Combustor-Turbine Aerothermal Interaction in an Axial Turbine: Influence of Varied Inflow Conditions on Endwall Heat Transfer and Film Cooling Effectiveness

Abstract

The Large Scale Turbine Rig (LSTR) at Technische Universit ät Darmstadt, Germany is used to examine the aerothermal interaction of combustor exit flow conditions on the subsequent turbine stage. The rig resembles a high pressure turbine and is scaled to low Mach number conditions. A baseline configuration with axial, low-turbulent inflow and an aerodynamic inflow condition of a state-of-the-art lean combustor is modeled by the means of swirl generators, whose clocking position towards the nozzle guide vane’s leading edge can be varied. A hub side coolant injection consisting of a double-row of cylindrical holes is implemented to examine the impact on endwall cooling. This paper is directed to study the effect of swirling inflow on heat transfer and film cooling effectiveness on the hub side endwall. Nusselt numbers are calculated using infrared thermography and the auxiliary wall method. This method allows for a high spatial resolution and in addition also yields adiabatic wall temperature data within the same measurement using a superposition approach. Aerodynamic measurements and numerical simulations complement the examination. The results for the baseline case show Nusselt numbers to increase significantly with higher coolant mass flux rates for the whole endwall area. With swirling inflow, in general, a decrease of film cooling effectiveness and an increase of Nusselt numbers is observed for identical mass flux rates in comparison to the baseline case. The difference varies depending on clocking position.

Influence of Combustor Exit Conditions on Cooling Performance of NGV Endwall with Double Row Cooling Holes

“…Werschnik et al (2015) conducted studies using a 1.5 stage large scale turbine rig (LSTR), and obtained the heat transfer and film cooling effectiveness of the endwall with cosideration of the influence of swirl clocking positions. In addition, the aero-thermal interaction between the flow condition at the exit of the combustor and the turbine has been studied by Werschnik et al (2016). Furthermore, Werschnik et al (2017aWerschnik et al ( , 2017b investigated the effect of swirl on the heat transfer and cooling characteristics of the endwall with variations of coolant MFR, and they pointed out that the swirl changes the Nusselt number and cooling effectiveness at different clocking positions.…”