Error in "Handbook of Hydraulic Resistance," I.E. Idelchik
Error in "Handbook of Hydraulic Resistance," I.E. Idelchik
(OP)
The formula for tau in Diagram 8.3 of the 3rd and 4th editions should be (2.4-l.bar)*10^(-phi(l.bar)). The values in the table are ok.
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RE: Error in "Handbook of Hydraulic Resistance," I.E. Idelchik
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RE: Error in "Handbook of Hydraulic Resistance," I.E. Idelchik
Can you compare the formula in the 2nd edition with the correct formula above?
Also, can you use the formula in the 2nd edition to check the values in the corresponding table.
Regards,
PT
RE: Error in "Handbook of Hydraulic Resistance," I.E. Idelchik
RE: Error in "Handbook of Hydraulic Resistance," I.E. Idelchik
To avoid copyright issues, I'll remove these images once others have a chance to verify my claim.
Regards,
PT
RE: Error in "Handbook of Hydraulic Resistance," I.E. Idelchik
Cheers,
John
RE: Error in "Handbook of Hydraulic Resistance," I.E. Idelchik
Can you provide the 2nd Edition form of the equations for tau and phi?
Thanks.
PT
RE: Error in "Handbook of Hydraulic Resistance," I.E. Idelchik
RE: Error in "Handbook of Hydraulic Resistance," I.E. Idelchik
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RE: Error in "Handbook of Hydraulic Resistance," I.E. Idelchik
2nd edition does not give a formula for tau, but a graph is given in Diagram 4-12. Does that graph look like the red curve in my file, Idelchik_tau.jpg?
PT
RE: Error in "Handbook of Hydraulic Resistance," I.E. Idelchik
RE: Error in "Handbook of Hydraulic Resistance," I.E. Idelchik
BTW, the graph in Diag 4-12 is taken from Idelchik's 1960 paper (Reference 30 on p. 537 of the 3rd edition).
PT
RE: Error in "Handbook of Hydraulic Resistance," I.E. Idelchik
What is right: the table or the ecuation?.
The equation for tau does not works if you check with the table given.
As example let take l/dh = 1 so lbar = 1
Table stand: tau = 0.24
From equation
Tau = (2.4 - lbar) phi
Where phi= 0.25 + (0.535 (lbar)8)/(0.05+(lbar)7)
So:
With lbar=1 (one).... phi= 0.7595
Them
Tau=(2.4 – 1)0.7595= 1.291182 (so different from table 1.291182 vs 0.24 )
If I use your corrected equation.
Tau = (2.4 - lbar) - phi
Tau = 0.7744 ( so different from table 0.7744 vs 0.24).
So what is right the table or the equation.?
Peaktop could you explain why you say the table is ok (step by step).
Here you can find a pdf with Diagram 8-3 from 3th edition, the pdf with the diagram you posted correspond to what edition?.
RE: Error in "Handbook of Hydraulic Resistance," I.E. Idelchik
so it did not take the exponent in the equations:
Tau = (2.4 - lbar)^phi .... eq 1
phi= 0.25 + (0.535 (lbar)^8)/(0.05+(lbar)^7) .... eq 2
solving for l/dh = 1 so lbar = 1:
phi= 0.25 + (0.535 (lbar)^8/(0.05+(lbar)^7)= 0.7595
Tau=(2.4 – 1)^0.7595= 1.291182
Tau from eq 1.291182 diferent from Tau from table 0.24
RE: Error in "Handbook of Hydraulic Resistance," I.E. Idelchik
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RE: Error in "Handbook of Hydraulic Resistance," I.E. Idelchik
peaktop please if you can send one of yours calcualtion I will check it, I am wondering how he or she do his cals.
Thanks.