Info

J <40 2

FIGURE 10.14 Computational grid for pitched blade turbine simulation.

downwards as it moves away from the leading blade. To examine the flow structure around the impeller blades, predicted mean velocity fields behind the impeller blades of the pitched blade turbine at four different angles from the blade (1°, 8°, 15°, 30°) are shown in Fig. 10.17. The presence of the trailing vortex and its movement within the impeller stream is clearly evident from these figures. Comparison of these predicted results with the experimental data of Schafer et al. (1997, 1998) shows good qualitative as well as quantitative agreement.

The predicted circumferential profiles at three different radial locations at z/T = 0.329 were compared with experimental data. Figs 10.18-10.20 show the results of normalized axial and radial velocity components, and normalized turbulent kinetic energy, respectively for the pitched blade turbine. It can be seen that the predicted results of axial velocity show good agreement with experimental data (Fig. 10.18). In the region near the trailing blade, predicted results show a sharp peak in the downward velocity, which was not observed in the experimental data. It may, however, be noted that experimental data measured using LDA generally has a large scatter in the region near the rotating blades. Outside the impeller swept region, the agreement between predicted and experimental data looks quite satisfactory. Similar

0 0

Post a comment