Integrated Hybrid Engine Cycle Design and Power Management Optimization

An integrated gas turbine cycle design and power management optimization methodology for parallel hybrid electric architectures is shown in this article. The gas turbine cycle design method is extended to both turboprop and turbofan architectures with trade studies performed initially at cycle level. It is shown that the degree of electrification is limited by the surge margin levels of booster for turbofan configuration. An aircraft mission level assessment is then performed using the integrated method initially for an A320 Neo style aircraft case. The results indicate that optimal cycle redesigned hybrid electric propulsion system (HEPS) favor take-off and climb power on-takes while optimal retrofit HEPS favor cruise power on-takes. It is shown that for current battery energy density (250 Wh/Kg), there is no fuel burn benefit. Furthermore, even for optimistic values (750 Wh/kg), the maximum fuel burn benefit for 500 nm mission is 5.5% and 4% for redesigned and retrofit HEPS, respectively. The power management strategies for HEPS configurations also differ based on gas turbine technology with improvement in gas turbine technology showing greater scope for electrification. The method is then extended to ATR 72 style aircraft case, showing greater fuel burn benefits across the flight mission envelope. The power management strategies also change depending on the objective function, and optimum strategies are reported for direct operating cost or fuel burn. Finally, a novel multi-mission approach is shown to highlight the overall fuel burn and direct operating cost benefit across the mission cluster.