EisenerZ - Influence of Inflow-Nonuniformieties onto the Excitation of LPTs of Modern Two-Spool Engines

Project: Research project

Description

Up to now all test rigs are designed for optimum periodic inlet boundary conditions. That is
necessary in order to be able to draw some general conclusions, saving measurement time
as well as to compare measurement data with results from simulations. That simulations are
usually performed for one periodic sector due to time reasons. However, in an engine under
representative operating conditions these ideal periodic boundary conditions are not present,
there will always be a variation at the inlet. Normally total pressure and/or total temperature
are altered by upstream components. For example the temperature can vary by about 100°C
to 200°C along the circumference downstream of the combustion chamber. The following
turbine stage especially the rotor blades are then excited and start to vibrate. Also struts in
turbine centre frames can produce different wakes, different pressure distributions due to
separations. Again, the following low pressure turbine stage is then excited. The excitation
will increase the shorter engine components are to safe weight and therefore fuel. With that a
significant reduction of emissions can be achieved. An environmental improvement is here
coupled to a worsening of the vibration situation of the turbine parts or engine components,
respectively. However, we can handle that situation with high quality measurement data
gained in high-grade research projects e.g. projects in the framework TAKE OFF.
Within that project the influence of these inlet distortions onto the vibration of a turbine rotor
will be investigated experimentally and numerically (2 way fluid-structure-interaction). The
investigation of that effect clearly separated that project from state-of-the-art projects. The
numerical challenge is that the complete circumference has to be modelled and simulated. It
is well known that these simulations are very time consuming and computational expensive
and therefore a fast and simple calculation tool will be developed in order to estimate the
stability margin of the system in a very short time. That tool should then be used in an early
design phase of a low pressure turbine.
StatusActive
Effective start/end date1/11/1631/10/19