01 - Ashrae - Aerodynamics

8/16/2019 01 - Ashrae - Aerodynamics

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1

Fan & Systems

Chris Carr PE

H. Clay Moore & Associates

Rod Furniss

Howden North AmericaKey Account Manaer ! Nuclear



"

# Pressure & Flow $e%initions and Measurement

# $eelo'ment o% Fan Cures

# Per%ormance o% (arious )lade Sha'es

# Fan Controls

• System E%%ects

Aerodynamics*



*

HNA Pro%ile



+

Aerodynamics

,hat is a Fan-

• Any device for producing a current of air by the movement

of a broad surface or a number of such surfaces.



AerodynamicsPressure & Flow $e%initions and Measurement

Fan Flow Rate

• Often called inlet volume

• Measured at the fan inlet, by convention

• Measured in cubic feet per minute (cfm)

• May be converted to scfm (standard cubic feet per minute), or mass flow (lb/hr)

• an manufacturers commonly use acfm (actual cubic feet per minute)



/


Pressure

• orce per !nit Area

• "ommonly measured in psi or inwg

A0solute Pressure

•

#ressure when the datum is absolute $ero• ii Always positive

)arometric Pressure

• Absolute pressure e%erted by the atmosphere• Always positive

aue Pressure

• #ressure when the datum is barometric pressure• May be positive or negative




Static Pressure

• #ressure due to degree of compression and density only

• May be positive or negative

(elocity Pressure

• #ressure due to rate of motion and density only• Always positive

3otal Pressure

• Algebraic sum of static and velocity pressures at a point• May be positive or negative




Fan 3otal Pressure

• &ifference in 'otal #ressure between the fan outlet and fan inlet• '# '#o '#i

Fan (elocity Pressure

• #ressure corresponding to the average velocity at the fan outlet

• *# *#o

Fan Static Pressure

• an 'otal #ressure minus an *elocity #ressure

• +# +#o '#i

Static Pressure Rise

• &ifference in +tatic #ressure between the fan outlet and fan inlet

• +#- +#o +#i



Fan Pressure 3erms

• or a iven an, +#- is

iii Always reater 'han +#

• f the +pecified #ressure is

iii Assumed to 0e +#, thean iii+elected 1ill 0e

+maller


6mae area



Pitot 8 Static 3u0e


6mae area



Fan 9a0oratory 3est Setu'


6mae area


http://slidepdf.com/reader/full/01-ashrae-aerodynamics 12/521"

Aerodynamics$eelo'ment o% Fan Cures

6mae area

Fan Cure



1*


6mae area

System Cure



1+


6mae area

P!( and Pea: Fan

Pressure



1


6mae area

Selection Rane



1/

AerodynamicsPer%ormance o% (arious )lade Sha'es

Common )lade Sha'es

• Airfoil

• 0ac2ward "urved / 0ac2ward nclined

• -adial / -adial 'ip

• orward "urved

• A%ial



12

Air%oil

• 3ighest 4fficiency

"entrifugal &&esign

• 5imit 5oad 3# "haracteristic

• 5ow 6oise

• !sually for "lean

Applications

•

5argest &iameter "entrifugal

• 3ighest "ost "entrifugal


6mae area



14


6mae area

)ac:ward Cured ;

)ac:ward 6nclined

• 4ssentially a +ingle

''hic2ness Airfoil

•

4fficiency slightly less than A Airfoil


• 5ow 6oise

• or "lean or &irty

A Applications

• 5ower "ost than Airfoil



15

Radial ; Radial 3i'

• 5ower 4fficiency

• "ontinuously -ising 3# ..""haracteristic

•

3igher 6oise 5evels

• May have #redominant 0#''one

• +maller &iameter

• 4asily Armored for 4rosive++ervice

• 5ower "ost


6mae area



"7

Forward Cured <Sirocco3M=

• 5ower 4fficiency

• "ontinuously -ising 3#

""haracteristic

• +mallest &iameter "entrifugal

• +uited for 3igh *olume/5ow

##ressure

•

&istinctive &ip in #* "urve

• +eldom !sed 'oday


6mae area



"1

A>ial

• Airflow #arallel to A%is of--otation

• 3igh 4fficiency


• 5ow 6oise

• +uited for 3igh *olume/5ow##ressure

• Ad7ustable or "ontrollable #itch

• &istinctive &ip in #* "urve

• "ontrollable #itch has 3igher ""ost


6mae area



""

AerodynamicsFan Controls

Fan Control

• -easons for #roviding an "ontrol

• Methods of "ontrol

• 4fficiency "omparison

• Mechanical Arrangements

• "ontrol "riteria



"*


Reasons %or Proidin Fan Control

• !ncertainty in +ystem "alculations

• +afety actor or Margin

• 4%pected "hanges in the +ystem with 'ime

• 6ormal #rocess *ariations

• #rovisions for 4%traordinary 4vents



"+


6mae area

System Pressure 9oss

and Fan $esin Pressure



"


6mae area

Moin the ?'eratin

Point



"/


6mae area

System $uty Cycle



"2


Methods o% Control

• 6one

• Outlet / +ystem &amper

• nlet 0o% &ampers

• *ariable nlet *anes (**)

• *ariable +peed

• 0lade #itch "ontrol

• "ombinations of the Above



"4


6mae area

?utlet $am'er ; System

$am'er



"5

Aerodynamics$ischare $am'er



*7


6mae area

6nlet )o> $am'ers



*1


6mae area

6nlet )o> $am'ers



*"


6mae area

6nlet )o> $am'ers



**



*+

0&

&ischarge



*

0&

&ischarge



*/


6mae area

(aria0le 6nlet (anes

A d i



*2


6mae area

Physical Arranement o%

Cantileered (6(

A d i



*4


6mae area


Radial (ane Control

A d i



*5


6mae area

(6( Fa0rication

A d i



+7


6mae area

(aria0le 6nlet (anes

A d i



+1


6mae area

(aria0le S'eed

A d i



+"

Rotatin

Stall


(aria0le S'eed! (F$

and @rol Fluid $rie

Aerod namics



+*


6mae area

)lade Pitch Control

Aerodynamics



++


6mae area

E%%iciency Com'arison

Aerodynamics



+


6mae area


(arious Control $eices

Aerodynamics



+/


6mae area


A>ial )lade Pitch Control

Aerodynamics



+2


Control Criteria

• 'urndown / 5ea2age

• +ensitivity to "hange / +tability / 'ransients

• Accuracy -e8uired

• -epeatability

• 4%pected 4fficiency

• Acoustic "onsiderations

• +tructural "onsiderations



+4

System E%%ects 8 Poor Flow



+5




7




1




Fan & Systems

Chris Carr PE

H. Clay Moore & Associates

Rod Furniss

Howden North AmericaKey Account Manaer ! Nuclear

Documents

01 - Ashrae - Aerodynamics