As vehicle turbochargers are developed toward higher performance and lower turbo lag, high cycle fatigue (HCF) of radial turbine blades is becoming increasingly common which greatly threatens the reliability of turbochargers. Tip leakage vortex is one of potential sources of blade excitation and it’s profoundly influenced by blade tip clearance. This paper studies the influence of tip clearance distribution on blade excitation of a vaneless radial turbine via experimentally validated one-way fluid-structure interaction (FSI) numerical method. The results suggest that blade vibration response is significantly influenced by tip clearance distribution in the meridional direction. Generalized energy method is proposed to determine the key factors for blade excitation. The results manifest that complex distributions of harmonic pressure amplitude on the blade dominate blade vibration response. Detailed flow field analysis is carried out to further investigate the mechanism of blade excitation. The results show that distributions of harmonic pressure amplitude on pressure surface (PS) and suction surface (SS) are both dominated by tip leakage vortex, whereas the roles that tip leakage vortex plays are quite different. Specifically, tip leakage vortex influences harmonic pressure amplitude on SS directly because of short distance between vortex core and SS, whereas it influences harmonic pressure amplitude on PS indirectly by interfering the evolution of passage vortex. This research can guide new designs for durable vaneless radial turbines without sacrificing aerodynamic performance.

随着汽车涡轮增压器朝着更高性能和更低涡轮迟滞的方向发展，径向涡轮叶片的高周疲劳（HCF）变得越来越普遍，这极大地威胁了涡轮增压器的可靠性。叶尖泄漏涡是叶片激励的潜在来源之一，它受叶尖间隙的影响很大。本文通过实验验证的单向流固耦合 (FSI) 数值方法研究叶尖间隙分布对无叶片径向涡轮机叶片激励的影响。结果表明，叶片振动响应受子午方向叶尖间隙分布的显着影响。提出了广义能量法确定叶片激励的关键因素。结果表明，叶片上谐波压力幅值的复杂分布支配着叶片振动响应。进行详细的流场分析以进一步研究叶片激励的机制。结果表明，压力面（PS）和吸力面（SS）上的谐波压力幅值分布均以叶尖泄漏涡为主导，而叶尖泄漏涡所起的作用却大不相同。具体而言，由于涡核与 SS 之间的距离较短，叶尖泄漏涡直接影响 SS 上的谐波压力幅值，而它通过干扰通道涡的演变间接影响 PS 上的谐波压力幅值。这项研究可以指导耐用无叶片径向涡轮机的新设计，而不会牺牲空气动力学性能。