Voltage rise anemometry in turbulent flows applied to internal combustion engines

Abstract

In an experimental procedure, a voltage rise anemometry is developed as a measurement technique for turbulent flows. Initially, fundamental investigations on a specific wind tunnel were performed for basic understanding and calibration purpose. Thus, a mathematical correlation is derived for calculating flow from measured secondary voltage of an ignition system under different thermodynamic conditions. Subsequently, the derived method was applied on a spark-ignited engine to measure in-cylinder flow. Therefore, no changes on combustion chamber were necessary avoiding any interferences of the examined flow field. Comparing four different engine configurations, a study of mean flow and turbulence was performed. Moreover, the results show a clear correlation between measured turbulence and analysed combustion parameters. Graphic abstract

Experimental evaluation of spark behavior under diluted conditions in an optically accessible engine

“…While vectors cannot be calculated within the spark gap through PIV, the surrounding instantaneous flow fields in the vicinity of the gap shown in the RS cycles are clear evidence that the spark elongation direction and length are heavily influenced by the stochastic behavior of the cyclic flow. It is important to note that instantaneous spark gap velocities can also be calculated through correlations using the measured secondary circuit voltage and thermodynamic conditions, such as the one proposed by Wörner and Rottenkolber 33 ; however, the development of such correlations require calibration in an optically accessible system such as a wind tunnel or flow bench and the directionality of the flow is not available. In the present study, voltage rise anemometry is not necessary as the simultaneous instantaneous velocities are available surrounding the spark plug as a supplement to the circuit and spark imaging data.…”