One dimensional model and pulse generation of a supercharger
A reduced order model that captures the key aspects of a roots type supercharger has been developed. The goal of this reduced order model is to obtain the greatest computation speed for an acceptable accuracy. Key phenomena that dominate the response in the supercharger were identified first, and then implemented in the reduced order model. The reduced order model was developed based on one dimensional supercharger model from Sorenson. This model was then improved by adding backflow slot features (previously done by Carroll), a carryback slot, and finally a pressure pulse generated by the carryback slot. The output of this model, supercharger performance (volumetric and J1723 isentropic efficiency), was then compared with measured data from Eaton Corporation. The results agree after a supercharger wall temperature is increased with respect to the pressure ratio and rotor speed. This suggests that there is another heat generation source in the supercharger that has not been accounted for in the model, such as mechanical loss due to friction. A further investigation on the supercharger wall temperature needs to be conducted to verify this hypothesis. If the investigation results do not support this hypothesis, other source of heat generation in the supercharger should be investigated.