A hot-streak (combustor) simulator suited to aerodynamic performance measurements

A new hot-streak (combustor) simulator has been designed and implemented in a turbine test facility at QinetiQ Farnborough (the QinetiQ Isentropic Light Piston Facility, ILPF) to study the impact of temperature distortion on high pressure (HP) turbine efficiency, aerodynamics, and heat transfer. The ILPF is an engine scale, short duration, rotating transonic turbine test facility, in which M, Re, T-g/T-w, and N/root T are matched to engine conditions. The research forms part of the EU Turbine Aero-Thermal External Flows (TATEF II) programme. The hot-streak simulator is a second-generation design, in which cold gas is introduced into a hot mainstream though radial and circumferential slots upstream of the turbine stage. The simulator is rotatable, so the effect of clocking (relative circumferential position of hot streak and nozzle guide vane leading edge) can easily be investigated. An emphasis was placed on accurate measurement of turbine inlet enthalpy flux so that the impact of hot streaks on turbine efficiency could be investigated. The hot-streak simulator differs from all previous systems in that a pronounced radial and circumferential temperature profile has been generated, with a hot-streak to vane count of 1:1. The profile is very well matched (non-dimensionally) to the target profile, which is a combustor temperature profile measured in a modern operating engine at the most extreme point in the cycle. The most accurate area survey of a simulated temperature profile has been conducted to date, and this demonstrates that the simulator offers an exceptionally high degree of circumferential symmetry and run-to-run repeatability. The design and commissioning of the simulator is described, and the measured temperature profiles are compared with the target profile.