Mean NO ppm, wet
NOx modeling (2) Equilibrium f Laminar Flamelet
model model
~ T (K )
~ T (K )
[ O ] ( kg / m ), wet
3
[ O ] ( kg / m ), wet
3
NOx modeling (3)
FLUENT软件在燃烧室中的应用 FLUENT软件在燃烧室中的应用
北京海基科技发展有限责任公司
FLUENT软件技术特点
完全非结构化网格 耦合/非耦合算法 耦合 非耦合算法 自适应网格功能 并行能力 用户自定义函数 Windows界面风格 界面风格
Leadership of CFD Technology
Turbulence modeling
Standard k−ε turbulence model
Path ribbons colored by temperature (K)
Gas phase combustion modeling (1)
Laminar Flamelet model
22 species, 104 reactions reduced GRI-MECH 1.22 mechanism A. Kazakov and M. Frenklach, /drm Flamelets solved in mixture fraction space Differential diffusion (Le effects) included
分散相燃烧模型
a. Stochastic Tracking model b. The Particle Cloud model
FLUENT在燃烧室流场分析中的应用 在燃烧室流场分析中的应用
GE LM-1600 gas turbine combustor
Graham Goldin
Courtesy of Nova Research and Technology Corp., Calgary, Canada Non-premixed, natural gas 12.8 MW, 19:1 pressure ratio (full load) Annular combustion chamber, 18 nozzles
swirl vanes fuel inlet nozzles dilution air inlets
Grid
3D, 1/18th geometry model due to periodicity Multi-block hexahedral mesh
Maximum equi-angle skew of 0.84 286k cells
Plot of NO flux exiting outlet vs. combustor load
r r ρX V ⋅ dA r r NO exit flux = 10 ∫ ∫ ρV ⋅ dA
6 NO
LES Example - Dump Combustor
A 3-D model of a lean premixed combustor studied by Gould (1987) at Purdue University Non-reacting (cold) flow was simulated with a 170K cell hexahedral mesh using second-order temporal and spatial discretization schemes.
Computed using RNG-based subgridscale model
Mean axial velocity at x/h = 5
LES Examples - Dump Combustor
RMS velocities predictions at x/h = 10;
Application of Premixed Combustion Model
d [ NO ] = 2k[O][ N 2 ], k = Ae− E / RT Zeldovich thermal NO dominant: dt
Species and temperature from Laminar Flamelet model Post-processed: assumed shape β pdf
Mean mass fraction of OH
Gas phase combustion modeling (2)
Deviation from chemical equilibrium measured by Damkohler no. ~ ~
Da = turbulent time scale k / ε = − chemical time scale aq 1
Iso-surface of instantaneous vorticity magnitude colored by velocity angle
LES Examples - Dump Combustor
Simulation done for
Re d = 10 5 (Re λ ≈ 150 )
Mean axial velocity prediction at x/h = 5;
aq is the laminar flamelet extinction strain rate = 11700 s-1
Damkohler number
Gas phase combustion modeling (3)
Mean temperature (K)
NOx modeling (1)
Thermal中的应用 在燃烧室流场分析中的应用
技术难点 复杂的几何形状
•复杂的流动现象 FLUENT技术特征 CAD接口，强大的网格能力 接口，
多种燃烧模型： 种燃烧模型：
气相燃烧模型： 气相燃烧模型：
a. The generalized finite rate (Magnussen) model b. The Mixture Fraction (pdf) model c. The Two Mixture Fraction model d. The Laminar Flamelet model e. The Premixed Combustion (Zimont) model
Axisymmetric Dump Combustor (Contours of Static Temperature)