# B-Wageningen propeller diagrams

Discussion in 'Props' started by zzerachiel, Jun 1, 2010.

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### zzerachielJunior Member

Hy,

I searched all over the internet for the B-Wageningen propeller diagrams and couldn't find any good diagram.

I need the Kt-J, Kq-J with n0, kd and kn coeficients displayed.

Can someone tell me where i can find them ?

The only diagrams i've found have't got the n0, kd and kn coeficients and i really need them.

BTW, n0 is eta0

I need those diagrams for a didactical project.

Thank you.

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### daiquiriEngineering and Design

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### zzerachielJunior Member

I already have those, but i cannot find the above mentioned coeficients.

I was wondering if i can find the diagrams separated ( Kt-J and Kq-J ), since at college we work with that kind of diagrams.

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### daiquiriEngineering and Design

Can you please define n0, kd ,and kn coefficients?

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### zzerachielJunior Member

Ok, here is how the diagram i work with is organized.

We have 2 diagrams KT-J and KQ-J, separated.

On each diagram we have :

P/D or H/D ( propeller pitch ) - family of horizontal curves ( ex. from 0.5 to 1.3 )
etaP = familily of vertical curves ( ex. from 0.1 to 0.75 )
etaOPT - another horizontal curve ( only one ), intersecting the etaP and P/D curves
DiameterOPT ( dOPT ) - a horizontal curve, just like etaOPT but beneath it

kd and kn are a series of curves intersecting all the above mentioned curves. Their profile is like a loose C.

The resulting diagram is similar to a rectangular triangle.

Those coeficients don't have a name, or at least i don't know it, they are part of the analitical formulas for the Kt and Kq

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### daiquiriEngineering and Design

You have confused me with therms "horizontal curves" and "vertical curves". I've had to rotate the J-K diagram by 90° to grasp the meaning of your words.

I think you are looking for Bp-delta charts. You can get yourself a copy of Dave Gerr's "The Propeller Handbook". It costs around \$10 + shipping fee at Amazon.com, but it is worth much more than that, you won't regret spending that money.

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### zzerachielJunior Member

As soon as i put my hands on the diagrams i will scan one of them and show it here

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### jehardimanSenior Member

Is it really eta"P"? or is it eta"B" or eta"D" or eta"R"

eta"B" is the behind hull efficiency = measured thrust*Va/(2*pi*n*measured torque)

eta"D" is the propulsive efficiency = effective power/delivered power = eta"H"*eta"R"*eta"O"

eta"R" is the relative rotative efficiency = eta"B"/eta"O" = open water torque/ behind hull torque

eta"O" is the open water efficiency = open water thrust*Va/(2*pi*n*open water torque)

eta"H" is the hull efficiency = thrust deduction/wake fraction = (1-t)/(1-w) in Taylor notation

If the purpose of the graphic was to find the optimum D, n, and P/D given an value of eta"B", then it all make sense. Therefore, from the description kd and kn would be curves of constant diameter and constant rps.

Anyway, a picture of the graphic would help make more sense of what you are trying to find...kd and kn are not coefficients that I recall from van Manen. UofM bookstore through university Mircofilms used to have the original NSMB text and Bp-delta curves from the series. My copies are buried in a box right now.

Last edited: Jun 1, 2010
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### zzerachielJunior Member

It is etaP as far as i can tell, the diagram i have is handwritten ( the letters/numbers not the lines ).

So, here is the path i must follow to make a preliminary design for the propeller :

calculate Kn = 0.565Va/sqrt(n)*sqrt(sqrt(rho*Va/Pd);
find out Jopt from the KQ-J
calculate Dopt
etc

In the end i must have P/D, J, eta0 ( propeller randament ), KT.

I don't know if i named eta0 correctly

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### b1ck0Senior Member

Kn - Optimal Diameter curve ( design parameter for D(opt) )
Kd - Optimal revolutions curve ( design parameter for n(opt) )

That's what he's looking for ... I have the diagrams of Bulgarian Ship Hydrodynamic Centre from 1983 and these curves are drown there but I don't have scaner now ....

The only thing I can do, is to interpolate the curves and give you the Equations ...

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### zzerachielJunior Member

Thank you b1ck0, that's what i'm looking for.

Sorry, but i'm rather new in the fied and i don't have much tehnical information.

I think that tomorow i will copy the diagrams tomorow and i hope this week i can scan them and upload them somewhere.

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### b1ck0Senior Member

You will copy them, from where ?

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### zzerachielJunior Member

Well, i must give the project/homework until Thursday, and all i have to do from now is insert the coeficients.

The project/homework is pretty straight-forward but i can't do much without the diagrams.

No need to interpolate, but it would be nice to upload those diagrams somewhere

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### zzerachielJunior Member

Wel, from a friend, but i can get them tomorow.

They are from a book "Propeller Calculation" written by Horia DUmitrescu.

Again, sorry for the translation.

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### b1ck0Senior Member

I will scan them ... but after 1-2 days ... if you want ... give me your propeller coefficients and I will tell you Kn and Kd

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