The present invention relates generally to a mechanism for limiting or preventing ice accretion and ingestion in a pump and relates more specifically relates to an impeller spinner for a fuel pump.
Low flow and low temperatures can cause small quantities of water in a liquid fuel to freeze and cause ice accumulation in a fuel system. A stagnation zone or zone of low flow can be present at an inlet of a fuel pump. When the fuel pump is operating at sufficiently low temperatures, the stagnation zone can cause ice accretion and build-up of snowball-like clusters of ice at the inlet. While a small amount of ice can be ingested by the fuel pump, the ingestion of larger snowball-like clusters of ice can block the flow of fuel through the pump. Reduction of the size of the stagnation zone can lower the rate at which ice accretes and is ingested by the fuel pump, thereby limiting or preventing blockage. Anti-icing is of particular importance in the aerospace industry where fuel systems are often operated in low temperatures. However, the problem is not limited to the aerospace industry or to liquid fuels.
An impeller spinner for a fuel pump can include a head and a shank. The head can have a base at one end and a tip at an opposite end. The shank can have a body portion and a fastener position. The body portion can be nearest the head with a first diameter and the fastener portion can be adjacent to the body portion at an end opposite the head with a second diameter.
An anti-icing apparatus for a fuel pump can include an impeller spinner. The impeller spinner can include a head and a shank. The head can have a base at one end and a tip at an opposite end. The shank can have a body portion and a fastener portion. The body portion can be nearest the base of the head with a first diameter and the fastener portion can be adjacent to the body portion at an end opposite the head with a second diameter. The first diameter of the body portion can be greater than the second diameter of the fastener portion and can be less than a diameter of the base of the head.
A method of reducing ice accretion on an impeller of a centrifugal fuel pump can include the steps of rotating an impeller of the centrifugal fuel pump and deflecting a flow of fuel upstream of the impeller. The flow of fuel can be deflected by a conical structure having a base engaged with the impeller and a pointed tip upstream of the impeller.
The present summary is provided only by way of example, and not limitation. Other aspects of the present disclosure will be appreciated in view of the entirety of the present disclosure, including the entire text, claims and accompanying figures.
While the above-identified figures set forth embodiments of the present invention, other embodiments are also contemplated, as noted in the discussion. In all cases, this disclosure presents the invention by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the invention. The figures may not be drawn to scale, and applications and embodiments of the present invention may include features, steps and/or components not specifically shown in the drawings.
An impeller spinner can be attached to an inlet of a fuel pump to deflect a flow of liquid fuel and reduce the size of a zone of low flow or stagnation at the inlet, thereby limiting ice accretion at the inlet and ingestion by the impeller.
During operation of fuel pump 10, impeller 16 rotates and draws fuel from a fuel line (not shown) into inlet 14 and impeller 16. In the absence of impeller spinner 18, a volume of low flow forms near a center position within inlet 14 at an end of impeller 16. Generally, velocities less than 1 foot per second (0.3 meters per second) in the embodiment shown pose risk for ice formation. Ice that forms can collect on the end of impeller 16, forming a snowball-like cluster, which can break free and enter impeller 16. While ingestion of small amounts of ice can be tolerated, ingestion of large clusters of ice can create a risk of blocking fluid flow. Impeller spinner 18 can deflect fluid flow around the end of impeller 16 and reduce a volume of low flow forward of impeller 16. Reducing the volume of the stagnation zone can limit or prevent the formation of larger snowball-like clusters of ice. Small amounts of ice that may form can be ingested by impeller 16 without blocking flow.
Impeller spinner 18, as shown in
Body 32 and fastener section 34 can be cylindrical in shape to substantially match cylindrical shafts extending through impeller 16 and rotor 20. The outer diameter d1 (see
Hole 30 (see
Impeller spinner 18 is generally suited to small pumps in which a single bolt is capable of fixing an impeller to a rotor. In the embodiments shown, impeller spinner 18 is approximately two inches (five centimeters) in length, however, impeller spinner 18 could be scaled up or down to accommodate different applications. Scaling does not require that the parts of impeller spinner 18 (head 22, body 32, and fastener section 34) maintain a fixed ratio. The dimensions of impeller spinner 18 can be modified to accommodate varying sizes of pumps. Fan spinners and nose cones commonly used on gas turbine engines generally utilize multiple fastening mechanisms and attachment locations and could not be directly adapted for the disclosed use.
The primary purpose of impeller spinner 18 is to function as an anti-icing apparatus. Impeller spinner 18 can deflect a fluid flow and reduce the size or volume of the stagnation or low flow zone at inlet 14, and thereby limit the rate of ice accretion and ingestion by impeller 16. Head 22 can be configured to deflect fluid flow. As shown in
The conical shape of head 22 shown in
The rounded shape of head 22′ shown in
In the absence of impeller spinner 18, a volume of low flow forms near a center position at inlet 14 toward impeller 16. Ice that forms can collect on the end of impeller 16, forming a snowball-like cluster, which can break free and enter impeller 16. While ingestion of small amounts of ice can be tolerated, ingestion of large clusters of ice can block fluid flow. Both the conical shaped impeller spinner 18 shown in
The following are non-exclusive descriptions of possible embodiments of the present invention.
