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The dynamics of a transitional propane jet diffusion flame with a fuel‐jet velocity of 2.2 m/s has been studied using an implicit, third‐order‐accurate, upwind numerical scheme. The large‐scale vortices outside the flame surface and the small‐scale ones inside were simulated simultaneously, and their interactions with the flame surface were investigated. Numerical experiments were conducted to gain insight into the influence of buoyancy and shear‐layer forcing on the development of the outer and inner vortices. In the presence of buoyancy forces, the outer vortices developed as part of the solution, and the vortex‐crossing frequency was approximately 15 Hz. The inner structures were manifested from a weak perturbation the vorticity that was introduced at the nozzle exit, and, at 185 Hz, these vortices were found to travel farther downstream. It was also found that the inner vortices do not play a role in the formation of the outer vortices, and vice versa. However, the growth of the inner vortices in the downstream locations is strongly influenced by the slowly moving outer vortices.

The purpose of this paper is to comprehensively evaluate the progress in the development of trapped vortex combustors (TVCs) in the past three decades. The review aims to identify the needs, predict the scope and discuss the challenges of numerical simulations in TVCs applied to gas turbines.

TVC is an emerging combustion technology for achieving low emissions in gas turbine combustors. The overall operation of such TVCs can be on very lean mixture ratio and hence it helps in achieving high combustion efficiency and low overall emission levels. This review introduces the TVC concept and the evolution of this technology in the past three decades. Various geometries that were explored in TVC research are listed and their operating principles are explained. The review then categorically arranges the progress in computational studies applied to TVCs.

Analyzing extensive literature on TVCs the review discusses results of numerical simulations of various TVC geometries. Numerical simulations that were used to optimize TVC geometry and to enhance mixing are discussed. Reactive flow studies to comprehend flame stability and emission characteristics are then listed for different TVC geometries.

To the best of the authors’ knowledge, this review is the first of its kind to discuss extensively the computational progress in TVC development specific to gas turbine engines. Earlier review on TVC covers a wide variety of applications including land-based gas turbines, supersonic Ramjets, incinerators and hence compromise on the depth of analysis given to gas turbine engine applications. This review also comprehensively group the numerical studies based on geometry, flow and operating conditions.

A two dimensional time‐dependent Navier Stokes formulation that encompasses aspects from both the LES formalism and the conventional k‐ε approaches was employed to calculate a range of reacting bluff‐body flows exhibiting high or low level large scale structure activity. Extensive regions of local flame extinction found in these bluff‐body flame configurations were treated with a partial equilibrium/two‐scalar exponential PDF combustion submodel combined with a local extinction criterion based on a comparison of the turbulent Damkohler number against the ratio of the scalar scale to the reaction zone thickness. A dual‐mode description, burning/ non‐burning, of combustion provided the local gas state. Comparisons between calculations and measurements indicated the ability of the method to capture all the experimentally observed variations in the momentum and reactive scalar mixing fields over a range of operating conditions from the lean to the rich blow‐out limit.

The purpose of this paper is to study the combustion and emission characteristics of an improved trapped vortex combustor (TVC).

An experiment is carried out to study the effect of the bluff bodies’ layout on the flow of the improved TVC. Results confirm that an equation achieving the proper cavity size of a TVC can be used to design the reasonable configuration of the improved TVC. A numerical simulation is used to study the flow, combustion and emission characteristics of the improved TVC.

The flow resistance, the vortex configuration, the combustion efficiency and the emissions of the improved TVC are influenced by the equivalence ratio of the main flow, the position and the flow injection angle in the cavity.

The investigation on the lean-premixed combustion of the improved TVC will provide a theory basis for the design of the improved TVC.

The improved TVC will be used in the gas turbines burning synfuels. There are the implications which offer an opportunity to avoid use of diluent gas to reduce the flame temperatures of the combustion in the gas turbines burning synfuels.

The improved TVC with the reasonable layout of the bluff bodies provides a method implementing lean-premixed combustion in the gas turbines burning synfuels.

The purpose of this paper is to study the soot formation and evolution by using this newly developed Lagrangian particle tracking with weighted fraction Monte Carlo (LPT-WFMC) method.

