Dry Low Emissions Premixer CCD Modeling and Validation

Abstract

Computational Combustion Dynamics has been used extensively at General Electric Company for combustion applications. This paper demonstrates an application of Advanced Combustion Code to GE’s lean premixed dry low NOx emissions LM2500 and LM6000 gas turbine combustors. A methodology for anchoring the Double Annular Counter-Rotating Swirler (DACRS) exit conditions to Laser Doppler Velocity data from a reacting single cup experiment is described. The DACRS exit velocity profiles and turbulence parameters are inlet boundary conditions for the annular combustor simulation. Since over 80 per cent of the total air enters the combustor via the premixers, inaccuracies in these boundary conditions have a significant impact on the predicted flame shape, liner temperatures and emissions. The paper shows comparisons between measured and predicted velocity in a rectangular duct equipped with a single DACRS. The k-ε turbulence model and the two-step eddy break up/eddy dissipation combustion models are used to predict the reacting flow field of the natural gas/air flame. The inlet velocity profiles are developed first to match the LV data and the observed flame impingement location at nominal settings of the inlet turbulence parameters. The sum square error between measured and predicted velocity is used as the optimization function. Next, a design of experiment computational study is conducted to determine the inlet turbulence length scale and kinetic energy in order to further improve the data match. The eddy break up model is shown to be more robust than the eddy dissipation model. The eddy dissipation model resulted in slow combustion rates, and high fuel and carbon monoxide emissions.

LES of a Multi-burner Annular Gas Turbine Combustor

“…For validation and comparison with earlier LES, [12,18], the laboratory combustor of Hura et al, [16], consisting of a single GE LM6000 premixer cup installed in a rectilinear combustor having metal top-and bottom walls as well as quartz side windows, providing optical access, Fig. 1a, is employed.…”

“…1b, based on the cross-section of the single burner laboratory combustor. In all computational models, the Dual Annular Counter-Rotating Swirler (DACRS) premixer, used in the laboratory experiments, [16], is replaced by a swirling air-fuel jet, injected through a circular inlet, with a diameter of D = 3.40 cm. The velocity profiles are provided by GEAE, and are based on laboratory measurements, [16], the sensitivity of which are computationally studied by Grinstein et al, [41].…”

“…In all computational models, the Dual Annular Counter-Rotating Swirler (DACRS) premixer, used in the laboratory experiments, [16], is replaced by a swirling air-fuel jet, injected through a circular inlet, with a diameter of D = 3.40 cm. The velocity profiles are provided by GEAE, and are based on laboratory measurements, [16], the sensitivity of which are computationally studied by Grinstein et al, [41]. According to Table 1, we here examine both CH 4 and n-C 10 H 22 combustion at an equivalence ratio of φ = 0.56, a nominal combustor pressure of p 0 = 6.18·10 5 Pa, a reactant temperature of T 0 = 644 K, and a centerline axial jet velocity of v 0 = 110 m/s.…”

“…Large Eddy Simulation (LES), [9,10], offer the best available alternative and has successfully been used to predict both canonical and complex non-reacting and reacting flows, [11][12][13][14][15], and therefore has the potential to address the key issues of multi-burner annular combustors. Here, we use LES to study some aspects of lean premixed combustion in a generic model 18 burner annular combustor developed from the laboratory single burner GE LM6000 combustor, [16], used in other studies, [12,17,18]. Primarily, we focus on the effects of the premixer, fuel and combustor outlet characteristics on the combustor dynamics.…”

Large eddy simulation modelling of combustion for propulsion applications

“…Fureby (submitted) made an attempt to examine whether LES could be used to shed some light on annular multi-burner combustor dynamics using a model annular combustor derived from the General Electric (GE) LM600 laboratory combustor (Hura et al 1998), used in several swirl combustor studies (Kim et al 1999;Grinstein & Fureby 2004). This model annular combustor consists of 18 burners characterized by velocity and fuel mass-fraction profiles (Magnussen (1981) and adapted to LES as described above), TFM model (Colin et al 2000) and G-equation model ( Nogenmyr et al 2008). provided by GE (Hura et al 1998), and representative of the DACRS burner, used in the single burner laboratory experiments (Hura et al 1998), which will be used as reference. According to table 1, we present results for both CH 4 and n-C 10 H 22 combustion at fZ0.56, a combustor pressure of p 0 Z6.18!10 5 Pa, a reactant temperature of T 0 Z644 K and a centreline axial jet inflow velocity of v 0 Z110 m s K1 .…”