Abstract

The Ultra Compact Combustor (UCC) offers a means to reduce overall combustor size. Unlike traditional axial flow combustors, the UCC utilizes an outboard circumferential cavity as the primary combustion zone. This combustor design enables the implementation of a Hybrid Guide Vane (HGV), located radially inboard of the circumferential cavity, to be positioned with the leading edge axially upstream of the hot combustion gases. Previous Computational Fluid Dynamics (CFD) efforts determined the viability of a passive cooling scheme where cooler compressor air was drawn into an opening at the stagnation region of the HGV and used for both internal and film-cooling of the vane. The present study investigates the performance of five cooled HGV configurations each having a unique combination of film-cooling, internal passage area, and internal passage geometry. The effectiveness of film-cooling holes to both protect the hardware and alter the flow path of the hot gases exiting the combustor cavity were evaluated for a range of core flow conditions. Further, the impact of a trailing edge slot to maintain an appropriate coolant flow rate through the HGV was evaluated. Results confirmed the efficacy of HGV with passive air ingestion. A solid structure located inside the cooled vanes affected the internal coolant mass flow and pressure rise and thus the overall cooling effectiveness. Further, optimal blowing ratios were demonstrated to buffer hot streaks in the freestream path resulting in a more uniform radial temperature distribution.

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