Question

Using MATLAB, plot the following curves for the crank angle range of 0-360:

a. For an engine that has R=3.5 and L=110 mm, plot the piston speed Sp at engine speeds of 500 RPM, 2000 RPM, and 5000 RPM on the same plot.

b. For an engine that has L=110mm and running at an engine speed of 5000 RPM, plot the piston speed Sp at R = 3, 4, and 5 on the same plot.

c. For each of the cases above, determine the crank angle at which the piston speed is maximum.

Answer 1

Ans a)Matlab code to plot the different piston speeds

syms pistonSpeed(N,L,r,theta)
pistonSpeed(N,L,r,theta) = (r*((2*pi*N)/60))*(sin(theta)+(sin(2*theta)/(2*sqrt((L^2/r^2)-sin(theta^2)))

fplot(pistonSpeed(500,110,3.5,theta),[0 2*pi])
xlabel('Crank angle (rad)')
ylabel('pistonspeed(mm/s)')

hold on

fplot(pistonSpeed(2000,110,3.5,theta),[0 2*pi])

hold on

fplot(pistonSpeed(5000,110,3.5,theta),[0 2*pi])

hold off

Ans b)Matlab code to plot the piston speed at different crank radius

syms pistonSpeed(r,L,N,theta)
pistonSpeed(r,L,N,theta) = (r*((2*pi*N)/60))*(sin(theta)+(sin(2*theta)/(2*sqrt((L^2/r^2)-sin(theta^2)))

fplot(pistonSpeed(3,110,5000,theta),[0 2*pi])

hold on

fplot(pistonSpeed(4,110,5000,theta),[0 2*pi])

hold on

fplot(pistonSpeed(5,110,5000,theta),[0 2*pi])

hold off

Ans c)Matlab code to determine crank angle at which piston speed is max

syms pistonSpeed(r,L,N,theta)
pistonSpeed(r,L,N,theta) = (r*((2*pi*N)/60))*(sin(theta)+(sin(2*theta)/(2*sqrt((L^2/r^2)-sin(theta^2)))

fplot(max(pistonSpeed(3,110,5000,theta)),[0 2*pi])