Analysis of the spray-gas interaction of a single GDI jet by means of velocimetry-based pressure evaluation

Velocimetry-based pressure evaluation is used to investigate the spray transport of a single-hole gasoline direct injection (GDI) spray for different operating conditions. The study provides novel, formerly hidden insights into the interrelation between spray formation, momentum exchange, and macroscopic spray properties such as penetration length and spray expansion. The former level of descriptive conclusions with respect to spray transport and spray gas interaction consequently have been verified on a quantitative evaluation basis. Increased momentum exchange between spray and ambient gas flow is uncovered for stronger spray disintegration, enhanced spray expansion, higher relative velocities, and higher ambient gas densities. A particularly strong momentum exchange in flash-boiling atomization is shown, which is attributed to the immediate and strong decay into small droplets, as well as to an increased area of drag due to a wide expansion of the spray. The penetration length of a single jet directly correlates with the level of exchanged momentum. The jet experiences a stronger deceleration for higher ambient gas densities, fuel temperatures, injection pressures, and levels of superheat. ... mehrIn this context, the applied statistical approach has been proven to accurately resolve even small pressure differences with respect to slight variations of thermodynamic conditions.