Partially premixed flame reactive flow characterization in a bluff body burner

Abstract

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.

The present work aims the characterization of a natural gas/air partially premixed flame (PPF) reactive flow in a bluff body burner under laminar conditions in equivalence ratio of 2.1, 1.7 and 1.2. The laboratorial bluff body burner is composed of a central outflow for the premixed reactants and an annular air flow. The latter allows for the stabilization of the flame meanwhile it prevents external aerodynamic influence on the behavior of the flame. For the velocity field measurements, a 2-D Particle Image Velocimetry, PIV, optical diagnostic system is employed. The PIV system comprises of two Nd:YAG lasers with an output wavelength of 532 nm. Titanium dioxide particles, TiO2, are used as seeding particles in the premixed flow. The displacement of the seeding particles between two laser pulses with a known short time difference allows a planar velocity field determination. The stored images are processed using a software integrated with the system in order to obtain the medium velocity field. The software uses statistic data to obtain the correlation between two images acquired in an interval of time of an overlapped interrogation window. The major objective of this study is to examine the flame velocity field of laminar partially premixed natural gas and air flames in rich conditions. Three premixed flames under rich conditions have been studied in the present work with equivalence ratios of 2.1, 1.7 and 1.2 respectively. The study focused on: (1) analyze the instantaneous velocity flow field of the three partially premixed flames, (2) analyze the mean velocity flow field formed from the instantaneous flow fields and (3) analyze the velocity behavior along the center line of the flame.