Stagnation specific enthalpy

We may gain a further insight into the implications of neglecting the interstage velocities by using the concept of stagnation specific enthalpy introduced in Section 14.5. Writing /for., = Aq., -I- Cgj/2, equation (16.2) converts to ... 

In Equation 2.61, it is clear that with increase in velocity (low-pressure downstream side) the specific enthalpy will reduce, and with decrease in velocity, the specific enthalpy will increase. The specific enthalpy will be a maximum when the velocity is zero, and this maximiun value is termed as stagnation enthalpy, h . The Equation 2.61 can further be modified as... 

The stagnation enthalpy follows directly by multiplying equation (14.40) throughout by the specific heat ... 

The critical mass flux is thus = G/hg, Pg, S). The Moody model (1965) is based on maximizing specific kinetic energy of the mixture with respect to the slip ratio whereas the Fauske model (1961, 1965) is based on the flow momentum with respect to the slip ratio. In Figure 22.18, the critical discharge rate of water at various stagnation pressure and enthalpy with Fauske slip model is shown. 

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