Pressure drop at pipe inlet

Steady-state incompressible flow 39 Since geometry and the conservation of mass imply that 

The process of converting potential energy into kinetic energy at the vena contracta is known to be very efficient. However, the pressure recovery process is less so. Accordingly we make the assumption that all the frictional losses associated with pipe inlet occur over the pipe section vc to 2 . As a result, we may now use the analysis of Section 4.9 directly in order to estimate the Mctional loss. Changing subscripts (3 - vc, 4- 2), equation (4.62) gives this loss as  

Applying the conservation of mass for the steady flow between station vc and station 2 gives 

The contraction coefficient, Kc , which has units of velocity heads, is given in Table 4.2. 

Tsbl 4.2 Contraction coefficient for an abrupt entrance (velocity heads) 

---