Question: a vertical axis kaplan turbine is to be designed for...
A vertical axis Kaplan Turbine is to be designed for an overall
head of 9 m, delivering 800 kW
at a rotational speed of 150 rev/min. The vanes and runner are to be mounted in an annular
duct of outer diameter 2 m and inner diameter 0.8 m. There is to be no exit swirl, and a draft
tube reduces the axial velocity by a factor of two. Making a reasonable assumption for the
overall efficiency, estimate the required flow rate and hence the flow angle at exit from the
vanes and the relative flow angles at inlet and exit for the runner. The losses of total head are
(a) across the guide vanes, 6% of exit velocity head
(b) across the runner, 8% of the exit relative velocity head
(c) in the draft tube, 20% of the change in the velocity head.
Calculate the overall efficiency (for comparison with your estimate)