Session: 34-05 Flow Control

Paper Number: 83374

83374 - Tip Flow Control in Optimized Large Gas Turbine Compressor Blading 

In transonic axial compressors of gas turbines, casing treatments (CTs) have the capability to improve the stability and delay stall. A full comprehension of the stall mechanism is essential to design a beneficial CT. Tip stall is needed. Nowadays, most CT investigations and publications investigate flight propulsions applications. There is a need for detailed investigations in stationary large gas turbines with typical small relative tip gaps due to the large absolute dimensions, especially for performance and stability optimization.

 

The goal of the present study is to increase the operating range towards stall without losing efficiency at design point conditions. Several axisymmetric active and passive CT types are investigated.

The model is based on an optimized tip critical rotor design, that matches the boundary conditions of a large gas turbine. Through numerical optimization, therefore, a CT was developed to improve the stability limits. The numerical investigations are carried out on a single rotor optimization using URANS simulations.

 

The study investigates in depth the ability of axisymmetric groove with mass injection to postpone stall for a modern large gas turbine compressor with small relative tip gaps. Whereas passive geometries like circumferential grooves does not improve the stability for the specific blade geometry. It is essential to quantify the influence of the different types of CT onto the rotor tip flow especially for near stall conditions. Of particular interest is how the circumferential grooves perform when used in combination with mass injection. For this aerodynamically optimized rotor, a mass injection is needed to energize the tip leakage and therefore reduce the blockage. The injection of 1% stall mass flow increases the stall margin by 15 % without a loss in efficiency at design point conditions.

Presenting Author: Katja Hummel Technische Universität Berlin

Presenting Author Biography: PhD student at Technische Univertit&#228;t Berlin <br/>working since 2014 for Siemens Energy AG in the field of compressor aerodynamics<br/>Diploma Engineer in Aeronautics and Astronautics with the specialization in Turbomachinery and Gas Turbines

Authors:

Katja Hummel Technische Universität Berlin
Anton Streit Siemens Energy AG
Dieter Peitsch Technische Universität Berlin, Institute for Aeronautics & Astronautics, Chair for Aeroengines