ID 31

Analysis of air entrainment of gasoline direct injection (GDI) nozzles by means of time-resolved stereo fluorescence particle image velocimetry

 

Abstract:

The development of modern gasoline direct injection (GDI) nozzles demands profound knowledge about the mechanisms of spray transport in order to minimize emissions and maximize fuel efficiency. To receive a fundamental understanding about spray-air interaction, the present study investigates the spatio-temporal air entrainment and spray induced flow of single jet plumes. Revealing a profound insight on the influence of air entrainment on penetration, spray angle and further spray features, disparate axisymmetric single-hole nozzles are analysed by means of time-resolved stereo particle image velocimetry (2D3C-FPIV).

In order to achieve phase discrimination, optical filtering is applied by doping the gaseous phase with fluorescent seeding particles. The investigation comprises global spray and injector near field characteristics, by using different field of views and optical magnifications. Under varying thermodynamic conditions, the impact of injection pressure, fuel temperature, backpressure and ambient gas temperature is examined. The single-hole nozzles are designed to provide stringy, directed as well as bushy, undirected sprays.

Depending on spray design and conditions, the spray-air interaction differs significantly in regard of spray transport and spray induced flow. Based on the extraction of 3-dimensional ensemble averaged velocity fields, a comprehensive analysis about the interaction between spray and surrounding gas as well as the resulting impact on spray transport is presented.