Abstract:
During operation, gas turbine components undergo various types of timedependent
degradation due to high temperatures and mechanical loading. In
the case of stationary GT engines for mechanical power, creep failure
mechanism problems are a very common cause of mechanical failure that
significantly reduces component life. The magnitude of the adverse effect is
highly dependent on the operating conditions and design parameter of the
components. Against this background, the research programme was aimed at
achieving a better scientific understanding of the major reasons for creep
failure. This would allow mechanical equipment to keep running free creep
problem for longer. Therefore, the aim of this research was to develop an
analytical life model capable of assessing the influence of humidity on the
turbine blade heat transfer and cooling processes considering the engine
design parameters, operating conditions and working environment which, in
turn, affect blade creep life.
The whole cooled blade row is regarded as heat exchanger with convective/film
cooling and a thermal barrier coating. The approach is based on an engine
performance model, heat transfer models and the change of properties of moist
air as a function of water to air ratio (WAR). The changes of fluid properties due
to the presence of water vapour were not only considered through a variation of
the specific heat, the ratio of major specific heats and gas constant, but also
with the variation of density, Reynolds number, Nusselt number and other
related parameters. Cont/d.
