Combustion Turbulence Flow in the Advanced Vortex Combustor with Built-In Obstacles

To obtain the advanced vortex combustor (AVC) and its optimal structure parameters in light of built-in obstacles, numerical simulation was performed. This research shows that inclined struts have optimal structural parameters with inclination angle α = 30 ° and blocking ratio BR = 12 %, while guide vane and its optimal structural parameter have three layers, which are a / B = 0.1 , b / h = 0.4 , and c / L = 0.2 , respectively; blunt body has the biggest height of H 1 / B 1 = 2 / 3 . According to these statistics, the research studies how inlet factors affect turbulence flow in combustion. The research finds increases in inlet velocity and flow resistance are in positive correlation. As inlet temperature increases, the flow resistance decreases. From field synergy theory, inlet factor has different effect on the heat transfer performance.

Effect of burner angle on the heat transfer of a frit furnace

In this work, a numerical analysis was performed about the effect of a flat-flame burner incidence degree on the heat transfer of an industrial scale frit melting furnace, which uses a flat-flame natural gas oxy-combustion burner. The thermal performance of the furnace was evaluated by predicting the temperature distributions, the recirculation of the combustion gases, and the heat flow to the load, using three different geometrical configurations, differing in the inclination of the burner at 0°, 3.5°, 7° with respect to the longitudinal axis. The simulations were carried out using the ANSYS® Fluent software. The Steady Laminar Flamelet (SFM) model, the k-epsilon realizable model, and the discrete ordinates model were used to model combustion, turbulence, and radiation, respectively. The weighted model of the sum of gray gases (WSGGM) was used for the coefficient of absorption of the combustion species. It was observed that the furnace temperature estimated with the simulations is similar to that found in the actual process. Additionally, the simulations showed that for the angle of 7°, the flame collides with the frit, which could generate deposition of frit particles in the internal walls of the furnace; this would affect the emissivity of the refractory material. The 3.5degree angle showed a better distribution of heat flow to the frit and recirculation rate compared to the burner at 0° and 7°.

Combustion Turbulence Flow in Trapped Vortex Combustor with Guide Vane and Blunt Body

Numerical calculation was conducted to obtain the optimum structure parameters of the trapped vortex combustor (TVC) with the guide vane and blunt body. The results show that the optimum structure parameters of the guide vane are a/Hf=0.5, b/Li=0.2, and c/L=0.1, and the optimum structure parameters of blunt body are S/L=0.7, L2/L=0.1, and L1/Li=0.25. Then, the influence of different inlet conditions on the combustion turbulence flow was studied. The results show that high inlet temperature and low inlet velocity can effectively reduce total pressure loss; the equivalence ratio has little effect on total pressure loss. The study of unsteady flow shows that double vortices undergo the process of preliminarily forming-breaking down-forming again-being stable gradually.

Prediction of hydrogen flame propagation in a channel with exit contraction

The propagation of a flame front in a homogeneous and initially quiescent hydrogen-air mixture in a channel with exit contraction is numerically analyzed by means of Computational Fluid Dynamics. For the given configuration, the compressibility effects are important, the average pressure increases in time due to the exit contraction, and pressure waves occur, which affect the flame propagation. Flowturbulence is modelled by the Realizable k-e model. In modelling combustion, turbulence-chemistry interactions are neglected. Predictions are compared with the measurements for evolution of the flame shape, propagation speed and pressure. It is observed that the flame propagation speed, and, thus, the rate of pressure increase are over-predicted by the present approach. Still, a fair qualitative agreementto measurements is observed.

Numerical Simulation of Reactive Turbulent Flows Over Bluff Body Flame Holders: A Parametric Study

In this paper, a numerical parametric study has been conducted to examine the effects of varying both inlet turbulent intensity and angle of attack for a bluff body flame holder (V-gutter) in a channel. The geometry used was based on previous experiments. The inlet turbulent intensity was varied from 2% to 100% while the angle of attack of the V-gutter was varied from −20° to 20°. The turbulent flow was modeled with a RANS-based realizable k-ε turbulence model. The combustion setup used was premixed propane-air combustion with an equivalence ratio of 0.6. The combustion-turbulence interaction is simulated with an eddy-dissipation model. Calculations were carried out using a finite volume based solver, and all equations were solved using the second order upwind method. Results indicate that increasing the inlet turbulent intensity and V-gutter angle of attack will result in an increase not only in the size but also in magnitude of the downstream high turbulence areas with vortexes.

CFD Assessment of a Wet, Low-NOx Combustion System for a 3MW-Class Industrial Gas Turbine

A wet low-NOx combustion system being developed for the AlliedSignal ASE40 industrial gas turbine is assessed using advanced 3-D CFD analysis. A PDF combustion-turbulence interaction model was modified to allow analysis of simultaneous injection of water with gaseous or liquid fuel. To the authors’ knowledge, such a CFD analysis is unique in the open literature. Analyses of the wet low-NOx combustion system were performed with and without water injection at full power engine conditions. Good qualitative agreement between engine emission data and predictions was seen. NOx reductions of 58% and 77% were measured for water-to-natural gas mass ratios of 0.5 and 1.0, respectively, compared to 75% and 93% for CFD calculations. Corresponding CO levels were measured to increase by factors of 3 and 9, compared to CFD predictions of 4 and 7. Similar trends were predicted for water injection with DF-2 diesel fuel. Predicted overall flow patterns were not significantly changed with water injection. NOx reductions were caused by a reduction in maximum flame temperatures in the primary and intermediate zones when water was injected. CO increases were caused by a reduction of CO oxidation downstream of the dilution zone (in the turn-around duct) due to lower gas temperatures with water injection.