In a motorcycle engine, a piston is forced down toward the crankshaft when the f
ID: 1718741 • Letter: I
Question
In a motorcycle engine, a piston is forced down toward the crankshaft when the fuel in the top of the piston’s cylinder undergoes combustion. The mixture of gaseous combustion products then expands adiabatically as the piston descends. Find the average power in (a) watts and (b) horsepower that is involved in this expansion when the engine is running at 4300 rpm, assuming that the gauge pressure immediately after combustion is 16 atm, the initial volume is 47 cm3, and the volume of the mixture at the bottom of the stroke is 250 cm3. Assume that the gases are diatomic and that the time involved in the expansion is one-half that of the total cycle.
Explanation / Answer
Given: Mean Pressure Pm: 16atm = 16.21 bar = 16.21 X 105 N/m2
Volume of Stroke Vs = (250-47) = 203 cm3 = 0.203 x 10-3 m3
n= 4300/(2 x 60) = 35.83 rps (Since, power is given only in one stroke therefore divided by 2)
Power = Pm X Vs X n
= 16.21 X 105 X 0.203 x 10-3 X 35.83
= 11790 W = 11.79 KW (Watts)
Power = 11790/ 746 = 15.80 hp (Horse Power)
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.