Internal Combustion Engine Indicating Measurements

Abstract

Engine indicating includes the measurement of instantaneous in-cylinder pressure, the determination of the top dead centre (TDC) and the measurement of the instantaneous crank angle (c.a.). These measurements are fundamental for engine combustion diagnosis and for indicated work calculation. In engine combustion diagnosis, the apparent heat release rate and the combustion reaction extent are the most useful quantities obtainable from engine indicating data. The apparent heat release rate is calculated by computing the amount of fuel chemical energy release necessary to obtain the experimentally observed pressure, while the combustion reaction extent is evaluated through the released fraction of the total fuel chemical energy. Heat release analysis is often complemented using optical techniques and its utilization as a diagnostic tool covers a wide range of objectives, including the development of new combustion systems, the analysis of alternative fuel burning, the validation of mathematical models for engine simulation, the investigation of combustion chamber insulation effects and the study of new injection strategies. Taking into account the importance of indicating measurements for engine research and development, this chapter addresses the description of a modern engine indicating measurement system and includes recommendations about good-practice procedures and cares that a researcher must observe in order to perform accurate experiments and to obtain valuable