Cannot understand author fully - Turbomachines

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SUMMARY

The discussion centers on the interpretation of the relationship between static effect (SE) and head (H) in turbomachines as described in the book "Fundamental Energy Systems." The author presents the equation for the rate of change in head as a function of velocities and rotational speeds, leading to confusion regarding the correct formulation of the ratio R. The conclusion reached is that R should be expressed as R = (0.5 * SE) / H, clarifying the author's original intent and correcting the misinterpretation of the static effect.

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SebastianRM
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Homework Statement
The author says, the reaction is the ratio of SE to H. So I interpret that as R = SE/H ; however, when looking at his working, he writes R = SE/2H.
Relevant Equations
I understand how he derives the R expression; however, his wording throws me off as it does not match mathematically what he states. Hope this is clear. Kind regards.
I am reading a book of Fundamental Energy Systems.
The author describes the rate of change in head for a turbomachine as:

$$ \frac{1}{2}[(V_1^2-V_2^2)+(U_1^2-U_2^2)+(V_{R2}^2-V_{R1}^2)] = H =U_1V_{u1} - U_2V_{u2} $$
and the static effect as:
$$SE =(U_1^2-U_2^2)+(V_{R2}^2-V_{R1}^2) $$

However he says:

Screen Shot 2021-01-15 at 11.10.38 AM.png

His wording states $ R = SE/H $. But he actually wrote it as we see above:
$$ R = \frac{SE}{2H} = \frac{(1/2)SE}{(1/2)2H} = \frac{(1/2)SE}{H} $$

I tried deriving his result from $ R = SE/H $ but it was not possible, I just want to make sure my conclusion is correct (R = (0.5*SE)/H ; instead of R = SE/H ) as the author does not seem to mind his own wording.

Thanks for illustrating me.
 
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As it turns out the static effect = 1/2 (Term sum). Which fixes all issues. The author did not say this explicitly so I misinterpreted him.
 
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