Fans and Blowers PAES 240-241:2010 Flashcards by Ebenezer Sales

shape of a wing or blade of a propeller, rotor, or turbine or sails as seen in cross section

airfoil

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asymmetry between the top and the bottom curves of an airfoil in cross-section

camber

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force cause by friction which slows down the movement of an object

drag, D

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device for moving air which utilizes a power-driven rotating impeller

fan blower

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structure mounted on the inlet and/or outlet part of fan/blower for safety purpose

fan/blower guard

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angle measured between the air inlet and lower camber of the fan/blower

angle of attack, α

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sum of all the forces on a body that force it to move perpendicular to the direction of flow

lift, L

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ratio between the lift force and the drag force on fan/blower blades during operatio

lift-drag ratio

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side of the fan/blower blade where the air comes in contact with at entry

leading edge, LE

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side of the fan/blower blade that is usually pointed and where the deflection of air occur

trailing edge, TE

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ratio between the hub diameter and the fan/blower wheel diameter

hub-tip ratio

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rotating device with blades projecting from a hub

rotor

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any revolving vane or vanes used for producing currents of air

fan/blower wheel

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Type of driving mechanism that can obtain any fan/blower speed by controlling the pulley ratio

Belt-Drive Fan/Blower

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Type of driving mechanism that directly transfers energy or power from engine crankshaft or motor shaft to the fan/blower. This enables better fan/blower efficiency and has less fan/blower components

Direct-Drive Fan/Blower

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Type of coupling that is used when the shafts are virtually collinear and when they remain in fixed angular relation with respect to each other (except for angular deflection)

Rigid Coupling

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Type of coupling that is designed to connect shafts which are misaligned either laterally or angularly. A secondary benefit is the absorption of impacts due to fluctuations in shaft torque or angular speed

Flexible Coupling

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Type of driving mechanism that uses hydraulic or magnetic couplings between fan/blower wheel shaft and motor shaft which allows control of fan/blower wheel speed independent of the motor speed.

Variable Drive Fan/Blower

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Blade that has a blunt leading edge and a pointed trailing edge. It has a streamline crosssectional shape

Asymmetrical Airfoil Blade

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Blade type that has pointed leading and trailing edge

Single-Thickness Sheet Metal Blade

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Fans that force the air to move parallel to the shaft on which the fan blades rotate

Axial-Flow Fans/Blowers

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Fans that are commonly used for supplying cool air to certain processes and exhausting hot or contaminated air and corrosive gases in buildings

Propeller Fan

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Fan that serves as exhausting material from an inlet duct.
Fan that consists of an axial-flow wheel within a cylinder and includes driving-mechanism supports either for belt drive or direct connection

Tube-Axial Fan (see Figure 9)

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Fan that neutralizes air spin for it to be used as blower in outlet duct and exhaust in inlet duct
Fan that consists of an axial-flow wheel within a cylinder, a set of guide located either before or after the wheel, and including driving-mechanism supports for either belt drive or direct connection.

Vane-Axial Fan (see Figure 10 and 11)

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This fan causes the air/gas to enter from the side fan wheel, deflected 90 degrees and accelerates due to centrifugal force as it flows over the fan blades and exits the fan housing. Type of fan that usually employ a volute or scroll-type casing. In this fan, the air inflow move axially and the air outflow move tangentially. Type of fan that consists of a wheel or rotor within a scroll spiral type housing. In this fan, the air enters parallel to the shaft, makes 90 degrees turn in the fan wheel, and is discharged from the wheel (and housing) in a radial manner.

Centrifugal Fans

This type of fan has the best mechanical efficiency and the lowest noise level among the centrifugal fans. Used primarily for clean air, gas application and for general ventilation

Centrifugal Fans with Airfoil Blades (see Figure 12)

Type of centrifugal fan that has single-thickness steel fan blade and can handle contaminated air streams This type of fan has blades that point to the direction opposite to the rotation at the tip and in the direction of rotation at the heel. This fan has single thickness type of blade and is designed for radial flow This type of fan has about 12 blades, essentially flat and tilted backward from the direction of fan wheel rotation. It is inherently a high speed type of fan with a self-limiting horsepower characteristic.

