Pumps are commonly known and used to pressurize fluids. For example, a pump may include an inducer that may have one or more blades that extend from a rotor to a radially offset tip. The rotor and blades rotate to pressurize fluid that enters the pump.
A pump according to an example of the present disclosure includes an axial inducer that has a housing having an internal surface that defines an axial fluid passage. A rotor is disposed about a central axis in the fluid passage of the housing and has at least one blade that defines at least one blade tip. The internal surface of the housing defines a plurality of grooves adjacent the at least one blade tip. The grooves are elongated in a circumferential direction.
In a further embodiment of any of the foregoing embodiments, each of the grooves is an endless groove.
In a further embodiment of any of the foregoing embodiments, the plurality of grooves includes an ended groove.
In a further embodiment of any of the foregoing embodiments, the plurality of grooves includes an endless groove and an ended groove aft of the endless groove.
In a further embodiment of any of the foregoing embodiments, the plurality of grooves includes a plurality of endless grooves and a plurality of ended grooves that are aft of the plurality of endless grooves.
In a further embodiment of any of the foregoing embodiments, the plurality of grooves includes a plurality of endless grooves, and the endless grooves are uniformly axially-spaced apart.
In a further embodiment of any of the foregoing embodiments, the plurality of grooves are of common aspect ratio with respect to groove depth and groove width.
In a further embodiment of any of the foregoing embodiments, the plurality of grooves have a constant cross-section.
In a further embodiment of any of the foregoing embodiments, the one or more blades begin at a first axial location. The one or more blades terminate at a second axial position. The plurality of grooves begin at a third axial location. The at least one groove terminates at a fourth axial position, and the fourth axial location is forward of the second axial location.
In a further embodiment of any of the foregoing embodiments, the internal surface of the housing includes a band aft of the plurality of grooves that excludes any of the one or more grooves.
In a further embodiment of any of the foregoing embodiments, the plurality of grooves define, with respect to a reference plane perpendicular to the central axis, a forward pitch angle, and the at least one blade defines, with respect to the reference plane, an aft pitch angle.
A pump according to an example of the present disclosure includes an axial inducer that has a housing having an internal surface that defines an axial fluid passage. A rotor is disposed about a central axis in the fluid passage of the housing and has at least one blade defining at least one blade tip. The internal surface of the housing defines a plurality of grooves adjacent the at least one blade tip. The plurality of grooves define, with respect to a reference plane perpendicular to the central axis, a forward pitch angle. The blade defines, with respect to the reference plane, an aft pitch angle.
In a further embodiment of any of the foregoing embodiments, the forward pitch angle and the aft pitch angle are congruent angles.
In a further embodiment of any of the foregoing embodiments, the congruent angles are in a range from 5° to 40°.
A pump according to an example of the present disclosure includes an axial inducer that has a housing having an internal surface that defines an axial fluid passage. A rotor is disposed about a central axis in the fluid passage of the housing and has at least one blade defining at least one blade tip. The internal surface of the housing defines a plurality of grooves adjacent the at least one blade tip. Each of the grooves defines, with respect to a reference plane perpendicular to the central axis, a pitch angle that varies along the groove.
In a further embodiment of any of the foregoing embodiments, the pitch angle is forward pitch angle.
The various features and advantages of the present disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows.
The pump 20 includes a shaft 22 that is generally rotatable about a central axis A. There is an inducer 24 disposed on the shaft 22. The inducer 24 includes a housing 26 that is static and a rotor 28 that is rotatable with the shaft 22. The housing 26 has an internal surface 30 that defines an axial fluid passage 32 for generally axial fluid flow between a pump inlet 34 and a pump outlet 36. The pump inlet and outlet 34/36 generally define “forward” and “aft” directions, and variations of those terms, wherein “forward” refers to directionality toward the inlet 34 and “aft” refers to directionality toward the outlet 36. Likewise, the central axis A generally defines directionality with regard to “axial,” “radial, “circumferential,” and variations of those terms.
The rotor 28 is disposed about the central axis A in the fluid passage 32 of the housing 26. The rotor 28 includes one or more blades 38 that define at least one blade tip or edge 40. A magnified view of the rotor 28 is also shown in
As shown in
In cross-section, as shown in a representative example in
Referring also to
During operation of the pump 20, as the rotor 28 and blades 38 rotate, there can be a backflow of fluid through the volume between the tips 40 of the blades 38 and the internal surface 30 of the housing 26, vortices at or near the blade tips 40, and/or cavitation at or near the blade tips 40 (the extent of which may relate to the type of fluid, pressures, temperatures, rotor speed, etc.). Collectively, such phenomenon are referred to herein as flow induced instabilities.
