SAE International Congress & Exposition
Feb. 26-29, 1996,
COMPUTER AIDED DESIGN OF AUTOMOTIVE ALTERNATOR FANS FOR IMPROVED COOLING
PERFORMANCE AND NOISE
H. Didandeh, C. Toksoy, D. Johnson and A. Ecer, Technalysis Inc.
M. Hull and D. Buening, Delphi Energy &
Engine Management Systems
Development process of a set
of duct fans for an automotive alternator is described. By computer
modeling, one can estimate the airflow characteristics of a given fan for
providing increased cooling performance and lower noise. The process
includes identification of several fan geometries and definition of an
optimum configuration. Test results are provided for the final design.
For an air-cooled alternator,
the heat generated by various electrical components of the alternator is
removed by properly managing the airflow. The packaging requirements result
in many restrictions for the airflow through the alternator. While the two
fans on each end drives the airflow, the details of the geometry of the
inlet, the electrical components and the rotor also strongly effect the
cooling characteristics of an alternator. Especially, the details of the
airflow on the regulator side of the alternator has to be studied carefully,
in terms of the amount of air and its distribution as a function of fan
performance and system restrictions. In the present paper, the design of
dual internal fans for cooling of an alternator is discussed for both the
Slip Ring End Fan (SRE) and the Drive End (DE) fans.
In this paper, the details of
the design process for improving the airflow performance of automotive
alternator is presented. Emphasis is given to the design of the fans. The
objectives of the design involves controlling the flow, managing its
distribution and reducing the flow induced noise. Only the details of the
flow analysis is presented in this paper although similar analyses were
performed for determining the heat transfer characteristics.
The DE Fan is designed to
cool the rotor segment and the windings of an alternator. While for the
previous designs, an external fan was employed for this purpose, the current
design is based on an internal DE fan which is located on the side of the
pulley and the drive end bearing. SRE fan is designed to cool the electrical
components of the alternator and it is located on the opposite side of the
drive end. The airflow entering through this fan controls the cooling
performance of the electronics. The procedure includes both the study of an
isolated fan and its installation.