By referring to the "Fluid Mechanics Fundamentals and Applications" by Yunus A. Cengel and John M. Cimbala around page 353, I notice the pressure will increase after expander.
Or can I use the Darcy-Weisbach equation to calculate the pressure drop by the expander? If yes, I found that the pressure drop of an expander is greater than that of reducer? Is this true?
Appreciate if anyone answer my question.
Thank you.
The static pressure may increase in a duct Expansion due to deceleration of the flow. However, the total pressure will be reduced by any flow change or friction. The Darcy-Weisbach equation gives only friction losses. Depending on the shape and Reynolds number, the duct expansion will include additional losses. Please refer to specific literature, e.g. Idelchik "Handbook of Hydraulic Resistance".
I am in agreement with Herr Riess. The total energy content of the flow will decrease, but the pressure may increase. The magnitude of pressure and energy change is a function of fluid velocity, geometry of the expansion, Reynolds number.
For a given geometry, yes, the energy loss across an expander is greater than that across a reducer.
Thank you for answer my question.
Is it mean, the pressure use in calculation of Bernoulli principle is static pressure but not total pressure?
If there is no elevation change to account for, then changes in static pressure will be the same as the changes in the total pressure. The remaining considerations are the pressure changes attributable to differing cross sectional areas, frictional losses, and hydraulic shape losses .
- Badges
- Science topic
- Similar topics
- Engineering
- Mechanical Engineering