![Sample our Engineering & Technology journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5933/TOC-Subject-Sample-2021-Engineering-Tech.jpg"})
ABSTRACT
Through accounting for the dominant effects of gas temperature fluctuation on the turbulent reaction rates, a presumed probability density function (PDF) model for temperature fluctuation is proposed and formulated in this paper for describing turbulence–complex reaction interactions. A 25-step skeletal mechanism for methane combustion is incorporated into the model. A set of analytical expressions is obtained for the multistep time-averaged reaction rates. The model, together with the algebraic Reynolds stress model for turbulence–swirl interactions, is applied to the simulation of methane partially premixed turbulent swirling jet flame. The calculated results are compared with the measured test data in terms of gas velocities, fluctuating velocities, Reynolds shear stress, temperature, fluctuating temperature, and species mass fractions. Agreement is achieved between the prediction and the measurement.
Nomenclature
| Bi | = | pre-exponential factor |
| = | mean specific heat capacity (J/kg K) | |
| D | = | diameter of bluff body (m) |
| Ei | = | activation energy (J/mol) |
| h | = | enthalpy (J/kg) |
| h0 | = | enthalpy of formation (J/kg) |
| hs | = | sensible enthalpy (J/kg) |
| kfall | = | fall-off rate |
| mi, ni | = | density and temperature exponents |
| M | = | molecular weight (kg/mol) |
| n | = | species number |
| p | = | static pressure (Pa or atm) |
| r | = | radial distance from axis (m) |
| R | = | universal gas constant (J/mol K) |
| SΦ | = | generalized source term |
| T | = | temperature (K) |
| Tm | = | adiabatic combustion temperature at stoichiometric condition for the fuel (K) |
| T0 | = | minimum temperature of combustion system (K) |
| T0 | = | reference temperature (298.15 K) |
| u, v, w | = | axial, radial, and tangential velocities (m/s) |
| Wi | = | reaction rate for the ith step (kg/m3 s) |
| x | = | axial distance from burner exit (m) |
| Y | = | species mass fraction |
| α, γ, η+, η− | = | parameters in presumed PDF |
| αΦ | = | generalized coefficient |
| βi | = | coefficient in ith step reaction rate |
| ΓΦ | = | generalized effective transport coefficient |
| η | = | nondimensional temperature |
| ηl | = | third body efficiency of species l |
| ρ | = | density (kg/m3) |
| Φ | = | generalized variable |
| Subscripts | = | |
| k | = | species |
| r | = | radial coordinate, reactant |
| x | = | axial coordinate |
| Superscripts | = | |
| ′ | = | fluctuating quantity |
| — | = | time-averaged quantity |
Nomenclature
| Bi | = | pre-exponential factor |
| = | mean specific heat capacity (J/kg K) | |
| D | = | diameter of bluff body (m) |
| Ei | = | activation energy (J/mol) |
| h | = | enthalpy (J/kg) |
| h0 | = | enthalpy of formation (J/kg) |
| hs | = | sensible enthalpy (J/kg) |
| kfall | = | fall-off rate |
| mi, ni | = | density and temperature exponents |
| M | = | molecular weight (kg/mol) |
| n | = | species number |
| p | = | static pressure (Pa or atm) |
| r | = | radial distance from axis (m) |
| R | = | universal gas constant (J/mol K) |
| SΦ | = | generalized source term |
| T | = | temperature (K) |
| Tm | = | adiabatic combustion temperature at stoichiometric condition for the fuel (K) |
| T0 | = | minimum temperature of combustion system (K) |
| T0 | = | reference temperature (298.15 K) |
| u, v, w | = | axial, radial, and tangential velocities (m/s) |
| Wi | = | reaction rate for the ith step (kg/m3 s) |
| x | = | axial distance from burner exit (m) |
| Y | = | species mass fraction |
| α, γ, η+, η− | = | parameters in presumed PDF |
| αΦ | = | generalized coefficient |
| βi | = | coefficient in ith step reaction rate |
| ΓΦ | = | generalized effective transport coefficient |
| η | = | nondimensional temperature |
| ηl | = | third body efficiency of species l |
| ρ | = | density (kg/m3) |
| Φ | = | generalized variable |
| Subscripts | = | |
| k | = | species |
| r | = | radial coordinate, reactant |
| x | = | axial coordinate |
| Superscripts | = | |
| ′ | = | fluctuating quantity |
| — | = | time-averaged quantity |