Triple Annular Research Swirler Research Articles

Proper Orthogonal Decomposition for Experimental Investigation of Flame Instabilities

An experimental investigation of both confined and unconfined flames on a Triple Annular Research Swirler (TARS) is presented. The paper focuses on post-processing techniques aiming at extracting information on the dynamics that are lost through classical statistics approach. POD together with a derived a-posteriori phase averaging procedure successfully reconstructed the dynamics of flames under thermo-acoustic instabilities in the confined case. For unconfined flames, an analysis of the azimuthal modes is performed.

A Comparative Study of Flamelet and Finite Rate Chemistry LES for a Swirl Stabilized Flame

Present-day demands on combustion equipment are increasing the need for improved understanding and prediction of turbulent combustion. Large eddy simulation (LES), in which the large-scale flow is resolved on the grid, leaving only the small-scale flow to be modeled, provides a natural framework for combustion simulations as the transient nature of the flow is resolved. In most situations; however, the flame is thinner than the LES grid, and subgrid modeling is required to handle the turbulence-chemistry interaction. Here we examine the predictive capabilities between LES flamelet models, such as the flamelet progress variable (LES-FPV) model, and LES finite rate chemistry models, such as the thickened flame model (LES-TFM), the eddy dissipation concept (LES-EDC) model, and the partially stirred reactor model (LES-PaSR). The different models are here used to examine a swirl-stabilized premixed flame in a laboratory gas turbine combustor, featuring the triple annular research swirler (TARS), for which high-quality experimental data is available. The comparisons include velocity and temperature profiles as well as combustor dynamics and NO formation.

LES of the interaction between a premixed flame and complex turbulent swirling flow

In this paper the Triple Annular Research Swirler, a fuel injector characterized by complex design with three concentric air passages, has been studied numerically. A swirl-stabilized lean premixed flame has been simulated by means of Large Eddy Simulation. The computations characterize successfully the dynamics of the flame and their interactions with the complex swirling flow. The flame is stabilized upstream the fuel injector exit, and the dynamics are led by a Precessing Vortex Core which seems to originate in the inner air passage. The results obtained by Proper Orthogonal Decomposition analysis are in agreement with previous findings in the context of swirling flows/flames.

Experimental and Computational Study of Nonreacting Vortex Breakdown in a Swirl-Stabilized Combustor

Non-reacting flow experiments are conducted in a swirl-stabilized combustor with several configurations of a triple annular research swirler (TARS) fuel injector. Particle Imaging Velocimetry (PIV) is used to measure mean axial and radial distribution of the velocity field from which swirl ratio and position of vortex breakdown are calculated for each injector configuration. The numerical simulat ions are based on the ReynoldsAveraged-Navier-Stokes (RANS) model equations of non-reacting flows, and provide insight into the characteristics of the axisymmetric vortex breakdown phenomenon in a circular, finite-length pipe with a sudden expansion downstream of a concentric, circular inlet pipe. Results show that flow states with vortex breakdown can be simulated numerically. Good agreement is found between the results of the simul ations and available theoretical predictions for the first appearance of breakdown downstream of the pipe expansion plane as well as its first appearance in the inlet pipe s ection as upstream swirl level is increased. We also show good agreement between the measured experimental data, simulations, and theoretical predictions. It is demonstrated that th e theoretical criteria and numerical simulations can be used to predict the appearance a nd location of vortex breakdown for several different nozzles of varying swirl numbers relevant to the stability of lean, premixed combustion.