Location
Weber State University
Start Date
5-8-2017 9:22 AM
End Date
5-8-2017 12:00 AM
Description
Inducers are used as a first stage in pumps to hinder cavitation and promote stable flow. Inducers pressurize the working fluid sufficiently such that cavitation does not develop in the rest of the pump, which allows the pump to operate at lower inlet head conditions. Despite the distinct advantages of inducer use, an undesirable region of backflow and resulting cavitation can form near the tips of the inducer blades. This backflow is often attributed to tip leakage flow, or the flow induced by the pressure differential across an inducer blade at the tip. We examine backflow of a single inducer geometry at varying flow coefficients with a tip clearance of τ = 0.32%, and no tip clearance. Removing the tip clearance prevents tip leakage flow. At all flow coefficients below design, we observe backflow penetrating up to 14% further upstream in the inducer with no tip clearance. The backflow region in the inducer with no tip clearance experiences higher velocities and extends further into the core flow. However, the inducer with tip clearance develops a larger vortex at the leading edge of the blades. A comprehensive analysis of these simulations suggests that diffusion as the working fluid is loaded onto the blades, not tip leakage flow, is the driving force for the formation of backflow.
Included in
A Numerical Study of the Development of Inducer Backflow
Weber State University
Inducers are used as a first stage in pumps to hinder cavitation and promote stable flow. Inducers pressurize the working fluid sufficiently such that cavitation does not develop in the rest of the pump, which allows the pump to operate at lower inlet head conditions. Despite the distinct advantages of inducer use, an undesirable region of backflow and resulting cavitation can form near the tips of the inducer blades. This backflow is often attributed to tip leakage flow, or the flow induced by the pressure differential across an inducer blade at the tip. We examine backflow of a single inducer geometry at varying flow coefficients with a tip clearance of τ = 0.32%, and no tip clearance. Removing the tip clearance prevents tip leakage flow. At all flow coefficients below design, we observe backflow penetrating up to 14% further upstream in the inducer with no tip clearance. The backflow region in the inducer with no tip clearance experiences higher velocities and extends further into the core flow. However, the inducer with tip clearance develops a larger vortex at the leading edge of the blades. A comprehensive analysis of these simulations suggests that diffusion as the working fluid is loaded onto the blades, not tip leakage flow, is the driving force for the formation of backflow.