Experimental Aerodynamic and Aeroelastic Investigation of a highly-loaded 1.5-stage Transonic Compressor with Tandem Stator

Authors

Jonas Foret - Technical Universtity of Darmstadt, Institute of Gas Turbines and Aerospace Propulsion
Daniel Franke - Technical Universtity of Darmstadt, Institute of Gas Turbines and Aerospace Propulsion
Fabian Klausmann - Technical Universtity of Darmstadt, Institute of Gas Turbines and Aerospace Propulsion
Alexandra Schneider - Technical Universtity of Darmstadt, Institute of Gas Turbines and Aerospace Propulsion
Heinz-Peter Schiffer - Technical Universtity of Darmstadt, Institute of Gas Turbines and Aerospace Propulsion
Bernd Becker - Rolls Royce Deutschland Ltd & Co KG
Hauke Müller - Rolls Royce Deutschland Ltd & Co KG

Abstract

Future aero engines face the environmental challenge of drastically reducing greenhouse gases. Thus, political defined regulations regarding emissions are becoming increasingly important. To achieve these regulations, novel approaches in technology development are inevitably necessary. Therefore, the development trends of aero engines aim for opportunities to increase efficiency in conjunction with reduced weight and size. The axial core compressor as a major component offers great potential by increasing the overall pressure ratio with a minimum number of compressor stages as well as reduced blade and vane counts. This results in highly-loaded compressor stages which are prone to flow separation. One possibility to withstand the high loading is the use of a stator in tandem arrangement.This paper investigates the aerodynamic and aeroelastic behavior of a highly-loaded 1.5-stage transonic axial compressor with a variable stator in tandem arrangement. The experiments were carried out at the transonic research compressor rig at Technical University Darmstadt. The test rig represents a front stage high-pressure compressor of modern jet engines. Using extensive steady and unsteady instrumentation, the global compressor performance as well as the transient behavior, focusing on aerodynamic and aeromechanic phenomena, are analyzed.A new designed compressor stage, comprising a BLISK rotor and variable tandem stator, has been investigated and compared to a reference stage using a conventional stator design. Due to the new stator vane design, a higher aerodynamic stator vane loading is pursued while the vane count is reduced. This in turn enables a rotor design with an increased work coefficient. The goal of this optimized highly-loaded compressor stage is to achieve an increased pressure rise while maintaining efficiency compared to the reference stage.The experimental study reveals several effects of the optimized compressor stage, considering both performance and corresponding aerodynamics as well as the aeroelastic behavior. Compared to the reference setup, the optimized compressor shows an increase in stage pressure rise for the entire operating range while the efficiency is also increased or at least equal. However, the stability margin for the optimized compressor stage is smaller, especially at high power conditions. Therefore, a detailed comparison of the two stages is conducted along the design speed line. The aerodynamic behavior is examined by stage exit instrumentation and five-hole probe measurements. Additionally, the aeroelastic behavior is investigated at the stability limit. Thus, this work might contribute to a better understanding of the loss behavior of highly-loaded compressor stages using stators in tandem arrangement.