Patent Application
20090035132
1. Field of the Invention
The present invention relates to a housing or chamber for a fan for moving air, pump for inducing fluid flow or torque generator, which is responsive to fluid flow such as a turbine. In particular it is directed to providing an improved housing for such apparatus to improve the efficiency of such devices.
2. Description of the Related Art
Centrifugal fans, blowers, pumps turbines and the like represent approximately half of the world's fan, pump and turbine production each year. As fans or pumps, they are used to produce higher pressure and less flow than axial impellers and fans. They are used extensively where these parameters must be satisfied. They have also been used advantageously where installation limitations might not permit an axial fan to be used.
For example, applications such as domestic exhaust fans require greater flow with a relatively low pressure difference. Such an application would normally be satisfied by an axial type of fan. However, in many cases, a centrifugal fan is used to turn the flow path at right angles so that it can fit into a roof or wall cavity. An axial fan will not fit into the cavity and maintain efficiency. In another example, the exhaust ducting in many buildings is only 3 or 4 inches in diameter. It is impractical to fit an effective high-output axial fan to such a small duct.
While centrifugal fans have been used for a long time, little attention has been given to the design of the housing in which the rotor is retained. Where issues of efficiency and noise are investigated, the designer's attention is given primarily to the impeller. Historically, such housings have not been optimized for: 1. fluid flow drag reduction; 2. noise reduction; 3. adjustment of the pressure/flow relationship. Additionally, the housings of typical centrifugal fans, blowers, pumps turbines and the like cause the incoming fluid to turn sharply before leaving the housing. Such shapes are detrimental to efficient performance of the device overall, often introducing significant turbulence.
In the previous disclosure of the applicant for a Fluid Flow Controller as published in W003056228, the applicant has noted the benefits that can be obtained by allowing fluid to flow in the manner followed in Nature.
Exemplary housings for a rotor are provided. In some embodiments, a housing includes an inlet portion with a shroud for guiding a fluid moving in association with the rotor, and an outlet portion to exhaust the fluid, the outlet portion extending the shroud from the inlet portion, the shroud expanding axially away from a region of rotation of the rotor, the shroud promoting vortical flow of the fluid through the housing. Such housings may be adapted for an axial rotor, a centrifugal rotor, or a rotor having a profile intermediate to that of an axial rotor and that of a centrifugal rotor.
In some embodiments, a rotor housing may include a shroud enclosing a region of rotation for a rotor, an inlet located on a first portion of the shroud and an outlet located on a second portion of the shroud, the second portion of the shroud being approximately opposed with respect to the first portion of the shroud, wherein an internal surface of the shroud includes a vortical formation that induces a vortical flow in a fluid traversing a fluid pathway between the inlet and the outlet. Such housings may be adapted for an axial rotor, a centrifugal rotor, or a rotor having a profile intermediate to that of an axial rotor and that of a centrifugal rotor.
Each of the embodiments is directed to a housing for a fan, blower, pump or turbine or the like, which provides an efficient fluid pathway. Hereinafter in this description the term ‘fan’ will be used generically to refer to any fan, blower, pump, turbine or the like. Where a reference is made to a fan driving or promoting fluid flow, it is to be appreciated that the reference is intended to encompass the situation where the fluid flow drives a rotor of a turbine or the like.
In order to appreciate the differences from the prior art, it is helpful to describe the key features of housings conventionally used for centrifugal fans. An example is illustrated diagrammatically in
The shape of a spiraling arc means that a space is provided between the inner surface of the edge panel and the imaginary surface swept by the outer edges of the vanes of the rotor. It will be appreciated that the depth of this space increases progressively from a minimum to a maximum through an angle of 360 degrees. In the vicinity of the maximum depth an outlet is provided to exhaust the fluid.
Each of the embodiments is directed to a housing for a fan, which provides an efficient fluid pathway for fluid passing through the housing. Such fans comprise a rotor which is normally provided with a plurality of vanes or blades although a rotor having a single blade is possible. The vanes are generally configured to provide an outward or radial component of acceleration to the fluid being driven, or in the case of a turbine, the fluid is deflected to provide a radial component to the force applied to the vane and thereby a deflection to the fluid including a radial component.
Nature provides excellent models of optimized streamlining, drag reduction, and noise reduction. Any biological surface grown or eroded to optimize streamlining has no angled corners and does not make fluid turn at right angles but generally follows the shape of an eddy constructed in accordance with a three-dimensional equiangular or Golden Ratio spiral. The underlying geometry of this spiral is also found in the design of a bird's egg, a snail, and a sea shell.
