Effect of Curved Radial Vane Cavity Arrangements on Predicted Inter-Turbine Burner (ITB) Performance

The demand for significantly higher performance gas turbine engines has led to the exploration and identification of "out of the box" innovative engine design concepts. These demands include increased thrust-to-weight ratio goals that can primarily be met by substantial engine performance increases such as specific thrust, engine weight and size reductions, and repackaging of engine components to create compact engines. Concepts of an ultra-compact-combustor (UCC) for use as a main combustor, or as an inter-turbine burner (ITB) to boost engine work output, reduce pollutant emissions and engine weight are being explored. The available experimental results and observations indicate that UCC/ITB can operate at 95-99% combustion efficiency over a wide range of operating conditions and with flame lengths up to 50% shorter than those of conventional combustors. In the present study the radial curved vane ITB design concept has been modeled using three-dimensional computational fluid dynamics (CFD). The objectives are to predict ITB flow field and combustion characteristics, guide ITB experimental investigations, identify the key design parameters driving performance, and use the results to optimize ITB design configurations. The CFD predictions demonstrated that intense burning in a high-g loaded cavity occurred which resulted in high combustion efficiency. Models with the radial vane cavity located in both the suction and pressure side have been developed. The circumferential cavity air is injected through the air injection tubes into the circumferential cavity. The orientation of this injection is used to create both a clock-wise (CW) and a counter-clock-wise (CCW) direction of circumferential flow in the outer cavity, when looking upstream from the aft end of the ITB configuration. The resulting five candidate configurations have been simulated and analyzed in detail. This study indicates improved exit profile characteristics for the curved radial vane (CRV) with the c- avity in the suction side and the air injected in the CCW direction, compared to the pressure side cavity with air injected either in CCW or CW direction and CRV with no cavity.