摘要：Ventilation of turbine blades is used in aeronautic jet engines to increase the
gas temperature inside the turbine, without incrementing the blades
temperature beyond certain limits and thus preserving their expected
lifetime. Ventilation is achieved by taking cold air from the compressor and
passing it through holes in a rotating disc previous to the turbine.
The shape of the hole plays a major role in the air flow and in the stress
distribution of the disc. Numerical optimization techniques were used to
solve this problem. These methods provide a computational tool for design and
a systematic approach to take design decisions that previously relied more on
experiments and intuition. Classical optimization algorithms usually
minimize an objective function under certain design constraints, by varying
the design variables within prescribed bounds. The optimization algorithms
use information computed by other analysis software to recalculate the design
variables at each iteration. The objective of the present study is the
optimization of the shape of the ventilation hole in order to maximize the
cross section area of the air channel and to minimize the equivalent
stress in the surroundings of the hole. In order to perform the optimization,
a parametric model of the disc was created. Several alternatives for defining
the optimization problem were evaluated, and a final mechanical design was
proposed that takes full account of the three-dimensional features of the
problem. The analysis was performed using the software Samcef. BOSS/Quattro
was the optimization module, while the mechanical analysis was made using
Mecano and Asef modules (nonlinear and linear modules, respectively) to carry
out the coupled thermo- mechanical analysis.
