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New scroll case design improves flow for experimental turbine

A new design developed for the scroll case of the Alden/Concepts NREC turbine doubles the flow without increasing the footprint of the scroll case. Alden Research Laboratory Inc. worked with EPRI to redesign the scroll case to increase flow and thus the power that may be extracted by the runner.

The turbine is designed to allow safe fish passage and to achieve power efficiencies that are competitive with conventional turbine runners. The Alden/ Concepts NREC turbine features a runner with three helical blades attached to a central hub and a shroud attached to the outside edges of the blades, eliminating all gaps. (See “R&D Forum,” June 2004.)

EPRI developed the new design after earlier tests using a pilot-scale version of the turbine indicated it did not produce enough power for its size to be competitive in the commercial market. To design the new scroll case, the research team performed computational fluid dynamics (CFD) simulations using FLUENT 6.2.16 software.

The scroll case developed as a result of this research project has an overall plan diameter only 2 percent larger than the pilot-scale Alden/Concepts NREC turbine scroll case, while passing 100 percent more flow at the same velocities.

EPRI released a technical report on this research. Program on Technology Innovation: Redesign of the Alden/Concepts NREC Helical Turbine for Increased Power Density and Fish Survival describes the development of the new design for the scroll case.

Future work to develop the Alden/ Concepts NREC turbine involves redesigning the runner to complement the revised scroll case design.

– For more information or to buy a copy of this report for $25,000, contact EPRI Customer Assistance Center, (1) 800-313-3774; E-mail: askepri@ epri.com.

Satellite-based sensors to aid in monitoring earth dams

Research being performed at the University of Missouri-Columbia aims to validate the applicability of using data from sensors on satellites to monitor dams. Interferometric synthetic aperture radar (InSAR) sensors mounted on satellites provide high-resolution deformation monitoring of large spatial areas.

InSAR sensors are located on three satellite platforms launched by the European Space Agency (ESA). ERS-1 was launched in July 1991, ERS-2 in April 1995, and ENVISAT in March 2002. These sensors transmit electromagnetic energy toward the terrain, where the energy interacts with the terrain and produces an echo. This echo is transmitted back to the sensor on the satellite, where it is recorded.

InSAR sensors can be used to remotely sense: soil water content within a dam and around the penstock; total settlement of the dam; and surface deformations caused by active sliding surfaces and/or piping within the dam. The current state-of-practice uses in situ tools – such as nuclear density gauges, surveying equipment, and slope indicators – to monitor these conditions. However, this equipment can be costly and provides spatially limited point measurements.

The researcher, Richard Coffman, is investigating the use of InSAR to monitor post-construction settlement, movement, and compaction of earth dams. Satellites carrying the InSAR sensors pass an orbit location every 32 days. The ERS-1 and ERS-2 satellites follow the same orbit, one day apart.

Because the satellites have been in orbit for as long as 16 years, this data can be used for post-construction analysis of dams built since 1991. InSAR satellite radar images are commercially available through the ESA for about $269.

In addition to post-construction monitoring, the images can be used to assess structural condition after a natural event (hurricane, tornado, or earthquake) or a man-made one (terrorist attack, explosion, or operational error).

CEATI publishes report on fire protection, suppression

CEATI announces availability of a report covering all aspects of fire protection and suppression in hydroelectric facilities. The report is titled Technology Review: Fire Protection and Suppression in Hydroelectric Plants.

Fire protection issues covered in the report include: fire investigation; live fire training; fire protection design, testing, commissioning, and management; emergency planning; risk and economic analysis; and computer hazard modeling.

The technology review contains:

– A copy of a PowerPoint presentation from a workshop on fire protection, held in February 2006;

– A comprehensive self-audit checklist that allows users to perform a high-level review of fire protection and fire safety at their plants;

– BC Hydro’s design standard for fire protection at hydroelectric facilities;

– Areas of investigation to be considered for future work by CEATI, including fire protection lessons learned, hydroelectric generator fire protection, hydroelectric fire scenarios, and special hazards and fire protection measures for underground hydro plants; and

– The U.S. Army Corps of Engineers’ 2005 report on carbon dioxide fire protection.

This technology review was developed by CEATI’s Hydraulic Plant Life Interest Group. This group is comprised of 40 power generators joined together through CEATI to share experiences and to address issues pertinent to their day-to-day operations and life cycle management of various plant assets.

– For more information or to purchase this report, contact (1) 514-866-5372; E-mail: publications@ceatech.ca.


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