6. The design of the nozzle
The second component of this machine is the nozzle, which together with the rotor
determines the efficiency of the turbine.
It is responsible for directing the flow of water towards the rotor. This transport should possess a
good acceleration and an even distribution of speeds in the output section like a low level of load
loss, so as to achieve the best possible transformation of potential energy into kinetic energy.
The nozzle can have distinct dimensions fundamentally differentiated by the angle of admission
and the regulating valve which it has, if indeed it has one.
One should keep in mind the placement of this regulating valve, which regardless of the element
in the interior of the nozzle can provoke disturbances in the exit flow.
The nozzle possesses a rectangular cross section composed of two straight lateral surfaces which
permits the discharge of the flow across all of the rotor (figure 3), and an upper bound face that
guides the flow.
This surface possesses an optimum, constant angle on each point of the curve. The absolute
speed will be at a tangent to this curve at every single point. The surface below is straight and can
have an angle of 5 degrees maximum.
Energietechnologie Entwicklung und Beratung
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Consultants in renewable energy, micro-hydro engineering ~ especially crossflow turbines and control
systems electronic actuators.
This document was translated by Sophie Ayling from the original Spanish document
produced by Soluciones Prácticas in August 2011.
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Rugby, Warwickshire, CV23 9QZ
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