Gaseous Fuel Flame Stabilization in a Modular Swirled Burner

Abstract

Stable combustion is one of the main requirements for combustion chambers of gas turbine engines. Therefore, the prediction of combustor stable operation limits during the design stage is an important task. The stable operation limits with a sufficient degree of accuracy can be determined by experiments or using computational fluid dynamics. The present paper describes a numerical and experimental investigation of swirled premixed flame stabilization in a modular swirled burner (MSB). The burner has a vane swirler and a diffuser with a cylindrical tube downstream of the swirler. This design has several advantages. First, the cylindrical tube protects the flame from external disturbances and acts as the pre-chamber in which combustion efficiency can reach high values. Secondly, the swirled flow of the fresh mixture passes along the walls of the tube and prevents them from overheating. The influence of the swirler vanes angle on MSB lean blow out (LBO) was experimentally and numerically investigated. The results of the experiments were also used to validate the simulation results. All studies were conducted under atmospheric conditions in an open-space laboratory environment. Three-dimensional modeling was carried out using the large eddy simulation (LES) with a Smagorinsky–Lilly subgrid model. Combustion was described within the Flamelet Generated Manifold model. Initially, the influence of the size and shape of outlet boundary, the mesh resolution and turbulent-chemistry interaction models was investigated. As a result the configuration of the model was received, which allows simulating LBO with sufficient accuracy. Stable operation limits for several types of MSB geometries and different fuels (methane and propane) were subsequently established. It was found that in the case of swirler vane angle equal to 45 degrees the range of stable operation limits is wider than in the case of 60 degrees. The influence of pre-chamber length on LBO was studied only numerically. It was discovered that with increasing pre-chamber length, the LBO limits become wider, but the possibility of the tube walls overheating becomes higher too.

Flame Stability in Swirling and Bluff-Body Burners: A Review

“…They found that the blowoff limits were poor in case of the low swirler vanes, whereas in the high swirler vanes the blowoff limits improved, as shown in Figure 4 (a). Also, an experimental and numerical analyses to evaluate the impact of swirler vanes angle on the lean blowoff limits (lean BLO) of a premixed methane-air flame in a swirl burner have been conducted by Zubrilin et al [75] (2016). They reported that the lean blowoff limits improve with the increasing angle of swirler vanes.…”

Experimental Study of the Effect of Swirl Number and Bluff Body Size on the Stability Map of Premixed LPG Flames in a Tangential Swirl Burner

“…Also, the swirl number has great effects on the operation map represented by the blowoff and flashback limits. It has been observed that when the swirl number increases, the blowoff limits improve [13] [19], while the flashback limits worsen [12[[13][20]. Jerzak and Kuźnia [21] reported that there was a significant improvement in the operating range of the burner when S was increased from 0.69 to 1.…”