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For a Kaplan turbine with runner diameter 4 m, the discharge is 60 m3⁄s and the hydraulic and mechanical efficiencies are stated to be 90 percent and 94 percent respectively. The diameter of the boss is 0.3 times the runner diameter and the speed ratio is 2.0. Assuming that discharge is free and there is no swirl at outlet, calculate the specific speed.
Correct answer is 'Range: 480 to 500'. Can you explain this answer?
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For a Kaplan turbine with runner diameter 4 m, the discharge is 60 m3...
If Do is the outside diameter of the runner and Db is the diameter of hub or boss, then
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Flow velocity Vf1 = 5.25 m/s Let H represent the net available head on the turbine.
Then In the absence of swirl at outlet,
V2 = Vf2 = 5.25 m⁄s Since hydraulic efficiency is 90%, ∴ 10% of the head leaves as kinetic head
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For a Kaplan turbine with runner diameter 4 m, the discharge is 60 m3...
Calculation of Specific Speed for Kaplan Turbine
Given data:
- Runner diameter (D) = 4 m
- Discharge (Q) = 60 m3/s
- Hydraulic efficiency (ηh) = 90%
- Mechanical efficiency (ηm) = 94%
- Boss diameter (Db) = 0.3D = 1.2 m
- Speed ratio (Ns) = 2.0
- No swirl at outlet
Formula for Specific Speed:
Ns = N√Q/H3/4
where,
- N = rotational speed of runner (rpm)
- H = net head (m)
Calculation of Net Head:
- Assume that there is no loss of head due to friction and other factors
- Therefore, net head = gross head
Calculation of Rotational Speed:
- The speed ratio (Ns) is given as 2.0
- Therefore, Ns = Ns1/Ns2 = (N/√H1)/(N/√H2) = √(H2/H1)
- Since the discharge is free, the velocity of water at inlet and outlet is zero
- Therefore, the velocity triangles at inlet and outlet are similar
- Hence, H2/H1 = (D2/D1)2 = (Db/D)2 = (1.2/4)2 = 0.09
- Therefore, Ns = √0.09 = 0.3
Calculation of Specific Speed:
- Ns = N√Q/H3/4
- Ns = 0.3N
- Therefore, N = Ns/0.3
- H = Q/(πD2/4) = 60/(π(4)2/4) = 2.395 m
- Therefore, N = Ns/0.3 = 480 rpm (approx)
- Specific speed Ns = N√Q/H3/4 = 480√60/2.3953/4 = 491.8 (approx)
Answer:
The calculated specific speed for the given Kaplan turbine is in the range of 480 to 500.
Given data:
- Runner diameter (D) = 4 m
- Discharge (Q) = 60 m3/s
- Hydraulic efficiency (ηh) = 90%
- Mechanical efficiency (ηm) = 94%
- Boss diameter (Db) = 0.3D = 1.2 m
- Speed ratio (Ns) = 2.0
- No swirl at outlet
Formula for Specific Speed:
Ns = N√Q/H3/4
where,
- N = rotational speed of runner (rpm)
- H = net head (m)
Calculation of Net Head:
- Assume that there is no loss of head due to friction and other factors
- Therefore, net head = gross head
Calculation of Rotational Speed:
- The speed ratio (Ns) is given as 2.0
- Therefore, Ns = Ns1/Ns2 = (N/√H1)/(N/√H2) = √(H2/H1)
- Since the discharge is free, the velocity of water at inlet and outlet is zero
- Therefore, the velocity triangles at inlet and outlet are similar
- Hence, H2/H1 = (D2/D1)2 = (Db/D)2 = (1.2/4)2 = 0.09
- Therefore, Ns = √0.09 = 0.3
Calculation of Specific Speed:
- Ns = N√Q/H3/4
- Ns = 0.3N
- Therefore, N = Ns/0.3
- H = Q/(πD2/4) = 60/(π(4)2/4) = 2.395 m
- Therefore, N = Ns/0.3 = 480 rpm (approx)
- Specific speed Ns = N√Q/H3/4 = 480√60/2.3953/4 = 491.8 (approx)
Answer:
The calculated specific speed for the given Kaplan turbine is in the range of 480 to 500.
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For a Kaplan turbine with runner diameter 4 m, the discharge is 60 m3⁄s and the hydraulic and mechanical efficiencies are stated to be 90 percent and 94 percent respectively. The diameter of the boss is 0.3 times the runner diameter and the speed ratio is 2.0. Assuming that discharge is free and there is no swirl at outlet, calculate the specific speed.Correct answer is 'Range: 480 to 500'. Can you explain this answer?
