High cycle fatigue (HCF) of radial turbine blades is one of key issues of turbochargers and it determines the reliability of the device. Most of researches about HCF of radial turbine blades focus on vaned turbines, whereas few investigations have been carried out on vaneless turbines which are widely applied in automobile turbochargers. This paper studies the blade vibration mechanism of a vaneless radial turbine at low excitation order via one-way fluid–structure interaction simulation method validated by experiments. The results surprisingly demonstrate that blade vibration response does not increase consistently with turbine load. Instead, a non-monotonic correlation is observed between vibration response and turbine load. The energy analysis is employed to understand the phenomenon and the results manifest that the variation of energy imposed on blade suction surface is the direct reason for the non-monotonic correlation. Detailed flow field analysis further suggests that the non-monotonic trend of energy on suction surface is caused by the interaction of two flow structures at different turbine loads: separation vortex at blade leading edge and tip leakage vortex caused by pressure difference between pressure surface/suction surface. The study of blade excitation in this research can enlighten the new design of vaneless turbine with both good performance and high reliability.

径向涡轮叶片的高周疲劳（HCF）是涡轮增压器的关键问题之一，它决定了装置的可靠性。径向涡轮叶片的 HCF 研究大多集中在叶片涡轮上，而对广泛应用于汽车涡轮增压器的无叶片涡轮进行的研究很少。本文采用经实验验证的单向流固耦合模拟方法研究了低激振阶无叶片径向涡轮机叶片振动机理。结果出人意料地证明叶片振动响应不会随着涡轮负载一致地增加。相反，在振动响应和涡轮负载之间观察到非单调相关性。采用能量分析来理解这一现象，结果表明，施加在叶片吸力面上的能量变化是非单调相关性的直接原因。详细的流场分析进一步表明，吸力面能量的非单调趋势是由两种流动结构在不同涡轮载荷下相互作用引起的：叶片前缘的分离涡和压力面/吸力差引起的叶尖泄漏涡。表面。本研究中对叶片激励的研究可以为性能良好和可靠性高的无叶涡轮机的新设计提供启发。详细的流场分析进一步表明，吸力面能量的非单调趋势是由两种流动结构在不同涡轮载荷下相互作用引起的：叶片前缘的分离涡和压力面/吸力差引起的叶尖泄漏涡。表面。本研究中对叶片激励的研究可以为性能良好和可靠性高的无叶涡轮机的新设计提供启发。详细的流场分析进一步表明，吸力面能量的非单调趋势是由两种流动结构在不同涡轮载荷下相互作用引起的：叶片前缘的分离涡和压力面/吸力差引起的叶尖泄漏涡。表面。本研究中对叶片激励的研究可以为性能良好和可靠性高的无叶涡轮机的新设计提供启发。