Investigation of the Impact of Realistic Inlet Distortions on a 1.5-Stage Transonic Compressor

Abstract

In this study the aerodynamic impacts of inlet distortions caused by a gas turbine inlet manifold are analyzed experimentally. The investigation is performed at the new transonic compressor test rig at Technical University of Darmstadt, that features high modularity and extensive instrumentation. The existing axial air inlet system of the test rig is replaced by a scaled inlet manifold. Analog to the design of a real gas turbine intake, bearing support struts are integrated in the experimental setup to investigate their interaction with the inlet distortions. For the detailed analysis of compressor performance, the measurement systems were extended to resolve the flow over the whole circumference at three different axial positions. At the stage inlet a traversable rake with radially distributed five hole probes allows the quantification of the inflow conditions. To determine global compressor characteristics and analyze the propagation of inlet distortions through the compressor, a fully traversable instrumentation at the stage exit is installed. Additionally, a 360°-traversable rotor casing ring, instrumented with unsteady measurement systems, enables the analysis of the effects of non-uniform inflow conditions on the unsteady flow field of the rotor.

Commissioning of a transonic compressor test rig for the investigation of vigv-induced asymmetric inflow conditions

“…Safe operation and continuous monitoring of the rotor in the presence of distorted inflow is ensured by a total of 16 strain gauges applied on the rotor blades, as well as a tip timing system that is also used to monitor tip clearance. More information about the rig and the measurement systems is given by Kunkel et al (2019), and the traversable instrumentation is described in further detail by Werner et al (2022).…”

“…In aero engines, these deviations are typically generated by changes in aircraft orientation, gusty crosswinds or boundary layer effects. In gas turbines, the inlet system, consisting of ducts and bends, is a possible cause (Stenning, 1980;Werner et al, 2022). In general, inlet distortions have a negative impact on compressor efficiency, total pressure ratio, mass flow rate and stability margin (Pazur and Fot-tner, 1990).…”

“…The applied procedure is similar to that described previously, although a 360 • -traverse without stepwise pattern shift is possible at the stage outlet. However, this does not seem suitable because the data would contain the influences of upstream probes (e.g., instrumented VGVs) and the tip gap is not necessarily identical at different angular positions, potentially resulting in a varying total pressure (Werner et al, 2022). The pattern shifting procedure does not suffer from these disadvantages and therefore provides data showing only the influence of the inlet distortion as can be seen in the next section.…”