High Bandwidth Heat Transfer and Optical Measurements in an Instrumented Spark Ignition Internal Combustion Engine 2002-01-0747

Heat transfer between the working fluid and the combustion chamber in an internal combustion engine is one of the most important parameters for cycle simulation and analysis. Heat transfer influences the in-cylinder pressure and temperature levels, engine efficiency and exhaust emissions.

Heat transfer is determined using platinum thin film resistance thermometers exposed to the combustion gases. These give a frequency response of greater than 100kHz; hence can track heat transfer rate changes on the piston and cylinder head surfaces adequately. The thin film gauges overcome the problems of low bandwidths and large uncertainties associated with thermocouples.

Combustion is a highly complex process where the mechanism of fuel oxidation causes many different chemical species to emit light on specific spectral lines; therefore, from a measured emission spectrum it is possible to infer the chemical species present. Measurements of the spectral content (300 to 850 nm) of the light intensities within the combustion chamber are presented.

A high frame-rate colour video camera is used to record a series of images of the firing cycle with a high spatial and temporal resolution through a cylinder head modified for optical access. The video data powerfully illustrates the complex and variable nature of the combustion process.

The three techniques form part of a Data Fusion study researching the application of data processing techniques in complex multidimensional areas such as combustion.