Numerical and experimental investigation of the flow structure in a diesel engine with different piston bowl structure

In this study, unfired (cold) flow application was investigated in a single cylinder die-sel engine with different combustion chamber geometries. In the experimental study, images obtained with the help of an endoscopic camera for different cycle points were instantly detected at constant speed. At the same time, velocity distributions of two dif-ferent combustion chambers for different crank angles were analyzed in Ansys Forte software at before and after TDC. Thus, the flow distributions of different combustion chamber geometries in the chamber were compared. It can be said that regional swirl is formed in the newly developed combustion chamber geometry and develop in the chamber rather than the piston base compared to the standard combustion chamber. In addition, especially during the compression process, the squish movement of the bowl was observed with the movement of the piston. Here, it could be said that the newly de-veloped chamber geometry is more effective than the standard bowl geometry. When the distribution of velocity vectors in the x-y and x-z axis were examined in numerical analysis, especially in the TDC position, it was determined that the interaction of the flow developed by the new bowl geometry with the fuel droplets was more evident. While it is seen that the vector velocity changes are close to each other at the 6920 CA before the fuel injection, it is seen that higher flow velocities are formed for the standard combustion chamber at the 7200 CA where the spraying continues and develops.

Keywords:

Piston bowl structure, cold flow swirl/squish moves, velocity distribution,

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