汽车理论课后习题2.7.doc
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第二次作业 车辆工程 八班 胡文贵 2013424032
解：汽车功率平衡图程序
clear all
f=0.013; G=38800;Ff=G*f; CdA=2.77;u1=0:1:120; Fw=CdA.*u1.^2/21.15;F=Ff+Fw;Ig=[5.56 2.769 1.644 1.000 0.793];k=1:5;
ngk=[600 600 600 600 600];
ngm=[4000 4000 4000 4000 4000];
r=0.367;I0=5.83;eta=0.85;
ugk=0.377*r*ngk(k)./(Ig(k).*I0);
ukm=0.377.*r.*ngm(k)./(Ig(k).*I0);
pz=F.*u1./3600;
for k=1:5
u=ugk(k):ukm(k);
n=Ig(k)*I0.*u./r/0.377;
Tq=-19.313+295.27*n/1000-165.44*(n/1000).^2+40.874*(n/1000).^3-3.8445*(n/1000).^4;
Ft=Tq.*Ig(k)*I0*eta/r;
pe=Ft.*u./3600;
plot(u1,pz,u,pe)
hold on,grid on
end
2)最高档和次高档百公里油耗曲线
n=600:1:4000;
m=3880;g=9.8;
G=m*g;
ig=[5.56 2.769 1.644 1.00 0.793];
nT=0.85;r=0.367;f=0.013;CDA=2.77;i0=5.83;
L=3.2;a=1.947;hg=0.9;If=0.218;Iw1=1.798;Iw2=3.598;
n0=[815 1207 1614 2012 2603 3006 3403 3804];
B00=[1326.8 1354.7 1284.4 1122.9 1141.0 1051.2 1233.9 1129.7];
B10=[-416.46 -303.98 -189.75 -121.59 -98.893 -73.714 -84.478 -45.291];
B20=[72.379 36.657 14.524 7.0035 4.4763 2.8593 2.9788 0.71113];
B30=[-5.8629 -2.0553 -0.51184 -0.18517 -0.091077 -0.05138 -0.047449 -0;
B40=[0.17768 0.043072 0.0068164 0.0018555 000-0.000038568];
B0=spline(n0,B00,n);
B1=spline(n0,B10,n);
B2=spline(n0,B20,n);
B3=spline(n0,B30,n);
B4=spline(n0,B40,n);
Ff=G*f;
ua4=0.377*r*n/ig(4)/i0;
ua5=0.377*r*n/ig(5)/i0;
Fz4=Ff+CDA*(ua4.^2)/21.15;
Fz5=Ff+CDA*(ua5.^2)/21.15;
Pe4=Fz4.*ua4./(nT*3.6*1000);
Pe5=Fz5.*ua5./(nT*3.6*1000);
for i=1:1:3401
b4(i)=B0(i)+B1(i)*Pe4(i)+B2(i)*Pe4(i).^2+B3(i)*Pe4(i).^3+B4(i)*Pe4(i).^4;
b5(i)=B0(i)+B1(i)*Pe5(i)+B2(i)*Pe5(i).^2+B3(i)*Pe5(i).^3+B4(i)*Pe5(i).^4;
end
pg=7.0;
Q4=Pe4.*b4./(1.02.*ua4.*pg);
Q5=Pe5.*b5./(1.02.*ua5.*pg);
plot(ua4,Q4,ua5,Q5);
axis([0 100 10 30]);
title(最高档与次高档等速百公里油耗曲线);
xlabel(ua(km/h));
ylabel(百公里油耗（L/100km）);
gtext(4),gtext(5);
六工况油耗计算
1）匀速25km/h
f=0.013; G=38800;Ff=G*f; CdA=2.77;eta=0.85;ua=25;
pe=(Ff*ua+CdA*ua.^3/21.15)/(eta*3600)
pe =
4.7897
r=0.367;I0=5.83;Ig=[5.56 2.769 1
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