Abstract
In this work, a double-high swirl gas turbine model combustor (GTMC) has been experimentally investigated to identify the effects of air partitioning and swirlers geometry on combustion characteristics in terms of flame stability, exhaust gas temperature, NOx generation, and combustion efficiency. This high swirl model combustor is originally developed in the German Aerospace Center (DLR) and known as GTMC and recently reconstructed at Sharif University's Combustion Laboratory (named as SGTMC). Here, SGTMC run for liquefied petroleum gas (LPG) fuel and air oxidizer at room temperature and atmospheric pressure. Eleven different burner geometries, M1–M11, are considered for the aims of this work. Furthermore, the effects of burner confinement are also investigated. The results show that under the confined state, the flame has a lower width and height than the unconfined one. Exchanging the swirlers of annular and central air inlets shows a more stable and lifted V type flame with almost zero levels of CO and CH4. In addition, measurement showed that the annular swirler removing leads to incomplete combustion. Moreover, an increment in discharged air velocity leads to more completed combustion and less pollutant exhaust gas but the attachment of flame to the burner hub. Strengthening the flow channeling is not reasonable in terms of emission aspects. Moreover, burner configuring to counterrotating swirlers leads to a more stable flame but with lower combustion efficiency. Among 11 test cases, the original configuration and the case of exchanging the swirlers of annular and central air inlets are the best choices in terms of combustion efficiency and stability. Measurements show the improvement of burner stability, 2–10%, due to inlet air preheating.
