Abstract
Jet engine spare parts are expensive. Hence, for economic reasons,
as many components as possible should be repaired. For
planning the repair or regeneration process, defects must be identified
early. The present paper explores whether the detection and
examination of inhomogeneities in the temperature distribution in
an exhaust gas stream of a jet engine can be used for the identification
and localization of defects before engine disassembly. In
order to be able to assign the defects to the resulting temperature
non-uniformity in the exhaust gas, the mixing characteristics of the
temperature inhomogeneities in the turbine caused by the defects
are examined. A three-dimensional unsteady CFD-simulation of a
whole turbine with a complex temperature distribution at the inlet is
carried out. The simulations show, that the temperature inhomogeneities
are barely mixed out with the surrounding flow. To
describe the mixing effects a coefficient (turbine mixing factor) is
derived. The factor enables an integral assessment of the mixing
behaviour of inhomogeneities within and outside of turbine stages.
