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[PhilippM]

Hello everyone,

 

I have a question about the hydraulic resistance of a tees: Suppose you have a 90 degree tee with an area ratio of 1 (i.e. the branch has the same diameter/area as the straight/combined leg) and flow ratio Q_branch/Q_qcombined of 1 (i.e. the entire flow changes direction and enters/leaves in the branch and leaves/enters at the combined leg).

For this situation, figures 2-14 and 2-16 of Crane TP 410 give different values for K_branch (1.1 for converging flow, 1.7 for diverging flow).

 

Up until now I always (naively) thought that the direction in which the flow through a tee occurs does not influence the pressure drop, as all the other sources/tables I found about equivalent lengths of fittings always state a single value for "Tee-branch", "Tee, flow through branch" (or whatever they call it) and don't distinguish between the directions.

 

Does anyone know the reason for this difference?

I am guessing flow separation that occurs at different parts of the tee depending on the direction.

 

Kind regards

Philipp

 

P.S. I already ordered the "Handbook of Hydraulic Resistance" by I.E. Idelchik this morning, as Crane TP 410 refers to it for more information about different configurations for tees and wyes