Abstract

Three-dimensional two-phase unsteady CFD simulations were run on three and four-blade inducers for the purpose of analyzing differences in cavitation stability at design and off-design flow rates. At design flow rates, there were very small differences between the breakdown curves for the three and four-bladed inducers. However, at lower cavitation numbers, the three-bladed inducer exhibited up to three times the rotor forces than the four-bladed inducer. When moving to off-design flow rates, both inducers experienced multiple modes of cavitation instabilities including rotating cavitation, alternate-blade cavitation, and cavitation surge. The four-bladed inducer began experiencing the formation of these modes of instability beginning at a cavitation number of $sigma = 0.047$ whereas the three-bladed inducer began at a cavitation number of $sigma = 0.091$. Additionally, the three-bladed inducer showed rotor forces up to ten times higher than the four-bladed inducer at similar cavitation numbers.Three-dimensional single-phase steady CFD simulations were run on four-blade inducer geometries with $7^{circ}$, $9^{circ}$, $11^{circ}$ and $14^{circ}$ inlet tip blade angles with a stability control device (SCD) installed. The simulations were ran at multiple flow coefficients. Results show interesting flow effects from the SCD. For example, at lower flow coefficients, the incidence angle actually decreases at greater than 70\% span. This is due to a region of accelerated axial flow coming from the recirculation of the SCD which occurs near the shroud. Results also show strong correlations between efficiency and head rise to the local mass flow gain experienced due to the recirculating flow through the SCD. A best fit curve was generated to predict mass flow gain based on the inducer's inlet tip blade angle and flow coefficient. Based on this research, the ability to predict mass flow gain and consequently efficiency and head rise for similarly designed inducers with varying inlet blade angles has been demonstrated.

Degree

MS

College and Department

Ira A. Fulton College of Engineering and Technology; Mechanical Engineering

Rights

http://lib.byu.edu/about/copyright/

Date Submitted

2015-05-01

Document Type

Thesis

Handle

http://hdl.lib.byu.edu/1877/etd7784

Keywords

inducer, high suction performance, cavitation, CFD

Share

COinS