Hydrogen Jet Characterization of an Internal Combustion Engine Injector Using Schlieren Imaging

As the world moves towards a decarbonized motorization, Hydrogen became a strong candidate to replace Diesel and Gasoline. Possibly used in a DI configuration, a huge challenge is the injection and mixing process of the hydrogen in the combustion chamber. In this paper we will focus on the characterization of a compressed hydrogen jet using Schlieren imaging technique and image processing. The injector used in those tests is designed and manufactured by BorgWarner to be used specifically with Compressed Hydrogen Gas (CHG). It operates at medium pressure. Two injection pressures had been used to study the jet development in different conditions. The cylinder pressure (back pressure) will vary between 1.2 bar and 15 bar while the temperature will go from 20°C to 150°C. The discussed tests were made in full nitrogen conditions to avoid any ignition of the hydrogen jet. The results show that both injection pressure and back pressure in the chamber have a huge effect on the jet development. Indeed, the velocity of the jet decreases when the back pressure gets higher or when the injection pressure decreases. Those parameters also have impact on the width of the jet and the timing at which it collapses. However, if we focus on the temperatures impact, the effect on the jet penetration or area is more moderate.