Title:	Large eddy simulation of turbulent combustion using Eulerian stochastic field based transported PDF method
DNr:	SNIC 2020/13-107
Project Type:	SNIC Small Compute
Principal Investigator:	Shijie Xu <shijie.xu@energy.lth.se>
Affiliation:	Lunds universitet
Duration:	2020-11-23 – 2021-12-01
Classification:	20304
Homepage:	http://www.fm.energy.lth.se/
Keywords:

Abstract

This project aims at the simulation of turbulent reacting flow using Computational Fluid Dynamics (CFD). Recently, we developed an Eulerian stochastic field (ESF) based transported probability density function (PDF) method, which provides reasonable accuracy in the prediction of sub-grid scale (SGS) effects at an affordable computational cost. The ESF method is a promising model for the modeling of turbulent combustion, which can be applied to simulate a multi-mode combustion problem involving diffusion flames, premixed flames, partially premixed flames, and auto-ignition. However, there are still some unsolved issues before the ESF can be used as a general-purpose SGS model applied to study complex chemically reactive turbulent flows. First, a Wiener operator is introduced in the modeling of the SGS stochastic process, which is known to cause spurious oscillations due to the high non-linearity of the chemical reaction rates. Second, the mixing constant $C_{\phi}$ is known to vary greatly in a different application. In this project, we plan to study the non-linear behaviour of the of the Wiener operator and the effects of the mixing constant in the simulation of multi-mode combustion of methanol/n-heptane under high pressure and high-temperature conditions. In the beginning of the project, the one-dimensional and two-dimensional premixed and non-premixed reacting cases will be set up and tested to improve the model accuracy in terms of the multi-mode combustion prediction. Then, the three-dimensional methanol/n-heptane flame will be studied to validate the Wiener operator and mixing constant in the one-dimensional and two-dimensional cases.