Miniaturized passively Q-switched Nd:YAG/Cr(4+):YAG lasers are promising candidates as spark sources for sophisticated laser ignition. The influence of the complex spatial-temporal pulse profile of such lasers on the process of plasma breakdown and on the energy transfer is studied. The developed measurement technique is applied to an open ignition system as well as to prototypes of laser spark...

We report on the design and output performances of a diode pumped, high-peak power Nd:YAG/Cr 4+ :YAG laser with four-beam output. The system posses the ability to chose independently the focus of each laser beam, being seen as a solution for a laser spark with multiple-point ignition. The laser ignition of a gasoline direct injected engine has several advantages in comparison with ignition by e...

Rise and delay times of mixtures of methane, propane, n-butane, iso-butane and isooctane mixed with air ignited by transient plasma discharge were investigated and compared with spark discharge ignition. Multi-ignition site effect and high electron energy are suggested to contribute to shortening of rise and delay times.

The spark advance determines the efficiency of spark-ignited (SI) engines by positioning the combustion in relation to the piston motion. Today’s spark-advance controllers are open-loop systems that measure parameters that effect the sparkadvance setting and compensate for their effects. Several parameters influence the best spark-advance setting but it would be too expensive to measure and acc...

There are many incentives to increase the fuel efficiency of combustion processes. This paper looks at two available options to achieve this goal. The former aims to develop an experimental method that can analyze combustion at extremely high pressures to improve the understanding of high pressure H2/air combustion. Experimental data has been lacking a suitable combustion diagnostic to visualiz...

conventional compression ignition (ci) engines are known for their high thermal efficiency compared to spark ignited (si) engines. gasoline because of its higher ignition delay has much lower soot emission in comparison with diesel fuel. using double injection strategy reduces the maximum heat release rate that leads to nox emission reduction. in this paper, a numerical study of a gasoline fuel...

A large eddy simulation (LES) model was developed to simulate the combustion process in a spark-assisted homogeneous charge compression ignition (SACI) engine. First, an ignition and flame propagation model based on a reaction progress variable is presented. The reaction progress variable is defined based on the normalized cumulative heat release. Transport equation for the progress variable is...

New generations of spark ignition engines require a correct ignition adjustment to guarantee optimal performance. In this paper, we address the challenge of knock detection improvements with time-frequency analysis. Two real time knock detection methodologies based on the sliding Discrete Fourier Transform and the pseudo Wigner-Ville distribution are exposed. Their relative performances and rob...

We report our results on non-periodic experimental time series of pressure in a spark ignition engine. The experiments were performed for a low rotational velocity of a crankshaft and a relatively large spark advance angle. We show that the combustion process has many chaotic features. Surprisingly, the reconstructed attractor has a characteristic butterfly shape similar to a chaotic attractor ...

To control the exhaust emissions from two stroke spark ignition engine, copper nano-particles coated on wire mesh at the junction of improved design as catalytic converter, AVL-422 gas analyzer was used for measurement and comparision for CO and unburnt hydrocarbon in the exhaust of the engine at various speeds and loads. In the present work, an improved design is proposed which is more suitabl...