Early stages of axial flow turbine design require a relatively simple prediction technique for estimating both blade row exit angle and loss profiles produced by secondary flows. Detailed experimental investigation of the flow field in a large scale linear cascade of high turning turbine rotor blades has been made. This gave improved understanding of cascade secondary flow phenomena. and a physical basis for secondary flow angle and loss predictions. Data suitable for comparison with three dimensional flow calculations is presented. Experimental data was obtained utilizing cobra probes throughout the flow field. and hot wire probes at cascade inlet and exit. Results are presented graphically on various planes through the flow field using both contour and vector plots. The developing passage and leading edge horseshoe vortic 3S are traced. and their interactions with the cascade inlet boundary layer are clearly visible. At cascade exit two major secondary loss components were identified: a loss core shed from the suction surface formed largely of inlet boundary layer fluid. and an area consisting of new endwall boundary layer fluid swept towards the suction surface. Highly turbulent flows were also evident close to these regions. Secondary losses were predicted using three discrete loss components: the loss core. a non skewed new endwall boundary layer. and an extra secondary loss related to the classical secondary flow kinetic energy. Experimental data from several sources was compared with secondary loss predictions with some success. Some modifications are clearly desirable to enhance the loss prediction technique. but the relatively simple method gives encouraging results.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:370328 |
| Date | January 1985 |
| Creators | Graves, C. P. |
| Publisher | Durham University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.dur.ac.uk/1238/ |
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