The ability to obtain correct estimates of the hydraulic characteristics of a nozzle check valve by finite-volume numerical simulation is discussed. The evaluation of the numerical results is performed by comparison of the computed pressure drops inside the valve with experimental measurements obtained on an industrial check valve. It is shown that, even with high mesh refinement, the obtained result is highly dependent on the choice of the turbulence model. The RNG k-epsilon model proves to be the more accurate to describe the flow inside the valve, which is characterized by repeated flow decelerations and accelerations and by boundary layer development under adverse pressure gradient. Pressure drop and flow coefficients computed by adopting the RNG model agree well with the experimental values at different positions of the plug. The opening transient of the valve is also analysed by an unsteady flow simulation where the motion of the plug is taken into account. The characteristic curve of the valve obtained in steady flow conditions is finally compared to the transient opening characteristic, highlighting a temporary increase in the pressure drop which occurs because of a large unsteady separation region downstream of the plug.
Hydrodynamic characterization of a nozzle check valve by numerical simulation
SIBILLA, STEFANO;GALLATI, MARIO
2008-01-01
Abstract
The ability to obtain correct estimates of the hydraulic characteristics of a nozzle check valve by finite-volume numerical simulation is discussed. The evaluation of the numerical results is performed by comparison of the computed pressure drops inside the valve with experimental measurements obtained on an industrial check valve. It is shown that, even with high mesh refinement, the obtained result is highly dependent on the choice of the turbulence model. The RNG k-epsilon model proves to be the more accurate to describe the flow inside the valve, which is characterized by repeated flow decelerations and accelerations and by boundary layer development under adverse pressure gradient. Pressure drop and flow coefficients computed by adopting the RNG model agree well with the experimental values at different positions of the plug. The opening transient of the valve is also analysed by an unsteady flow simulation where the motion of the plug is taken into account. The characteristic curve of the valve obtained in steady flow conditions is finally compared to the transient opening characteristic, highlighting a temporary increase in the pressure drop which occurs because of a large unsteady separation region downstream of the plug.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
