For more information, please visit cooling tower fan blade angle.

Today I tested a belt driven induced draft cooling tower. The tower bearings and especially the motor showed very high blade pass vibration (over 1"/sec on the motor). I have done tests in many towers identical to this and cannot recall such high blade pass. Three other similar towers on this project had little or no blade pass. The five bladed fan runs on a vertical shaft. The shaft bearings are secured to a vertical mounting surface that is mounted to a box beam that spans the length of the tower. The beam is centered in the tower. Any thoughts on the cause for this vibration?

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Fan blades angle

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Fan blades angle

Fan blades angle

JKALLPA

(Mechanical)

(OP)

21 Jan 13 22:10

I'm going to buy such goniometer to measure angles... I have 33 fans in Air Cooled Condenser system , so what is the best type of goniometer to measure it? Is a goniometer digital a good option?

I appreciate your help.

Regards,

Jorge

RE: Fan blades angle

berkshire

(Aeronautics)

22 Jan 13 01:03
http://www.pacprop.com/tip_4.html

B.E.

You do not say how big your fans are. a goniometer will give you an angle like an adjustable protractor but no zero reference. you may need a propellor protractor.B.E.

RE: Fan blades angle

JJPellin

(Mechanical)

22 Jan 13 07:44

We prefer to set blade pitch using a digital inclinometer designed for the purpose. The fan manufacturer should provide a recommended pitch and the proper location to measure it. Adjustment of the pitch up or down from the manufacturer's recommendation can be optimized to whatever limit concerns you. We often pitch our fans to the limit of the motor amps to get maximum cooling.

Johnny Pellin

RE: Fan blades angle

JKALLPA

(Mechanical)

(OP)

22 Jan 13 21:18

What kind of digital inclinometer do you use? My fan has 7 blades whose diameter is 36ft and the blade angle is 11.1° (85.4 rpm)
If you have some procedure I'll be grateful.

I'm concern in the efficiency of my ACC... Adjustment the angle is not an easy work, when you have to move them, sometimes is no safety because of instalation or if you have a few time to do it.

Regards,

JC

RE: Fan blades angle

berkshire

(Aeronautics)

22 Jan 13 22:45

J pellin,

We prefer to set blade pitch using a digital inclinometer designed for the purpose

So is that in fact a propellor protractor. Or are you just measuring off a convenient baseline not the propellor itself?
B.E.

RE: Fan blades angle

JJPellin

(Mechanical)

23 Jan 13 08:01

This is quite a large fan. I believe our largest cooling tower fans are 26 feet in diameter. I don't have ready access to the exact type of inclinometer we use. A simple internet search should find a multitude of options.

I don't know what a propeller protractor is. Our inclinometer sets the angle of the blade at a certain angle relative to a level line. This assumes that the fan is installed properly and leveled. The surface of the blade where we place the inclinometer is defined by the fan manufacturer. I believe all of our blades have a flat area near the blade tip that is there for this purpose.This is quite a large fan. I believe our largest cooling tower fans are 26 feet in diameter. I don't have ready access to the exact type of inclinometer we use. A simple internet search should find a multitude of options.

Johnny Pellin

RE: Fan blades angle

berkshire

(Aeronautics)

24 Jan 13 00:20

JJ,
Here is a description of a propellor protractor. They essentialy have two spirit levels or digital inclinometers and can measure between the two reference planes.It sounds like you have a digital version that can do the same thing.
B.E.


""The WK-23- Propeller Protractor is a four-way precision instrument that measures angles directly between any two planes or any number of planes, such as setting a detachable blade type propeller on an airplane.

Snug fitting circles are tooled to close tolerances that minimize the error and play found in other protractors.

The circle and plate vial are accurate to 45 minutes per 2 mm. The vernier reads to six minutes.

Measures 7.25' base x 7.25' high with a 5.5' face. Has a matte finish to cut glare. Weight: 2 lbs.""

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