Rotary kinetic fluid motors or pumps – Working fluid passage or distributing means associated with... – Plural rigidly related blade sets
Reexamination Certificate
2001-02-23
2003-07-08
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
Working fluid passage or distributing means associated with...
Plural rigidly related blade sets
Reexamination Certificate
active
06589013
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to fluid flow equipment, and more particularly, to fluid flow controlling equipment such as compressors and pumps.
2. Description of the Related Art
The information described below is not admitted to be prior art by virtue of its inclusion in this Background section.
Fluid flow controlling equipment (“fluid flow controllers”) may be considered to include those apparatuses that are capable of controlling (e.g., pumping, compressing) fluid flow (e.g., liquids, gases, combinations thereof). Two of the most important types of fluid flow controllers are pumps and compressors. Pumps are fluid flow controllers that may be used to raise and/or transfer fluids, often by pressure or suction. Compressors are fluid flow controllers that may be used to increase the pressure of a fluid (typically gases). There are several types of pumps and compressors. Many compressors and pumps have overlapping characteristics (e.g., many types of each are similar in design), and thus the device types are usually distinguished by their primary intended use.
One particularly important type of compressor is the centrifugal compressor. Centrifugal compressors typically operate by accelerating a fluid introduced into the compressor and then decelerating the fluid to induce a rise in the fluid static pressure. The principle of operation behind a centrifugal compressor is similar to that of a centrifugal pump; the difference is essentially in the nature of the fluids operated on by each device. Centrifugal compressors are often preferred over other compressor types because of their potential for smaller size and greater pressure rise.
Centrifugal compressors typically include an impeller, or rotor, positioned within a stationary casing (e.g., a stator). In a typical centrifugal compressor configuration, the rotor is essentially a wheel with curved vanes, or blades. The blades extend from the hub of the rotor to the tip of the rotor. The hub of the rotor has hub opening that extends through the rotor. A shaft for rotating the rotor within the casing extends through the hub and is attached to the rotor. During operation, fluid flow typically enters a centrifugal compressor in a direction substantially parallel to the rotational axis of the rotor, and exits the rotor in a direction substantially perpendicular to the rotational axis of the rotor. By appropriately rotating the rotor within the casing, the blades of the rotor may accelerate fluid fed into the compressor, allowing the fluid to exit the rotor with increased velocity (and possibly pressure). The accelerated fluid may then be directed into a collector (e.g., a volute). From the collector, the accelerated fluid may enter a diffuser where the fluid is slowed, allowing further conversion from kinetic energy (velocity) to potential energy (pressure) to occur.
In a centrifugal compressor, the degree of fluid flow acceleration is largely affected by the orientation of the blades on the rotor. Generally speaking, rotor blades can be oriented in radial, forward (flow directed into the direction of rotation), or backwards (flow directed opposite the direction of rotation) orientations. By orienting the blades in a particular manner, and by otherwise molding the rotor blades into particular shapes (e.g., twisting or leaning the blades), fluid directed into a compressor can be turned a certain way by the rotor and a desired degree of fluid acceleration can be obtained.
Unfortunately, the extent to which the orientation of rotor blades may be effectively manipulated to enhance fluid flow acceleration is limited. As noted above, conventional compressor blades may extend from a point proximal the hub of the rotor to a point proximal the rotor tip. When attempting to accelerate fluid with such blades, the rotated fluid preferably follows a blade or blades of the rotor for the length of the blade(s). That is, in an ideal centrifugal compressor entering fluid travels along a blade from the inner edge of a blade to the outer edge of the blade before exiting the rotor into the collector. If, however, the angles of the rotor blades are too large, and the rotated fluid is turned to an excessive degree (given a variety of fluid and compressor parameters), then the fluid may not follow (e.g., may separate from) the rotor blades. The separated fluid may increase the turbulence of the fluid sent into the collector, making the fluid flow more difficult to handle efficiently. Such a situation may undesirably prevent the desired degree of acceleration (and thus pressurization) from being achieved.
In an attempt to circumvent this problem, many compressor designers are forced to abandon more compact, single stage designs in favor of larger, multiple stage designs. Multiple stage compressors typically include multiple rotors arranged in series to obtain greater pressure rises than may usually be obtainable from single stage compressors using the same type of rotor. Because such multiple stage compressors are larger, however, one of the advantages of using a centrifugal pump may be reduced or lost. In addition, the efficient transport of an accelerated fluid from one stage to another is difficult, and thus the efficiency of multiple stage compressors is often less than a similarly configured single stage compressor.
Therefore, it would be desirable to develop a fluid flow controller, e.g., a compressor or pump, which has an enhanced ability to accelerate fluid flow. Such a fluid flow controller should reduce or eliminate the need to use multiple stages to achieve a desired degree of performance.
SUMMARY
The problems described above may be in large part addressed by the present fluid flow controller and method of operation thereof. The fluid flow controller may include a casing having a casing blade. The fluid flow controller may also include a rotor including a first rotor blade and a second rotor blade. The first and second rotor blades are preferably truncated such that they are radially spaced from each other. That is, the first and second rotor blades preferably do not extend the length of the rotor (e.g., from the hub of the rotor to the tip of the rotor) as do many conventional blades, but instead each extend to radially spaced points along the rotor. The casing blade is preferably also a truncated blade having a length less than the radial spacing between the first and second rotor blades. Thus, the rotor may be configured to rotate relative to, and preferably within, the casing such that the casing blade passes between the first and second rotor blades during use.
Compared to conventional pumps or compressors, the present fluid flow controller may have an enhanced ability to accelerate (and possibly to subsequently pressurize) fluid flow. As noted above, when the angles of a rotor blade become too extreme, and the rotated fluid is turned to an excessive degree (given a variety of fluid and controller parameters), the fluid may not follow the rotor blades and the desired degree of acceleration may not be obtained. In addition, the maximum extent to which rotor blades may efficiently turn fluid flow is influenced by the length of the blades. Thus, the maximum degree to which each truncated blade can turn or accelerate fluid flow may be slightly less than that of a conventional rotor blade that extends from the rotor hub to the rotor tip. But since the number of discrete blades on the rotor and casing may be significantly increased over conventional designs, the present fluid flow controller may provide greater fluid flow acceleration.
One reason for this benefit may be that each blade of the present fluid flow controller (whether on the casing or the rotor) may be configured specifically for the flow characteristics it is expected to encounter during operation. Further, instead of having to be turned by, and thus follow, one long, continuous blade over its entire length, fluid flow may instead be turned by several discrete blades in series. In addition, because of the presence of the casing blad
Conley & Rose, P.C.
Daffer Kevin L.
Look Edward K.
Macro-Micro Devices, Inc.
McCoy Kimya N
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