Bubble size characteristics in the wake of ventilated hydrofoils with two aeration configurations

Ashish Karn, Christopher R. Ellis, Christopher Milliren, Jiarong Hong, David Scott, Roger E.A. Arndt, John S. Gulliver

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Aerating hydroturbines have recently been proposed as an effective way to mitigate the problem of low dissolved oxygen in the discharge of hydroelectric power plants. The design of such a hydroturbine requires a precise understanding of the dependence of the generated bubble size distribution upon the operating conditions (viz. liquid velocity, air ventilation rate, hydrofoil configuration, etc.) and the consequent rise in dissolved oxygen in the downstream water. The purpose of the current research is to investigate the effect of location of air injection on the resulting bubble size distribution, thus leading to a quantitative analysis of aeration statistics and capabilities for two turbine blade hydrofoil designs. The two blade designs differed in their location of air injection. Extensive sets of experiments were conducted by varying the liquid velocity, aeration rate and the hydrofoil angle of attack, to characterize the resulting bubble size distribution. Using a shadow imaging technique to capture the bubble images in the wake and an in-house developed image analysis algorithm, it was found that the hydrofoil with leading edge ventilation produced smaller size bubbles as compared to the hydrofoil being ventilated at the trailing edge.

Original languageEnglish (US)
Pages (from-to)73-84
Number of pages12
JournalInternational Journal of Fluid Machinery and Systems
Volume8
Issue number2
DOIs
StatePublished - Jan 1 2015

Keywords

  • Auto-venting turbines
  • Bubble size distribution
  • Hydroturbine aeration
  • Shadow Image Velocimetry
  • Ventilated hydrofoil

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