What is the function of draft tube in hydraulic turbines?
The draft tube is an important component of a Francis turbine which influences the hydraulic performance. It is located just under the runner and allowed to decelerate the flow velocity exiting the runner, thereby converting the excess of kinetic energy into static pressure.
What is the main principle of draft tube?
The principal purpose of the draft tube is to convert water kinetic energy into pressure energy. To decrease the velocity of the water and to raise the pressure of the water before joining the tailrace, the pipe is used to steadily increase the cross-sectional area.
Why do we use draft tube in reaction turbine?
The draft tube has two purposes as follows: It permits a negative or suction head to be established at the runner exit, thus making it possible to install the turbine above the tailrace level without loss head. It is used to convert kinetic energy at the exit of the turbine to the pressure energy.
What are the advantages of a draft tube?
The advantages of using the draft tube are: The net head of the turbine is increased as the hight between the exit of the turbine and tailrace is increased due to usage of the draft tube. The use of a draft tube considerably reduces the amount of kinetic energy available at the tailrace.
What is the turbine draft tube used for?
reaction turbine
Why is it used in a reaction turbine?
Reaction turbines develop torque by reacting to the gas or fluid’s pressure or mass. The pressure of the gas or fluid changes as it passes through the turbine rotor blades. Reaction turbines are better suited to higher flow velocities or applications where the fluid head (upstream pressure) is low.
Which turbine has highest speed?
Which turbine has highest speed? Explanation: Francis turbine has a specific speed of 60 to 300 rpm. Specific speed of Pelton turbine is lowest. Speed of Kaplan turbine is 2 to 3 times more than that of Francis turbine.
What is difference between impulse and reaction turbine?
What is the difference between the Impulse and Reaction Turbine? In an Impulse turbine, All hydraulic energy is converted into kinetic energy by a nozzle whereas In a Reaction turbine Only some amount of the available energy is converted into kinetic energy.
What is reaction turbine simple definition?
: a turbine with rotating blades curved and arranged so as to develop torque from gradual decrease of steam pressure from inlet to exhaust — compare impulse turbine.
What is the another name of reaction turbine?
Steam Turbines The fixed blades act as nozzles. The moving blades move as a result of the impulse of steam received (caused by a change in momentum) and also as a result of expansion and acceleration of the steam relative to them. In other words, they also act as nozzles (Figure 6.16).
What are the types of turbines?
Types of Turbines Based on Energy Exchange between the water and the Machine
- Impulse Turbines.
- Reaction Turbines.
- Radial Flow Turbine.
- Tangential or Peripheral Flow Turbines.
- Axial Flow Turbines.
- Mixed Flow Turbines.
- Low Head Turbines.
- Medium Head Turbines.
How many type of reaction turbine are there?
Reaction based turbines include three subtypes: Francis turbine, propeller turbine (bulb turbine, Straflo turbine, Kaplan turbine types), and kinetic turbine.
Which turbine is used for high head?
Hydropower Turbines
| Hydropower Turbine Type | Typical Site Characteristics |
|---|---|
| Kaplan turbine | Low to medium heads (1.5 – 20 metres) Medium to high flows (3 m3/s – 30 m3/s) For higher flows multiple turbines can be used. |
| Pelton/Turgo turbine | High heads (greater than 25 metres) Lower flows (0.01 m3/s – 0.5 m3/s) |
Which principle is used in hydraulic turbine?
Which principle is used in Hydraulic Turbines? Explanation: A Hydraulic Machine uses the principle of momentum which states that a force is generated which is utilized in a turbine. Explanation: Turbines use blades and buckets to alter the direction of water.
Where are hydraulic turbines used?
Hydro turbines are devices used in hydroelectric generation plants that transfer the energy from moving water to a rotating shaft to generate electricity. These turbines rotate or spin as a response to water being introduced to their blades.
What is the function of hydraulic turbine?
A hydraulic turbine converts the potential energy of a flowing liquid to rotational energy for further use. In principle, there is no restriction on either the liquid or the use for the energy developed. However, in most cases, these are respectively water and electrical generation.
What are the applications of hydraulic turbine?
Usages of Hydraulic Turbine : It is used for the generation of electric power in dams. It will control the floods in the rivers. The water which stays in a reservoir can be used for agriculture purposes.
What is impulse turbine give example?
Artwork: A Pelton water wheel is an example of an impulse turbine. It spins as one or more high-pressure water jets (blue), controlled by a valve (green), fire into the buckets around the edge of the wheel (red).
How do you classify hydraulic turbine?
Hydraulic turbines may be classified in the following ways: i) According to the type of energy at inlet. a) Impulse turbine b) Reaction turbine. ii) According to the direction of flow through runners. a) Tangential flow b) Radial flow c) Axial flow d) Mixed flow turbines.