The trend to use advanced simulation tools for engine performance prediction is continuing and even emphasized due to shortening of development cycles. The highly accurate prediction of steady and transient engine behaviour becomes increasingly important. Complete drive cycle simulations (e.g. NEDC) help to assess turbocharged engine performance at very early stages of complex engine and vehicle development projects.
The turbocharger has recently developed away from an auxiliary part towards an integral component of the internal combustion engine. Hence, the accuracy of turbine and compressor maps becomes more and more relevant to achieve reliable simulation results and predictions. High quality turbocharger performance data are necessary over a wide range of operation conditions as input for engine simulation programs.
Especially modelling the turbine stage efficiency for engine-like operating conditions (pulsed flow) still is under research. In this context, many researchers raised the question about unsteady effects within the turbine stage and whether the stage, the volute and/or the wheel behave quasi-steadily or have to be considered as unsteady devices.
In the paper at hand, a contactless shaft torque detection technique - that has been integrated into an automotive turbocharger - is presented. It is possible to measure the turbine shaft torque with high accuracy and time resolution. A turbocharger equipped with the detection system has been adapted to a modern four cylinder gasoline engine with direct injection. Engine cycle resolved torque data has been gathered in order to assess the crank angle resolved, on-engine performance of the turbine stage
The available measurements represent an excellent basis for advancements in the modelling and simulation of turbocharger turbine stages with engine simulation tools. Furthermore, the results give a clear indication about the significance and magnitude of unsteady effects within the turbine stage under pulsed flow conditions.