Heat transfer and inhomogeneous flows in the turbine inhibit the calculation of the isentropic efficiencies from hot gas test data using conventional methods. In previous works the basis for such a calculation has been built such as special measurement devices and a power-based approach for calculating the heat flows. The main objective of the present work is the calculation of the isentropic turbine efficiencies and further development of the approach for obtaining isentropic compressor efficiencies from hot gas test data. The turbocharger is described aerodynamically and thereby the friction power can be calculated by setting up the power balance. For validation of the compressor, adiabatic measurements are used as well as CFD simulations for the turbine. Reasons for the latter are changing inlet conditions that do not allow the transfer of adiabatic data to diabatic or hot conditions.

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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.

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