Aeroelastic control of gas turbine blades

点击翻译按钮获取中文摘要

Blade vibration and noise generation are both undesirable consequences of the unsteady flow processes that occur within an axial-flow turbomachines and are, therefore, important concerns of the designer. Of the two, vibration problems have received more attention because they can lead to a structural failure of the engine and, possibly, to extensive damages including life losses. Aerodynamically-induced blade vibrations are usually classified into two general categories: self-sustained and forced problems. In the former, the aerodynamic forces that sustain the blade motion are regarded as being dependent solely on that motion (e.g. in flutter), whereas in the latter, the aerodynamic forces that excite the blade motion are independent of that motion (e.g. in buffeting and blade mistuning). This research will be more focused in the latter class of problems. The development of new integrated rotor-blade designs (BLISKS) led to renewed concerns about vibration-related problems because the natural structural damping due to the traditional blade attachments is now absent. Therefore, control systems for the interrogation of the structural integrity of turbomachines and/or reduction of vibration using "smart" structures actuators and sensors such as piezoelectrics are a matter of research effort. The actuator device nicknamed Smart Spring is best suited to be used to actively alter the boundary conditions of structures using friction and, as such, they may be incorporated to BLISKS to provide theur artificial damping augmentation. In the current application this approach will be taken to attenuate the forced-vibration problems most commonly encountered in turbine and compressor stages of turbomachineries. This objective will require the use of complex Computational Fluid Dynamic models that must be linked to structural control idealizations for the numerical simulations. For this, reduced-order aeroelastic models of cascade flows including unsteady aerodynamic effects, blade inter-phase angles and mistuning will be firstly developed using reduced-order aeroelastic models for the sake of computation efficiency.