Free Stream Behavior of Hydrogen Released from a Fluidic Oscillating Nozzle

The H₂ internal combustion engine (ICE) is a key technology for complete decarbonization of the transport sector. To match or exceed the power density of conventional combustion engines, H₂ direct injection (DI) is essential. Therefore, new injector concepts that meet the requirements of a H₂ operation have to be developed. The macroscopic free stream behavior of H2 released from an innovative fluidic oscillating nozzle is investigated and compared with that of a conventional multi-hole nozzle. This work consists of H₂ flow measurements and injection tests in a constant volume chamber using the Schlieren method and is accompanied by a LES simulation. The results show that an oscillating H₂ free stream has a higher penetration velocity than the individual jets of a multi-hole nozzle. This behavior can be used to inject H₂ far into the combustion chamber in the vertical direction while the piston is still near bottom dead center. As soon as the oscillation of the H₂ free stream starts, the spray angle increases and therefore H2 is also distributed in the horizontal direction. In this phase of the injection process, spray angles comparable to those of a multi-hole nozzle are achieved. This behavior has a positive effect on H2 homogenization, which is desirable for the combustion process.