Inverse Jet Flame Based Swirl Combustor

Abstract

The stringent requirements for ultra-low emission in aviation based gas turbine engines have provided an opportunity for the combustion researchers to look into new avenues. One promising method proposed for curbing emissions in gas turbine combustors is the employment of lean premixed combustion where the fuel is burned with excess air for lowering the exhaust gas temperature and reducing the emission levels. Unfortunately, safety issues such as flame flashback and lean blowout exist in the lean premixed flame based gas turbine combustors. In the present chapter, feasibility of employing a distinct nonpremixed coaxial jet flame called inverse jet flame (IJF) as an alternative flame configuration for adaption in gas turbine combustors is explored to overcome the safety issues associated with the lean premixed combustion. Apart from the absence of flame flashback and lean blowout issues, the ability to control the air and fuel jets independently in IJF configuration helps in attaining near uniform temperature distribution and subsequent reduction in the exhaust emission levels. In the initial part of this chapter, inherent issues associated with the lean premixed combustion are listed and the advantages of employing a swirl inverse jet flame in gas turbine combustors as an alternative to lean premixed swirl flame are delineated. Subsequently, the design of a labscale IJF based swirl combustor and its characterization are discussed in detail. A description on the experimental methods utilized for the characterization of swirl IJF in a labscale combustor is provided. Various characteristics of swirl IJF established within the quartz confined dump combustor such as visible appearance, flame height and flame stability are investigated. Importantly, the thermal and emission characteristics of this swirl IJF combustor in terms of exit temperature profiles and the nitric oxide (NOx) emission index are also reported in this chapter.