio can bring smaller average grain size.The extrusion speed and friction coefficient have slight effects on the average grain size of the extruded pipe.
基金Project(2014CB046600)supported by the National Basic Research Program of China
文摘In order to explore drum instability problems of thinning spinning ultra thin-walled tubes with large diameter-to-hickness ratio, experiments of thinning spinning ultra thin-walled tubes with different clearances between the mandrel and the tube were carried out. The phenomena of drum instability were analyzed. Drum instability mechanism was studied. The important influence of the mandrel-locked ring on stable thinning spinning was found. Besides, two important parameters, namely drum ratio and drum stiffness, were proposed to characterize the drum instability of spinning ultra thin-walled tubes with large diameter-to-thickness ratio. What's more, numerical simulations were applied to explore the influences of different clearance ratios and diameter-to-thickness ratios on the drum instability. As a result, it is found that the mandrel-locked ring is the key to the stability and precision of spinning; drum ratio can reflect the degree of the deformation of the tubes; drum stiffness is a comprehensive index to measure the influences of the tube's own parameters on the spinning instability; both the clearance ratio and diameter-thickness ratio have significant influences on the drum ratio and drum stiffness.
文摘The principle and method for measuring the wall thickness of transparent tube are presented.The measurement is based on total-refection vanishing light. The transmittance of transparent tube in the parallel light is studied. The critical conditions of total--reflection are discussed.
