1. Fig. 4.10 Inward flow reaction turbines
A course in Turbomachinery…………………………………..….…Lecturer: Dr.Naseer Al-Janabi
4.4 Classification of Reaction turbines
The reaction turbines may be classified into the following three
types, depending upon the direction of flow of water:
1. Radial flow turbines.
2. Axial flow turbines.
3. Mixed flow turbines.
4.4.1 Radial flow turbines
In such turbines, the flow of water is radial
i Inward flow turbines: in such turbines, the water enters the wheel
at the outer periphery, and then flows inward (i.e. towards the center
of the wheel).
Fig Inward flow reaction turbines
ii Outward flow turbines: in such turbines, the water enters at the
center of the wheel, and then flows outward (i.e. towards the the
outer periphery of the wheel).

2. Fig. 4.11 Outward flow reaction turbines
A course in Turbomachinery…………………………………..….…Lecturer: Dr.Naseer Al-Janabi
Fig Outward flow reaction turbines
EX:A retrofit Francis radial-flow hydroturbine is being designed to replace
an old turbine in a hydroelectric dam. The new turbine must meet the
following design restrictions in order to properly couple with the existing
setup: The runner inlet radius is r2 = 8.20 ft (2.50 m) and its outlet radius is
r1= 5.80 ft (1.77 m). The runner blade widths are b2 =3.00 ft (0.914 m) and
b1 = 8.60 ft (2.62 m) at the inlet and outlet, respectively. The runner must
rotate at N= rpm (ω = rad/s) to turn the 60-Hz electric
generator. The wicket gates turn the flow by angle α2 = 33° from radial at
the runner inlet, and the flow at the runner outlet is to have angle α1
between -10° and 10° from radial for proper flow through the draft tube.
The volume flow rate at design conditions is 9.50 ⨯ 106 gpm (599 m3/s),
and the gross head provided by the dam is Hgross = 303 ft (92.4 m).
(a) Calculate the inlet and outlet runner blade angles β2 and β1,
respectively, and predict the power output and required net head if
irreversible losses are neglected for the case with α1 = 10° from radial
(withrotation swirl).

3. A course in Turbomachinery…………………………………. …. …Lecturer: Dr
A course in Turbomachinery…………………………………..….…Lecturer: Dr.Naseer Al-Janabi
(b) Repeat the calculations for the case with α1 = 0° from radial (no swirl).
(c) Repeat the calculations for the case with α1 = -10° from radial (reverse
swirl).