Experimental and numerical analysis of a classical bleed slot system for a turbocharger compressor

This paper presents an insight into the performance and inducer flow field of a turbocharger centrifugal compressor incorporating a classical bleed slot system with various slot positions. The bleed slot is popular widely used map width enhancement method in the turbocharger industry. Even though the technique has been used for a long time, further study is still required to gain a better understanding of the flow structures inside the compressor stage due to the bleed slot. Therefore, this detailed study of the bleed slot system has been performed through a careful CFD analysis validated against experimental data. Three different positions of the bleed slot opening on the impeller shroud have been analysed and discussed in terms of their impact on the map width of the compressor. Discussion focuses on the slot flow variation throughout the speedline, the inducer inlet swirl near the surge flow condition and its impact on map width enhancement. The paper also demonstrates the capability of CFD analyses to predict the surge point.