Turbine Operation and Measurement at DLRs Next Generation Turbine Test Facility

Abstract

Test facilities are important to validate new developments before bringing them into aero engines. The challenge is to have a deep understanding of the individual facility to be able to state measurement uncertainties, boundary conditions and stability to ensure high quality data which allow for comparison with predictions mostly done by simulations. Especially in todays environment with the big challenge to bring disruptive technologies into service to meet the climate goals. One large test facility is the Next Generation Turbine test facility (NG-Turb) situated at the German Aerospace Center in Göttingen. Together with Rolls-Royce Deutschland a turbine test rig with the option to use a combustor simulator was operated. The turbine rig was designed as TRL 6 technology demonstrator with representative cooling scheme, realistic Mach and Reynolds number to determine the turbine characteristics like capacity and efficiency but also to get insight into local flow phenomena. A necessity is the determination of all boundary conditions with mass flow rate, total temperature and total pressure. These must be deduced from different measurements but they are discrete in place and time. A major tool to determine the flow conditions are pneumatic probes which need to be traversed to cover a minimum number of positions for averaging. During that time the operation point of the turbine must be kept as constant as possible. This paper presents the operation of the test rig within the facility including reached stability of operation conditions and thermal behaviour of facility, test rig and flow characteristics. It is shown that very good stability of boundary conditions is reached but that there are also challenges mainly belonging to thermal gradients which are always present. By improving the instrumentation thermal gradients are resolved and can be taken into account when evaluating the gained turbine characteristics.