The subject matter disclosed herein relates to rotary elements (e.g., impellers) for use in turbomachines.
Centrifugal compressors, blowers, and like compressor devices often include an impeller (also “rotor”) that rotates to change the pressure of a working fluid (e.g., gas and liquid). The impeller has blades (also “vanes”) with geometry that can raise the energy of the working fluid. This geometry describes complex shapes and profiles, which in turn define operating characteristics (e.g., operating speed, operating pressure, etc.) for the compressor device.
The shape of the blades can dictate construction and/or manufacture of the impeller. Use of computer-aided machining tools and similar fabrication techniques, for example, are generally necessary to form the impeller with the appropriate profiles for the blades. These techniques can generate impellers from a single piece of material. In alternative construction, the blades are separate pieces that secure to the impeller, e.g., by welding.
Conventional impeller designs comprise metals (e.g., aluminum, steel, stainless steel, etc.) compatible with use of the impeller in the compressor device. For example, impellers made of metal can withstand the high pressure and operating speeds of the compressor device. These materials are also resistant to corrosion and other chemically aggravated failure modes due to properties of the working fluid.
On the other hand, while metals and like materials offer some advantages, these materials can impede progress as relates to compressor performance and cost management. Metals introduce weight constraints that can limit operating speeds for the compressor devices. These weight constraints can also dictate size and/or shapes for impeller, which can narrow the range of applications that require impellers of metal design. Moreover, metals have material properties (e.g., hardness) that can slow manufacture time. These material properties may require extensive machine time because the machining tools must run at slower speeds to render the profiles and other features found on the impeller.
This disclosure describes new construction for rotary elements that find use in compressor devices, e.g., centrifugal compressors and blowers. This construction utilizes composite materials (e.g., carbon fiber composites) that require less machine time and reduce the weight of the rotary element as compared to conventional metal (e.g., steel) designs, while meeting the operational characteristics of compressor devices for use in a wide range of industrial applications. In one embodiment, the rotary element has a bifurcated material design, which uses a first material (e.g., carbon fiber) to form blades and other features of an impeller and a second material (e.g., metal) to form a sleeve with properties that can securely affix the impeller to a drive shaft of the compressor device.
Reference is now made briefly to the accompanying drawings, in which:
Where applicable like reference characters designate identical or corresponding components and units throughout the several views, which are not to scale unless otherwise indicated.
Broadly, construction of the rotary element 100 uses a bi-furcated material design that improves the physical characteristics of the rotary element 100 as compared to conventional, single material designs. This bi-furcated design includes a first material and a second material to construct, respectively, the body element 102 and the sleeve element 104. In one embodiment, the second material is different from the first material. The second material can comprise metals (e.g., steel, stainless steel, etc.) and other materials with material properties (e.g., material hardness) that afford the sleeve element 104 with characteristics to couple securely with the drive shaft 112. For example, the second material can withstand loading (e.g., torque loading) that can occur during operation of the compressor device 108. Moreover, the second material can facilitate installation and assembly of the rotary element 100 on the compressor device 108. For example, the second material is amenable to removal of portions, e.g., by drilling and/or machining of material. This feature is helpful to balance the rotary element 100 during fit-up and assembly on the compressor device 108.
The first material can comprise a composite that provides the body element 102 with characteristics that benefit robust designs of the rotary element 100 for a broad range of applications. Examples of the first material can comprise fiber-reinforced materials, e.g., carbon-fiber reinforced materials and similar composites and derivations thereof. These types of composites are often chemically inert and/or resistant to corrosive working fluids and, thus, amenable to applications not often suitable for conventional metal impellers. These composites are also amenable to manufacturing processes (e.g., machining, turning, milling, etc.) that can shape blocks and/or billets of material into the body element 102, e.g., with grooves, blades and fins, and other features. This characteristic can reduce costs to manufacture the rotary element 100. For example, composites may take less machining time to form the features of the body element 102 as compared to conventional impellers made of metals. Moreover, the ability to manufacture the features of the body element 102 from a single piece of material, e.g., via machining, eliminates certain assembly steps (e.g., welding) and secondary processes (e.g., heat treatment) necessary for construction of some types of impellers, e.g., found on closed impeller pumps.
