Dynamic mode decomposition and reconstruction of tip leakage vortex in a mixed flow pump as turbine at pump mode. (August 2020)

• Record Type: Journal Article
• Authors: Han, Yadong; Tan, Lei
• Is Part Of: Renewable energy. Volume 155(2020)
• Page Start: 725
• Page End: 734
• Publication Date: 2020-08
• Subjects: Mixed flow pump -- Tip clearance -- Tip leakage vortex -- Dynamic mode decomposition -- Proper orthogonal decomposition; Renewable energy sources -- Periodicals; Power resources -- Periodicals; Énergies renouvelables -- Périodiques; Ressources énergétiques -- Périodiques; 333.794
• DOI: 10.1016/j.renene.2020.03.142
• Languages: English
• ISSNs: 0960-1481

Abstract

Abstract: In the present work, the tip leakage vortex (TLV) in a mixed flow pump as turbine at pump mode is decomposed and reconstructed by Dynamic Mode Decomposition (DMD) for the first time. The flow field is solved by the k-ω SST turbulence model with validation of experimental data. The unstable primary tip leakage vortex (PTLV) can be mainly classified as two parts, oscillating PTLV-A and shedding PTLV-B. The evolution frequency of PTLV is 8.4 f i ( f i is the impeller rotating frequency). Results of DMD show that DMD can exactly decompose the dominant frequency of TLV evolution and its harmonic frequencies. The coherent structures captured by DMD mainly distribute near the trajectory of PTLV. Meanwhile, DMD can successfully reconstruct the flow field on basis of mean flow mode and the first mode. Proper Orthogonal Decomposition (POD) can also capture the main coherent structures of PTLV, due to the dominant frequencies of the most energetic modes contain the characteristic frequency of TLV. Highlights: The evolution frequency of tip leakage vortex is 8.4 times of impeller rotating frequency. Dynamic mode decomposition is used to decompose and reconstruct the coherent structure of a mixed flow pump. The coherent structures of tip leakage flow can be divided into two types. Major vortex structures by dynamic mode decomposition and proper orthogonal decomposition are compared.