Orifice X is using an exit discharge coefficient loss model but is an inline junction. Consider using the Cd (Inline) loss model

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Orifice X is using an exit discharge coefficient loss model, but is an inline junction. Consider using the Cd (Inline) loss model.

Explanation

The orifice is using the Cd (Exit) discharge coefficient loss model. Prior to xStream 4, this was the only orifice discharge coefficient loss model and is still the loss model appropriate for exit orifices. This loss calculation has no recovery of the dynamic pressure at the throat since the static pressure at the vena contracta is assumed to equal the downstream stagnation pressure. This is true when the orifice is open to the atmosphere, but not when there is a pipe downstream of the orifice. Dynamic pressure recovery is incorporated in the Cd (Inline) loss model, which uses a different discharge coefficient method.

Required Action

If the orifice flows into a pipe and not into the atmosphere, the Cd (Inline) loss model should be used.