Backward-Curved Blades (see Figure 12)

Type of centrifugal fan that is more economical in production and has low structural strength and efficiency. In this type, the direction of the outflow air is opposite to the inclination of the blades This type of fan has blades that point to the direction opposite to the rotation at the tip and in the direction of rotation at the heel. This fan has single thickness type of blade and is designed for radial flow

Backward-Inclined Blades (see Figure 13)

Type of centrifugal fan that have blades which are curved forward to the direction of the rotation and have larger flow rate when compared to other centrifugal fans of the same size and speed. This type of fan have blades that are shallow and curved so that both the tip and the heel point at the direction of rotation. This fan has single thickness type of blade and is designed for radial flow. This type has a rotor similar to a squirrel cage and a large number of blades up to 60, narrow in the radial dimension but wide parallel to the shaft and facing forward in the direction of rotation like a scoop. It is a low speed fan, capable of operating at several inches pressure under most conditions but is limited to handling clean air.

Centrifugal Fans with Forward-Curved Blades (see Figure 14)

Type of centrifugal fan that are rugged and self cleaning and have non-tangential flow at the leading edge. This type can handle corrosive fumes and abrasive materials from grinding operations In this type of fan the blades are radial from tip to heel. This fan has single thickness type of blade and is designed for radial flow

Centrifugal Fans with Radial blades (see Figure 15)

Type of centrifugal fan that is curved, with good flow condition at the leading edge and blade tips are radial In this type of fan the blades are radial from tip and curved at the heel to point in the direction of rotation. This fan has single thickness type of blade and is designed for radial flow. This type has a smaller number of blades (from 6 to 20) and the blades are essentially in a plane radiating from the shaft. The blades are normally about two to three times as long radially as they are wide.

Centrifugal Fans with Radial Tip Blades (see Figure 16)

This type of fan is also known as tubular centrifugal fan, in-line centrifugal fan or mixed flow fan

Axial-Centrifugal Fans (see Figure 17)

In this type of fan, the air stream has to make two 90 degrees turns before exiting the fan housing.

Fan Wheel with Flat Back Plate

In this type of fan, the air stream has to make two 45 degrees turns before exiting the fan housing.

Fan Wheel with Conical Back Plate

These types of fan have up blast, down flow and radial discharge of air. This is mainly use for exhausting and supplying air from and into the building

Roof Ventilators

In this type of fan, the airflow passes twice through a fan wheel with forward-curved blades. This type is mainly used as air curtains, long and narrow heating or cooling coils and dry blowers.

Cross-Flow Blowers

This type of fan causes the airflow to circle around in an annular, torus-shaped space. (see Figure 21) The rotating fan blades, which are located on one side of the torus, are throwing the air outward, and then airflow is guided back by the other side of the torus for it to reenter the inner portion of the rotating blade

Vortex or Regenerative Blowers

For airfoil type of blade, the upper camber shall be at most ___ of the total chord and shall be located at about ___ of the chord from the leading edge. The lower camber shall be at most ___ of the total chord and shall be located at about ___ of the chord from the leading edge

13.3% 36% 2.4% 64%

Single-thickness metal type of blade shall have the maximum camber of __ of the total chord. It shall be located at about ___ of the chord from the leading edge.

8% | 38%

The range for angle of attack for each fan blade shall be between _______ to ensure high lift drag ratio and good performance of the fan. (Fan Handbook Selection, Application and Design by Frank P. Bleier)

One (1) degree to ten (10) degrees

For radial tip centrifugal fans that are being used for industrial purposes, range of _____ wheel shall be used to endure severe conditions of high temperature and high concentrations of solids.

76.2 cm to 152.4 cm (30 inches to 60 inches)

For large size propeller fan ___, belt-drive shall be used. For small size propeller fan ___, direct and belt-drive shall be used.

(3-phase) | (single phase)

Hub tip Ratio | Propeller fan --- --- Tube-axial fan --- --- Vane-axial fan --- --- Two-stage axial fan --- ---

40, 30 to 50, 45 to 80 and 50 to 80

with Airfoil blade (# of blades, size range, Hub tip, %)

9 to 12, 12 to 132, 65 to 80

with Backward-curved blade (# of blades, size range, Hub tip %)

9 to 12, 12 to 132, 60 to 80

with Backward-inclined blade (# of blades, size range, Hub tip %)

9 to 12, 12 to 132, 60 to 80

with Radial-tip blade (# of blades, size range, Hub tip %)

12 to 24, 25 to 110, 50 to 80

with Forward-curved blade (# of blades, size range, Hub tip %)

24 to 64, 2 to 73, 75 to 90

with Radial blade (# of blades, size range, Hub tip %)

6 to 10, 12 to 122, 30 to 60

Cross-Flow Blowers --- --- (hub tip %)

70 to 80

Vortex Blowers (no. of blades, hub tip ratio)

18 to 42 --- 22 to 30

Split-phase (Power Rangers kW hp)

0.04 to 0.37 , 1/20 to 1/2

Load Starting Ability Split Phase

Develops 150% of full-load torque

Capacitor start (Power Rangers kW hp)

