Effect of inlet leakage flow on the instability in a radial vaneless diffuser

• Published in: Physics of fluids (1994) Vol. 35; no. 1
• Main Authors: Fan, M., Dazin, A., Bois, G., Romanò, F.
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 01.01.2023
• Subjects: Engineering Sciences; Fast Fourier transformations; Flow stability; Flow velocity; Fluid dynamics; Fluid flow; Fluids mechanics; Impellers; Internal flow; Mechanics; Propagation velocity; Vaneless diffusers; Wavelet analysis; Condensed Matter Physics; Flow instabilities; Computer simulation; Fluid dynamics; Fluid Flow and Transfer Processes; Mechanics of Materials; Signal processing; Computational Mechanics; Mechanical Engineering; Linear stability analysis
• ISSN: 1070-6631; 1089-7666
• DOI: 10.1063/5.0133948

The internal flow structures in a vaneless diffuser of a radial pump are experimentally and numerically investigated. Numerical simulations are used for investigating the prominent features of the fluid flow in the vaneless diffuser upon a change of the flow rate and of the impeller-to-diffuser radial gap. Comparisons between experimental and numerical results on the overall pump and diffuser performances are presented and discussed. The influence of inlet diffuser leakages on the development of flow instabilities is specifically addressed, owing to the remarkable impact that a small impeller-to-diffuser radial gap can have on the diffuser flow. Highlights on the rotating instabilities in terms of stall cell number and propagation velocity at design and off-design conditions are the main focus of this study and will be investigated using the numerical and experimental results post-processed by fast Fourier transform and wavelet analysis.