These spirals or vortices generally comply with a mathematical progression known as the Golden Ratio or a Fibonacci like Progression.
Each of the embodiments, in the greater part, serves to enable fluids to move in their naturally preferred way, thereby reducing inefficiencies created through turbulence and friction which are normally found in housings for centrifugal fans.
Previously developed technologies have generally been less compliant with natural fluid flow tendencies.
It has been found that it is a characteristic of fluid flow that, when it is caused to flow in a vortical motion through a pathway that the fluid flow is substantially non-turbulent and as a result has a decreased tendency to separate or cavitate. It is a general characteristic of the embodiments that the housings described are directed to promote vortical flow in the fluid passing through the housing. It has also been found that vortical flow is encouraged where the configuration of the housing conforms to a two-dimensional or three-dimensional spiral. It has further been found that such a configuration tends to be optimized where the curvature of that spiral conforms substantially or in greater part to that of the Golden Section or Ratio. It is a characteristic of each of the embodiments that the greater proportion of the internal surfaces which form the housing have a curvature which takes a two dimensional or three dimensional shape approaching the lines of vorticity or streak lines found in a naturally occurring vortex. The general form of such a shape is a logarithmic spiral. It has further been found that the performance of the embodiments will be optimized where the curvature of the surfaces of the housing substantially or in the greater part conform to the characteristics of the Golden Section or Ratio. It has further been found that the performance is optimized if any variation in cross-sectional area of the fluid pathway also substantially or in greater part conforms to the characteristics of the Golden Section or Ratio.
It has also been found fluid flow is more efficient if the surfaces over which the fluid flows have a curvature substantially or in greater part correspond to that of the Golden Section. As a result of the reduced degree of turbulence which is induced in the fluid in its passageway through such a fan, the housing according to the various embodiments can be used for conducting fluid with less noise and wear and with a greater efficiency than has previously been possible with conventional housing of equivalent dimensional characteristics.
The greater percentage of the internal surfaces of the housings of each of the embodiments described herein are generally designed in accordance with the Golden Section or Ratio and therefore it is a characteristic of each of the embodiments that the housings provides a fluid pathway which is of a spiraling configuration and which conforms at least in greater part to the characteristics of the equiangular or Golden Section or Ratio. The characteristics of the Golden Section are illustrated in
This invention may, alternatively, use a snail or sea shell-like shaped flow path housing which may be logarithmic but not a Golden Ratio. Although it is not optimized if it doesn't conform to the three-dimensional Golden Ratio, it will still provide superior performance in its intended use over conventional designs.
A first embodiment of the invention is a fan assembly as shown in
The fan assembly 11 comprises a fan rotor 12 having a plurality of vanes 13, the rotor 12 being adapted to be rotated by an electric motor, not shown. The fan motor is supported within a housing 14 having an inlet 16 and an outlet 17.
The housing 14 has a whirl-shaped form, at least on the internal surfaces which resembles the shape of shellfish of the genus Trochus. This shape corresponds generally to the streamlines of a vortex. In the drawings it is to be appreciated that the form indicated on the external surfaces is intended to correspond with the form of the internal surface, although in a real fan the form of the external surface is not of importance to the performance of the fan as such and may be quite different from the internal surfaces. Indeed, the housing might be constructed with an internal shroud which comprises a separate component from the external surface of the housing, and it is to be appreciated that where such a design is undertaken, it is the internal surfaces of the separate shroud which must conform to the principles as described herein.
In the first embodiment, the housing is formed in two portions, 18 and 19. The first of these comprises an inlet portion 18 which includes the inlet 16 and also provides mounting means (not shown) to support the fan motor to which the fan rotor 12 is attached. The inlet portion 18 also acts as a shroud around outer extents of the vanes 13 of the rotor 12 and provides a space 22 between the inner surface 21 of the inlet portion 18 and the imaginary surface swept by the outer edges 23 of the vanes 13 during rotation of the rotor 12. It will be seen in
As mentioned earlier, while a housing having a generally vortical internal form can be expected to provide significant improvements in higher efficiency and reduced noise, the benefits will be optimized by configuring the housing to have a vortical form in the nature of a three dimensional equi-angular spiral or “Golden- Section” spiral. Such a shape should have the internal surfaces configured to have a curvature conforming to the Golden Section. Such a shape will conform with the natural flow tendencies of fluids, thereby further improving efficiency.
