NOx is a key emission metric for Commerical Supersonic Transport (CST). CRAFT Tech has developed a tool as a foundation for operational capability to perform trade studies and design optimization of CST combustors.
Title: A Multi-Time-Scale Flamelet Progress Variable Approach in OpenNCC for Predicting NOx Applied to Commercial Supersonic Transport Combustor Designs
Authors: Andrea C. Zambon, Balaji Muralidharan, Ashvin Hosangadi, and Kumud Ajmani
This paper presents the implementation of a Multi-Time Scale Flamelet/Progress Variable (MTS-FPV) approach into OpenNCC for performing NOx prediction studies of Commercial Supersonic Transport (CST) gas turbine combustor design concepts. With the MTS-FPV approach, the primary flame and the NOx production are decoupled due to the disparate time scales associated with each process. A multiphase flamelet progress variable approach that has been developed and validated in our prior work is employed for the primary flame and the NOx species are transported independently as separate scalars. Detailed NOx chemistry is employed through the use of a dedicated chemistry manager. Such a framework is shown to accurately capture the NOx emission evolution in a cost-effective manner. To demonstrate the implementation of the multiphase extension of the MTS-FPV, results are presented for a steady RANS of a Lean Direct Engine (LDI) model combustor using conventional aviation jet fuel (A2) as the baseline fuel. The primary flame and NOx predictions are compared between a spray injection and a gas-phase injection of the fuel. Some differences are observed in the flame and species distribution which are discussed. Finally, to showcase the capability of the MTS-FPV approach to perform design trade studies, the sensitivity of the NOx predictions to two different fuels (C1 and RP2) are evaluated relative to the baseline fuel. The predicted EINOX levels were found compare reasonably well with experimental values (extrapolated to the current condition).