TY - JOUR

T1 - Correlations of high-pressure lean methane and syngas turbulent burning velocities

T2 - 30th International Symposium on Combustion

AU - Shy, S. S.

AU - Liu, C. C.

AU - Lin, J. Y.

AU - Chen, L. L.

AU - Lipatnikov, A. N.

AU - Yang, S. I.

N1 - Publisher Copyright:
© 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

PY - 2015

Y1 - 2015

N2 - This paper investigates correlations of high-pressure turbulent burning velocities (ST) using our recent ST measurements of lean methane and syngas spherical flames at constant elevated pressures (p) and constant turbulent Reynolds numbers (ReT = u′ LI/ν), where u′, LI, and ν are the r.m.s. turbulent fluctuation velocity, the integral length scale of turbulence, and the kinematic viscosity of reactants, respectively. Such constant constraints are achieved by applying a very large high-pressure, dual-chamber explosion facility that is capable of controlling the product of u′ LI in proportion to the decreasing m due to the increase ofp. We have found that, contrary to popular scenario for ST enhancement with increasingp at any fixed u′, ST actually decreases similarly as laminar burning velocities (SL) with increasing p in minus exponential manners when values of ReT are kept constant. Moreover, ST increases noticeably with increasing ReT varying from 6700 to 14,200 at any constantp ranging from 1 atm to 10 atm. It is found that a better correlation for the normalization of ST is a power-law relation of ST/u′ = aDab where Da = (LI/u′)(SL/dF) is the turbulent Damköhler number, δF ≈ α/SL is the laminar flame thickness, and α is the thermal diffusivity of unburned mixture. Thus, the very scattering ST data for each of lean methane and syngas mixtures can be merged on their ST/u′ vs. Da curves with very small data fluctuations. For lean methane flames with the Lewis number (Le) ≈ 1, ST/u′ ≈ 0.12Da0.5. supporting a distributed reaction zone model anticipated by Ronney (1995), while for lean syngas flames with Le ≈ 0.76 < 1, ST/u′ ≈ 0.52Da0.25. supportinga theory predicted by Zimont (1979). A simple physical mechanism is proposed in attempt to explain what causes the aforesaid discrepancy on the power-law constants.

AB - This paper investigates correlations of high-pressure turbulent burning velocities (ST) using our recent ST measurements of lean methane and syngas spherical flames at constant elevated pressures (p) and constant turbulent Reynolds numbers (ReT = u′ LI/ν), where u′, LI, and ν are the r.m.s. turbulent fluctuation velocity, the integral length scale of turbulence, and the kinematic viscosity of reactants, respectively. Such constant constraints are achieved by applying a very large high-pressure, dual-chamber explosion facility that is capable of controlling the product of u′ LI in proportion to the decreasing m due to the increase ofp. We have found that, contrary to popular scenario for ST enhancement with increasingp at any fixed u′, ST actually decreases similarly as laminar burning velocities (SL) with increasing p in minus exponential manners when values of ReT are kept constant. Moreover, ST increases noticeably with increasing ReT varying from 6700 to 14,200 at any constantp ranging from 1 atm to 10 atm. It is found that a better correlation for the normalization of ST is a power-law relation of ST/u′ = aDab where Da = (LI/u′)(SL/dF) is the turbulent Damköhler number, δF ≈ α/SL is the laminar flame thickness, and α is the thermal diffusivity of unburned mixture. Thus, the very scattering ST data for each of lean methane and syngas mixtures can be merged on their ST/u′ vs. Da curves with very small data fluctuations. For lean methane flames with the Lewis number (Le) ≈ 1, ST/u′ ≈ 0.12Da0.5. supporting a distributed reaction zone model anticipated by Ronney (1995), while for lean syngas flames with Le ≈ 0.76 < 1, ST/u′ ≈ 0.52Da0.25. supportinga theory predicted by Zimont (1979). A simple physical mechanism is proposed in attempt to explain what causes the aforesaid discrepancy on the power-law constants.

KW - Elevated pressure

KW - Expanding spherical flames

KW - Turbulent burning velocities

KW - Turbulent Damköhler and Karlovitz numbers

KW - Turbulent Reynolds number

UR - http://www.scopus.com/inward/record.url?scp=84964282418&partnerID=8YFLogxK

U2 - 10.1016/j.proci.2014.07.026

DO - 10.1016/j.proci.2014.07.026

M3 - 會議論文

AN - SCOPUS:84964282418

SN - 1540-7489

VL - 35

SP - 1509

EP - 1516

JO - Proceedings of the Combustion Institute

JF - Proceedings of the Combustion Institute

IS - 2

Y2 - 25 July 2004 through 30 July 2004

ER -