Flow characteristics of V-Cone flowmeter in wet steam
Wet steam is a common two-phase flow whose mass flow-rate can be measured by V-Cone flowmeter. The mass flow coefficient CD of V-Cone is no longer approximately constant which affects the measuring accuracy subject to the complex flow characteristics of wet steam and discrete droplets. Firstly, five main impact factors for CD of V-Cone were obtained by dimensional analysis, namely, vapor Reynolds number, liquid-vapor density ratio, mass loading ratio, potential to kinetic energy ratio and dimensionless droplet diameter respectively. Then CFD simulation was carried out to study the influence of these parameters. Eulerian multiphase model and SST k-ω turbulence model were adopted for steady simulation. The simulation results coincided well with the experimental results. The results indicate that CD is almost not affected by vapor Reynolds number and potential to kinetic energy ratio; it increases with the liquid-vapor density ratio, mass loading ratio and dimensionless droplet diameter, among which mass loading ratio is the main factor.
Influence of Key Factors on Discharge Coefficient in V-cone Flowmeter
By combining the computational fluid dynamics (CFD) simulation experiment with the real physical calibration experiment,this study is to discover the characteristics of the discharge coefficient of V-cone flowmeter.Here,the turbulence model is RNG k-e.The key factors include different values of equivalent diameter ratioβ,fore-and-aft V-cone angle and the Reynolds number.The pipe diameter of all the prototypes is 100 mm with theβ,0.50,0.65,0.85,respectively,the fore V-cone angle,40°,45°, 50°,respectively,the aft V-cone angle,120°,130°,140°,respectively.Therefore,there are 27 tested models in all.The medium for simulation is water of 293 K.The 27 characteristic curves are obtained from the numerical simulation.In order to further verify the computational results,a new automated special device for calibration is set up,which depends on an established water calibration and test device.From the both test data,we discover that the discharge coefficient of V-cone flowmeter relates not only to the Reynolds number,but also to the values of equivalent diameter ratioβ,fore-and-aft angles of V-cone.Firstly,the discharge coefficient increases while theβis decreased,and it is influenced more easily by Reynolds number while theβis increased.Secondly,if theβkeeps the same value,the fore V-cone angle is crucial,and the aft can infuence the linearity to a certain extent.Thirdly,larger fore V-cone angle will weaken the influence of the Reynolds number.The average error of simulations is approximately 5%,the maximum,less than 10%.
Investigations of dielectric gratings using electrodynamic models based on volume integral equations
Eigenmodes of planar and cylindrical dielectric gratings (DGs) and electromagnetic wave scattering from multiplayer DGs are investigated. The DG characteristics are calculated using numerical-analytical solution of integral equations (IEs).