The work carried out in the first 18 months of IDA is separated into two work packages addressing, respectively, experimental and computational activities. For the experimental work, carried out by Loughborough University (UK), an existing low-speed test facility has been modified to add a new single stage axial compressor and compressor transition duct representative of the UltraFan demonstrator engine. The system aerodynamics were extensively studied by taking measurements through the compressor and duct using miniature pneumatic five-hole probes and constant temperature anemometry. Importantly the data show that the aerodynamic design is valid. Subsequently, an engine representative bleed flow was added between the compressor and duct. Experimental data provided a better understanding of system interaction highlighting the acceptable limits of bleed. This information has been fed back to the design team and will be used to inform/design a second test configuration. In the computational work, carried out at Chalmers University of Technology (Sweden), the goal is to develop advanced, accurate and efficient numerical design tools for compressor transition ducts. Hence, time has been spent exploring advanced CFD (Computational Fluid Dynamic) approaches. This has included examining parameters such as the turbulence model, mesh strategy, boundary conditions, and interfaces between stationary and rotating components. An initial computational study had been performed which examines the Loughborough University experiment using commercial CFD solver, ANSYS CFX. Initially both steady and unsteady RANS (Reynolds Averaged Navier Stokes) predictions were made using a k−ω SST two equation turbulence model. This was then extended to a hybrid, scale-resolving approach using a SBES (Stress Blended Eddy Simulation). The k−ω SST was again used for the RANS regions whereas for the in the LES (Large Eddy Simulations) the sub-grid-scale turbulence was modeled using the WALE algebraic model. The predicted data from the three CFD simulations showed good agreement in the time-averaged flow with the uRANS and SBES each giving more information on the time-resolved flow.
In the second, and final, 18 months of the IDA project a second experimental campaign was undertaken by Loughborough University. This included the development of a second design solution which was optimised for a more effective bleed extraction, a lower impact on system performance, and an improved stall margin. Work was also undertaken to evaluate the sensitivity of the system to engine installation tolerances and geometrical features. Experimental data provided showed that the new design offers a performance benefit. Data have been fed back to the Topic Manager and this will be used to inform future product design. In the computational work, carried out at Chalmers University of Technology, the experimental data were used to further develop and validate advanced, accurate and efficient numerical design tools for compressor transition ducts. Data from the high fidelity, unsteady CFD provided new insight into the aerodynamic interactions that take place between the compressor, the bleed, and the transition duct.
The first IDA paper has been submitted to the ASME Journal of Turbomachinery. At the time of writing this paper has entered the second round of peer reviews.
- Spanelis, A., and Walker A.D. “PRELIMINARY STUDY INTO THE INFLUENCE OF A BLEED ON THE AERODYNAMICS OF A LOW-PRESSURE COMPRESSOR AND S-SHAPED TRANSITION DUCT”
A number of other papers are also current in preparation or planned:
- EXPERIMENTAL INVESTIGATION OF BLEED ON THE AERODYNAMICS OF A LOW-PRESSURE COMPRESSOR AND S-SHAPED TRANSITION DUCT
- ADVANCED/INTEGRATED BLEED FOR COMPRESSOR TRANSITION DUCTS
- ADVANCED CFD TECHNIQUES FOR THE INVESTIGATION OF COMPRESSOR TRANSITION DUCTS
