An isokinetic sampling probe is designed and constructed to measure entrained liquid droplet fluxes in separated gasliquid pipe flows. This probe also has the capability of working as a non-standard Pitot tube when th...An isokinetic sampling probe is designed and constructed to measure entrained liquid droplet fluxes in separated gasliquid pipe flows. This probe also has the capability of working as a non-standard Pitot tube when the sampling is stopped. CFD simulations using the commercial software Ansys CFX were carried out for single phase gas flow to analyze the non-standard design. Pitot tube velocity calculations and isokinetic sampling conditions were studied. The predicted results were compared against theoretical velocity profiles from the literature and with gas single phase experimental data acquired in a horizontal 49 m long steel pipeline with an internal diameter of 69 mm. The experiments were done by using a dense gas (SF6) at 7 bara. An asymmetry of the experimental velocity profiles reproduced with the numerical simulations. The CFD simulations made it possible to verify the design and predict and correct an installation problem.展开更多
A probe-hole field emission microscope system,controlled by the Apple Ⅱ computer,has been developed and operated successfully for measuring the work function of a single crystalplane.The detection screen,the phototub...A probe-hole field emission microscope system,controlled by the Apple Ⅱ computer,has been developed and operated successfully for measuring the work function of a single crystalplane.The detection screen,the phototube and the amplifier are combined for measuring theprobe-hole current.The combination is calibrated and the calibrated data are used in the com-puter program.The high voltage on the viewing screen is adjusted by using a D/A converter.The total current and the probe-hole current are acquired by using an A/D converter.A programin BASIC is used for processing all data and the Fowler-Nordheim plot parameters are given.Work functions of single crystal planes can then be calculated;as examples,the work functionson the clean W(100)and W(111)planes are measured to be 4.67 eV and 4.45 eV,respectively.展开更多
The high temperature gas flow field in a PVTM cyclone separator was measured by using a specially-fabricated,hemispherical five-hole pitot probe.The temperature of test air ranged from 293 K to 973 K and the cyclone i...The high temperature gas flow field in a PVTM cyclone separator was measured by using a specially-fabricated,hemispherical five-hole pitot probe.The temperature of test air ranged from 293 K to 973 K and the cyclone inlet velocity from 16 m·s-1 to 36 m·s-1.The experimental results showed that the three-dimensional velocity components are good in axisymmetry and similarity along the axis but the tangential velocity value attenuated down the axis.The non-dimensional tangential velocity increased slightly and the dividing surface between inner and outer vortex also moved outwards with the increase of inlet velocity.With the rise of gas temperature,the tangential velocity decreased and its attenuation along the axis became greater.The effect of the gas temperature and inlet velocity can be reflected by a Reynolds number based on the axial flow in the vortex finder and an empirical expression for the maximum non-dimensional tangential velocity vs.Re was given.展开更多
文摘An isokinetic sampling probe is designed and constructed to measure entrained liquid droplet fluxes in separated gasliquid pipe flows. This probe also has the capability of working as a non-standard Pitot tube when the sampling is stopped. CFD simulations using the commercial software Ansys CFX were carried out for single phase gas flow to analyze the non-standard design. Pitot tube velocity calculations and isokinetic sampling conditions were studied. The predicted results were compared against theoretical velocity profiles from the literature and with gas single phase experimental data acquired in a horizontal 49 m long steel pipeline with an internal diameter of 69 mm. The experiments were done by using a dense gas (SF6) at 7 bara. An asymmetry of the experimental velocity profiles reproduced with the numerical simulations. The CFD simulations made it possible to verify the design and predict and correct an installation problem.
基金Subject Supported by the Natural Science Fund of China.
文摘A probe-hole field emission microscope system,controlled by the Apple Ⅱ computer,has been developed and operated successfully for measuring the work function of a single crystalplane.The detection screen,the phototube and the amplifier are combined for measuring theprobe-hole current.The combination is calibrated and the calibrated data are used in the com-puter program.The high voltage on the viewing screen is adjusted by using a D/A converter.The total current and the probe-hole current are acquired by using an A/D converter.A programin BASIC is used for processing all data and the Fowler-Nordheim plot parameters are given.Work functions of single crystal planes can then be calculated;as examples,the work functionson the clean W(100)and W(111)planes are measured to be 4.67 eV and 4.45 eV,respectively.
文摘The high temperature gas flow field in a PVTM cyclone separator was measured by using a specially-fabricated,hemispherical five-hole pitot probe.The temperature of test air ranged from 293 K to 973 K and the cyclone inlet velocity from 16 m·s-1 to 36 m·s-1.The experimental results showed that the three-dimensional velocity components are good in axisymmetry and similarity along the axis but the tangential velocity value attenuated down the axis.The non-dimensional tangential velocity increased slightly and the dividing surface between inner and outer vortex also moved outwards with the increase of inlet velocity.With the rise of gas temperature,the tangential velocity decreased and its attenuation along the axis became greater.The effect of the gas temperature and inlet velocity can be reflected by a Reynolds number based on the axial flow in the vortex finder and an empirical expression for the maximum non-dimensional tangential velocity vs.Re was given.
