Discharge coefficients for choked gas—liquid flow through nozzles and orifices and applications to safety devices

Vertically upward two-phase flow with a highly viscous liquid-phase in a nozzle and orifice plate

“…This is in contrast to the findings of Wood and Dickson (1973) and Morris (1990). Morris analysed the Wood and Dickson (1973) data by comparing the measured critical mass flux with the predictions of a critical flow model by McNeil and Morris (1988).…”

“…They concluded that viscosity did not have a significant effect on the flow processes and attributed this to fluid friction being relatively unimportant to these flows. To some extent Morris (1990) disagreed with this conclusion, as he was unable to include some of this data in his discharge coefficient correlation. The excluded orifice plate data had orifice to pipe diameter ratios of less than 0.418.…”

“…Wood and Dickson (1973) only had overall measurements of pressure drop to work with, and were therefore misled into believing that shear stress was unimportant in these flows. Morris (1990) reported that data obtained with lower diameter ratios by Wood and Dickson (1973) behaved differently to those obtained at higher diameter ratios. This is consistent with the conclusions of this study.…”

Prediction of Single- and Two-Phase Flow Contraction through a Sharp-Edged Short Orifice

“…This value is reasonably justified for two-phase flow compared with a mean average value of 0.91 determined by Morris [12]. However, this mean average value refers to a critical mass flux, where no contraction in the two-phase flow can possibly appear.…”

“…After some algebraic arrangements, using the definitions of the mass flux and the mass flow quality (12) the contraction coefficient of the two-phase flow is obtained as (13) The contraction coefficient for two-phase flow, in terms of that for single-phase flow and mass flow quality, is a function of the parameters of influence, including mass flux, density, upstream pressure, and the pressure in the vena contracta in terms of the model parameters and the orifice-to-tube area ratio. It is implicitly assumed that each phase contracts independently to the same extent as in single-phase flow and that the downstream position of the vena contracta remains the same.…”