posted 11 months ago

(a) Estimate the drag on the plywood for the case suggested by your friend.

(b) Estimate the drag on the plywood if you turn the sheet so that the long edge is front to back.

(c) Explain why your friend suggested the sideways configuration.

posted 11 months ago

(a) the sign is aligned lengthwise to the wind.

(b) the sign is crosswise to the wind.

posted 11 months ago

where V is the truck speed in m/s, Vo = 30 m/s and fr (the coefficient of rolling resistance) is approximately0.008 for a truck on concrete or asphalt. Plot the total power the engine must supply as a function of trucks peed, V. Comment on the relative importance of drag and rolling friction in the fuel consumption of the truck.

F_{\mathrm{rf}}=W f_{r}\left(1+\frac{V}{V_{0}}\right)

posted 1 years ago

posted 1 years ago

posted 1 years ago

posted 1 years ago

a) Consider the blades rotating at 2000 RPM. If the velocity far downstream ofthe propeller is measured to be 40m/sec, find the resulting thrust coefficient.

b) For the same RPM, the collective is now changed so that C, = 0.006 . What is the percent change in the velocity far downstream?

c) What is the distribution of thrust on the disk? Explain your answer.

posted 1 years ago

a) Using the blade element method and 2 elements, estimate the power coefficient of the turbine. For the section coefficients, let C, = 2ra ,C, =0.005+0.004C’.

b) Is your result consistent with the Betz limit? Why or why not?

posted 1 years ago

b) Write the local pressure coefficient C, in terms of free stream Mach number M, and the ratio P/P .

c) Combining your results from a) and b), write an expression for the local pressure coefficient C, in terms of local and free stream Mach numbers.

d) If the peak C, in incompressible flow is -0.43, estimate the critical Mach number. Hint: place all terms on one side of the equation and use a trial and error approach.

posted 1 years ago