Large Eddy Simulation of Turbulent Combustion at Supercritical Conditions

The primary objective of the proposed project is to develop and validate turbulence and combustion models for high-fidelity simulation of combustion under supercritical conditions relevant to direct-fired supercritical CO2 power cycles. Supercritical CO2 cycles have gained much interest recently because of their potential for increased efficiency over the traditional power cycles. Direct-fired cycles involve oxy-fuel combustion of natural gas or syngas with high-pressure CO2 as a main product of combustion which facilitates the car- bon capture process. Designing direct-fired supercritical CO2 combustors requires detailed understanding of the combustion under supercritical conditions which is still not mature. Owing to the difficulties associated with experimental studies at such extreme conditions, computational fluid dynamics (CFD) can play a major role in acquiring fundamental knowledge to facilitate design of advanced combustors. In order to provide predictive CFD simulations, however, it is essential to employ accurate models to describe turbulent combustion phenomena. While there has been significant progress in this areas for low-pressure flows over the past several decades, development of models suitable for high-pressure conditions has received much less attention. The proposed study focuses on developing and validating turbulence and combustion models valid for supercritical pressure in the context of large eddy simulation (LES). Subgrid scale (SGS) models will be developed to contain high-pressure flow physics such as real-gas equation of state, real transport and thermodynamic property models and generalized diffusion effects. The closure strategy also includes the filtered density function (FDF) methodology which provides a closed form for chemical reaction effects. Evaluation of the SGS models will be done by a priori and a posteriori assessments using direct numerical simulation (DNS) data and by validating against experimental data. The outcome of the project is a computational software for high-fidelity simulation of turbulent combustion in devices operating in supercritical regimes. This software is of key relevance to wide range of applications such as supercritical power cycles, automotive engines, gas turbines and rocket engines. Successful completion of the proposed work can contribute to advance technologies that are crucial for energy affordability, energy security, environmental sustainability as well as many applications in defense, aerospace, automotive and transportation industries.