The weighted soot particles are used in this MC framework and is tracked using Lagrangian approach. A detailed soot model based on the LPT-WFMC method is used to study the soot formation and evolution in ethylene laminar premixed flames.

The LPT-WFMC method is validated by both experimental and numerical results of the direct simulation Monte Carlo (DSMC) and Multi-Monte Carlo (MMC) methods. Compared with DSMC and MMC methods, the stochastic error analysis shows this new LPT-WFMC method could further extend the particle size distributions (PSDs) and improve the accuracy for predicting soot PSDs at larger particle size regime.

Compared with conventional weighted particle schemes, the weight distributions in LPT-WFMC method are adjustable by adopting different fraction functions. As a result, the number of numerical soot particles in each size interval could be also adjustable. The stochastic error of PSDs in larger particle size regime can also be minimized by increasing the number of numerical soot particles at larger size interval.

Reports numerical simulations of an unconfined methane‐air turbulent diffusion flame expanding from a porous burner. Turbulent combustion is simulated using the eddy dissipation concept (EDC) which supposes that the reaction rate is controlled by the turbulent structures which enhance the mixing of fuel and oxidant. Two statistical k‐ε turbulence models have been tested: a standard high Reynolds number (HRN) and a more recent model based on the renormalization group theory (RNG). Radiation heat transfer and soot formation have been taken into account using P1‐approximation and transport submodels which reproduce the main phenomena encountered during soot production (nucleation, coagulation, surface growth). The set of coupled transport equations is solved numerically using a high order finite‐volume method, the velocity‐pressure coupling is treated by a projection technique. The numerical results confirm that 20‐25 percent of the combustion heat released is radiated away from the flame. Unsteady and unsymmetrical flame behaviour is observed for small Froude numbers which results from the development of Rayleigh‐Taylor like instabilities outside the flame surface. For higher Froude numbers the steady‐state and symmetrical nature of the solution is recovered.

The purpose of this paper is to provide an overview of the computational progress in the development of hydrogen-fired gas turbines. This review aims to identify suitable combustion models, appropriate NO_x chemistry mechanisms and NO_x emission levels for effective utilization of hydrogen as an alternative fuel in gas turbines.

Hydrogen is recognized as a potential alternative fuel for achieving exceptionally low emissions in gas turbines. The developments in conventional, trapped vortex combustor and micromix combustors are discussed, along with various computational models aimed at accurately predicting combustion and emission characteristics. The results of numerical simulations were then discussed with emphasis on their role in optimizing the combustor geometry.

Computational studies that were used to optimize the combustor geometry to reduce NO_x emissions and the flashback phenomenon are discussed. To retrofit existing gas turbines for hydrogen fuel, minor modifications that are required were discussed by analyzing extensive literature. The influence of key design and geometrical parameters on NO_x emissions and the appropriate selection of combustion models for numerical simulations in optimizing various combustion systems are elaborated.

The review emphasizes the computational studies in the progress of hydrogen-fired gas turbine developments. The previous reviews were primarily focused on the combustion technologies for hydrogen-fired gas turbines. This comprehensive review focuses on the key design parameters, flame structure, selection of combustion models, combustion efficiency improvement and impact of parametric studies on NO_x formation of various combustion systems, in particular hydrogen combustion for gas turbine applications.

The purpose of this paper is to shed light on the biofuels debate in air transport.

The controversies about biofuels sustainability in general and research findings on biofuels are complemented by the specific circumstances the aviation industry encounters in its attempt to become more sustainable. The author's corporate affiliation allows for insights from an airline's perspective and experience with biojet fuel.

The paper highlights accountability and accounting advances required by the aviation industry as well as further stakeholders to safeguard sustainability of biofuels.

The paper provides a viewpoint taking account of research findings but written from a corporate perspective. The intention is not to provide a complete review of the growing academic literature in the biofuels field, nor to elaborate on the entire array of challenges in practice.

The paper integrates macro‐level societal limitations for sustainable biofuel feedstock production with micro and meso‐level corporate and industry perspectives on sustainable biofuels.