Abstract—
This work presents a methodology for the selection
and design of propeller oriented to the experimental verification of
theoretical results. The problem of propeller selection and design
usually present itself in the following manner: a certain air volume
and static pressure are required for a certain system. Once the
necessity of fan design on a theoretical basis has been recognized, it
is possible to d eterminate the dimensions for a fan unit so that it will
perform in accordance with a certain set of specifications. The same
procedures in this work then can be app lied in other propeller
selection.
Keywords—
airfoil, axial flow, blade, fan, hub, mathematical
algorithm, propeller design, simulation, wheel.
I. INTRODUCTION
HE term axial flow fan indicates that the air flows through
the fan in an approximately axial direction. On the inlet
side, as the flow approaches the fan bl ades, the direction of the
flow is axial, in other words, parallel to the axis of rotation,
provided there are no inlet vanes or other restrictions ahead of
the fan wheel. The fan blade then deflects the airflow, as show
in the fig. 1:
Fig. 1 Airfoil as used in an axial flow fan blade [1]
A propeller is a mechanism designed to produce a tractive
force or push, when submerged in a fluid medium. The
D. Almazo is an student of the Mechanical Engineering Department of the
SEPI ESIME Zacatenco of IPN, Mexico City, Mexico (e-mail:
diegomoisesal@hotmail.com).
C. Rodríguez is a researcher with the Mechanical Engineering Department
of the UANL, Monterrey City, Mexico (e-mail: crodrigue1@hotmail.com).
M. Toledo is a researcher with the Mechanical Engineering Department of
the SEPI ESIME Zacatenco of IPN, Mexico City, Mexico (e-mail:
mtv49@yahoo.com).
propellers are aerod ynamic elements that are composed of a
hub or central core and a number of blades.
The operating principle of axial-flow fans is simply
deflection of airflow [2]. Past the blade, therefore, the pattern
of the deflected airflow is of helical shape, like a spiral
staircase. This is true for all three t ypes of axial-flow fans:
propeller fans, tubeaxial fans, and vaneaxial fans.
Accordingly, the design procedures and the design
calculations are similar for all three types.
The helical pattern of the airflow past the blade of an axial
flow fan the air velocity the can be resolved into two
components: an axial velocity a tangential velocity. The axial
velocity is the useful component. It moves the air to the
location where we need it.
II. AIRFOIL
An airfoil is a streamline shape. Its main application is as the
cross section of an airplane wing. Another application is as the
cross section of a fan blade.
There are symmetric and asymmetric airfoils. The airfoils
used in fan blade are asymmetric. Fig. 2 shows an asymmetric
airfoil that has been developed by the National Advisory
Committee for aeronautics (NACA); it is the NACA airfoil
no.6512.
Fig. 2 NACA 6512 airfoil obtained from Matlab
As an airfoil moves through the air, it normally produces
positive pressure on the lower surface of t he airfoil and
negative pressure or suction on the upper surface [3]. The
suction pressure on the top surface are about twice as large as
the positive pressures on the lower surface, but all these
positive and negative pressures push and pull in approximately
the same direction and reinforce each other. The combination
of these positive and negative pressures results in a force F.
This force F can be resolved into two components: a lift force
L, perpendicular to the relative air velocity; and a drag force
D, parallel to the relative air velocity. The lift force L is the
useful component.
D. Almazo, C. Rodríguez, and M. Toledo
Selection and Design of an Axial Flow Fan
T
World Academy of Science, Engineering and Technology
International Journal of Aerospace and Mechanical Engineering
Vol:7, No:5, 2013
923International Scholarly and Scientific Research & Innovation 7(5) 2013 scholar.waset.org/1307-6892/15827
International Science Index, Aerospace and Mechanical Engineering Vol:7, No:5, 2013 waset.org/Publication/15827
