Simscape Language Chamber with Orifice

Question

Cedric Götze 2015-7-16

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/230054-simscape-language-chamber-with-orifice

回答： Cedric Götze 2015-7-21

Unfortunately it is not possible to create Subsystem automated inside a Simscape Library. So I have to find an other way to solve the following problem.

I have a chamber which is similar to the constant volume chamber of the pneumatic library. I want to connect it to an orifice and an atmospheric reference in just one block.

My idea was the following code

component chamber2
% Constant Volume Pneumatic Chamber with opening
nodes
    A = test.test; % A:top
end
parameters
    Volume = { 1e-3, 'm^3' };        % Chamber volume
    Area  = { 1e-5, 'm^2' };         % Opening area
    p2 = { 1e5, 'Pa' }; % Pressure at opening
end
parameters(Access = private)
    Bcr   = { 0.5283 , '1' };  % Critical pressure ratio (for choked flow)
    % Collected constant terms for flow equation
    c_1 = { 0, 'kg*K/J' };
    c_2 = { 0, '1' };
    c_3 = { 0, '(kg*K/J)^0.5' };
    c_4 = { 0, '(kg*K/J)^0.5' };
    c_5 = { 0, '1' };
end
variables
    G  = { 0, 'kg/s' }; % Mass flow rate
    Q  = { 0, 'J/s' }; % Heat flow into port A
    p1 = { 1e5, 'Pa' }; % Pressure at port A
end
variables(Conversion=absolute)
    T1 = { 300 , 'K' }; % Temperature at port A
end
function setup
    % Calculate critical pressure ratio
    Bcr = (2/(A.kappa+1))^(A.kappa/(A.kappa-1));
      % Calculate collected constant terms for flow equation
      c_1 = 2*A.kappa/(A.R*(A.kappa-1));
      c_2 = (A.kappa+1)/A.kappa;
      c_3 = sqrt( (A.kappa/A.R)*Bcr^((A.kappa+1)/A.kappa) );
      c_5 = 2/A.kappa;
  end
  branches
      G : A.G -> *;
      Q : A.Q -> *;
  end
  equations
          p1 == A.p;
          T1 == A.T;
          if p2/p1 > Bcr % Subsonic flow
              G == Volume/A.R/T1^2 * (p1.der*T1 - p1*T1.der)+Area*p1*sqrt(c_1 /T1 * ( (p2/p1)^c_5 - (p2/p1)^c_2) );
          else                 % Choked flow
              G == Volume/A.R/T1^2 * (p1.der*T1 - p1*T1.der)+Area*p1*T1^-0.5*c_3;
          end
          Q == A.c_v * Volume / A.R * p1.der+G*A.c_p*T1;
  end
  end

p2 is the atmospheric pressure.

the domain is kind of similar to the pneumatic one.

Because of some reasons nothing happen to pressure and temperature at A at all. it stays constant at its value.

If this code isn't working at all that's fine for me. But i need some kind of solution to perform this problem with just one block. Has anybody an idea? Thanks in advanced