Investigation of Automotive Cooling Fan Performance
This work was conducted in collaboration with
DaimlerChrysler
The experimental
investigations were the responsibility of my research group and hence are
mentioned now in more detail. A M. A. Sc.
student by the name of Philip Nourse obtained his
thesis based on the design, construction and testing of a 3m x 3m x 3m fan test
facility which contained a fan and shroud combination located in the
ceiling. The fan was attached to a
vertical rotating shaft, which was driven by a variable speed DC motor
arrangement. An X-array hot-wire probe
was used to determine the three-components of velocity. The “ram air” effect was simulated by drawing
additional air through the fan using a blower on the exhaust from the test
chamber. An orifice plate was used to
determine the overall flow rate through the facility and the entire operation
automated using a microcomputer.
A
second M.A.Sc. student by the name of Michael
Brown continued the work by modifying the facility to allow measurement of the
three-components of the upstream velocity field using a Laser
Doppler Anemometer.
This project resulted in the establishment of
an excellent facility for use in further fan studies. The expertise gained also
led to the establishment of research collaboration with Dr. S. Kouidri, of Ecole Nationale Supérieure d’Arts et Métiers (ENSAM), Paris, France in the area of axial
fan aerodynamics and noise generation.
Two students from ENSAM have worked in this area during 5 month appointments at the
The first study involved the development and
implementation of an engineering model for predicting the spectrum of noise
emanating from an axial flow fan. An existing semi-empirical method was modified for this purpose. It is based on the assumption
that the radiated acoustic pressure is primarily due to the fluctuating
pressures exerted on the fluid medium by the rotating fan blades. Simplified
techniques were used to determine the blade surface
force distribution for input to the model. In this initial work, no effort was made to account for the effects of the shroud, radiator,
condenser or engine compartment shape. Characteristic dimensions and shape
parameters as well as operating conditions such as rotational speed and
volumetric flow rate were inputs to the model. The model was compared
with narrow band measurements of the radiated noise from an axial flow fan.
The second investigation involved a computational
fluid dynamic (CFD) study of the flow field and noise generated by the cooling
fan of an electronic computer board. The flow measurements were in a reasonable
agreement with the predictions. Due to the extreme limitations of time and the
oversimplification of the noise prediction models used, however, comparisons of
the noise predictions with measurements were not in good agreement.
The fan noise work is being conducted in collaboration with Dr. Smaine Kouidri of ENSAM in