Annual Report 2016 - Mechanical Engineering

117

Turbomachinery and Flight Propulsion

Experimental investigation and numerical simulation of

turbomachinery components and flight propulsion systems

Compressor Aerodynamics, Performance

and Operating Range Extension

The stability of transonic axial compres-

sors is mainly triggered by the tip gap flow

and its interaction with the passage main

flow. Several secondary flow phenomena

occur, e.g. shock-vortex interaction.

Casing treatments (CTs) have shown their

ability to enhance the stability of transonic

axial compressor rotors at near stall con-

ditions by influencing the near casing flow

field. CTs are applied over the compressor

rotor and can be designed differently, but all

of them energize the near casing flow field.

At the LTF, especially tip blowing (TBCT)

and axial slot casing treatments (AxCTs)

have been investigated. These CT types

recirculate flow from a downstream part

against the main flow direction in front

of the leading edge of the compressor

rotor. Besides a tremendous extension of

the operating range, studies at the LTF

have also shown a positive effect on the

peak efficiency point at design speed of

the treated rotor. Most of the previous

investigations have been carried out using

a rotor only model. To use CTs in real

applications, it is necessary to gain more

knowledge on how the CTs behave in a

multistage environment.

The focus of the present studies lies on

the influence of CTs on the stage match-

ing of a multi-stage compressor. For this

purpose, CFD studies are carried out for a

three-stage transonic axial compressor.

The unsteady interaction between main

flow and the exiting and re-entering treat-

ment flow is investigated using state of

the art phase lag simulations. The studies

are performed in close cooperation with

associated national research institutes and

industry partners.

Research activities of the Institute of Flight Propulsion in 2015 covered

topics in the fields of flight propulsion, gas turbines and thermal turboma-

chinery. Based on a long tradition the institute develops thermo-dynamic

engine models in order to investigate steady and unsteady gas turbine

engine and turbomachinery behavior.

Prof. Dr.-Ing.

Volker Gümmer

www.ltf.mw.tum.de sekretariat@ltf.mw.tum.de

Phone +49.89.289.16164

Contact

The history of the Institute of Flight

Propulsion (LFA) reaches back to 1964,

when Prof. Münzberg was first appointed

head of the chair in downtown Munich.

Since its foundation the institute has been

dedicated to research and teaching in the

field of jet propulsion and gas turbines.

The institute is an active member of

national research associations, participant

in European research projects and long-

term partner of leading aero-engine and

component manufacturers. One highlight

is the framework agreement between the

Institute of Flight Propulsion/TUM, the

Bavarian Government and GE Global Re-

search Europe. The cooperation includes

the development of the world’s most

advanced high-speed research radial and

axial compressor laboratories focused on

developing tomorrow’s aircraft engines

and gas turbines. At the end of 2016 the

first test vehicle on the new axial com-

pressor testbed was commissioned and

tested at Garching.

Flow field visualization of an axial slot casing treatment

applied on a tip critical transonic compressor rotor:

flow with negative axial velocity component (blue),

streamlines of tip gap vortex, recirculated flow entering

the passage (red).