Combustion Solved Problems

1. A fve-cylinder fve-cylinder,, our-str our-stroke oke cycle cycle SI engine has a compressi compression on ratio rc = 11:1, or ore ! = "."# "."#cm cm,, str stroke oke S = ".$# ".$# cm, cm, and and conn connec ecti ting ng rod rod leng length th % = 11.&&cm. 11.&&cm. 'ylinder inlet condition conditions s are ()*' and +#ka. +#ka. %he intake valve closes at 1*a!' and the spark plug is fred at/1:"*%'. 'alculate: 0a %emperature and pressure in the cylinder at ignition, assuming 2tto cycle analysis 0i.e., assume the intake valve closes at !' and ignition is at %'. 34, ka5 0 67ective compression ratio 0i.e., actual compression o the air-uel mi8ture eore ignition. 0c Actual temperature and pressure in the cylinder at ignition. 34, ka5 Solution: 0a %# = %10rck-1 = 0))( 4011 &.)" = $$9 4 = "&" °' # = 10rck = 0+# ka011 1.)" = #)# ka 0 'rankshat 'rankshat o7set = a = S# = ".$# ".$# # = #.9( cm ; = ra = 11.&#.9( = ).9" 'rank angle c = 1  ?0rc @ 1 3;  1 - cos θ - 0;# @ sin#θ1#5 >I>'>c = 1  ?011-1 0).9"  01 @ cos0##1 ° @ 30).9" #  @ sin#0##1°51#B = 1&.&" 'omustion chamer volume ig>c = 1  ?011-1 0).9" 01 @ cos0)" ° @ 30).9" #  @ sin#0)"°51#B = 1.#1 67ective compression ratio >I>'>ig = 0>I>'>c  0>ig>c = 01&.&"  01.#1 = 9.#9 0c %# = 0))( 4 09.#9 1.)"-1 = $& 4 = )1 °' # = 0+# ka 09.#9 1.)" = 1"+( ka

#. A ).(-liter, >( SI engine is designed to have a ma8imum speed o $&&& ;C.  %here are td = ).(( = &.(  = &.&&&( m) = 0J01.&(!) ! = &.&9+$ m = 9.+$ cm S = 01.&(09.+$ cm = +."& cm 0a Sonic velocity at inlet conditions ' = 3k;%51# = 301.&0#9$ Kkg.40)))45 1# = )(( msec Average piston velocity at ma8imum speed 0Lpma8 = #SM = 0# stokescycle0&.&+"& mstroke0$&&&(& revsec = ##.1$ msec Area or the # valves Ai = '!#30Lpma8c15 = 01.+09.+$ cm #0##.1$ msec0)(( msec = (.) cm # Hor 1 valve A1 = (.)# = ).1$ cm # = Jdvl = Jdv0dv = 0Jdv# dv = #.&1 cm 0 Ca8imum Eo< velocity ma8 = c= )(( msec 0c

Nith proper design valves could e ft into comustion chamer