The first material also affords the rotary element 100 with favorable physical properties. Examples of the first material can make the rotary element 100 lighter and stiffer than impellers made from metals. Carbon fibers and other select materials, for example, may reduce the weight of the rotary element 100 by 60% or more, e.g., with respect to impellers made of steel. Increasing the stiffness of the rotary element 100 can raise the modal frequency of the rotary element 100. This feature can prevent vibration, e.g., at resonance frequency, and other problems that can limit operating speeds for the compressor device 108. The first material can also reduce deflection of the body element 102. During operation of the compressor device 108, this feature can minimize leakage of the working fluid about the periphery of the body element 102 by reducing the clearance necessary to allow the body element 102 to rotate without interference in the inlet 118.
The first material can also reduce the weight of the rotary element 100, which effectively reduces loading on the shaft 112. The resulting loading can, in turn, require smaller and/or more compact bearings (e.g., journal bearings) on the compressor device 108. The changes in bearing size can reduce parasitic loses and, ultimately, improve performance of the compressor device 108. In some implementations, favorable weight characteristics of the rotary element 100 can permit configurations (e.g., larger sizes) of the rotary element 100 to expand the operating envelope of the compressor device 108 to accommodate a broader range of operating parameters (e.g., higher speeds and higher pressures) as compared to compressors that use conventional metal impellers. Moreover, the lighter weight of the rotary element 100 increases the bending mode, which in turn can result in configurations of the rotary element 100 that can achieve aerodynamically optimal length for use in multi-stage compressor applications.
Broadly, examples of the components 124, 126 are found in carbon-fiber reinforced polymers, carbon-fiber reinforced thermoplastics, and similar materials that provide excellent physical properties (e.g., light weight) and mechanical properties (e.g., high strength and stiffness). In one example, the composition 122 is generally homogenous throughout the body element 102. This homogeneity affords the rotary element 100 with uniform properties throughout the body element 102 and/or throughout the constituent components (e.g., blades and fins) of the body element 102.
The matrix component 124 can comprise a resin of one or more polymers, e.g., epoxy, polyester, vinyl ester, and/or nylon. Selection of the resin may depend on one or more operating characteristics of the compressor device 108 (
As mentioned above, the woven component 126 embodies a three-dimensional (3D) fiber pattern. Examples of this fiber pattern arranges the fiber components 128, 130, 132 in different directions (e.g., a first direction, a second direction, and a third direction) to form and to interlock one or more of the layers 136, 138, 140, 142 to one another. As shown in
Fibers in the woven component 126 can include carbon fibers, although the present disclosure contemplates other fibers that have different material compositions. The material composition can determine the physical and mechanical properties of the body element 102. Use of carbon fibers (and compositions and derivations thereof), for example, can reduce the weight, increase the stiffness, and improve uniformity of the body element 102 as compared to elements that use metals. In one example, the fibers can vary in stiffness (also “modulus”), with one example of the fiber components 128, 130, 132 utilizing carbon fibers of standard and/or intermediate modulus. This disclosure contemplates other constructions that may utilize low modulus and high modulus fibers, as well as combinations of fibers having relatively different modulus (e.g., intermediate and high modulus) within the fiber component 126.
Broadly, the body element 202 and the sleeve element 204 integrate with one another to allow the rotary element 200 to operate in the compressor device 208 (
In one embodiment, the rotary element 200 may include one or more fasteners (e.g., screws, bolts, etc.) that penetrate one or more of the body element 202 and the sleeve element 204. These fasteners can help couple the body element 202 with the sleeve element 204, and vice versa. To further enhance engagement, and/or in lieu of the fasteners, the rotary element 200 may include a first material layer (also a “first coating”) disposed between, for example, the first bore inner surface 252 and the outer sleeve surface 256. Examples of the first material layer can include adhesives, bonding agents, and/or carbon prepreg tapes, e.g., that adhere to the first material (e.g., carbon-fiber composites) and the second material (e.g., stainless steel).
Examples the body element 202 can have a monolithic and/or contiguous structure that integrates the blades 248 with the base 246. As discussed above, use of the first material (e.g., carbon fiber composite) can permit machining of the contours, surface profiles, and features of the blades 248 and the base 246 from a single, block of material. In one example, the block of material comprises a preform of the first material. Preparation of the preform can utilize carbon fibers of standard modulus and/or glass fibers to form a fiber component (e.g., the fiber component 126 of
Turning now to the sleeve element 204, the second bore 258 allows the rotary element 200 to receive and secure to a shaft (e.g., shaft 212 of
As used herein, an element or function recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural said elements or functions, unless such exclusion is explicitly recited. Furthermore, references to “one embodiment” of the claimed invention should not be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.