NOx and soot emissions remain critical issues in diesel engines. One method to address these problems is to achieve homogeneous combustion at lower peak temperatures – the goal of research on controlled autoignition. In this paper n-heptane is used to represent a large hydrocarbon fuel and some of the effects of internal and external EGR, oxygen concentration, and engine speed on its combustion...

Simulations of forced ignition of non-premixed laminar counterflow flames are used to study the effect of strain rate on ignition success. A one dimensional calculation is performed, using detailed methane chemical kinetics and treating the spark as an instantaneous heat release in an inert mixing layer. Ignition success depends on the mixture composition at the spark location, resulting in lea...

In an effort to reduce dependence on petroleum-based fuels and increase engine efficiency, fuel-flexible engines with advanced technologies, including variable valve timing, are being developed. Fuel-flexible spark-ignition engines permit the increased use of ethanol–gasoline blends. Ethanol, an alternative to petroleum-based gasoline, is a renewable fuel, which has the added advantage of impro...

In this paper we analyze the cycle-to-cycle variations of maximum pressure pmax and peak pressure angle αpmax in a four-cylinder spark ignition engine. We examine the experimental time series of pmax and αpmax for three different spark advance angles. Using standard statistical techniques such as return maps and histograms we show that depending on the spark advance angle, there are significant...

Simulations of forced ignition in a non-premixed laminar counterflow are used to study the effect of the strain rate on ignition success. A one dimensional calculation is performed, using detailed methane chemical kinetics, and treating the ignition event as an instantaneous heat release. Ignition success is seen to depend on the mixture composition and spark location, resulting in lean and ric...

Nowadays, increased attention has been focused on internal combustion engine fuels. Regarding environmental effects of internal combustion engines particularly as sources of pollution and depletion of fossil fuels, compressed natural gas has been introduced as an alternative to gasoline and diesel fuels in many applications. A high research octane number which allows combustion at higher co...

Multi-point laser ignition (LI) is one of the key potential advantages that LI can offer over conventional spark ignition (SI). Previous research found that multi-point ignition produced more stable and faster combustion. This paper demonstrates a diffractive multi-point LI technology which is experimentally attempted at Liverpool University Laser Group. Sparks with arbitrary geometrical locati...

GENERATED NOISE IN IGNITION SYSTEMS High-frequency electromagnetic interference (EMI), commonly referred to as Radio Frequency Interference (RFI), generated by a gasoline engine ignition system, comes primarily from the high-voltage side of the circuit. Ignition systems produce sparks at the coil where the battery voltage is converted into high voltage pulses, at the distributor where the high ...

Sammanfattning For every operating condition of an internal combustion engine there exists an optimal spark timing, called maximum brake torque (MBT), which maximises the output torque and the efficiency of the engine. Traditionally MBT timing is implemented as an open-loop control where the ignition timing is found by using a combination of static lookup tables and sensor information. With a d...