Design, construction and testing of an outward radial-flow reaction water turbine

Thesis Overview

<p> INTRODUCTION<br>1.1 Statement of the Problem<br>Water in nature is a useful source of energy. Its energy comes directly in<br>mechanical form, without the losses involved in heat engines and fuel cells, and no<br>fuels are necessary. Solar heat evaporates water, mostly from the oceans, where it is<br>mixed into the lower atmosphere by turbulence, and moved by the winds. Through<br>meteorological processes, it falls on the earth as precipitation, on the oceans, but also<br>on high ground, where it makes its way downhill to the sea, without evaporative and<br>other losses. A cubic meter of water can give 9800J of mechanical energy for every<br>meter it descends, and a flow of a cubic meter per second in a fall of 1m can provide<br>9800W, or 13hp. The efficiency of hydraulic machines can be made close to 100%, so<br>that this energy is available, and it can be converted to electrical energy with an<br>efficiency of over 95%. Hydropower and increasing population cannot co-exist; the<br>limits of hydropower are fixed and obvious. The percentage of hydropower is<br>dropping by the day. It is not that hydropower is decreasing in absolute terms; it had<br>remained roughly constant while the total market had expanded greatly. The oil<br>reserve is depleting and the cost is constantly on the increase.<br>Sprinklers are mainly used for sprinkling water in many areas, namely; Truck<br>crops, nurseries, orchards, gardens, lawns, application of fertilizer, soil amendments,<br>log curing, water distribution for compaction of earth fills, setting of dust, farm fire<br>protection, frost protection, cooling crops and animals, dewatering of mines and<br>excavation.<br>– 23 –<br>Considering these areas where sprinklers are used, lighting these places will<br>greatly enhance the working time, and ease working in the places at night. This is<br>currently possible by using power from National grid or other power sources which<br>are costly and could be eliminated if we can use the residual power head to rotate a<br>dynamo and generate electricity.<br>1.2 Significance of the Study or Justification for the<br>Study<br>Hydro-energy technology is environment friendly, renewed naturally by<br>rainwater and melting of snow on high mountains during summers and simple.<br>Waterpower is available whenever a sufficient volume of steady water flow exists.<br>Hydro schemes are multipurpose. The water is used before and after power generation<br>and there is no wastage of water. Only the head is lost during power generation. The<br>operating cost of water turbine is very low, it has long service life and the renewable<br>energy resource occurs free of cost.<br>Energy is essential for sustaining civilization, the economic prosperity of a<br>nation or region or state or individual consumer is directly influenced by the quantity<br>of energy generated and consumed. Thus, there is a need to generate as much energy<br>as possible from all sources to meet human requirements. One way of achieving this is<br>through power generation from reaction hydro turbines (sprinkler heads).<br>– 24 –<br>A system is more efficient and effective, if it is made to operate as<br>independent as possible from other system which is the case of this reaction turbine<br>(sprinkler).<br>1.3 Theoretical Framework<br>The real flow through a rotor is three-dimensional, that is to say the velocity of<br>the fluid is a function of three positional coordinates, say, in the cylindrical system, r,<br> and z. Thus, there is a variation of velocity not only along the radius but also across<br>the passage in any plane parallel to the rotor rotation, which constitutes an abrupt<br>change – a discontinuity. Also, there is variation of velocity in the meridional plane,<br>i.e. along the axis of the rotor. The velocity distribution is, therefore, very complex,<br>and dependent upon the width of the rotor and its variation with radius.<br>The one – dimensional theory simplifies the problem very considerably by<br>making the following assumptions.<br>(i) That the flow is axisymmetric, which means that there is a perfect<br>symmetry with regard to the axis of rotor rotation. Thus;<br> 0<br><br>V<br>(ii) Over that part of the rotor where transfer of energy takes place,<br>There is no variation of velocity in the meridional plane, i.e. across the<br>width of the rotor. Thus,<br> 0<br>z<br>V<br><br><br>The result of these assumptions is that whereas, in reality,<br>– 25 –<br>V  V(r, , z)<br>For the one-dimensional flow<br>V  V(r) ï‚¥<br>The suffix ï‚¥ stipulates axisymmetry<br>(iii) That there is imaginary body forces acting on the fluid and producing<br>torque<br>1.4 Objectives of the Study<br>Given that there is increasing need to find other sources of energy and the fact<br>that a sprinkler is the simplest form of a reaction water turbine, it is necessary to<br>devise a means by which electricity could be generated from the sprinkler heads. In<br>view of the importance of lighting the places that sprinklers are used when it is dark,<br>use of other power sources rather than the sprinkler head will be eliminated. The<br>objective of this research is therefore to review the design of a simple outward flow<br>reaction water turbine and develop it to serve as a water sprinkler as well as a source<br>of mechanical power for driving an electric dynamo for the generation of electricity to<br>lighten up the place it is used when it is dark whenever there is water in the supply<br>mains. Test is also to be carried out to ascertain the efficiencies of the device under<br>various water pressures.<br>1.5 Statement of Research Questions<br>The fact that sprinklers could be built to serve as water turbine as well, and<br>given that hydro power had remained roughly constant while the total market had<br>– 26 –<br>expanded greatly, water could be further exploited by building water turbines to serve<br>as sprinklers as well as a source of mechanical power for driving electric dynamos for<br>the generation of electricity to lighten up the places. They would be used when it is<br>dark whenever there is water in the supply mains.<br>The focus of this work is therefore how to exploit energy from water turbines<br>(sprinklers) to generate electricity. The effect of load (electric dynamo) on the<br>efficiency of sprinkler is also to be determined.<br>– 27 – <br></p>