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The reduction of combustion emissions and fuel consumption can be achieved by controlling the fuel mixture to be burned and therefore the fuel injection. In this study a gasoline direct injection (GDI) piezo hollow cone injector is investigated by visualization measurements. Both single and double injection events are examined in a pressurized chamber. For the single injection, the influence of the ambient temperature and pressure is analysed in detail. For the double injection, the ambient conditions and the time interval between two injections are varied. For the single injection, the general shape of the spray, the recirculation eddy formed at the spray edge, the stringy structure of the hollow cone, and defined quantities such as the penetration length or the spray width are examined with respect to the influence of the ambient conditions. For the double injection, the same properties are evaluated, with the focus put not only on the influence of the ambient conditions, but also on the mutual interaction of two spray events. The experimental results show a clear impact of both the ambient conditions and the time difference between two injections. In particular, the investigation of the recirculation eddy may be helpful in determining possible positions for the spark plug, since the spark plug is preferably placed in regions where the air-fuel mixture variations are minimal.

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