INTEGRATED APPROACH OF PREDICTION AND VALIDATION OF MECHANICAL FUEL INJECTION SYSTEM CHARACTERISTICS FOR A SINGLE CYLINDER DIESEL ENGINE BY USING SIMULATION TOOL

The objective of this paper is to develop a methodology and approach followed for the prediction, validation and optimization of a simple low pressure mechanical fuel injection system characteristics. The characteristics such as nozzle needle lift, dynamic start of injection, end of injection, injection duration, maximum injection pressure, injection rate, effect of nozzle hole size which are very critical to achieve the stringent emission norms along with the desired engine performance. The prediction and optimization work is carried out on a very modest, low pressure, individual mechanical fuel injection pump fitted on a simple constant speed single cylinder, water cooled, naturally aspirated diesel engine to meet the stringent emission limits applicable to power generating set applications.

The objective of the work is to establish a methodology by which most suitable Fuel injection System parameters are incorporated so that the experimental combustion optimization period and the testing expenses can be reduced to a greater extent. The technique is based on the one-dimensional modeling of the fuel flow and the mechanical motion of the injection system with the simulation software.

In this work, an effort is made to describe the effect of cavitation on the performance of the fuel injection system. Validation of the FIS model is carried out by comparing predicted results with the experimental results.

The results confirm that the 1D model is capable of predicting the pressure values for all cases which were investigated. Parametric studies also carried out for investigating the influence of nozzle specifications on the hole flow exit characteristics such as spray penetration, spray cone angle, etc., The results have revealed the important influence of the design of various geometric parameters of the fuel injection system on the spray structure.