Tight VSV & KOmpakt

The project focuses on core engine compressor technology for improved operating range and mechanical design process with targeted compact design and high compressor discharge temperatures.

In modern two-shaft aircraft engines, the front stages of the high-pressure compressor are equipped with variable vanes. Variable in this context means that the stagger angle of the blade can be adjusted during engine operation. The aim of this mechanism is to reduce the blade load during part speed operation of the following rotor by changing the inflow conditions. Without this countermeasure, the blade load on the rotor would increase even further till flow separation occurs.

To safe fuel and reduce emissions, the overall weight and size of the engine play an important role. One of the heaviest components of the engine is the compressor, which means that reducing the weight of the compressor has a major impact on the overall weight.

The two projects TigHT VSV and KOmpakt, currently running at the Transonic Compressor 1 (TSV1) at the GLR deal with the effects of a variable shrouded stator and a variable cantilevered stator on the overall stage behaviour. In the first project, a classic variable shrouded stator with a non-rotating inner end wall is investigated. The focus is on the investigation of the occurring secondary flow phenomena due to the variable blade geometry. The second project involves the first-time use of a variable cantilevered stator at the TSV1. In this setup the inner end wall rotates with the rotor speed under the stator vane. Cantilevered stators have the big advantage that their weight is lower due to the smaller number of components compared to a shrouded stator. In addition, their overall performance should be higher compared to the classic shrouded stator because of the less complex flow path. The aim of the second project is to prove the latter point, that the performance of the cantilevered stator is higher than the one of the shrouded stator.

Methodology

The experiments will take place at the TSV1. The TSV1 is equipped with extensive steady and unsteady measurement techniques to capture the required data. The measurements will take place in different measurements sections across the test rig.

Steady measurement techniques:

  • Static pressure probes at the casing
  • Boundary layer rake
  • Stator leading edge instrumentation for total pressure and total temperature
  • Combined total pressure and total temperature rake
  • 3-hole rake
  • Traversable 5-hole probe
  • Static pressure ports in penny cavity due to 3D-printed stator vanes
  • Unsteady measurement techniques:
  • Unsteady wall pressure transducers
  • Strain gauges at the rotor blades
  • Blade tip timing and blade tip clearance system
  • Traversable virtual 4-hole probe
  • Unsteady total pressure rake

Key Scientific Takeaways

  • Performance Comparison Shrouded vs. Cantilevered Stator
  • Further understanding of occurring secondary flow phenomena in variable stators at different speeds and throttle conditions
  • Proof of concept variable cantilevered stator

Funding and cooperation

The project is placed in LuFo VI, GLR is subcontracted.