Axial Fan Testing Equipments

7/27/2019 Axial Fan Testing Equipments

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AXIAL FLOW FAN TESTING EQUIPMENTS

(With discharge tunnel)

Axial Flow Fan Test Rig uses a standard axial fan of 480mm diameter. A

detailed study of this fan can be carried out using the reduced plenum chamber

method. The full characteristics of the axial fan can be determined.

The great advantage of this particular method is that for given ambient

conditions the flow, pressure, work and power calculations are derived from a

single pressure reading.

DESCRIPTION:-

The main body of the apparatus consists of a 2 m long air flow duct mounted on

the test bench. Upstream of the fan there is a tapered contraction which leads

into a circular section.

Anemometer is provided and is attached to the discharge side duct by means of

fastners. The butterfly valve serves as control the outlet flow rate. Traversing

pitot tube is provided in the duct.

The fan is driven by a variable speed, AC motor. The power of the motor is red

by energy meters and the pressure in the duct is measured by manometer.

An axial flow fan single stage in its simplest form consists of a rotor made up of

a 6 blades fitted to the hub. When it is rotated by an electric motor with drive,

Flow is established through the rotor. The rotation action of the rotor causes an

increase in the stagnation pressure of air or gas across it. A cylindrical duct

encloses the blades. It through the flow through a converging passage as shown

in figure.

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MEASUREMENTS AND INSTRUMENTATION:

1. Discharge can be measured for different valve openings with the help of

anemometer.

2. Pressure developed can be measured by using pitot tube for variable

discharge.

3. Power can be measured for different discharges using energy meter.

4. Overall efficiency for different discharge can be estimated.

TECHNICAL DATA:

Standard axial fan : of 1 HP motor variable speed

Diameter : 480mm

Number of blade : 6

Speed : 1440 rpm (variable)

Manometer : Projection type with mm scale

Digital meters : Displaying fan speed.

POWER SUPPLY:

Standard : 440v, Three phase 50 HZ 1HP

DIMENSIONS

Air duct : Overall length 2 m

Complete assembly including bench : for setting operation

Length (complete frame) : 2.45 mWidth : 0.56 m

Power input to ac motor as read by energy meter:

60 60 1000

HPinput = ---------------------------- (1)

t emc 1000

Where

= number of blinks (energy meter reading)

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t = time taken is sec for two revolution of energy meter

Energy meter constant: 2400 rev/kw = emc

1000 is conversion factor from watts to KW

60 conversion factors to secs

Volume flow rate

Q = A (m2) anemometer reading (m/sec) m3sec (2)

How to calculate hfstatichead

hfsta ww where

Hfsta = -------- x ----- -1

1000 wa (4)

Hfsta = 0.774 hfsta

Where

hfsta = water tube manometer static head

wa = density of air @ ambient 30C 1.29kg/m3

ww = density of water =1000 kg/m3

1000 is conversion factor from mm to m

A = Area of duct=0 .045m2

d= 240mm

Air (HP) calculated from the outlet of axial fan

HPoutput= wa Q Hfsta9.81

-----------------------

1000 KW (5)

HPoutput

Overall of the axial fan = % = ------------- x 100HPinput

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valve opening

Axial fan

speed(RPM)

Energy

meter

reading(for

3 revns)

(secs)

pitot tube(manometer)

Readings(mm) Anemometer(m/sec)

1

2

3

4

5

GRAPHS:

Discharge V/s %

Discharge V/s speed

Discharge V/s HPinput

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GUIDANCE CALCULATIONS AND READINGS :( only for guidance)

SL.NO. valve opening

Axial

fan

speed

Energy

meter

reading(for

3 blinks)

pitot tube

(manometer

)

Readings Anemometer

HP INPUTin KW

VOLUME

FLOW

RATE Q

IN m3sec

Hfsta IN

m

HP OUTPUTin KW

%h

11st position (full

open) 1500 36.53 10 6.8 0.18478 0.3604 7.74 0.035301 19.10427

2 2nd position 1500 36 8 6.1 0.1875 0.3233 6.192 0.025334 13.511213 3rd position 1500 36.08 5 5.2 0.187084 0.2756 3.87 0.013497 7.21459

4 4th position 1500 35.96 5 4.6 0.187709 0.2438 3.87 0.01194 6.360911

61st position (full

open) 1200 63.4 5 4.6 0.106467 0.2438 3.87 0.01194 11.2147

7 2nd position 1200 63.38 4 4.2 0.1065 0.2226 3.096 0.00872 8.18905

8 3rd position 1200 64.01 3 3.5 0.105452 0.1855 2.322 0.00545 5.16903

9 4th position 1200 63.51 2 2.9 0.106282 0.1537 1.548 0.00301 2.83297

111st position (full

open) 1000 79.91 3 3.78 0.08447 0.20034 2.322 0.00589 6.96925

12 2nd position 1000 80.06 3 3.4 0.084312 0.1802 2.322 0.0053 6.280413 3rd position 1000 80.12 2 2.8 0.084249 0.1484 1.548 0.00291 3.45065

14 4th position 1000 79.98 2 2.2 0.084396 0.1166 2.322 0.00343 4.05973

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GUIDANCE CALCULATIONS:

DIMENSIONS

Air duct : Overall length 2 m

Complete assembly including bench : for setting operation

Length (complete frame) : 2.45 m

Width : 0.56 m

Power input to ac motor as read by energy meter:

60 60 1000 3 60 60 1000

HPinput = -------------------------- = ---------------------------- = 0.184KWt emc 1000 36.5316001000

Where

= number of blinks (energy meter reading)

t = time taken is sec for two revolution of energy meter

Energy meter constant: 2400 rev/kw = emc

1000 is conversion factor from watts to KW

60 conversion factors to secs

Volume flow rate

Q = A (m2) anemometer reading (m/sec) m3sec

= 0.053 6.8 D= 260mm

= 0.3604 m3sec

How to calculate hfstatichead

hfsta ww where

Hfsta = -------- x ----- -1

1000 wa

Hfsta = 0.774 hfsta = 0.774 x 10 = 7.74

Where

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hfsta = water tube manometer static head

wa = density of air @ ambient 30C 1.29kg/m3

ww = density of water =1000 kg/m3

1000 is conversion factor from mm to m

A = Area of duct=0 .053m2

d= 260mm

Air (HP) calculated from the outlet of axial fan

HPoutput= wa Q Hfsta9.81 1.29 x0.3604 x7.74 x9.81

--------------------- = ------------------------------------ = 0.0351000 1000

HPoutputOverall of the axial fan = % = ------------- x 100

HPinput

0.035

% = ------------- x 100 = 19.10 %0.184

GRAPHS:

Discharge V/s %

Discharge V/s speed

Discharge V/s HPinput

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Axial Fan Testing Equipments