I am trying to estimate the Thrust and Torque generated by a propeller blade by utilising the Blade Element Theory. I was able to get Lift but not Drag. Below is the code generated by Matlab.(adsbygoogle = window.adsbygoogle || []).push({});

The calculation procedure is,

T1 = twist pitch ratio

RTheta = root pitch angle

Phi = atan(V/(Omega*r))

ro = 1.225 (density)

C = 0.15 m

Cdo = 0.008 (zero lift drag)

Alpha = RTheta + T1*r - Phi

Here the twist is negative which makes the tip to have a small pitch angle.

for i = 1:3:132 % Forward Speed of the Aircraft

for j = 1:3:39 % rps (rpm/60)

syms r

omega(j) = 2*pi*j;

W2(i,j) = i^2 + (omega(j)*r)^2;

Alpha(i,j) = deg2rad(RTheta) + deg2rad(T1)*r - atan(i/(omega(j)*r));

CD(i,j) = Cdo + K*(a*Alpha(i,j))^2;

W2CD(i,j) = expand (W2(i,j)*CD(i,j));

Drag(i,j) = double(0.5*ro*Cr*int(W2CD(i,j),r,Hr,D/2));

end

end

As the calculation is run, I always gets a message saying below details,

??? Error using ==> sym.maple at 87

Error, (in IntegrationTools:-Utils:-Simplify) too many levels of recursion

Error in ==> sym.int at 51

r = reshape(maple('map','int',f(:),[x.s '=(' a.s ')..(' b.s ')']),size(f));

Error in ==> New at 74

Drag(i,j) = double(0.5*ro*Cr*int(W2CD(i,j),r,Hr,D/2));

I would like to know how to get the drag values. I have tried every possible method, but I still get this message.

Furthermore, independent to the above question, is it OK to get the real part of a complex number to calculations?

Say if,

R = 2*D

where,

D = 0.45 + 09i

and if you take only the real number then,

R = 0.90

Is it correct? or possible? if so or not, is there is an exception where you can take R=0.90?

Advice me on both questions please. Thank you in advanced

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Drag Calculation from Matlab

Can you offer guidance or do you also need help?

**Physics Forums | Science Articles, Homework Help, Discussion**