Investigation of the Interaction between Blade Tip Flow and Blade Vibrations in highly loaded axial compressors

在涡轮机械中，叶片尖端的间隙流动效应会导致巨大的损失和稳定性损害，特别是对于高负荷的压气机级。这些现象的科学研究是非常困难的，因为研究流动的数值和实验方法都由于间隙内复杂的过程而达到了极限。此外，空气动力学和结构力学效应之间的相互作用，到目前为止只能进行初步的研究和建模。在该项目中，采用新颖的基于激光的测量方法，可以同时高精度测量叶片尖端流动剖面和压气机叶片振动振幅和模态振型。因此，本文将在跨声速压气机试验台上对间隙流动与叶片振动之间的相互作用机理进行实验研究，并结合数值模拟，以更好地了解涡轮机械，特别是高负荷压气机级的气动弹性过程。研究结果对涡轮增压机的设计具有重要的参考价值，例如将来能够减小叶片排距。因此，可以实现更高的功率密度和改善转子动力学。这将直接提高运行可靠性和负荷变化的灵活性。此外，未来涡轮机器（如飞机发动机）的能源效率也可以得到提高。

In turbomachinery, gap flow effects at the blade tips lead to large losses and stability impairments, especially for highly loaded compressor stages. The scientific investigation of these phenomena is very difficult because both the numerical and experimental methods for studying the flow reach their limits due to the complex processes in the gap. In addition, interactions occur between aerodynamic and structural-mechanical effects that could be studied and modelled only rudimentary up to now.Within this proposed project, simultaneous high-precision measurements of both the blade tip flow profile and the compressor blade vibration amplitudes and mode shapes will be enabled employing novel laser-based measurement methods. Therewith, the mechanisms of interaction between gap flow and blade vibrations will be investigated experimentally at a transonic compressor test rig alongside with numerical simulations in order to gain a better, fundamental understanding of the aeroelastic processes in turbomachinery, especially in highly loaded compressor stages.The results would be very valuable for turbo machine design, e.g. for being able to reduce the blade row spacing in future. Accordingly, higher power density and improved rotor dynamics can be achieved. This would directly allow for an increase in both operating reliability and flexibility of load changes. Furthermore the energy efficiency of future turbo machines, such as aircraft engines, could be improved.