Short Helical Combustor: Concept Study of an Innovative Gas Turbine Combustor With Angular Air Supply

An innovative design of a gas turbine annular combustor is investigated analytically and numerically. Its principal feature is the helical arrangement of the burners around the turbine shaft. Hence, a shorter combustor with lower aerodynamic losses and cooling air demand might be realized. A generic model of the combustor is developed and analyzed by means of a parametric study. Scaling laws for the geometry of the flame tube and the burners are derived. Thereby, the relevant similarity parameters for fluid flow, combustion, and heat transfer are maintained constant. Subsequently, nonreacting and reacting flow regimes of selected design variants are numerically investigated. It is shown that a double annular (DA) configuration with a tilting angle of beta = 45 deg, where circumferentially adjacent swirls are corotating and radially are counter-rotating, is the superior design in terms of (1) maintaining the relevant similarity rules, (2) size and location of the recirculation zones and swirl flames, and (3) flow pattern at the combustor exit. The deflection angle of the nozzle guide vanes (NGV) as well as the axial length of such a short helical combustor (SHC) could be reduced by approximately 30%.