Test investigation of the influence of injection rate shaping on the spray characteristics in high-pressure common rail system

As the mixing process of fuel and air heavily deepens on the way the spray develops when injected into the cylinder, injection rate shaping in diesel engines play an important role for engine performance. In this experimental study, effect of three different injection rate shapes on spray process have been investigated. By using the dual pressure injection system, it is possible to obtain high injection pressures up to 200 Mpa. According to the results, high initial injection pressure leads to higher spray tip penetration due to the higher pressure at the start of injection, Ramp always has medium penetration and boot the lowest one. Furthermore, the experiments have analyzed the influence of backing pressure on the injection rate and spray evolution in test bench by using EFS8246 instantaneous fuel mass instrument and high speed spark photography.