Patent Application
20180105242
The field of the disclosure relates generally to propulsion systems and, more particularly, to a method and system for improved flow characteristics of composite marine propellers.
At least some known marine propulsion systems rely on a rotating propeller assembly including a central hub and propeller blades extending from the central hub. During operation, fluid generally flows across surfaces of the propeller assembly and through gaps defined between blades of the propeller assembly. Performance of the propeller assembly is highly dependent on the shape of the propeller assembly surfaces including those of the blades and the central hub. As a result, propeller assemblies in which the shape of propeller assembly components are limited by construction methods, material limitations, component sizes, and the like, may result in sub-optimal flow characteristics, decreasing the efficiency of the propeller assembly and requiring more powerful drive systems to achieve required propulsion.
In one aspect, a propeller assembly is provided. The propeller assembly includes a central hub including a forward end, an aft end, and a hub body extending therebetween. The propeller assembly further includes a first retention member including a first radial interference member, the first retention member coupled to the forward end of the central hub, and a second retention member including a second radial interference member, the second retention member coupled to the aft end of the central hub. The propeller assembly also includes a fairing platform extending between the first retention member and the second retention member, wherein the fairing platform is retained by the first radial interference member and by the second radial interference member.
In another aspect, a fairing structure supportable by a central hub of a propeller assembly, the central hub including a forward end, an aft end, and a hub body extending therebetween, is provided. The fairing structure includes a first retention member including a first radial interference member, the first retention member couplable to the forward end of the central hub, and a second retention member including a second radial interference member, the second retention member couplable to the aft end of the central hub. The fairing structure further includes a fairing platform extending between said first retention member and said second retention member, said fairing platform configured to engage said first radial interference member and said second radial interference member.
In yet another aspect a method of manufacturing a fairing structure supportable by a central hub, the fairing structure including a fairing platform including a radially outer platform surface is provided. The method includes determining a first flow coefficient for a first propeller assembly including the central hub without the fairing structure. The method further includes determining a platform profile for the radially outer platform surface such that a second propeller assembly including the radially outer platform having the platform profile has a second flow coefficient greater than the first coefficient. The method also includes forming the fairing platform such that the radially outer platform surface substantially conforms to the platform profile.
These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
Unless otherwise indicated, the drawings provided herein are meant to illustrate features of embodiments of this disclosure. These features are believed to be applicable in a wide variety of systems comprising one or more embodiments of this disclosure. As such, the drawings are not meant to include all conventional features known by those of ordinary skill in the art to be required for the practice of the embodiments disclosed herein.
In the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings.
The singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise.
“Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.
Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” “approximately,” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged; such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise.
As used herein, the terms “axial” and “axially” refer to directions and orientations that extend substantially parallel to a centerline of the propeller assembly. Moreover, the terms “radial” and “radially” refer to directions and orientations that extend substantially perpendicular to the centerline of the propeller assembly. In addition, as used herein, the terms “circumferential” and “circumferentially” refer to directions and orientations that extend arcuately about the centerline of the propeller assembly.
Embodiments of the systems and methods described herein provide improved flow characteristics for marine propeller assemblies. Systems described herein include a fairing structure configured to be included in a propeller assembly. The fairing structure generally includes forward and second retention members configured to be coupled to forward and aft faces of a central propeller hub, respectively. The forward and second retention members are configured to retain and support a fairing platform therebetween. The fairing platform includes a radially outer surface configured to facilitate efficient flow of fluid across the propeller assembly and, in particular, between adjacent propeller blades of the propeller assembly. The radially outer surface of the fairing platform is generally shaped such that the propeller assembly including the fairing platform has a flow coefficient that exceeds that of the propeller assembly without the fairing platform, i.e., with the central hub exposed between adjacent blades.
While described in the context of a marine propeller, it should be understood that the systems and methods described herein are also applicable to other propulsion and turbomachine systems including, without limitation, turboprop engines, turboshaft engines, turbojet engines, open rotor engines, and any other turbine engine where improved flow characteristics are desirable.
