The turbocharger test facility can be operated in two different modes. In the first mode, the turbocharger turbine is driven by an external blower and a combustor. The compressor blows off through the chimney. In the second mode the turbocharger is operated similar to a gas turbine: the turbine drives the turbocharger compressor which pressurizes the combustion chamber. This study is focused on the surge cycle of the turbocharger for both operation modes of the test facility. The turbocharger has to withstand surge for all pressure ratios it is designed for without damaging the test rig. Especially for small compressors large plenum volumes can cause such damages. The dynamical model of the system is developed based on the work done by Greitzer [5], [6] and has been extended to the special requirements of the turbocharger test rig. For the components of the turbocharger a quasi-steady behavior with respect to the time scales of the surge cycle is assumed. Consequently, the experimentally obtained steady state characteristics for both compressor and turbine are applied to the model. In order to describe the compressor behavior for backflow conditions, the compressor map is extended for negative mass flow. The theoretical model is calibrated on experimental data. Thereafter the model is used to predict the surge cycle for different operation conditions. For the two operation modes, the blow-off and the recirculation operation, the time resolved values of static pressure and speed oscillation were recorded and compared to the theoretical predictions.

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