avaliações numéricas de chaminés de equilíbrio - ppgerha ...

ABSTRACT
The detailed study of the hydraulic transients of water power circuits of high head
hydropower plants and the design of surge tanks is an effort that can indicate the
need for substantial changes of the structures, and the opportunity for defining them
more economically. With the present easy and cheap availability of computational
resources different computational methods for the solution of the non-permanent flow
equations in conduits can be developed without major difficulties. The aim of this
dissertation is the comparison among the results of computational models based on
numerical methods of different complexities and the data taken from a prototype
installed in a hydraulic laboratory.
Basically four methods were compared: the first is based on ordinary differential
equations of the permanent flow. The second one corresponds to the solution of the
non-permanent flow equations by the characteristic method and the third is based on
the criteria edited by ELETROBRÁS. The second and the third methods are widely
used by designers because its simplicity. The forth is the solution of the variable flow
by the Lax diffusive scheme using Pascal computer language and finite differences
method.
Generally all four methods presented results adherent to the prototype data. The
computational methods have only shown greater differences on the valve opening
data. The exception resulted from the application of ELETROBRÁS’ criteria that
showed major differences and conservative results, generally leading to anti
economic design. Thus this method is just applicable for preliminary studies.
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