An Intelligent Optimization Method for Vortex-Induced Vibration Reducing and Performance Improving in a Large Francis Turbine

Abstract

Abstract:In this paper, a new methodology is proposed to reduce the vortex-induced vibration (VIV) and improve the performance of the stay vane in a 200-MW Francis turbine. The process can be divided into two parts. Firstly, a diagnosis method for stay vane vibration based on field experiments and a finite element method (FEM) is presented. It is found that the resonance between the Kármán vortex and the stay vane is the main cause for the undesired vibration. Then, we focus on establishing an intelligent optimization model of the stay vane's trailing edge profile. To this end, an approach combining factorial experiments, extreme learning machine (ELM) and particle swarm optimization (PSO) is implemented. Three kinds of improved profiles of the stay vane are proposed and compared. Finally, the profile with a Donaldson trailing edge is adopted as the best solution for the stay vane, and verifications such as computational fluid dynamics (CFD) simulations, structural analysis and fatigue analysis are performed to validate the optimized geometry.

Effects of trailing-edge modification of guide vanes on the wake vortices under different inflow conditions

“…9 demonstrated that the cross-sectional shape of a trailing edge has a significant effect on vortex shedding. Same conclusion can be found in the studies of Donaldson, 11 Do et al., 12 Peng et al., 13 and Wang et al. 14 Do et al.…”

“…Lee et al 9 demonstrated that the cross-sectional shape of a trailing edge has a significant effect on vortex shedding. Same conclusion can be found in the studies of Donaldson, 11 Do et al, 12 Peng et al, 13 and Wang et al 14 Do et al 12 studied the flow past a blunt-edged two-dimensional NACA 0015 section with various base cavity shapes and sizes at high Reynolds numbers. The numerical prediction showed that the presence of a base cavity at the trailing edge of NACA0015 does not change the inherent Strouhal number of the 2 D section examined.…”

“…However, the base cavity does have an apparent effect on the wake structure, local pressure fluctuations, and lift force fluctuations. Peng et al 13 proposed an intelligent optimization model for the vane's trailing edge profile to eliminate the resonance of the stay vane. Wang et al 14 studied the wake flow of a turbine blade corresponding to a high Reynolds number using delayed detached eddy simulations.…”

Fatigue Strength Analysis of a Prototype Francis Turbine in a Multilevel Lifetime Assessment Procedure Part II: Method Application and Numerical Investigation

“…As more sophisticated turbulence models for numerical calculation of this phenomenon are required, and more complex meshes are necessary, the number of relevant publications is relatively tiny. Mostly, it is experimental investigations that provide a basis for the validation, such as [6] of 2019, or singular analysis of individual components, see [7] in 2017, without investigating the effects on the entire unit.…”

Optimization and Mechanism of the Wicket Gate Closing Law for High-Head Pumped Storage Power Stations

“…Simultaneously, the WGCL optimization problem has multiple objective functions and constraints, referred to as a multi-objective WGCL (MOWGCL) problem. Previous researchers have applied the heuristic optimization algorithms to the flow channel design and parameter optimization of hydraulic equipment [14][15][16], and several optimization studies have examined the MOWGCL problem [17][18]. However, previous studies usually converted the multi-objective optimization problem (MOOP) into one or two objective functions by setting weighting coefficients, which has intense subjectivity in optimization.…”