Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2001-07-26
2003-03-25
Thompson, Gregory (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C415S200000, C415S208200
Reexamination Certificate
active
06538887
ABSTRACT:
TECHNICAL FIELD
This invention relates in general to air moving devices, such as fans and blowers, and more specifically to blades for use in such air moving devices that are configured having a roughened surface, e.g., with dimples or ribs, to induce a turbulent boundary layer, which enables enhanced performance in air movement provided by such blades by delaying air separation during operation.
BACKGROUND
Air moving devices, such as fans and blowers, are becoming an increasingly important aspect of system cooling designs in today's electronics. It is often desirable to provide an electronic device with great functionality and relatively small size. Thus, it is often important to generate as much performance as possible from air moving devices without being required to increase the size of such air moving devices. That is, it is often desirable to generate greater performance (e.g., greater air flow) for an air moving device of a given size without being required to increase the size of such air moving device. Development efforts for cooling systems of the prior art have primarily been focused on improving cooling techniques (e.g:, improving the performance of active sub-cooling modules, including compressors, evaporators, etcetera, as well as passive cooling modules, such as heat sinks), but fan blade designs have generally been overlooked. That is, relatively little focus has been placed on improving fan blade design to enhance performance of cooling systems.
In typical implementations of the prior art, the performance of air moving devices, such as fans, has been limited by the angle of attack of the fan blades because of the occurrence of air separation off of the top side (or low pressure intake side) of the blades. In many cases, the angle of attack of the blades dictates the maximum speed at which the air moving device can operate efficiently due to separation. “Separation” is defined as when the boundary layer of the fan separates from the surface of the blade. This is analogous, for example, to when separation occurs off of an aircraft wing, which is generally referred to as a “stall” wherein lift is lost. As is well known in the art, such air separation behavior may be encountered during operation of a fan blade implementation, at which point there is a significant decrease in fan performance. Accordingly, a desire exists for a blade configuration that delays the point at which separation occurs to enable improved performance of an air moving device.
SUMMARY OF THE INVENTION
The present invention is directed to a system and method which include at least one blade implemented within an air moving device to enable enhanced performance of such air moving device. According to at least one embodiment, the blade(s) of an air moving device are implemented with a rough surface to effectively delay the operational point at which air separation from the blade(s) is encountered, thereby enabling enhanced performance of the air moving device without requiring an increase in fan blade size. In one embodiment, dimples are arranged on the blade(s), in a similar manner to dimples arranged on a golf ball, to provide a rough surface that improves the aerodynamic performance of such blade(s).
According to one embodiment of the present invention, an air moving device is disclosed that is operable to generate a flow of air from a low pressure region to a high pressure region. The air moving device comprises at least one blade that is operable to generate a flow of air as a result of movement thereof. The blade(s) include a rough surface on a side facing the low pressure region, and such rough surface is arranged to induce a turbulent boundary layer that enables operation of the air moving device in a manner that would otherwise result in separation of air from the blade(s).
According to another embodiment of the present invention, a system is disclosed that comprises an air moving device operable to generate a flow of air from a low pressure region to a high pressure region. The air moving device includes at least one blade operable to generate the flow of air as a result of movement thereof. The blade(s) include a means, arranged on a side facing the low pressure region, for inducing a turbulent boundary layer to enable operation of the air moving device within an operating region that would otherwise result in separation of air from the blade(s).
According to yet another embodiment of the present invention, a method of generating air movement is disclosed, which comprises utilizing an air movement device that is operable to generate a flow of air from a low pressure region to a high pressure region. The air movement device includes at least one blade operable to generate the flow of air as a result of movement thereof, and the blade(s) include a rough surface arranged on a side facing the low pressure region. The method further comprises operating the air movement device within an operating region, wherein the rough surface induces a turbulent boundary layer to avoid encountering an aerodynamic stall that would otherwise be encountered within such operating region.
REFERENCES:
patent: 4720239 (1988-01-01), Owezarek
patent: 5193983 (1993-03-01), Shyu
patent: 5480284 (1996-01-01), Wadia et al.
patent: 5927944 (1999-07-01), Belady
patent: 6126395 (2000-10-01), Shingai
patent: 6162136 (2000-12-01), Aoyama
patent: 6183197 (2001-02-01), Bunker et al.
“Fan Handbook, Selection Application & Design” by Frank P. Bleier, McGraw Hill 1997, pp. 2.4-2.7 and pp. 4.28-4.33.
All You Need to Know About Fans by Mike Turner et al., printed from Internet site 222.electronics-cooling.com/Resources/EC_Articles/May 1996.
Application Ser. No. 09/867,194 filed May 29, 2001, Inventor Christian Belady.
Belady Christian L
Zeighami Roy M.
Hewlett--Packard Company
Thompson Gregory
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