Effects of Power Generation on the Carbon Cycle DISCLAIMER Thisreport wasprepared as anaccount of work sponsored byanagencyof the UnitedStates Government. Neitherthe UnitedStatesGovernment noranyagencythereof, noranyoftheir employees, makesanywarranty, express orimplied, or assumes anylegalliability orresponsibilityforthe accuracy, completeness, orusefulness of anyinformation, apparatus, product, or process disclosed, orrepresents that its use would not infringe privately ownedrights. Referencehereinto anyspecific commercial product, process, orservice bytradename, trademark, manufacturer, or otherwise doesnot necessarily constitute or implyits endorsement, recommendation, or favoring by the UnitedStatesGovernment or anyagencythereof. Theviews andopinions of authorsexpressed hereindo not necessarily state or reflectthoseof the UnitedStatesGovernment oranyagency thereof.

Effects of Power Generation on the Carbon Cycle DISCLAIMERThisreport wasprepared as anaccount of work sponsored byanagencyof the UnitedStates Government. Neitherthe UnitedStatesGovernment noranyagencythereof, noranyoftheir employees, makesanywarranty, express orimplied, or assumes anylegalliability orresponsibilityforthe accuracy, completeness, orusefulness of anyinformation, apparatus, product, or process disclosed, orrepresents that its use would not infringe privately ownedrights. Referencehereinto anyspecific commercial product, process, orservice bytradename, trademark, manufacturer, or otherwise doesnot necessarily constitute or implyits endorsement, recommendation, or favoring by the UnitedStatesGovernment or anyagencythereof. Theviews andopinions of authorsexpressed hereindo not necessarily state or reflectthoseof the UnitedStatesGovernment oranyagency thereof.

This study is part of our effort to implement and refine microjet-based flow control in realistic and challenging applications. Our goal is to reduce/eliminate rotating stall in the radial diffuser of a production compressor used in commercial heating, ventilation, and air conditioning (HVAC) systems, using microjet arrays. We systematically characterize the flow using pressure and velocity field measurements. At low load conditions, the flow is clearly stalled over a range of RPM where the presence of two rotating stall cells was documented. Circular microjet arrays were integrated in the diffuser and the flow response to actuation was examined. The array closest to the initiation of stall cells was most effective in reattaching the flow. Control led to a very significant increase in the stall margin, reducing the minimum operational mass flow rate to 14% of the design flow rate, half of the original 28% flow rate before microjet control was implemented. The results will show that the parameters found be most effective in the simple configurations proved to be near-optimal for the present surge control application in a much more complex geometry. This provides us confidence that the lessons learned from prior studies can be extended to more complex configurations.