Experimental and LES investigation of flame propagation in a hydrogen/air mixture in a combustion vessel  

作　　者：Huahua Xiao Zhanli Mao Weiguang An Jinhua Sun 

机构地区：[1]State Key Laboratory of Fire Science, University of Science and Technology of China [2]Department of Fire Protection, Chinese People’s Armed Police Force Academy

出　　处：《Chinese Science Bulletin》2014年第20期2496-2504,共9页

基　　金：financially supported by the National Natural Science Foundation of China(51376174);the Chinese Postdoctoral International Exchange Program(2013);the National Basic Research Program of China(2012CB719702)

摘　　要：This work presents an experimental and numerical investigation of premixed flame propagation in a hydrogen/air mixture in a closed combustion vessel.In the experiment,high-speed schlieren video photography and pressure sensor are used to examine the flame dynamics and pressure transient.In the numerical study,a large eddy simulation(LES)based on a RNG sub-grid approach and a LES combustion model is applied to reproduce experimental observations.The effects of four physical phenomena on the burning velocity are considered in the combustion model,and the impact of grid type on the combustion dynamics is examined in the LES calculations.The flame experiences four stages both in experiment and LES calculations with structured and unstructured grids,i.e.,spherical flame,finger-shaped flame,flame with its skirt in contact with the sidewalls,and tulip-shaped flame.The flame speed and pressure in the vessel develop with periodical oscillations in both the experiment and LES simulations due to the interaction of flame front with pressure wave.The numerical simulations compare well with the detailed experimental measurements,especially in term of the flame shape and position,pressure build-up,and periodical oscillation behaviors.The LES combustion model is successfully validated against the bench-scale experiment.It is put into evidence that mesh type has an impact to a certain extent on the numerical combustion dynamics,and the LES calculation on structured grid canpredict the flame dynamics and pressure rise more accurately than that on unstructured grid with the same mesh resolution.The flame shape is more asymmetrical in the LES on an unstructured grid than that on a structured grid,and both the flame speed and the pressure rise at the later flame stage are underestimated in the LES on the unstructured grid.This work presents an experimental and numerical investigation of premixed flame propagation in a hydrogen/air mixture in a closed combustion vessel. In the experiment, high-speed schlieren video photography and pressure sensor are used to examine the flame dynamics and pressure transient. In the numerical study, a large eddy simulation （LES） based on a RNG sub-grid approach and a LES combustion model is applied to reproduce experi- mental observations. The effects of four physical phenomena on the burning velocity are considered in the combustion model, and the impact of grid type on the combustion dynamics is examined in the LES calculations. The flame experiences four stages both in experiment and LES calculations with structured and unstructured grids, i.e., spherical flame, finger-shaped flame, flame with its skirt in contact with the sidewalls, and tulip-shaped flame. The flame speed and pressure in the vessel develop with periodical oscillations in both the experiment and LES simulations due to the interaction of flame front with pressure wave. The numerical simulations compare well with the detailed experimental measurements, especially in term of the flame shape and position, pressure build-up, and periodical oscillation behaviors. The LES combustion model is successfully validated against the bench-scale experiment. It is put into evidence that mesh type has an impact to a certain extent on the numerical combustion dynamics, and the LES calculation on structured grid canpredict the flame dynamics and pressure rise more accu- rately than that on unstructured grid with the same mesh resolution. The flame shape is more asymmetrical in the LES on an unstructured grid than that on a structured grid, and both the flame speed and the pressure rise at the later flame stage are underestimated in the LES on the unstructured grid.

关 键 词：火焰传播 实验测量 空气混合物 燃烧器 LES 非结构化网格 燃烧动力学 数值模拟 

分 类 号：TK16[动力工程及工程热物理—热能工程]