need to solve for a variable numerically

Question

joshua payne 2022-10-10

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1821663-need-to-solve-for-a-variable-numerically

回答： David Hill 2022-10-10

HW_3_problem_2_data.xlsx

need to solve for M1 based off data and equations.

gamma=1.4;
M=((((Po./P).^((gamma-1)./gamma)-1)*2)/(gamma-1)).^(1/2);
Msonic=find(abs(M-1)<.005)
values=M(305)
values=M(696)
   
Po1=P.*(1+((gamma-1)/2).*M.^2);
index1=1:304; %subsonic
index2=697:1000;%subsonic
index3=305:696; %supersonic
figure
plot(t(index1),M(index1), 'b')
hold on
plot(t(index2),M(index2), 'b')
plot(t(index3),M(index3), 'r')
M2=((((M1).^(2))+(2/(gamma-1)))./((((2*gamma)/(gamma-1)).*(M1).^2)-1))
pr=Po(index3)./P(index3)
preq=((1+((gamma-1)/2).*M2.^2)^(gamma/gamma-1)).*(((gamma+1).*M1.^2)/(2+(gamma-1).*M1.^2))
syms M1 pr gamma
eqn=preq==pr
pretty(eqn)
superM=vpasolve(eqn,M1, 'real')

for index3 i need to solve for M1. pr is calculated using the attached excel document data. Po is stagnation pressure, P is static pressure, t are the indexes.

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Answer 1

David Hill 2022-10-10

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1821663-need-to-solve-for-a-variable-numerically#answer_1070868

在 MATLAB Online 中打开

m=readmatrix('HW_3_problem_2_data.xlsx');
index3=305:696;
pr=m(index3,2)./m(index3,3);
gamma=1.4;
syms M1
M2=((((M1).^(2))+(2/(gamma-1)))./((((2*gamma)/(gamma-1)).*(M1).^2)-1));
preq=((1+((gamma-1)/2).*M2.^2)^(gamma/gamma-1)).*(((gamma+1).*M1.^2)/(2+(gamma-1).*M1.^2));
for k=1:length(pr)
 superM(k,:)=vpasolve(preq==pr(k),M1);
end