IOP CONFERENCE SERIES. EARTH AND ENVIRONMENTAL SCIENCE
Abstract
The first part of the paper illustrates the set-up and the methodologies adopted for the
numerical analysis of the flow in a 6-jet Pelton turbine with vertical axis. At first, steady state
simulations of flow in a distributor for three positions of needle stroke were performed. The results
were used for the calculation of flow energy losses, analysis of jet quality and setting inlet boundary
conditions for runner analysis. Runner analysis was done only for the maximal opening. The purpose
of runner analysis for the model size was efficiency prediction. Numerical results were validated with
the results from the test rig. Simulations for the prototype were done in order to check whether water
sheets evacuating from the buckets impact the previous bucket and whether there is any interaction
between the evacuating water sheets and the incoming jets. Analysis was done also for one nozzle
operation. In the second part of the paper cavitation prediction for the prototype of a 2-jet Pelton
turbine is presented. The problem, because of computational cost, was reduced to five runner buckets
and one jet. A multiphase flow consists of water, air and water vapour. For cavitation pitting the
vapour has to stick to the buckets and mass transfer from vapour to water has to happen in a very short
time without the presence of air. With detailed analysis of numerical results it was concluded that in
this case no cavitation pitting is expected.
