Several automotive industry changes are leading to the need for wide-range, high-boost turbocharging systems. Engine emission requirements require good turbocharger performance over a very wide range of flow rates. Trends in engine downsizing require turbochargers to have both good high flow performance, and good low flow performance, to cover a wide range of engine rpm operation. Current methods of extending compressor range are not sufficient to meet these growing requirements. The objective of this Phase I effort is to design a variable bypass compressor configuration, where a variable bypass stream is used to adjust the compressor performance for both high and low flow conditions, allowing the compressor to operate efficiently in both operating regimes. A secondary objective is to incorporate the design into a compressor rig, so that component rig testing can then begin. Phase I tasks include defining an appropriate cycle to be used for the design work, the aerodynamic and structural design of the variable bypass compressor, and rig selection and modification to accept the new compressor configuration. If the project is carried over into Phase II or Phase III, the concept will be demonstrated with both rig and engine testing, and will achieve a technical readiness level such that the concept can be incorporated into OEM turbocharger designs. Public benefits include wide range turbocharger technology that is relatively inexpensive to implement, leading to automobiles that are compliant with emissions standards, and with downsized, less expensive engine configurations.