An impeller spinner for a fuel pump can include a head and a shank. The head can have a base at one end and a tip at an opposite end. The shank can have a body portion nearest the head with a first diameter and a fastener portion adjacent to the body portion at an end opposite the head with a second diameter.
The impeller spinner of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:
A further embodiment of the foregoing impeller spinner, wherein the head can have a conical shape.
A further embodiment of the foregoing impeller spinner, wherein the tip of the head can be substantially pointed.
A further embodiment of the foregoing impeller spinner, wherein the tip of the head can be rounded.
A further embodiment of the foregoing impeller spinner, wherein a hole can extend through the head such that the hole traverses a cross-section of the head at a location between the base and the tip and is configured to accept a pin.
A further embodiment of the foregoing impeller spinner, wherein a distance between the base and hole can be less than a distance between the hole and the tip.
A further embodiment of the foregoing impeller spinner, wherein the head can be axisymmetric and can have a substantially smooth surface.
A further embodiment of the foregoing impeller spinner, wherein the fastener portion of the shank can be threaded and the first diameter can be greater than the second diameter and less than a diameter of the base of the head.
An anti-icing apparatus for a fuel pump can include an impeller spinner. The impeller spinner can include a head and a shank. The head can have a base at one end and a tip at an opposite end. The shank can have a body portion nearest the base of the head with a first diameter and a fastener portion adjacent to the body portion at an end opposite the head with a second diameter. The first diameter can be greater than the second diameter and less than a diameter of the base of the head.
The anti-icing apparatus of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:
A further embodiment of the foregoing anti-icing apparatus, wherein the anti-icing apparatus can further include a rotor shaft, an impeller, and a housing. The impeller can have a first and a second section each having an inner radial surface. A portion of the first inner radial surface can be engaged with an outer radial surface of the rotor shaft. The housing can substantially surround the impeller and have an inlet. The shank can extend into both the impeller and a bore of the rotor shaft, such that the body portion is adjacent to the inner radial surface of the second section of the impeller, the fastener portion is engaged with an inner radial surface of the rotor shaft, and the head extends axially outward from an end of the second section of the impeller toward the inlet of the housing.
A further embodiment of the foregoing anti-icing apparatus, wherein the base of the head and the end of the impeller can be separated axially by a gap.
A further embodiment of the foregoing anti-icing apparatus, wherein the head can have a conical shape and the tip of the head can be substantially pointed.
A further embodiment of the foregoing anti-icing apparatus, wherein the tip of the head can extend substantially to an outer edge of the impeller inlet
A further embodiment of the foregoing anti-icing apparatus, wherein the tip of the head can be rounded.
A further embodiment of the foregoing anti-icing apparatus, wherein a hole can extend through the head such that the hole traverses a cross-section of the head at a location between the base and the tip and is configured to accept a pin.
A further embodiment of the foregoing anti-icing apparatus, wherein a distance between the base and hole can be less than a distance between the hole and the tip.
A further embodiment of the foregoing anti-icing apparatus, wherein the body portion of the shank can axially engage a portion of the impeller and/or a washer positioned between the impeller and the body portion, and wherein the fastener portion of the impeller spinner can be threadedly engaged with the inner radial surface of the rotor shaft.
A further embodiment of the foregoing anti-icing apparatus, wherein the impeller further includes a third section. The third section can axially engage the rotor shaft and can have an inner radial surface adjacent to the fastener portion of the impeller spinner.
A method of reducing ice accretion on an impeller of a centrifugal fuel pump can include rotating an impeller of the centrifugal fuel pump and deflecting a flow of fuel upstream of the impeller. The flow of fuel can be deflected by a conical structure having a base engaged with the impeller and a pointed tip upstream of the impeller.
The method of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:
A further embodiment of the foregoing method, wherein the tip of the conical structure extends substantially to an outer edge of a housing of the centrifugal pump.
Any relative terms or terms of degree used herein, such as “substantially”, “essentially”, “generally”, “approximately” and the like, should be interpreted in accordance with and subject to any applicable definitions or limits expressly stated herein. In all instances, any relative terms or terms of degree used herein should be interpreted to broadly encompass any relevant disclosed embodiments as well as such ranges or variations as would be understood by a person of ordinary skill in the art in view of the entirety of the present disclosure, such as to encompass ordinary manufacturing tolerance variations, incidental alignment variations, transient alignment or shape variations induced by thermal, rotational or vibrational operational conditions, and the like. Moreover, any relative terms or terms of degree used herein should be interpreted to encompass a range that expressly includes the designated quality, characteristic, parameter or value, without variation, as if no qualifying relative term or term of degree were utilized in the given disclosure or recitation.
While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.