Spring 2013 Dr. Pierluigi Pisu
Due Jan 24th, 2013 @ 5pm Problem 1 (15 points) Consider a typical mid-size SUV. The table below summarizes some of the typical parameters associated with vehicle in that class: Table 1. Typical mid-size SUV vehicle parameters Parameters Value Notes 2.84 m2 Vehicle frontal area Af 7.1 m2 Vehicle side area Ac 0.39 Vehicle aerodynamic drag Cd coefficient 2.6 0.010+0.0028*(v/100) Rolling resistance Cr coefficient, smooth pavement, v in km/h 3450 lbs Curb mass Mv 2 5.6 m Trailer frontal area1 Af,t 1 Trailer aerodynamic drag Cd,t coefficient (blunt shape) 2200 lbs Trailer mass Mt 0.355 m Tire rolling radius Rw 3 1.29 kg/m Air density ρa The purpose of this exercise is to evaluate some of the basic power and torque requirements at the wheel for this type of vehicle under a variety of driving conditions. Specifically, for each of the set of conditions listed below, evaluate the power requirement at the wheel, Pw (in kW) and torque at the wheel, Tw (in Nm), as a function of vehicle speed, v. Show your calculations, and tabulate your detailed results (including aerodynamic, rolling, and grade force, total force, total torque and total power) for v = 15, 35, 55, 75 and 100 km/h unless otherwise noted. Use SI units. Use Matlab™ to perform your calculations1. Tabulate results for the following driving conditions: a) Level ground, no wind, no trailer, smooth pavement 1
With the trailer towed, only the aerodynamic resistance of the trailer is to be considered, owing to the much larger projected frontal area and bluntness of the trailer shape.
b) Level ground, no wind, with trailer, smooth pavement c) 2% grade, no wind, no trailer, smooth pavement d) 2% grade, no wind, with trailer, smooth pavement e) Mild acceleration (1.2 m/sec2), no grade, no wind, no trailer, smooth pavement f) Level ground, head wind 5 mph, no grade, no trailer, smooth pavement g) 2% grade, 30 deg head wind 5 mph, no...