Efficiency of draft tube Calculator

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Draft Tube

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Fluid Machinery

Fluid Statistics

Forces and Dynamics

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✖Velocity of water at inlet of draft tube is the velocity of water entering the inlet of draft tube which is the part with smaller area of cross section.ⓘ Velocity of water at inlet of draft tube [V₁]			+10% -10%
✖Velocity of water at outlet of draft tube is the velocity of water flowing though the outlet of draft tube which is the end with bigger area of cross section.ⓘ Velocity of water at outlet of draft tube [V₂]			+10% -10%
✖Loss of head in draft tube is defined as the difference in head at the start and end of the draft tube.ⓘ Loss of head in draft tube [h_f]			+10% -10%

✖The Efficiency of Draft Tube is defined as the ratio of the actual conversion of the kinetic head into the pressure head in the draft tube to the kinetic head at the inlet of the draft tube.ⓘ Efficiency of draft tube [η_d]

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Formula

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Efficiency of draft tube

Formula

`"η"_{"d"} = (((("V"_{"1"}^2)/(2*"[g]"))-(("V"_{"2"}^2)/(2*"[g]")))-("h"_{"f"}))/(("V"_{"1"}^2)/(2*"[g]"))`

Example

`"0.905519"=((((("6m/s")^2)/(2*"[g]"))-((("1.2m/s")^2)/(2*"[g]")))-("0.1m"))/((("6m/s")^2)/(2*"[g]"))`

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Efficiency of draft tube Solution

STEP 0: Pre-Calculation Summary

Formula Used

Efficiency of Draft Tube = ((((Velocity of water at inlet of draft tube^2)/(2*[g]))-((Velocity of water at outlet of draft tube^2)/(2*[g])))-(Loss of head in draft tube))/((Velocity of water at inlet of draft tube^2)/(2*[g]))
η_d = ((((V₁^2)/(2*[g]))-((V₂^2)/(2*[g])))-(h_f))/((V₁^2)/(2*[g]))
This formula uses 1 Constants, 4 Variables

Constants Used

[g] - Gravitational acceleration on Earth Value Taken As 9.80665

Variables Used

Efficiency of Draft Tube - The Efficiency of Draft Tube is defined as the ratio of the actual conversion of the kinetic head into the pressure head in the draft tube to the kinetic head at the inlet of the draft tube.
Velocity of water at inlet of draft tube - (Measured in Meter per Second) - Velocity of water at inlet of draft tube is the velocity of water entering the inlet of draft tube which is the part with smaller area of cross section.
Velocity of water at outlet of draft tube - (Measured in Meter per Second) - Velocity of water at outlet of draft tube is the velocity of water flowing though the outlet of draft tube which is the end with bigger area of cross section.
Loss of head in draft tube - (Measured in Meter) - Loss of head in draft tube is defined as the difference in head at the start and end of the draft tube.

STEP 1: Convert Input(s) to Base Unit

Velocity of water at inlet of draft tube: 6 Meter per Second --> 6 Meter per Second No Conversion Required
Velocity of water at outlet of draft tube: 1.2 Meter per Second --> 1.2 Meter per Second No Conversion Required
Loss of head in draft tube: 0.1 Meter --> 0.1 Meter No Conversion Required

STEP 2: Evaluate Formula

Substituting Input Values in Formula

η_d = ((((V₁^2)/(2*[g]))-((V₂^2)/(2*[g])))-(h_f))/((V₁^2)/(2*[g])) --> ((((6^2)/(2*[g]))-((1.2^2)/(2*[g])))-(0.1))/((6^2)/(2*[g]))

Evaluating ... ...

η_d = 0.905518611111111

STEP 3: Convert Result to Output's Unit

0.905518611111111 --> No Conversion Required

FINAL ANSWER

0.905518611111111 ≈ 0.905519 <-- Efficiency of Draft Tube

(Calculation completed in 00.004 seconds)

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Created by Peri Krishna Karthik

National Institute of Technology Calicut (NIT Calicut), Calicut, Kerala

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National Institute Of Technology (NIT), Hamirpur

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< 4 Draft Tube Calculators

Efficiency of draft tube

Go Efficiency of Draft Tube = ((((Velocity of water at inlet of draft tube^2)/(2*[g]))-((Velocity of water at outlet of draft tube^2)/(2*[g])))-(Loss of head in draft tube))/((Velocity of water at inlet of draft tube^2)/(2*[g]))

