SBIR-STTR Award

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.

Increasingly stringent exhaust emissions and fuel economy legislation is forcing automotive engine designers to: 1) demand increased pressure ratios from turbocharger compressors to ensure complete fuel combustion, 2) use Exhaust Gas Recirculation for emission reduction, and 3) reduce engine displacement while maintaining or even increasing output power to reduce fuel consumption. These three changes have led to the need for significantly improved turbocharger operability. Specifically, the compressor must operate over a wider flow range, while achieving both high pressure ratios and high efficiency for high and low flows. While a variety of range extension devices have been developed, a novel compressor configuration is proposed which allows a single compressor to mimic the behavior of a small and a large compressor with minimum complexity. Based on the prior development work performed, we anticipate the compressor technology to have the following benefits compared to current commercially available turbochargers: 1) 3% improvement in fuel economy compared to a commercial turbocharger, and 2) significantly larger range, allowing low-flow low-pressure ratio conditions to be achieved that would not be possible with a current commercial turbocharger. In the Phase II project, several candidate configurations will be designed and fabricated, allowing for detailed component testing to be performed. Based on those tests, a preferred configuration will be selected and tested with an engine relevant to automotive gasoline applications to determine overall engine performance enhancements of the novel technology. Commercial Applications and Other

Benefits:
Upon successful completion of Phase II, automotive and truck turbocharger designers and manufacturers can be supplied with intellectual property licensing and associated tools to help them design and/or produce high performance turbochargers that will operate over a wider range of operating conditions compared to current commercial turbocharger systems, increasing fuel economy and reducing emissions without a significant increase in cost, weight or size.