Enhanced aircraft electrification is one of the main drivers of the short-to-medium-term technology roadmaps in the aviation sector. The success of the ‘More Electric Aircraft’ has the potential to enable, and guide, the longer term goal of a medium-haul mild-hybrid and/or full electric aircraft. Enhanced aircraft electrification is currently the most promising trend to achieve, or set, the baselines for the step-change advancements necessary to curb local and global emissions as well as the noise caused by the substantial growth of air transport. 

As part of this path to enhanced aircraft electrification, the work presented in this paper focuses on the design of an electrically powered compressor for active flow control to delay the onset of stall on high-lift systems for future commercial aircraft. This active flow control technology will combine boundary layer suction with steady blowing to create a Coanda jet and hence delaying boundary layer separation. The benefits of such systems include the reduction of the aircraft noise Sound Exposure Levels footprint and the reduction of the impact of aviation emissions on local air quality by allowing shorter take-offs and landing.

The design considerations of the different components of such electrically powered active high-lift system for a 200 passenger reference aircraft with a 2000Km operating range have been already presented as part of the Collaborative Research Centre 880 "Efficient High-Lift for Future Civil Aircraft" and funded by the German science foundation (DFG). The focus of the research programme was on the compressor located under the aileron as it has the most stringent installation space limitations and the most challenging operational conditions. The latter is due to the higher pressure ratios required to support aircraft roll manoeuvres in addition to the tasks of increasing lift. As part of this research work, a compressor meeting the requirements under the given constraints was developed using a newly developed multi-disciplinary optimization approach at the Institute of Turbomachinery and Fluid Dynamics of the Leibniz University Hannover. The optimization resulted in an unusual transonic mixed-flow compressor design featuring low aspect ratio blades with rotational speeds between 20,000 and 60,000 rpm.

In the work presented in this paper this optimised stage will be further improved by using a 3D inverse design method that computes the blade geometry to match a specific distribution of the blade loading. The goals of this redesign include a wider operating range and a higher pressure ratio at the highest rotational speed while keeping the high levels of efficiency of the previous, optimized, design. As a consequence, the target pressure ratio is obtained at lower rotational speed which, in turn, decreases the electric load. More than a 1.5% increase in stage efficiency is obtained at the design point with the duty points located within the range of high efficiency at the different speed lines, hence improving the overall efficiency of the system.


Design of a Mixed-Flow Transonic Compressor for Active High-Lift System Using a 3D Inverse Design Methodology

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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