What are the different types of draft tube?
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.
How many types of draft are there?
Drafts are produced by the rising combustion gases in the stack, flue, or by mechanical means. For example, a blower can be put into four categories: natural, induced, balanced, and forced. Natural draft: When air or flue gases flow due to the difference in density of the hot flue gases and cooler ambient gases.
What is draft tube Slideshare?
The draft tube is pipe of gradually increasing area which connects the outlet of the runner to the tail race. It is used to discharging water from the exit of the turbine to the tail race. This pipe of gradually increasing area is called Draft tube.
What is draft tube and its functions?
Draft tube: 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 conical draft tube?
1 Conical Diffuser Draft Tube: This draft tube is fabricated with mild steel plates. It is tapered in shape and the outlet diameter is larger than inlet diameter of this draft tube. The tapered angle of draft tube should not be too large as it will cause the sepeartion of flow from the wall of draft tube .
What type of pressure does the draft tube depend upon?
gauge pressure
What type of pressure does the draft tube depend upon? Explanation: Draft tube is mainly used to determine the gauge pressure of the turbine and pumps and is located at the inlet of the turbine. Explanation: Gauge pressure of the draft tube is denoted by ‘P’.
What is balanced draft?
Applied to combustion units in which forced and induced drafts are adjusted to give atmospheric pressure in the combustion chamber to avoid the infiltration of unwanted cold air.
What is draft tube pressure?
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.
Why draft tube is used in reaction turbine?
It is one of the important component of reaction turbine and connects runner exit to tail race. The main functions of draft tube is to allow the installation of turbine above the tail race level without loss of head and to convert major part of kinetic energy coming out of runner into pressure energy.
Why draft tube is submerged in water?
A draft tube is a connecting pipe fitted generally at the outlet or exit of a turbine in order to convert the kinetic energy of water at the outlet into static pressure. with this component, wastage of the kinetic energy of water is avoided. This outlet is always submerged in water.
What is the maximum value of efficiency in a draft tube?
90 percent
Explanation: The maximum value of efficiency in a draft tube is 90 percent. It cannot exceed more than 90 percent because of the heat losses due to flow of fluid.
What are the different types of draft tubes?
Conical diffuser or straight divergent tube- This type of draft tube consists of a conical diffuser with half angle generally less than equal to 10° to prevent flow separation. It is usually employed for low specific speed, vertical shaft Francis turbine. Efficiency of this type of draft tube is 90%
What is a conical diffuser draft tube?
Conical diffuser or straight divergent tube- This type of draft tube consists of a conical diffuser with half angle generally less than equal to 10° to prevent flow separation. It is usually employed for low specific speed, vertical shaft Francis turbine.
What is the efficiency of draft tube?
) The efficiency of draft tube depends upon the shape of the draft tube. Pressure at the exit of runner is suction pressure and it should not be reduced to vapour pressure. This is all about draft tube types, purpose, function, efficiency etc.
What is the purpose of a draft tube in a turbine?
You are reading a preview. Create your free account to continue reading. Draft tube is used to increase the pressure from the low turbine exit pressure to the pressure of the surrounding to which the fluid is rejected. Pratik Patil , Student at N.D.M.V.P.Samajs College of Education, Satana,Tal. Baglan, Dist.Nashik 423301 2 years ago 1.