In this regard, the grooves 42 facilitate a reduction in flow instabilities. For instance, as the fluid flows near the blade tips 40, the rotation of the blades 38 moves the fluid into the grooves 42. Once in the grooves 42, the sides of the groove 42 stop the fluid from flowing any further forward in the pump 20, thereby reducing backflow.
Referring again to
The groove pitch 46 has a forward pitch angle and the blade pitch 48 has an aft pitch angle. Stated another way, the blade tips 40 are generally sloped in the aft direction from the central axis A, while the elongated directions of the grooves 42 are generally slanted in the forward direction from the central axis A. In one example, the forward pitch angle of the groove pitch 46 and the aft pitch angle of the blade pitch 48 are congruent angles. For instance, the groove tangent line forms a groove pitch angle of 10° with the reference plane 50 and the blade tangent line forms a blade pitch angle of 10° with the reference plane 50. Alternatively, if a nomenclature scheme is employed in which forward and aft are designated with opposite signs such as “+” (plus symbol) and “−” (minus symbol), the groove pitch angle may be represented as −10° and the blade pitch angle may be represented as +10°, or vice versa. As used herein, an angle that is negative and an angle that is positive due to a chosen nomenclature are considered to be congruent as long as the absolute values are equal.
The congruent angles may be varied in accordance with the type of fluid being pumped, expected operating temperature, expected operating pressure, and speed of the blade tips 40, for example. Most typically, the congruent angles are in a range from 5° to 40° (assuming a nomenclature in which forward and aft are both positive), or alternatively, one of the angles is in a range from +5° to +40° and the other angle is equal but opposite sign in a range from −5° to −40° (assuming a nomenclature in which forward and aft are opposite signs).
In further examples, the groove pitch angles can vary along the lengths of the grooves 42. For instance, the grooves 42 initially may have shallow groove pitch angles from the distinct first ends 42a, i.e., low angles relative to the plane 50. The groove pitch angle may then increase along the length of the grooves toward the distinct second ends, i.e., higher angles relative to the plane 50. Finally, the groove pitch angles may then decrease up to the distinct second ends 42b. That is, each groove 42 may have an initial low-angle extent, an intermediate higher-angle extent, and a trailing lower-angle extent. This permits the groove pitch angle to remain congruent with the blade pitch angle as the blade pitch angle varies axially along the blade tips 40 (edges). In one further example, the groove pitch angle may continuously vary along the length of the grooves.
During operation of the pump 20, the forward pitch angle of the grooves 42 coupled with the aft pitch angle of the blades 38 enhances reduction in flow induced instabilities in comparison to a no groove configuration. For instance, as the fluid near the internal surface 30 attempts to backflow toward the pump inlet 34, the rotation of the blades 38 moves the fluid into the grooves 42. Since the grooves 42 are pitched forward via the forward pitch angle and the blades 38 are pitched aft via the aft pitch angle, the blades tips 40 (edges) bridge the grooves 42. The rotational movement of the blades 38 across the grooves 42 serves to sweep the fluid to flow downstream in the groove 42 toward the pump outlet 36. To flow upstream, the fluid would need to overcome the sweeping action and pressure at the blade tips 40. The forward pitch angle and the aft pitch angle thereby generate a flow dynamic in which flow downstream in the grooves 42 is favored, thereby enhancing backflow reduction.
In the illustrated example, there is a group of consecutive endless grooves 150, followed by a group of consecutive ended grooves 152 downstream or aft of the endless grooves 150. At the upstream location of the endless grooves 150, there is generally a lower pressure and thus a lesser need to resist backflow, while at the downstream position of the ended grooves 152, there is a greater pressure and need to resist backflow and thus grooves that have a forward pitch angle are used.
As also shown in each of
Although a combination of features is shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of this disclosure. In other words, a system designed according to an embodiment of this disclosure will not necessarily include all of the features shown in any one of the Figures or all of the portions schematically shown in the Figures. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments.
The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from this disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims.
This application claims priority to U.S. Provisional Application No. 62/592,662 filed Nov. 30, 2017.
This invention was made with government support under contract number NNM16AA02C awarded by the National Aeronautics and Space Administration. The government has certain rights in the invention.
Filing Document | Filing Date | Country | Kind |
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PCT/US2018/055534 | 10/12/2018 | WO | 00 |
Number | Date | Country | |
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62592662 | Nov 2017 | US |