Update on Development of Auto-Venting Turbine Technology

摘要

Since the 1970s, the Tennessee Valley Authority (TVA) has been active in development of technology for the auto-venting turbine. Auto-venting turbines increase the concentration of dissolved oxygen in hydropower releases by aspirating and mixing air with the water passing through the runner. Prior to 1990, much of the emphasis for auto-venting turbine (AVT) technology focused on the development of methods to retrofit existing units by adding hub baffles, installing headcover ventilation pipes, and enhancing airflow through the vacuum breaker systems. Now, TVA is focusing on the development of aerating turbines for upgrades containing new runners. These new units include aeration objectives as an integral part of the turbine design, thus improving efficiency not only for hydraulic performance but also for environmental performance. At TVA's Norris Dam, new upgrade turbines installed in 1995 and 1996 represent the first of these new type of units in the world. This paper gives a brief summary of the performance obtained by the Norris auto-venting turbines. Each of these units contain several options to aerate the flow. The fundamental site-specific conditions needed to implement AVT technology are provided. The range of applicability is illustrated in terms of plans for new auto-venting turbines in TVAs Hydro Modernization Program. Ongoing investigations for turbine aeration are summarized, as well as comments concerning basic criteria that should be included in specifications for new AVT units.