Reo Kai

A flamelet-generated manifold (FGM) method that explicitly considers the preferential diffusion effect, referred to as FGM-PD method, is employed for large-eddy simulations (LESs) of a lean-premixed H2/air low-swirl lifted flame, and the validity is examined by comparing with the experiment. First, the applicability of the FGM-PD method is investigated by one-dimensional numerical simulations of planar laminar premixed H2/air flames. Next, LESs of a lean-premixed H2/air low-swirl lifted flame ar

Owing to the increasing worldwide demand for natural gas, the development of a large submerged combustion vaporizer is required. Its burner is equipped with a water spray nozzle to reduce nitrogen oxides, and a practical simulation method is required for the optimal design. The non-adiabatic flamelet approach can predict the combustion emissions and is useful for reducing simulation costs. However, as the number of control variables increases, the database requires larger memory and cannot be de

The flame–turbulence interaction and statistical behavior of the surface density function (SDF; i.e. magnitude of the reaction progress variable gradient) in the vicinity of the wall for a stoichiometric methane-air flame are investigated using a three-dimensional direct numerical simulation of a turbulent premixed V-flame interacting with an isothermal inert wall in a fully developed turbulent channel flow at a friction Reynolds number Reτ=395. The results show that the mean SDF significantly d

Conjugate heat transfer analyses of premixed flames propagating toward the insulation or Al alloy wall are performed for C1 to C3 alkanes and H2 flames at different equivalence ratios of φ = 0.6, 0.8, 1.0 and 1.2 under a high pressure condition of 2MPa in terms of one-dimensional numerical simulations with detailed reaction mechanisms (70 species and 321 reactions for alkanes, 9 species and 19 reactions for H2). The effects of the equivalence ratio and fuel properties on the heat loss reduction

Importance of the considerations of preferential diffusion and flame stretch effects in the flamelet-generated manifold (FGM) method on the prediction accuracy is investigated by two-dimensional numerical simulations of cylindrical NH3/air premixed flames, under the conditions of an unburnt gas temperature of 673 K, an ambient pressure of 2 MPa, and equivalence ratios of 0.8 to 1.2. Results of the numerical simulations using the detailed chemistry, in which 32 species and 204 reactions are direc

In this study, the applicability of the flamelet approach to numerical simulations of hydrazine (N2H4)/nitrogen tetroxide (NTO, N2O4) combustion, in which hypergolic ignition and thermal decomposition occur, is investigated in terms of two-dimensional numerical simulations of two types of N2H4/NTO jet flames, namely, the gaseous N2H4/NTO jet flame and the N2H4 spray jet flame in the gaseous NTO stream. In case of the gaseous jet flame, the numerical simulation is performed employing the unsteady

Effects of species diffusion models on the laminar burning velocity SL of lean hydrogen-air premixed flame are investigated by performing one-dimensional numerical simulations of lean hydrogen-air premixed flames at an equivalence ratio of 0.5. Maxwell-Stefan (MS) diffusion, mixture-averaged (MA) diffusion, and unity Lewis number diffusion are compared as the concentration diffusion models at a pressure of 0.1 MPa. Moreover, the contribution of the species thermal diffusion is also investigated

2D numerical simulations of a wrinkled lean hydrogen (H2)-air premixed flame are performed with and without considering the Soret effect to investigate the Soret effect on flame propagation. The equivalence ratio and temperature of unburnt premixed gas are 0.5 and 300 K, respectively, and ambient pressure is 1 atm. Results show that neglecting the Soret effect underestimates the burning velocity and flame surface area by approximately 4% and 5.5%, respectively. Neglecting the Soret diffusion of