On a multi spark ignition experimental platform retrofitted from a rapid compression and expansion machine

the influence of the number of spark plugs on indicated work

maximum combustion pressure

maximum pressure rise rate

heat release rate and knock characteristics was studied. The conclusions are as follows: when hydraulic pressure and mixed gas concentration are kept constant

the indicated work increases at first and then decreases with the advancement of the ignition phase from 5 to 35 mm before TDC. There is an optimum ignition time

and it is delayed accordingly as the number of spark plugs increases. The heat release rate

maximum combustion pressure

pressure rise rate and indicated work with multi spark ignition are significantly higher than those with single spark ignition

and their increase rates are not linear with the number of spark plugs; increased burning rate and indicated work are more obvious in thin mixed gas with more than one spark plug. Multi spark ignition is more inclined to cause knock at the same ignition phase with higher hydraulic pressure.