0.09 to 7.46 ,1/8 to 10

Load Starting Ability Capacitor start

Develops 350 to 400% of full-load torque

Two-value capacitor

1.49 to 14.92 ,2 to 20

Two-value capacitor Load Starting Ability

-Develops 350 t0 400% of full-load torque

Permanentsplit capacitor (Power Rangers kW hp)

0.04 to 0.75 ,1/20 to 1

Permanentsplit capacitor Load Starting Ability

-Develops 150% of full-load torque

Shaded-pole (Power Rangers kW hp)

0.003 to 0.37 ,1/250 to 1/2

WOUNDROTOR (repulsion) (Power Rangers kW hp)

0.12 to 7.46 ,1/6 to 10

WOUNDROTOR (repulsion) Load Starting Ability

-Develops 350 to 400% of full-load torque

Lift-drag ratio for airfoil type of blade shall have range value of ____

40 to 63.

Lift-drag ratio for single-thickness sheet metal type of blade shall have range value of ____

20 to 57.

Fan guard shall be provided at the exposed fan inlets and/or outlets when the fan is being installed less than ______ from the ground to avoid accidents

2.13 m (7 ft)

Propeller fan STATIC PRESSURE (in WC)

0 to 1

Propeller fan MECHANICAL EFFICIENCY, %

Tube-axial fan STATIC PRESSURE (in WC)

½ to 2 ½

Tube-axial fan MECHANICAL EFFICIENCY, %

Vane-axial fan STATIC PRESSURE (in WC)

1 to 9

Vane-axial fan MECHANICAL EFFICIENCY, %

Two-stage axial fan STATIC PRESSURE (in WC)

4 to 18

Two-stage axial fan MECHANICAL EFFICIENCY, %

Centrifugal Fans with Airfoil blade STATIC PRESSURE (in WC)

5 to 35

Centrifugal Fans with Airfoil blade MECHANICAL EFFICIENCY, %

Centrifugal Fans with Backward-curved blade STATIC PRESSURE (in WC)

5 to 60

Centrifugal Fans with Backward-curved blade MECHANICAL EFFICIENCY, %

Centrifugal Fans with Backward-inclined blade STATIC PRESSURE (in WC)

5 to 30

Centrifugal Fans with Backward-inclined blade MECHANICAL EFFICIENCY, %

Centrifugal Fans with Radial-tip blade STATIC PRESSURE (in WC)

10 to 40

Centrifugal Fans with Radial-tip blade MECHANICAL EFFICIENCY, %

Centrifugal Fans with Forward-curved blade STATIC PRESSURE (in WC)

1 to 10

Centrifugal Fans with Forward-curved blade MECHANICAL EFFICIENCY, %

Centrifugal Fans with Radial blade STATIC PRESSURE (in WC)

20 to 40

Centrifugal Fans with Radial blade MECHANICAL EFFICIENCY, %

Cross-Flow Blowers STATIC PRESSURE (in WC)

0 to 1.55

Cross-Flow Blowers MECHANICAL EFFICIENCY, %

35 to 45

Vortex Blowers STATIC PRESSURE (in WC)

0 to 54

Vortex Blowers MECHANICAL EFFICIENCY, %

The noise emitted by the fans/blowers measured one meter away shall not be more than ____

96 db (A)

part of the energy per unit time that is imparted by the fan to the air by increasing its total pressure from the inlet to the outlet

air power

angle measured between the air inlet and the lower camber of the fan/blower

angle of attack

when the air flow/movement produces by fan/blower starts to reverse direction

back-flow

device for moving air which utilizes a power driven rotating impeller

fan ,blower

ratio between the hub diameter and the fan/blower wheel diameter

hub-tip ratio

ratio between the lift force and the drag force on fan/blower blades during operation

lift-drag ratio

tube that is being connected to a manometer and is being used to measure the static and total force of air in the testing duct of fan/blower (see Figure 3

pitot tube

part of the energy per unit time that is imparted by the fan/blower to the air in overcoming static pressure from the inlet to the outlet

static air power

potential energy put into the system by the fan/blower and is given up to friction in the ducts and at the duct inlet as it is converted to velocity pressure

static pressure

conical structure or orifice rings that are being used at the end of testing duct of fan/blower to enable variation in air volumetric flow rate (see Figure 1a and 1b)

throttling device

sum of the static and velocity pressure

total pressure

point in the duct at which measurement using pitot tube shall be done (see Figure 4)

traverse point

pressure along the line of the flow that result from the air flowing through the duct

velocity pressure

Fans and Blowers PAES 240-241:2010 Flashcards

(103 cards)