An investigation of the effects of diesel pilot injection parameters on natural gas combustion under diesel conditions

The effects of the diesel pilot injection parameters on combustion of natur al gas (NG) under diesel engine conditions were studied numerically using a three-dimensional (3-D) model and experimentally in a constant-volume comb ustion bomb (CVCB). The 3-D model, incorporating complex interaction betwee n diesel and NG during combustion was used to predict the main combustion c haracteristics (pressure, temperature and species concentrations). Numerica lly, combustion pressure traces are validated satisfactorily by the corresp onding experimental values. The 3-D simulations are then performed to inves tigate the effects of diesel pilot injection parameters on NG combustion un der diesel conditions. The investigated parameters are nozzle hole size and injection pressure. Predicted results suggest that NG combustion under die sel conditions can be improved by applying an injector with a great number of small holes and also by increasing the injection pressure of pilot diese l spray.