The Effect of the Precessing Vortex Core on Combustion in a Swirl Burner

This study reports on experimental investigations on isothermal and reacting swirled nonpremixed flows under varying pressure conditions. In this configuration, a central high speed fuel jet was surrounded by a heated swirling air flow. For the reacting case natural gas served as fuel whereas for isothermal conditions fuel was replaced by a mixture of helium and air to achieve Reynoldssimilarity. The optically accessible combustor allowed for application of laser diagnostics. Here we report on Laser Doppler Anemometry and planar laser-induced fluorescence (PLIF) experiments used to characterize the flow field and visualize selected scalars, respectively. Acetone served as a fluorescence marker for mixture fraction investigations. The hydroxyl radical was used to provide general features of the reaction zone such as flame shape and mean stabilization. To expose the influence of pressure on the flame structure three different operating points were investigated varying the combustor pressure between 2 and 6 bar while the inflow bulk velocities remained the same. Striking features of the present configuration are a detached flame, multiple recirculation zones, and complex coherent flow structures.

Section: Time Series Measurementsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Experimental Study on Stabilization of Lifted Swirl Flames in a Model GT Combustor

Janus

Dreizler

Janicka

2005

“…In the presented work the PVC varies its shape constantly but keeps its rotational frequency. The PVC lies between the zero axial velocity of the reverse flow zone and the zero streamline (see [19]) which is in the TECFLAM case on top of the radial edge of the bluff body. In Figure 8 a snapshot of the PVC-structure is plotted together with streamlines to visualize the effect the PVC has on the fluid flow.…”

Section: Characterization Of the Precessing Vortex Corementioning

confidence: 98%

Direct Numerical Simulation of a Recirculating, Swirling Flow

Freitag

Klein

2005

A direct numerical simulation (DNS) of a recirculating, swirling flow is performed at a Reynolds number of 5000. Detailed one and two point statistics are presented in this paper. Flow visualization and frequency analysis are used to identify a precessing vortex core and to characterize its position, extent and influence on the flow field. The results are compared with laser Doppler velocimetry (LDV) measurements as well as large eddy simulation (LES) data reported in the literature. The present work constitutes a first step in setting up a DNS data base for complex flows.

“…Since then, there have been numerous studies dealing with this phenomenon, which have recently been reviewed by Lucca-Negro and O'Doherty [19]. Although the underlying mechanisms are not well understood, there is some evidence, that these periodic coherent structures strongly influence mixing and combustion and can even lead to instable behavior of combustion systems by a coupling with acoustic modes of the geometry [1,17,27]. Hence, the influence of PVC on mixing processes deserves some attention.…”

mentioning

confidence: 98%

Study of Flow and Mixing in a Generic GT Combustor Using LES

Wegner

Staufer

Sadiki

et al. 2007

While the basic capability of large eddy simulation (LES) has been amply demonstrated on a number of relatively simple academic configurations, there is still a lack of works applying LES to practical systems also performing detailed quantitative comparisons based on experimental data. In this paper, we tend to approach the simulation of real gas turbine combustor step by step as we first present results of the isothermal LES of a generic gas turbine combustor rig. The available detailed measurements are used to thoroughly validate the LES results. Beyond a pure validation, the LES is used to analyze the influence of the precessing vortex core present in the studied configuration on the mixing of fuel and oxidizer, and possible implications for reacting conditions are discussed.