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Which of the following turbine does not require draft tube ?
- a)Kaplan turbine
- b)Pelton turbine
- c)Francis turbine
- d)Propeller turbine
Correct answer is option 'B'. Can you explain this answer?
Verified Answer
Which of the following turbine does not require draft tube ?a)Kaplan t...
Concept:
- In Impulse Turbine, the available hydraulic energy is first converted into kinetic energy by means of an efficient nozzle
- The high-velocity jet issuing from the nozzle then strikes a series of suitably shaped buckets fixed around the rim of a wheel
- The buckets change the direction of the jet without changing its pressure
- The resulting change in momentum sets buckets and wheels into rotary motion and thus mechanical energy is made available at the turbine shaft
- The fluid jet leaves the runner with a reduced energy
- The impulse turbine doesn't use a draft tube. Ex. Pelton wheel
- The draft tube is used only in Reaction turbines. Ex. Francis turbine, Kaplan turbine, Propeller turbine
Draft Tube:
- The draft tube is a conduit that connects the runner exit to the tailrace where the water is being finally discharged from the turbine. It is used with reaction turbines only.
- The draft tube has two purposes as follows if
- 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 converts a large proportion of velocity energy rejected from the runner into useful pressure energy.
- A draft tube is made divergent so as to reduce the velocity at the outlet to a minimum. Therefore, a draft tube is basically a diffuser and should be designed properly with the angle between the walls of the tube to be limited to about 8 degrees so as to prevent the flow separation from the wall and to reduce accordingly the loss of energy in the tube.
From the equation of the continuity,
A1V1 = A2V2
V∝1/A
The area at the exit is higher, therefore the velocity of discharged water will be lower.
Most Upvoted Answer
Which of the following turbine does not require draft tube ?a)Kaplan t...
Concept:
- In Impulse Turbine, the available hydraulic energy is first converted into kinetic energy by means of an efficient nozzle
- The high-velocity jet issuing from the nozzle then strikes a series of suitably shaped buckets fixed around the rim of a wheel
- The buckets change the direction of the jet without changing its pressure
- The resulting change in momentum sets buckets and wheels into rotary motion and thus mechanical energy is made available at the turbine shaft
- The fluid jet leaves the runner with a reduced energy
- The impulse turbine doesn't use a draft tube. Ex. Pelton wheel
- The draft tube is used only in Reaction turbines. Ex. Francis turbine, Kaplan turbine, Propeller turbine
Draft Tube:
- The draft tube is a conduit that connects the runner exit to the tailrace where the water is being finally discharged from the turbine. It is used with reaction turbines only.
- The draft tube has two purposes as follows if
- 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 converts a large proportion of velocity energy rejected from the runner into useful pressure energy.
- A draft tube is made divergent so as to reduce the velocity at the outlet to a minimum. Therefore, a draft tube is basically a diffuser and should be designed properly with the angle between the walls of the tube to be limited to about 8 degrees so as to prevent the flow separation from the wall and to reduce accordingly the loss of energy in the tube.
From the equation of the continuity,
A1V1 = A2V2
V∝1/A
The area at the exit is higher, therefore the velocity of discharged water will be lower.
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Community Answer
Which of the following turbine does not require draft tube ?a)Kaplan t...
Explanation:
A draft tube is a component of a hydraulic turbine that is used to recover the kinetic energy of the water leaving the turbine. It helps to increase the efficiency of the turbine by reducing the pressure at the outlet of the turbine and allowing the water to flow smoothly into the tailrace.
Among the given options, the turbine that does not require a draft tube is the Pelton turbine.
Reason:
The Pelton turbine is a type of impulse turbine that is specifically designed for high head applications. It consists of a set of double or multiple cups or buckets mounted on the periphery of a wheel. The water jet is directed onto the cups/buckets, which causes the wheel to rotate. The water jet leaves the cups/buckets with high velocity and strikes the splitter, which redirects the water into the tailrace.
Key Points:
- The Pelton turbine operates on the principle of impulse, where the change in momentum of the water jet causes the turbine wheel to rotate.
- The high head and low flow rate characteristic of the Pelton turbine results in a high velocity of the water jet.
- The high velocity of the water jet allows the water to flow directly into the tailrace without the need for a draft tube.
- Since the Pelton turbine does not require a draft tube, it is suitable for high head applications where the available head is sufficient to generate the required energy without the need for pressure recovery.
- On the other hand, turbines like Kaplan, Francis, and propeller turbines operate on the principle of reaction, where the change in pressure of the water causes the turbine wheel to rotate.
- These turbines operate at lower heads and higher flow rates compared to the Pelton turbine, which necessitates the use of a draft tube for pressure recovery and efficient operation.
In conclusion, the Pelton turbine does not require a draft tube as it operates on the principle of impulse and is designed for high head applications.
A draft tube is a component of a hydraulic turbine that is used to recover the kinetic energy of the water leaving the turbine. It helps to increase the efficiency of the turbine by reducing the pressure at the outlet of the turbine and allowing the water to flow smoothly into the tailrace.
Among the given options, the turbine that does not require a draft tube is the Pelton turbine.
Reason:
The Pelton turbine is a type of impulse turbine that is specifically designed for high head applications. It consists of a set of double or multiple cups or buckets mounted on the periphery of a wheel. The water jet is directed onto the cups/buckets, which causes the wheel to rotate. The water jet leaves the cups/buckets with high velocity and strikes the splitter, which redirects the water into the tailrace.
Key Points:
- The Pelton turbine operates on the principle of impulse, where the change in momentum of the water jet causes the turbine wheel to rotate.
- The high head and low flow rate characteristic of the Pelton turbine results in a high velocity of the water jet.
- The high velocity of the water jet allows the water to flow directly into the tailrace without the need for a draft tube.
- Since the Pelton turbine does not require a draft tube, it is suitable for high head applications where the available head is sufficient to generate the required energy without the need for pressure recovery.
- On the other hand, turbines like Kaplan, Francis, and propeller turbines operate on the principle of reaction, where the change in pressure of the water causes the turbine wheel to rotate.
- These turbines operate at lower heads and higher flow rates compared to the Pelton turbine, which necessitates the use of a draft tube for pressure recovery and efficient operation.
In conclusion, the Pelton turbine does not require a draft tube as it operates on the principle of impulse and is designed for high head applications.
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Which of the following turbine does not require draft tube ?a)Kaplan turbineb)Pelton turbinec)Francis turbined)Propeller turbineCorrect answer is option 'B'. Can you explain this answer?
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