Aeroelastic control of gas turbine blades

叶片振动和噪声的产生都是轴流式涡轮机内发生的非定常流动过程的不良后果，因此是设计者的重要关注点。在这两个问题中，振动问题受到了更多的关注，因为它们可能导致发动机的结构故障，并可能导致包括生命损失在内的广泛损害。气动诱导叶片振动通常分为两大类：自持和强迫问题。在前者中，维持叶片运动的气动力被认为仅取决于该运动（例如在颤振中），而在后者中，激发叶片运动的气动力与该运动无关（例如在抖振和叶片失谐中）。本研究将更侧重于后一类问题。新的一体化转子叶片设计（BLISKS）的发展导致了对振动相关问题的重新关注，因为传统叶片附件导致的自然结构阻尼现在不存在。因此，用于询问发动机的结构完整性和/或使用“智能”结构致动器和传感器（诸如压电体）来减少振动的控制系统是研究工作的问题。致动器设备昵称智能弹簧是最适合用于主动改变结构的边界条件，使用摩擦，因此，他们可能会被纳入BLISKS提供theur人工阻尼增强。在当前的应用中，将采用这种方法来衰减在涡轮机的涡轮机和压缩机级中最常遇到的强迫振动问题。这一目标将需要使用复杂的计算流体动力学模型，必须与结构控制理想化的数值模拟。为此，为了提高计算效率，本文首先采用降阶气动弹性模型建立了包含非定常气动力效应、叶片相间角和失谐的叶栅流场降阶气动弹性模型。

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.