Hub 102 includes a first face 108, a second face 110 (not shown in
In certain alternative embodiments, fairing structure 150 is retained by other components of propeller assembly 100. In such alternative embodiments, first retention member 152 and second retention member 154 may be omitted from marine propeller assembly. For example, in one alternative embodiment, fairing structure 150 is configured to receive a radial retention member, such as a pin, rod, bolt, or fastener, configured to extend through fairing structure 150 in a radial direction and to couple fairing structure 150 to one of hub body 112 and one of the plurality of wedges 104. In another alternative embodiment, fairing structure 150 includes a lip, an overhang, a hook, or a similar feature configured to couple with a complementary feature, such as a groove, of one or more of first face 108 and second face 110.
In the example embodiment of propeller assembly 100, fairing platform 156 is configured to be floatingly retained by each of first retention member 152 and second retention member 154. The term “floatingly retained” is used herein to describe retention in which clearance between fairing platform 156 and each of first retention member 152 and second retention member 154 facilitates at least some movement of fairing platform 156 in at least one direction. For example, in certain embodiments, such clearance facilitates fairing platform 156 to move circumferentially about hub 102 between adjacent blades 106. By doing so, flexing or bending of blades 106 caused by loading during operation is not impeded by fairing platform 156 and any stresses induced by fairing platform 156 on 106 is reduced.
The tongue and groove engagement of
Fairing platforms according to certain embodiments of the present disclosure are generally configured to improve fluid flow characteristics of propeller assemblies during operation as compared to fluid flow characteristics of propeller assemblies absent such fairing platforms. For example, fairing platform 156 is configured to improve flow characteristics of propeller assembly 100 (as shown in
In light of the foregoing, a method of manufacturing a fairing structure including a fairing platform may generally include determining a first flow coefficient of a propeller assembly including a central hub without a fairing structure. Such a determination may be made using techniques including, but not limited to, physical testing of a full-scale or reduced-scale version of the propeller assembly and computer modelling of the propeller assembly. Next, a platform profile for a radially outer surface of the fairing platform may be determined such that a second propeller assembly including a fairing platform having the platform profile has a second flow coefficient greater than the first coefficient. The fairing platform may then be formed such that the radially outer surface of the fairing platform substantially conforms to the platform profile. The fairing platform may be formed by any suitable manufacturing technique including, but not limited to one or more of casting, machining, additive manufacturing (such as 3D printing), injection molding, hydroforming, and stamping.
The above-described marine propeller systems provide a method for improving flow characteristics of a marine propeller assembly. Specifically, the above-described marine propeller system includes a fairing structure that improves the flow coefficient of the propeller assembly by facilitating the use of a fairing platform for use between adjacent blades of the propeller assembly. The fairing platform may be formed to have improved flow characteristics as compared to the central hub of the propeller assembly.
An exemplary technical effect of the methods, systems, and apparatus described herein includes at least one of: (a) improving overall efficiency of the propeller assembly; (b) increasing propulsion produced by the propeller assembly for a given drive; (c) reducing the drive required to achieve a desired level of propulsion; and (d) facilitating the use of separable composite blades in a propeller assembly.
Exemplary embodiments of marine propeller systems are described above in detail. The marine propeller systems, and methods of manufacturing such systems and component devices are not limited to the specific embodiments described herein, but rather, components of the systems and/or steps of the methods may be utilized independently and separately from other components and/or steps described herein. For example, the methods may also be used in combination with other propeller-related systems, and are not limited to practice with only the systems and methods as described herein. Rather, the exemplary embodiment can be implemented and utilized in connection with many other machinery applications that are currently configured to receive and accept propeller assemblies.
Although specific features of various embodiments of the disclosure may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the disclosure, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.
This written description uses examples to disclose the embodiments, including the best mode, and also to enable any person skilled in the art to practice the embodiments, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure 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.
