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  1. touch84

    Air flow in a pipe

    the flow of mass is m [kg/s]= rho*u*S and this is constant in every section (if you are in a stable condition). rho= density; u=speed; S=Area of the section that is constant in this case. If the pipe is frictionless and the flow is adiabatic the total rho is constant (1.225 kg/m^3) so you can...
  2. touch84

    3D best fit tendline

    Report the data on Excel and go to the ‘Chart’ menu and click on the ‘Add Trendline’ option. Click the ‘Options’ tab in the window . Check the ‘Display equation on chart’ option and click ‘OK’. This plots a linear fit and gives the slope and the offset of the fit.
  3. touch84

    Ducted Fan Thrust

    However overlooking the loss due to the viscous effect on fairing under the same power you can calculate the thrust at fixed point (asintotic velocity = 0 ) in this way: T = rho*pi*(D^2/4)*lambda*ve^2 where rho = density of air pi = 3.1415 D = diameter of propeller disk lambda = ratio between...
  4. touch84

    Ducted Fan Thrust

    Under the same power the thrust depends on the fairing (casing) because the trhust is the sum of two factor: 1)the thrust due to the rotor (propeller) ( and for a given rotor you can't change it) 2)the thrust due to the fairing. So you can choose the fairing: converging, cylindrical or...
  5. touch84

    Turbine Engine Surge Stall

    I notice that it's difficult to see the figures, so I give you the links: figure 1 http://img64.imageshack.us/my.php?image=untitled24qz.jpg figure 2 http://img394.imageshack.us/my.php?image=untitled32zw.jpg figure 3 http://img107.imageshack.us/my.php?image=untitled42mn.jpg
  6. touch84

    Turbine Engine Surge Stall

    SURGE In the figure you can see the map curve for a given number of rpm for a compressor. If you consider the pressure ratio of project the compressor can work in 2 point of the curve, the one on the right is stable (B) the one on the left is unstable(A) If your compressor is working in B and...
  7. touch84

    Matrix problem

    examples: Build matrix A and B if you wanna take the first 4230 data from the first column of A: C=A(1:4230,1); if you wanna take the first 2000 data from the first column of A and the last 2230 dat from the first column of B: C=[A(1:2000),B(1770:4000)];
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