A new effective technique, useful in telecommunications industry for passing an optical telephone cord attached to a connector through pipeline,has been developed using the spiral flow. Using this technique, the cord ...A new effective technique, useful in telecommunications industry for passing an optical telephone cord attached to a connector through pipeline,has been developed using the spiral flow. Using this technique, the cord could be passed through a straight pipeline 150 meters long and a roll of vinyl tube 50 meters long. However, under the same condition, the cord could not pass through when using the turbulent flow. To obtain a high speed stable spiral flow, a nozzle with an annular slit connected to a conical cylinder was used. A pressurized fluid with no tangential flow was supplied through this slit and the fluid, passing through the conical cylinder, was deformed into spiral flow with the steeper axial velocity distribution compared to that of turbulence pipe flow due to Coanda effect and instability. As a result, the cord was attracted to the axis area of the pipe, which effectively increased the ability for the work of cord passing. This high ability for cord passing is attributed mainly to the reduction of the friction made between the cord and the pipe wall, caused by the deformation to spiral flow.展开更多
A refined theoretical analysis for using the spiral airflow and axial airflow to purge residual water in an inclined pipe was presented. The computations reveal that, in most cases, the spiral flow can purge the resid...A refined theoretical analysis for using the spiral airflow and axial airflow to purge residual water in an inclined pipe was presented. The computations reveal that, in most cases, the spiral flow can purge the residual water in the inclined pipe indeed while the axial flow may induce back flow of the water, just as predicted in the experiments presented by Horii and Zhao et al. In addition, the effects of various initial conditions on water purging were studied in detail for both the spiral and axial flow cases.展开更多
Based on the observation of a model test and in combination with some theoretical analysis, the researches of some basic hydrodynamics characteristics of cavity spiral flow in a large size level pipe with a shaft-inle...Based on the observation of a model test and in combination with some theoretical analysis, the researches of some basic hydrodynamics characteristics of cavity spiral flow in a large size level pipe with a shaft-inlet is presented in the paper, which include the basic flow pattern, formation condition of the cavity spiral flow, discharge Q, cavity diameter d0, wall pressure coefficient Cpw, velocity distribution, total energy dissipation rate η etc. The results show that the basic flow patterns can be divided into three zones according to the variations in amount of ventilation Ф, cavity diameter d0 and gas pressure p0 within cavity spiral flow when the upstream and downstream water level changes and that the basic hydrodynamics characteristics change with the flow pattern and have the different behaviour.展开更多
A concise definition of Transport Efficiency (TE) was given to examine the amount of transported grains in the pipe flow with certain energy consumption. The transport characteristics and the so-called 'roto-float...A concise definition of Transport Efficiency (TE) was given to examine the amount of transported grains in the pipe flow with certain energy consumption. The transport characteristics and the so-called 'roto-floating' characteristics were studied from the tests of sediment transport in the normal pipe flow and the spiral pipe flow, and hereby the energy gradients of the two kinds of pipe flows were obtained. By comparing the mean concentrations at the same gradient, it was concluded that the TE of the latter is several times to over ten times higher than that of the former, and the lift of the latter is 200 times larger than that of the former for the nearly same TE. The spiral flow in circular pipe is suitable for transporting fine grains of high concentration, and with sedimentation trend and coarse grains.展开更多
文摘A new effective technique, useful in telecommunications industry for passing an optical telephone cord attached to a connector through pipeline,has been developed using the spiral flow. Using this technique, the cord could be passed through a straight pipeline 150 meters long and a roll of vinyl tube 50 meters long. However, under the same condition, the cord could not pass through when using the turbulent flow. To obtain a high speed stable spiral flow, a nozzle with an annular slit connected to a conical cylinder was used. A pressurized fluid with no tangential flow was supplied through this slit and the fluid, passing through the conical cylinder, was deformed into spiral flow with the steeper axial velocity distribution compared to that of turbulence pipe flow due to Coanda effect and instability. As a result, the cord was attracted to the axis area of the pipe, which effectively increased the ability for the work of cord passing. This high ability for cord passing is attributed mainly to the reduction of the friction made between the cord and the pipe wall, caused by the deformation to spiral flow.
文摘A refined theoretical analysis for using the spiral airflow and axial airflow to purge residual water in an inclined pipe was presented. The computations reveal that, in most cases, the spiral flow can purge the residual water in the inclined pipe indeed while the axial flow may induce back flow of the water, just as predicted in the experiments presented by Horii and Zhao et al. In addition, the effects of various initial conditions on water purging were studied in detail for both the spiral and axial flow cases.
文摘Based on the observation of a model test and in combination with some theoretical analysis, the researches of some basic hydrodynamics characteristics of cavity spiral flow in a large size level pipe with a shaft-inlet is presented in the paper, which include the basic flow pattern, formation condition of the cavity spiral flow, discharge Q, cavity diameter d0, wall pressure coefficient Cpw, velocity distribution, total energy dissipation rate η etc. The results show that the basic flow patterns can be divided into three zones according to the variations in amount of ventilation Ф, cavity diameter d0 and gas pressure p0 within cavity spiral flow when the upstream and downstream water level changes and that the basic hydrodynamics characteristics change with the flow pattern and have the different behaviour.
文摘A concise definition of Transport Efficiency (TE) was given to examine the amount of transported grains in the pipe flow with certain energy consumption. The transport characteristics and the so-called 'roto-floating' characteristics were studied from the tests of sediment transport in the normal pipe flow and the spiral pipe flow, and hereby the energy gradients of the two kinds of pipe flows were obtained. By comparing the mean concentrations at the same gradient, it was concluded that the TE of the latter is several times to over ten times higher than that of the former, and the lift of the latter is 200 times larger than that of the former for the nearly same TE. The spiral flow in circular pipe is suitable for transporting fine grains of high concentration, and with sedimentation trend and coarse grains.
