A hydraulic machine transfers mechanical energy between a liquid flowing through it and its operating member (such as a runner or piston). Turbines and pumps are two types of hydraulic machines. Turbines can be classified according to the type of energy at their inlet (impulse or reaction), the direction of fluid flow through the runner (tangential, radial, axial, or mixed), or the head of water at their inlet (high, medium, or low head). They can also be classified based on their specific speed, which is a measure of the speed a geometrically similar turbine would operate at to produce unit power under unit head. Common examples of turbines that fall under each classification are provided.

1. Hydraulic machine
Device in which mechanical energy is transferred from the
liquid flowing through the machine to its operating member
(runner, piston and others) or from the operating member of
the machine to the liquid flowing through it.
Turbines Pumps

2. Classification of Turbines

4. According to the type of energy at inlet:
1. Impulse turbine:
Eg. Pelton wheel turbine.
Efficient when operated with a large head and lower flow rate.
1. Reaction turbine:
Eg. Francis turbine and Kaplan turbine
Efficient when operated with a low-head and high-flow rate

5. Impulse turbine:

6. Reaction turbine

7. According to the direction of flow through runner:
1. Tangential flow turbines: Eg. Pelton wheel turbine
2. Radial flow turbines
I. Inward flow turbine: Eg. old Francis turbine.
II. Outward flow turbine : Eg. Fourneyron turbine.
3. Axial flow turbine: Eg. Kaplan turbine and propeller turbine.
4. Mixed flow turbine: Eg. Modern Francis turbine.

8. Tangential flow turbines
Axial flow turbine
Radial flow turbines
Mixed flow turbine

9. Tangential flow turbines:
Eg. Pelton wheel turbine

10. 1. Radial flow turbines
I. Inward flow turbine: Eg. old Francis turbine.
II. Outward flow turbine : Eg. Fourneyron turbine
Inward flow turbine

11. Outward flow turbine : Eg. Fourneyron turbine

12. Axial flow turbine: Eg. Kaplan turbine and propeller turbine.

13. Axial flow turbine: Eg. Kaplan turbine and propeller turbine.

14. Mixed flow turbine: Eg. Modern Francis turbine.
Cut here

15. Mixed flow turbine: Eg. Modern Francis turbine.

16. According to the head at inlet of turbine:
1. High head turbine: In this type of turbines, the net head
varies from 150m to 2000m or even more, and these turbines
require a small quantity of water. Eg: Pelton wheel turbine.
2. Medium head turbine: The net head varies from 30m to
150m, and also these turbines require moderate quantity of
water. Eg. Francis turbine.
3. Low head turbine: The net head is less than 30m and also
these turbines require large quantity of water. Eg. Kaplan
turbine.

18. According to the specific speed of the turbine
The specific speed of a turbine is defined as, the speed of
a geometrically similar turbine that would develop unit power
when working under a unit head (1m head).
1. Low specific speed turbine:
The specific speed is less than 50. Eg: Pelton wheel turbine.
2. Medium specific turbine:
The specific speed is varies from 50 to 250. Eg. Francis turbine.
3. High specific turbine:
The specific speed is more than 250. Eg. Kaplan turbine.