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For a Kaplan turbine with runner diameter 4 m, the discharge is 60 m3⁄s and the hydraulic and mechanical efficiencies are stated to be 90 percent and 94 percent respectively. The diameter of the boss is 0.3 times the runner diameter and the speed ratio is 2.0. Assuming that discharge is free and there is no swirl at outlet, calculate the specific speed.Correct answer is 'Range: 480 to 500'. Can you explain this answer? for Civil Engineering (CE) 2024 is part of Civil Engineering (CE) preparation. The Question and answers have been prepared according to the Civil Engineering (CE) exam syllabus. Information about For a Kaplan turbine with runner diameter 4 m, the discharge is 60 m3⁄s and the hydraulic and mechanical efficiencies are stated to be 90 percent and 94 percent respectively. The diameter of the boss is 0.3 times the runner diameter and the speed ratio is 2.0. Assuming that discharge is free and there is no swirl at outlet, calculate the specific speed.Correct answer is 'Range: 480 to 500'. Can you explain this answer? covers all topics & solutions for Civil Engineering (CE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for For a Kaplan turbine with runner diameter 4 m, the discharge is 60 m3⁄s and the hydraulic and mechanical efficiencies are stated to be 90 percent and 94 percent respectively. The diameter of the boss is 0.3 times the runner diameter and the speed ratio is 2.0. Assuming that discharge is free and there is no swirl at outlet, calculate the specific speed.Correct answer is 'Range: 480 to 500'. Can you explain this answer?.
For a Kaplan turbine with runner diameter 4 m, the discharge is 60 m3⁄s and the hydraulic and mechanical efficiencies are stated to be 90 percent and 94 percent respectively. The diameter of the boss is 0.3 times the runner diameter and the speed ratio is 2.0. Assuming that discharge is free and there is no swirl at outlet, calculate the specific speed.Correct answer is 'Range: 480 to 500'. Can you explain this answer? for Civil Engineering (CE) 2024 is part of Civil Engineering (CE) preparation. The Question and answers have been prepared according to the Civil Engineering (CE) exam syllabus. Information about For a Kaplan turbine with runner diameter 4 m, the discharge is 60 m3⁄s and the hydraulic and mechanical efficiencies are stated to be 90 percent and 94 percent respectively. The diameter of the boss is 0.3 times the runner diameter and the speed ratio is 2.0. Assuming that discharge is free and there is no swirl at outlet, calculate the specific speed.Correct answer is 'Range: 480 to 500'. Can you explain this answer? covers all topics & solutions for Civil Engineering (CE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for For a Kaplan turbine with runner diameter 4 m, the discharge is 60 m3⁄s and the hydraulic and mechanical efficiencies are stated to be 90 percent and 94 percent respectively. The diameter of the boss is 0.3 times the runner diameter and the speed ratio is 2.0. Assuming that discharge is free and there is no swirl at outlet, calculate the specific speed.Correct answer is 'Range: 480 to 500'. Can you explain this answer?.
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For a Kaplan turbine with runner diameter 4 m, the discharge is 60 m3⁄s and the hydraulic and mechanical efficiencies are stated to be 90 percent and 94 percent respectively. The diameter of the boss is 0.3 times the runner diameter and the speed ratio is 2.0. Assuming that discharge is free and there is no swirl at outlet, calculate the specific speed.Correct answer is 'Range: 480 to 500'. Can you explain this answer?, a detailed solution for For a Kaplan turbine with runner diameter 4 m, the discharge is 60 m3⁄s and the hydraulic and mechanical efficiencies are stated to be 90 percent and 94 percent respectively. The diameter of the boss is 0.3 times the runner diameter and the speed ratio is 2.0. Assuming that discharge is free and there is no swirl at outlet, calculate the specific speed.Correct answer is 'Range: 480 to 500'. Can you explain this answer? has been provided alongside types of For a Kaplan turbine with runner diameter 4 m, the discharge is 60 m3⁄s and the hydraulic and mechanical efficiencies are stated to be 90 percent and 94 percent respectively. The diameter of the boss is 0.3 times the runner diameter and the speed ratio is 2.0. Assuming that discharge is free and there is no swirl at outlet, calculate the specific speed.Correct answer is 'Range: 480 to 500'. Can you explain this answer? theory, EduRev gives you an
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