Short Description

The sealing between static and rotating components in axial turbomachines in the hub area of ​​compressor stators is usually carried out with the help of an inner shroud or by using cantilevered vanes. The choice of configuration is influenced by aerodynamic, mechanical and economic factors and must therefore be assessed in a multidisciplinary environment. It directly influences both the compressor efficiency and its operating range, as well as the thermal behaviour of the rotors and thus the life of the compressor components. The heat transfer effects associated with the stator configuration in the hub area are playing a critical role especially in the rear-block of the high pressure compressor. Furthermore, the stator configuration in this area has an indirect impact on the secondary air system of ​​the turbine.

The flow losses in the main gas path depend heavily on the individual design, i.e. the specific aerodynamic stage parameters of the respective turbomachine, and differ fundamentally between the two configurations. The aerodynamic losses caused by the leakage flow are largely determined by the work coefficient, the flow coefficient, the degree of reaction, the pitch-to-chord ratio for cantilevered stators and the number of seal fins at the inner air seal for shrouded  stators [2]. For this reason, the decision regarding the stator hub configuration cannot be made universally, but requires a separate assessment for each machine.

In close cooperation with MTU Aero Engines AG, a concept decision for future aero-engine generations is to be made. As part of the collaboration, the aerodynamic performance of the compressor and the thermal and operating behaviour will be investigated using numerical flow simulation and 1D / 2D approaches. Within the higher-level project, the efficiency of the whole engine, structural-mechanical aspects as well as manufacturing strategies and costs are to be assessed.

References:

[1]        Albrecht, G.: Grundlagen der Triebwerkskonstruktion, Manuskript zur Vorlesung, BTU Cottbus, 2004

[2]        Yoon, S.; Selmeier, R.; Cargill, P.; Wood, P.: Effect of the Stator

Hub Configuration and Stage Design Parameters on Aerodynamic Loss in                      

Axial Compressors, In: Journal of Turbomachinery 137, 2015

Project Target

• Development of the superior stator hub configuration for the specific application
• Optimization of the chosen configuration with regard to aerodynamic and thermal requirements
• Selection and definition of possible hardware tests

Project Partners

MTU Aero Engines AG 

Person in Charge

Hulusi Altay Damgacioglu, M.Sc.