调节阀附加耦合负载的形成机制

舰船执行复杂战术动作时,舰船调节阀承受着流体振荡导致的附加耦合负载,导致阀门动作异常,危及舰船安全.为了保证舰船调节阀在调节过程中的安全及可靠,基于ANSYS Fluent建立了调节阀的有限元模型,分析舰船突变工况下调节阀的阀芯轴向受力及流体压力,讨论调节阀在不同的阀芯移动方向和不同阀门入口压力下的阀芯负载变化,揭示舰...     

Comparison of Reynolds average Navier-Stokes turbulence models in numerical simulations of the DC arc plasma torch

Five turbulence models of Reynolds average Navier-Stokes(RANS),including the standard k-ω model,the RNG k-e model taking into account the low Reynolds number effect,the realizable k-ω model,the SST k-ω model,and the Reynolds stress model(RSM),are employed in the numerical simulations of direct current(DC)arc plasma torches in the range of arc current from 80 A to 240 A and air gas flow rate from 10 m^3 h^-1 to 50 m^3 h^-1.The calculated voltage,electric field intensity,and the heat loss in the arc chamber are compared with the experiments.The results indicate that the arc voltage,the electric field,and the heat loss in the arc chamber calculated by using the standard k-ω model,the RNG k-ωmodel taking into account the low Reynolds number effect,and the realizable k-ω model are much larger than those in the experiments.The RSM predicts relatively close results to the experiments,but fails in the trend of heat loss varying with the gas flow rate.The calculated results of the SST k-ω model are in the best agreement with the experiments,which may be attributed to the reasonable predictions of the turbulence as well as its distribution.