The thesis describes an experimental investigation of nucleating flows of steam in a cascade of nozzle turbine blading. To obtain nucleation in subsonic flows of steam, a supercooled supply is necessary which has been achieved under blow-down conditions. The literature survey covers the early investigations of condensation in flowing steam, the development of nucleation theory, droplets growth laws and their simple applications in the study of phenomena associated with condensation in nozzles. Finally some of the problems associated with wetness in turbines are considered. Next the experimental facility is described. The facility is a blow-down steam tunnel constructed for the study of two-dimensional two-phase flows. The instrumentation caters for the measurements of surface pressure distributions, wake traverses downstream of the cascade as well as for the optical observations and droplet size measurements. The main experimental chapter includes the results of the surface pressure measurements, wake traverses downstream of the cascade, flow observations and droplet size measurements. Some measurements of the thermodynamic nucleation losses are also presented together with the calibration of the probe used for the wake traverses. Comparisons of results under steam superheated and nucleating flows reveal the blades to have different characteristics when the outlets have been supersonic or sonic. The most notable difference has been the pressure rise associated with the zone of rapid condensation, its location and its insensitivity to changes in inlet temperatures and overall pressure ratios. In contrast, when the outlet has been subsonic, the blades exhibit similar characteristics under steam superheated and nucleating conditions. In addition, comparisons made with the results obtained previously by other investigators using different blades suggest that the interaction between the zone of rapid condensation and the aerodynamic performance of the blades can vary depending on the blade shape.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:643566 |
| Date | January 1996 |
| Creators | Mamat, Zainul Asri |
| Publisher | University of Birmingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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