It is to be appreciated that the configuring of the housing to be in two portions is to provide ease of manufacture, assembly and maintenance, only. The two portions of such a housing may be held together by releasable clasping means such as clips (not shown), or may include cooperating flanges, bayonet fastenings, or other suitable joining means.
In a second embodiment, as shown in
While a housing according to the first and second embodiments will provide improved performance when used with rotors having a wide range of vane configurations, it is to be appreciated that performance of the fan assembly will also depend on the configuration of the rotor. It has been found that performance may be further improved where the rotor itself is designed to provide flow in accordance with the principles of nature. Such a rotor is described in the applicants co-pending application entitled “Vortical Flow Rotor.” It is to be understood that such a rotor is directed to providing a vortical flow stream, and when appropriately configured in conjunction with a housing according to the first or second embodiment, an optimized performance characteristic can be achieved.
It can be understood in light of the above description that a housing according to the first and second embodiments will provide performance improvements where a centrifugal rotor is used. As mentioned in relation to
This discovery has led to a further advance. The vanes of the rotor that can be used within the housing of the first embodiment may be configured with a profile that is intermediate between an axial and a centrifugal rotor. As mentioned earlier, axial and centrifugal rotors have quite differing performance characteristics: the axial rotor promoting high flow at low pressure while the centrifugal rotor promotes low flow at high pressure. By selecting a rotor with an intermediate characteristic, the performance of the fan can be “tailored” to more precisely match the application. The precise configuration of the housing may also be “tuned” to cooperate fully with the selected rotor to even further improve the design characteristics. Such flexibility has not been appreciated previously.
A designer can now approach a project knowing that he can properly design an appropriate fan for the task, rather than adopting an inappropriate fan due to physical constraints.
Additionally, it has been found that the compound curves of the housing of the above embodiments have rigidity and structural integrity considerably beyond flat sided panels found in conventional housings and thereby can be built from lighter and thinner materials. Nevertheless, the inherent stiffness, combined with the lack of turbulence within the fluid flow also reduce noise—a major problem in conventional housings. Flat-sided housings vibrate, drum, resonate, and amplify noise. The housing of the embodiments reduces vibration, drumming, resonance, and amplification of noise.
While it is believed that a fan having superior performance will generally be achieved by designing the housing in a three-dimensional vortical form as described in relation to the first embodiment, there will be instances where it will not be practicable to adopt such a form. This is more likely to be the case where the fan is to be used in an existing installation that has previously incorporated a conventional centrifugal fan. Nevertheless, significant improvements can be obtained by incorporating into the design of a conventional centrifugal fan the principles revealed in the first embodiment.
When assembled together, the first and second halves provide a fluid space between the internal surface of the housing and the imaginary surface swept by the outer edges of the vanes 13 during rotation of the impeller 69. This space increase from a minimum at a point “A” to a maximum at an adjacent point “B.”
At the maximum point “B” the housing incorporates an outlet opening 71 transverse to the plane of rotation of the impeller which is co-planar with the axis. In use an outlet duct 72 (as shown in dotted lines) will normally be mounted to the outlet to convey the fluid from the housing.
The walls of the two halves around the space are curved with a curvature which substantially conforms with the Golden Section. This curvature is also be configured to cause the fluid to flow within the space in a spiraling, vortical motion. As a result, drag in the fluid flow through the space is reduced.
This drag reduction minimizes vibration, resonance, back pressure, turbulence, drumming, noise and energy consumption and efficiency is improved in comparison to a conventional fan of the type shown in
It has also been found to be advantageous that this space increases at a logarithmic rate conforming to the Golden Ratio.
The fifth embodiment may be adapted further. A sixth embodiment is shown in
Throughout the specification, unless the context requires otherwise, the word “comprise” or variations such as “comprises” or “comprising,” will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.
The present application is a continuation and claims the priority benefit of U.S. patent application Ser. No. 11/496,013 filed Jul. 28, 2006, which is a continuation and claims the priority benefit of Patent Cooperation Treaty application number PCT/AU2005/000116 filed Jan. 31, 2005, which claims the priority benefit of U.S. provisional patent application Nos. 60/540,513 filed Jan. 30, 2004; 60/608,597 filed Sep. 11, 2004; and 60/624,669 filed Nov. 2, 2004. The disclosure of the aforementioned applications is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60540513 | Jan 2004 | US | |
| 60608597 | Sep 2004 | US | |
| 60624669 | Nov 2004 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11496013 | Jul 2006 | US |
| Child | 12221711 | US | |
| Parent | PCT/AU2005/000116 | Jan 2005 | US |
| Child | 11496013 | US |