Head loss in draft tube given efficiency

Go Loss of head in draft tube = (((Velocity of water at inlet of draft tube^2)/(2*[g]))-((Velocity of water at outlet of draft tube^2)/(2*[g])))-(Efficiency of Draft Tube*((Velocity of water at inlet of draft tube^2)/(2*[g])))

Velocity of water at inlet of draft tube given draft tube efficiency

Go Velocity of water at inlet of draft tube = sqrt(((Velocity of water at outlet of draft tube^2)+(Loss of head in draft tube*2*[g]))/(1-Efficiency of Draft Tube))

Velocity of water at outlet of draft tube given draft tube efficiency

Go Velocity of water at outlet of draft tube = sqrt((Velocity of water at inlet of draft tube^2)*(1-Efficiency of Draft Tube)-(Loss of head in draft tube*2*[g]))

Efficiency of draft tube Formula

What is the purpose of draft tube?

The draft tube, in addition to serving a passage for water discharge, has also other purposes. It permits a negative head to be established at the outlet of the runner and thereby increases the net head on the turbine. The turbine may be placed above the trail race without any loss of net head and hence turbine may be inspected properly. It converts a large portion of kinetic energy rejected at the outlet of the turbine into useful pressure energy. Without the draft tube, the kinetic energy rejected at the outlet of the turbine will go waste to the trail race.

What are the types of draft tubes?

The following are the important types of draft tubes that are commonly used. Conical draft tubes, simple elbow draft tubes, moody spreading tubes, and elbow draft tubes with circular inlet and rectangular outlet.

How to Calculate Efficiency of draft tube?

Efficiency of draft tube calculator uses Efficiency of Draft Tube = ((((Velocity of water at inlet of draft tube^2)/(2*[g]))-((Velocity of water at outlet of draft tube^2)/(2*[g])))-(Loss of head in draft tube))/((Velocity of water at inlet of draft tube^2)/(2*[g])) to calculate the Efficiency of Draft Tube, The Efficiency of draft tube formula is defined as the ratio of actual conversion of kinetic head into pressure head to the kinetic head at the inlet of the draft tube. Efficiency of Draft Tube is denoted by η_d symbol.

How to calculate Efficiency of draft tube using this online calculator? To use this online calculator for Efficiency of draft tube, enter Velocity of water at inlet of draft tube (V₁), Velocity of water at outlet of draft tube (V₂) & Loss of head in draft tube (h_f) and hit the calculate button. Here is how the Efficiency of draft tube calculation can be explained with given input values -> 0.905519 = ((((6^2)/(2*[g]))-((1.2^2)/(2*[g])))-(0.1))/((6^2)/(2*[g])).

FAQ

What is Efficiency of draft tube?

The Efficiency of draft tube formula is defined as the ratio of actual conversion of kinetic head into pressure head to the kinetic head at the inlet of the draft tube and is represented as η_d = ((((V₁^2)/(2*[g]))-((V₂^2)/(2*[g])))-(h_f))/((V₁^2)/(2*[g])) or Efficiency of Draft Tube = ((((Velocity of water at inlet of draft tube^2)/(2*[g]))-((Velocity of water at outlet of draft tube^2)/(2*[g])))-(Loss of head in draft tube))/((Velocity of water at inlet of draft tube^2)/(2*[g])). Velocity of water at inlet of draft tube is the velocity of water entering the inlet of draft tube which is the part with smaller area of cross section, Velocity of water at outlet of draft tube is the velocity of water flowing though the outlet of draft tube which is the end with bigger area of cross section & Loss of head in draft tube is defined as the difference in head at the start and end of the draft tube.

How to calculate Efficiency of draft tube?

The Efficiency of draft tube formula is defined as the ratio of actual conversion of kinetic head into pressure head to the kinetic head at the inlet of the draft tube is calculated using Efficiency of Draft Tube = ((((Velocity of water at inlet of draft tube^2)/(2*[g]))-((Velocity of water at outlet of draft tube^2)/(2*[g])))-(Loss of head in draft tube))/((Velocity of water at inlet of draft tube^2)/(2*[g])). To calculate Efficiency of draft tube, you need Velocity of water at inlet of draft tube (V₁), Velocity of water at outlet of draft tube (V₂) & Loss of head in draft tube (h_f). With our tool, you need to enter the respective value for Velocity of water at inlet of draft tube, Velocity of water at outlet of draft tube & Loss of head in draft tube and hit the calculate button. You can also select the units (if any) for Input(s) and the Output as well.

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