Is draft tube used in Francis turbine?
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 a draft tube in turbine?
Draft Tube is a diverging tube fitted at the exit of runner of turbine and used to utilize the kinetic energy available with water at the exit of runner. This draft tube at the end of the turbine increases the pressure of the exiting fluid at the expense of its velocity.
What are the 4 types of draft tubes?
There are mainly 4 types of draft tube, and those are:
- Conical draft tube.
- Simple elbow draft tube.
- Moody spreading draft tube.
- Elbow draft tube with a varying cross-section.
Which turbine needs draft tube?
A reaction turbine always runs completely filled with the working fluid. The tube that connects the end of the runner to the tail race is known as a draft tube and should completely to filled with the working fluid flowing through it. The kinetic energy of the fluid finally discharged into the tail race is wasted.
What is the use of 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 is a draft tube and what is its purpose?
The draft tube is a conduit which connects the runner exit to the tail race where the water is being finally discharged from the turbine. The primary function of the draft tube is to reduce the velocity of the discharged water to minimize the loss of kinetic energy at the outlet.
What is the use of draft tube answer?
The draft tube is a conduit which connects the runner exit to the tail race. The primary function of the draft tube is to reduce the velocity of the discharged water to minimize the loss of kinetic energy at the outlet.
Which type of turbine is a Francis turbine?
inward-flow reaction turbine
The Francis turbine is a type of water turbine. It is an inward-flow reaction turbine that combines radial and axial flow concepts. Francis turbines are the most common water turbine in use today, and can achieve over 95% efficiency.
In which type of turbine draft tube is used?
Explanation: The draft tube is used only in reaction turbine as there is a change in pressure energy involved. In an impulse turbine, there is no change in pressure so no need of a draft tube.