Measurements of conditional velocities in turbulent premixed flames by simultaneous OH PLIF and PIV

Journal Article · Fri Jan 01 04:00:00 EST 1999 · Combustion and Flame

DOI:https://doi.org/10.1016/S0010-2180(98)00041-8· OSTI ID:675657

Frank, J H; Kalt, P A.M.; Bilger, R W ^[1]

---

1. Univ. of Sydney, New South Wales (Australia). Dept. of Mechanical Engineering

Joint velocity/scalar imaging measurements are performed in turbulent premixed natural-gas/air flames to better characterize the turbulent flux of mean reaction progress variable, pu{double_prime}c{double_prime}. Simultaneous two-dimensional measurements of the velocity field and the relative OH concentration are obtained by particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) of the OH radical, respectively. The data are used to obtain conditional mean velocities in both reactant and product regions. The relative mean velocity of reactants and products provides an indication of whether turbulent diffusion of the mean progress variable occurs in the gradient or counter-gradient sense. Five flames having different ratios of rms velocity, u{prime}, to laminar flame speed, S{sub L}, are considered. The results indicate that a transition from counter-gradient to gradient diffusion occurs as u{prime}/S{sub L} is increased. Such a transition has previously been predicted by direct numerical simulation (DNS) but has not been observed experimentally. The existence of this transition must be taken into account when developing models of turbulent premixed combustion.

• OSTI ID: 675657
• Journal Information: Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 1-2 Vol. 116; ISSN CBFMAO; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
CHEMICAL COMPOSITION
COMBUSTION KINETICS
DIAGNOSTIC TECHNIQUES
FLAME PROPAGATION
FLAMES
HYDROXYL RADICALS
NATURAL GAS
TURBULENT FLOW