Transient Thermodynamic Simulation of the DLR Turbine Test Facility NG-Turb

Abstract

The operation of large-scale test facilities for gas and aircraft turbines is complex and costly. Especially, during the planning phase of measurement campaigns, it is important to identify challenging operating points in advance. For the considered turbine test bench facility NG-Turb investigations have shown that the warm-up phase has a significant influence on the operational procedure and the operational time that is needed to reach requested turbine conditions. Consequently, this paper deals with the transient prediction of the NG-Turb test facility on thermodynamic level. Therefore, the impacts of different transient effects have been evaluated: the heat soakage, the inertia and the accumulation of mass flow (the transient mass balance). This evaluation led to the conclusion that the heat soakage of the hot section is the dominant transient effect due to the large piping network. In order to do a thermodynamic simulation of the NG-Turb test facility, the performance tool DLRp2, which is part of the GTlab framework, has been extended by a new computational logic that enables the hybrid usage of the already existing modules and new created transient modules. Moreover, the chosen implementation allows an easy extension of the modules for a transient computation. For the considered test facility, the following new modules have been introduced: a piping module that estimates the radial heat flux and a measurement point representation that investigates the deviations between computed and measured values. Additionally, an already existing heater module was equipped with a transient computation mode. By employing these new modules, a model of the hot section of the test facility has been built. A first comparison with measurement data shows a significant improvement of the simulation accuracy. Finally, a calibration of the simulation model has been carried out to further improve the accuracy.