A Software Toolkit to Accelerate Emission Predictions for Turboelectric/Hybrid Electric Aircraft Propulsion

Electric propulsion represents an attractive path for reducing overall emissions. For larger commercial aircrafts operating in the mega-watt range, power turboelectric and hybrid electric aircraft propulsion will continue to rely on gas turbine engines/generators to provide part of the thrust, charging batteries and driving generators. As a result, reduction of emissions such as oxides of nitrogen (NOx) remains a key concern. The innovation proposed is a software toolkit supporting high-fidelity yet computationally-tractable predictions of NOx emissions and other pollutants in gas-turbine engines/generators within the context of unsteady Computational Fluid Dynamics (CFD) simulations. A well-known difficulty limiting the accurate prediction of NOx levels in turbulent flames is related to the fact that NOx production can evolve through several different chemical pathways characterized by drastically different time scales. In this regard, a fast-running turbulent combustion approach called Multi-TimeScale Flamelet/Progress Variable (MTS-FPV) is being developed to address NOx emissions in a computationally-tractable manner and by capturing the relevant characteristic chemical time scales. The MTS-FPV formulation will be matured and extended to model two-phase droplet vaporization and then subsequently packaged as a software toolkit. Furthermore, this software toolkit will be interfaced with NASA’s OpenNCC CFD code. As a result, at the conclusion of the SBIR program, NASA will have available in-house (i) the enhanced emission prediction capabilities of OpenNCC as well as (ii) a methodology for leveraging these capabilities in system-level trade analyses of hybrid electric aircraft propulsion concepts.