DANSK DS/EN 62097 + CD-ROM PDF

1.1 General remarks Advances in the technology of hydraulic turbo-machines used for hydroelectric power plants indicate the necessity of revising the scale effect formula given in IEC Publication 60193-1999. (1) The advance in knowledge of scale effects originates from work done by research institutes, manufacturers and relevant working groups within the organizations of IEC and IAHR. (2) – (7) The method of calculating prototype efficiencies, as given in this code, is supported by experimental work and theoretical research on flow analysis and has been simplified for practical reasons and agreed as a convention. (8) – (10) The method is representing the present state of knowledge of the scale-up of performance from model to a homologous prototype. Homology is not limited to the geometric similarity of the machine components, it also calls for homologous velocity triangles at the inlet and outlet of the runner/impeller. (2) Therefore, compared to the previous Code IEC 60193, a higher attention has to be paid to the geometry of guide vanes. According to the present state of knowledge, it is certain that, in most cases, the formula for the efficiency step-up calculation given in the previous Code IEC 60193-1999 and earlier codes, overstated the step-up increment of the efficiency for the prototype. Therefore, in the case where a user wants to restudy a project for which a calculation of efficiency step-up was done based on any previous method, the user shall re-calculate the efficiency step-up with the new method given in this code, before restudying the project of concern. This standard is intended to be used mainly for the assessment of the results of contractual model tests of hydraulic machines. If it is used for other purposes such as evaluation of refurbishment of machines having very rough surfaces, special care should be taken as described in Annex B. Due to the lack of sufficient knowledge about the loss distribution in Deriaz turbines or storage pumps, this code does not provide the scale effect formula for them. Note: Numbered references in this document are assembled in Annex F : Informative references.