Abstract

Current and future legal requirements for internal combustion engines (ICE) are increasing the complexity of modern charging systems. Test system manufacturers are facing high demands in terms of hardware specifications and methods for turbocharger testing on a hot-gas test bench. Innovative test systems and methodologies help to improve the quality of the turbocharger and engine matching process and significantly optimize the operating strategy in engine process simulation, especially in the early development and design phase.

The compressor and turbine characteristic maps are the most important sources of information in order to quantify the performance of the turbocharger. This is achieved in practice by thermodynamically evaluating turbochargers on the hot-gas test bench under test conditions that are as close as possible to real engine operation conditions. Turbocharger compressor mapping relies on the measurement of pressure and temperature upstream and downstream of the compressor at designated operating points. For use in the turbocharger matching process, mostly equidistant points on the operation line between surge and choke are required. Comparison to Computational Fluid Dynamics (CFD) requires a higher density of measurement points, especially in the vicinity of maximum compressor efficiency to analyze different geometries. The requirement to measure different point distributions at fixed rotational speed is the logical consequence.

The primary objective of this paper is to develop and evaluate a methodology that allows different operating point distributions of compressor speed lines for the compressor mapping on the hot-gas test bench. The secondary objective deals with the prediction of the measurement points with respect to pressure ratio and volume flow rate at a fixed rotational speed. This facilitates the pre-selection of settings on the hot-gas test bench.

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