Fluid reaction surfaces (i.e. – impellers) – Rotor having flow confining or deflecting web – shroud or... – Axially extending shroud ring or casing
Reexamination Certificate
2000-05-04
2001-11-13
Kwon, John (Department: 3747)
Fluid reaction surfaces (i.e., impellers)
Rotor having flow confining or deflecting web, shroud or...
Axially extending shroud ring or casing
Reexamination Certificate
active
06315521
ABSTRACT:
FIELD OF THE INVENTION
The invention generally relates to axial flow fans for use in cooling systems. The invention particularly relates to a fan design which reduces tonal components of noise at the blade passing frequency while maintaining flow and pressure generated by the fan.
BACKGROUND OF THE INVENTION
An axial flow fan may be used to produce a flow of cooling air through the heat exchanger components of a vehicle. For example, an airflow generator used in an automotive cooling application may include an axial flow fan for moving cooling air through a liquid-to-air heat exchanger such as an engine radiator, condenser, intercooler, or combination thereof. The required flow rate of air through the fan and change in pressure across the fan vary depending upon the particular cooling application.
Generally, axial flow fans are designed by using a free vortex or forced vortex flow/pressure distribution. A free vortex design ensures that a constant total pressure rise is achieved everywhere across the span of the fan blade. The forced vortex designs are usually a slight deviation from the free vortex designs since the forced vortex designs maintain a relatively two-dimensional flow through the blade passage.
Conventional fans are often designed such that the blade profiles work close to their peak ratio of lift to drag. The efficiency of the fan is related to how closely the blades operate to their peak lift to drag value. The high lift coefficient on the blades results in a strong pressure pulse. Gutin's principle shows that strong pressure pulse results in a tonal component of noise at the blade passing frequency.
Accordingly, there is a need to provide a fan to reduce the tonal component while maintaining the flow and pressure generated by the fan.
SUMMARY OF THE INVENTION
An object of the invention is to fulfill the need referred to above. In accordance with the principles of the present invention, this objective is achieved by providing an axial flow fan for producing airflow through an engine compartment of a vehicle. The fan includes a hub rotatable about an axis; an annular band concentric with the hub and spaced radially outward from the hub; fan blades distributed circumferentially around the hub and extending radially from the hub to the annular band. Each blade has specific parameters defined by:
r, the non-dimensional radius from the rotational axis (r=R/R
tip
with R being the radius from the rotational axis and R
tip
being the radius from the rotational axis at the blade tip),
&xgr;, the stagger angle of the blade at the radial distance r,
&thgr;, the camber angle of the blade at the radial distance r,
&sgr;, the solidity C/S, with C being chord length and S being the circumferential blade spacing at the radial distance r,
c, the non-dimensional chord length (C/R
tip
) of the blade at the radial distance r,
t, the non-dimensional thickness (T/C where T is the actual thickness at R) of the blade at radius r,
&Lgr;, the skew angle of the blade at the radial distance r calculated at 30% chord where the skew at the hub radius is defined as zero skew, and
dH/dR, the slope of the dihedral measured at r.
Other objects, features and characteristics of the present invention, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawings, all of which form a part of this specification.
REFERENCES:
patent: 5326225 (1994-07-01), Gallivan et al.
patent: 6238184 (2001-05-01), Giribaldi
patent: 6241474 (2001-06-01), Alizadeh et al.
Kwon John
Siemens Automotive Inc.
LandOfFree
Fan design with low acoustic tonal components does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fan design with low acoustic tonal components, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fan design with low acoustic tonal components will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2604907