Influence of nozzle geometry on ignition and combustion for high-speed direct injection diesel engines under cold start conditions

► Low temperature cold start combustion has been investigated at an optical engine. ► Different nozzles have been tested to show influence on combustion. ► For each nozzle, flow characterization has also been included. ► Increasing fuel mass per orifice show reduced ignition probability if maximum velocity is constant. ► Increasing nozzle momentum improves IMEP.