Hydrodynamic Design Considerations for Hydroacoustic Facilities: Part II—Pump Design Factors

Abstract

The St. Anthony Falls Hydraulic Laboratory has been involved in the hydrodynamic design of large cavitation facilities, which require a high performance axial flow pump that is cavitation free to meet stringent design conditions. As cavitation has been shown to be the largest noise source in an otherwise well designed facility, it must be eliminated for the design range of flow conditions. To reduce the possibility of blade cavitation it is desirable to have a near uniform, or at least, a near symmetrical approach velocity distribution at the pump inlet. The design of flow facilities to achieve such an inflow was the subject of extensive investigations. These investigations consisted of both numerical and physical modeling of critical components in the test loop. The influence of these components, which included the contraction, diffuser, and turning vanes was carefully documented. The combination of the two modeling techniques will be demonstrated as an effective design tool for a high performance, hydrodynamic test facility.

Design and Validation of a Recirculating, High-Reynolds Number Water Tunnel

“…The volumetric flowrate (0.232 m 3 /s) is readily available given the cross section and maximum speed (10 m/s). However, the total system losses are often severely underestimated due to nonuniform flow entering components [38] and assembly imperfections. From experience, the calculated total pressure losses (91 kPa) [23] are typically 3 to 4 times smaller than the as-built.…”

Numerical Investigation of Background Noise in a Circulating Water Tunnel

“…Several large water tunnels worldwide are renowned for their low background noise levels, including the French grand tunnel hydrodynamics (GTH) [19], the American large cavitation channel (LCC) [20], the German hydrodynamic and cavitation tunnel (HYKAT) [21], and the Australian Maritime College cavitation tunnel (AMCCT) [22]. Consequently, numerous methods have been developed to accurately measure sound signals within the test section of water tunnels.…”

Experimental Methods for the Study of Hydrodynamic Cavitation

“…The flow is then returned (usually after passing through a diffuser where the pressure rises) to the prime mover to continue recirculation. Examples of modern cavitation tunnels are the Grand Tunnel Hydrodynamique (GTH) in France (Lecoffre et al 1987), the Large Cavitation Channel (LCC) in the U.S.A. (Etter et al 2005), and the Hydrodynamics and Cavitation Tunnel (HYKAT) in Germany (Wetzel and Arndt 1994a;Wetzel and Arndt 1994b). Turbomachinery may be tested with closed recirculating flow loops as well, as described by Avellan et al (1987).…”