Influence of Engine Vibration on Mixture Quality of Air and Port-Injected bioCNG in Dual-Fuel Diesel Engine

In a dual-fuel diesel engine, the bioCNG is inducted through the port-fuel injector, which mixes with the incoming air. While in progression, it experiences the engine vibration. The aim of the study is to examine the effect of engine vibration signature on the homogeneity of the air-bioCNG mixture, and its flow through the intake manifold. The optimization of the intake manifold design for different bioCNG substitutions to deliver a homogeneous mixture was done in the earlier study. Further, the experiment was conducted to record the vibration signature at a range of engine loads. The present study considers the same optimized intake manifold geometry for bioCNG substitutions of 80%, 60%, 40% and 20%. It simulates the flow of air-bioCNG mixture through the vibrating intake manifold, carried out with ANSYS Workbench 19.2. The manifold domain uses the boundary conditions, such as the vibration amplitude, the mass flow rates of air and CNG observed from the experimental data. The parameters to analyse the flow characteristics of the mixture are pressure, velocity, turbulence intensity and mass fraction of CH
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. The objective of this study is to analyse the extent to which the flow characteristics get affected by the vibration, which has been hardly explored to date. From the study, it is found that the mixture quality in the manifold under the engine vibration improves to that of mixing without the vibration. Despite this, bioCNG substitutions cannot be employed in the engine below 40%, for better homogeneity and engine performance.