Influence of electronic fuel injection parameters on combustion-induced noise in a small diesel engine.

摘要

The present study involves the exploration of effects of varying fuel injection parameters in a small, direct injection diesel engine, mainly from the perspective of combustion-induced noise and fuel consumption.;With co-operation from Bosch, an electronic fuel injector nozzle was fabricated which was custom-designed to allow an asymmetric spray pattern as dictated by the inclined installation of the injector on the cylinder head. Following this, a preliminary study was carried out to explore the effects of varying injection parameters (main injection timing, pre-injection timing and pre-injection quantity) on combustion noise and fuel consumption. The results were compared with corresponding baseline measurements made with the original mechanical injection system. Improvements over mechanical injection system were observed with electronic injection, in both overall noise and fuel consumption. Also, employment of split injection strategy exhibited improvements on both counts in some cases, when compared to having only single injection pulse.;In the final phase, a detailed study of combustion-induced noise was performed on the basis of decomposition of in-cylinder pressure signals measured under a wide range of fuel injection settings. Spectral analysis, i.e., Fourier analysis, was performed to understand the contribution of the different components of the in-cylinder pressure to overall noise. Time-frequency analysis was also performed to study the non-stationary nature of combustion-induced noise components. Corresponding acoustic measurements were also performed to try and realize the changes in sound power as predicted by the in-cylinder pressure analysis.