Hydro-Electric Turbines
Environment and Fish-Friendly Design
By
A. S. Rangwala
Preface
Hydro-electric turbines offer the marvelous option of producing lean, clean and green electrical power, standing in stark contrast to emissions of fossil fuel powered electricity generating stations. Rain and melting snow gushing down the slopes of mountainous heights provide more than enough potential energy to the flowing rivers to permit the waters to drive hydro- dynamic turbines and generators that produce electricity. The sheer volume of water flowing over the Niagara Falls of North America and the tremendous height of Victoria Falls of Africa are testimony to the vast amount of energy the flowing waters possess.
The potential energy of the waters tumbling down from a great height and of the kinetic energy due to the velocity of the flowing streams and rivers has been elected to put to use for mankind's benefit. Energy in its many forms, whether thermal, mechanical and electrical, is necessary for the society to creatively function while allowing people to live a comfortable life.A most valuable resource, hydropower plants make use of this tremendous treasure. The renewableand constantly replenishing energies of flowing wateroffer the most attractive benefit of not requiring any fuel, while at the same time being free of harmful pollutants.
At the same time, harmful effects from hydropower on fish and other marine life as they get mutilated in the rotating blades of the hydraulic turbines can never be ignored. Spurring scientific research and investigation over the past decades throughout the world,vast amount of efforts have focused on understanding swimming abilities of the species, hydrologic conditions and methods to alleviate fish injury and mortality. Remedies in the form of modified turbine runner, protective screens and physical barriers have led to dramatic reductions in injury to fish. Diversions in the waterways have produced innovative habitat for many forms of life, which also have led to the interesting side benefit of protecting the fish from predatory creatures.
The myriad problems associated with water power development are put into sharp focus, with fish migration and survival topping the list. Protecting the environment for aquatic life and improving on the quality of drinking water are primary issues. Formation of air bubbles within the turbine's system achieves maximum uptake of dissolved oxygen, providing valuable aeration of water bodies.Dissolved in water in the form of microscopic bubbles, oxygen is necessary for aquatic organisms fof respiration. Since the rotating machinery of hydraulic turbines require shafts supported in bearings, greaseless technologies are of essence tomaintain water quality. Mineral oil or animal fat based lubricants invariably leakin Francis and Kaplan type hydraulic turbines,where the bearing support is in close proximity to the runner. Research pertaining to fluid flow dynamicsfocuses on strivingto obtain safe passages forvarious fish species, while also maximizing power output and minimizing capital cost.
The primary intent is to balance the needs of Nature and those of the growing world community to meet its present and future energy needs in a manner that protects the environment by improving hydropower projects and operating them more effectively. Hydro- dynamic power offers the valuable operating benefits of enhancing value to the electric system in the form of effciency, security, and most important, reliability. Impact on environment and on species living in water from the effects of hydraulic power have been successfully overcome to a great extent through application of the latest advances in scientific technologies.
The intent of this treatise is to understand and evaluate the dynamicsof obtaining the best profiles of the rotating turbine blades, stationery guide vanes and spiral casing. A hydro-dynamic turbine in its many different forms has the potential to be a very complex subject. When dealing with multi-dimensional curved surfaces of all its components,multiple objectives in the form of ensuring site compatibility for head and flow, extracting maximum power and minimizing losses are of significance. Coinciding with design requirements are operational concerns of mitigating failure as a consequence of cavitation, vortex in flow, turbulence, erosion and corrosion. The benefits of various electronic control devices to regulate opening and closing of wicker gates, vanes and swiveling of rotating runner blades are advantageously put to use. Developing the most amount of power in the generator heavily depends on the flow of water and available head as it varies between winter and summer.
This book is written to meet the needs of students in engineering colleges and practicing engineers in large and small power generating utilities. Remotely located communities not within the limits of a power distribution grid have the freedom of obtaining cheap power from a nearby flowing stream or body of water. Hydro-dynamic turbines are available ranging from micro size of a few hundred kilowatts to mega units of several hundredmegawatts. Depending on site location, the hydro-dynamic turbine and power plant system can be tailor made to meet the most challenging requirements while satisfying objections of the environmentalists.
All of the material has been carefully selected for college undergraduate and graduate level design engineering courses. Electronic spreadsheet type of calculation is used in certain example problems to design blade contours, maximize performance, avoid catastrophic failures and calculate loads, stresses dynamic response, stability and other related design parameters.
Contents
1 – Harnessing Power of Flowing Water
2 – Hydro Power, A Renewable Energy Source
3 – Water Powered Power Plants
4 – Research and Scientific Investigation to Meet Environmental Concerns
5 – Fish Swimming Characteristics and Protection Screens
6 – Fish –Friendly Turbine Design Criteria
7 – Applying Fluid Mechanic and Thermo-Dynamic Principles
8 – Extracting Power with Fluid Machinery
9 – Impact of Specific Speed on Turbine Type
10 – Pure Impulse Pelton Turbine
11 – Combined Impulse-Reaction Francis Turbine
12 – Reaction Type Kaplan, Bulb and Propeller Turbines
13 – Erosion and Cavitation Damage
14 – Maximizing Turbine Performance
15 – Rotating Unbalance and Vibration
16 – Advanced Electrical Generator
17 – Load Management, Control, Governing Systems
18 – Operation, Inspection, Preventive Maintenance
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