Ported shroud centrifugal compressor modification for reduced noise and improved efficiency
An improvement to the design of ported shrouds for centrifugal compressor resulting in reduced noise and improved efficiency
Implementing a ported shroud casing treatment is often used to extend the operating range of a centrifugal compressor. A centrifugal compressor is used in an engine to increase the pressure of the air entering the engine. This allows the engine to burn more fuel and air, producing more power. Centrifugal compressors are typically used in turbocharged and supercharged automotive engines. The main benefits of using a centrifugal compressor with an engine are: increased power output, fuel efficiency, and faster throttle response. However, the drawback is that it comes with increased cost, increased noise, and reduced reliability.
Researchers at The Ohio State University, led by Dr. Richard Dehner, have created a modified ported shroud compressor design to reduce engine whoosh noise and improve engine efficiency. The ported shroud compressor design provides a secondary, parallel flow path to recirculate flow at the inlet of a centrifugal compressor. This recirculated flow increases the flow rate through the inlet of the impeller, which improves stability and performance at low-flow operating points. Traditional non-ported shroud centrifugal compressors suffer from high levels of broadband 'whoosh' noise. Addition of a traditional ported shroud significantly reduces 'whoosh' noise, but it also greatly increases tonal noise at the impeller blade-pass frequency (BPF). Increased tonal noise is well known throughout the automotive industry to be a drawback to traditional ported shroud compressors. The OSU ported shroud design modification maintains the 'whoosh' noise reduction and does not increase BPF noise, which results in a much quieter compressor and improved efficiency according to simulations.