Patent Grant
9562502
Reference is made to application Ser. No. 14/507,388 entitled “Volute for Engine-mounted Boost Stage Fuel Pump”, which was filed on even date and are assigned to the same assignee as this application.
The present invention relates generally to centrifugal pumps and, more particularly, to a centrifugal fuel pump mounted to an aircraft engine.
The fuel delivery system of an aircraft supplies fuel to aircraft engines and typically includes a boost pump mounted to the engine. The boost pump receives fuel from fuel tanks mounted on the aircraft and supplies fuel to the main frame pump mounted to the aircraft frame.
The boost pump impeller, imparting increased pressure and flow rate to the fuel, and the volute collector, guiding fuel from the impeller to the boost pump outlet, are among the principle contributors to boost pump performance. Fuel flowing through pumps has potential energy, generally characterized by static pressure, and kinetic energy, generally characterized by dynamic pressure. The sum of the static and dynamic pressures defines a total pressure of the fuel. Efficient pump impellers impart tangential velocity, and therefore dynamic pressure, to the fuel exiting the impeller with minimal input power. The volute collector reduces the velocity and thereby coverts dynamic pressure into static pressure, a process sometimes referred to as pressure recovery. The combination of impeller and volute collector geometry govern pump performance.
Fuel boost pumps are designed to provide an uninterrupted supply of fuel to the main frame pump within a particular pressure and flow rate envelope under all operating conditions encountered by the fuel delivery system during an aircraft flight. Under normal in-flight operating conditions, the fuel tank pressure decreases as altitude increases following the natural depression in the ambient atmospheric pressure, and the fuel temperature varies between −40° F. and 300° F. Under abnormal conditions, the main frame pump can fail or the boost pump can become partially obstructed. Under each set of conditions, the boost pump delivers 100% liquid fuel when a ratio of fuel vapor to liquid fuel (V/L) at the boost pump inlet is 0.45 or more. Furthermore, boost pumps are designed to deliver a maximum outlet pressure such that heat exchangers, filters, and other downstream components do not fail under the boost pump pressure. Maintaining the operational envelope and overall efficiency of the boost pump in view of all the operational conditions during an aircraft flight sometimes involves multiple pumps, each pump tailored for a subset of the operating conditions encountered during flight. However, multiple pumps increase the weight and complexity of the fuel delivery system.
Reducing the weight and complexity of fuel delivery systems while increasing component performance and efficiency continues to be a goal of designers and manufacturers. Therefore a need exists for a high-performance, efficient boost pump that can deliver fuel to the main frame pump within an operational envelope for all conditions during an aircraft flight.
A rotor for a centrifugal pump has an inducer. The inducer has first and second pluralities of blades, each having a plurality of polygonal cross-sections defined by a plurality of vertices. The pluralities of vertices are defined by tables of vertex locations.
A method of making a centrifugal pump includes forming a rotor that has an inducer and an impeller. The inducer has first and second pluralities of blades, each having a plurality of polygonal cross-sections defined by a plurality of vertices. The impeller is fluidly connected downstream of the inducer and has third, fourth, and fifth pluralities of blades, each having a plurality of polygonal cross-sectional areas defined by a plurality of vertices. The pluralities of vertices are defined by tables of vertex locations.
Fuel enters boost pump 14 at inlet 49. Impeller 26 pressurizes the fuel and delivers it to volute collector 50. Labyrinth seal 52a minimizes fuel leakage between impeller 26 and housing 28 while labyrinth seal 52b performs the same function between impeller 26 and center plate 30. Face seal 54 contains the fuel within housing 28 and center plate 30 by preventing fuel flow between impeller 26, center plate 30, and shaft 32. Seal 56 further contains the fuel within housing 28 and center plate 30 by preventing fuel flow therebetween.
Inducer section 58 includes primary blades 62 and secondary blades 64 having leading edges 62a and 64a, respectively. Leading edges 62a and 64a form tapers at the edges of primary and secondary blades 62 and 64, respectively, to facilitate fuel ingestion into inducer section 58. Primary blades 62 and secondary blades 64 are oriented to progressively drive fluid in an axial direction with respect to pump axis 24 such that the fuel pressure gradually increases as it traverses inducer section 58 towards impeller section 60. Inducer section 58 contains a two-phase mixture of fuel, a portion of the fuel being vapor and a portion of the fuel being liquid. The ratio of fuel vapor to liquid fuel (V/L) can be equal to or greater than 0.45 when it enters inducer section 58 that has a larger volume near its inlet to accommodate the two phase mixture. Near the outlet of inducer section 58, the fuel is completely compressed into a liquid state.
Impeller section 60 has main blades 66, primary splitter blades 68, and secondary splitter blades 70. Blades 66, 68, and 70 work by engaging the incoming flow from inducer section 58 at leading edges of blades 66, 68, and 70, each blade forming an incidence angle between the leading edge portion of the blade and the incoming flow direction of fuel. Blades 66, 68, and 70 guide the fuel through impeller section 60, the blade geometries being selected such that the fuel remains attached to the impeller surfaces and that no eddies are produced in the fuel. Main blades 66 extend radially outward with respect to pump axis 24 in a generally spiral shape between an inlet and an outlet of impeller section 60. As the fuel traverses impeller section 60, the cross-sectional area between main blades 66 increases. Primary splitter blades 68 and secondary splitter blades 70 are introduced to tailor the cross-sectional area profile between main blades 66 to efficiently impart mechanical energy to the fuel.
Alternatively, blades 62, 64, 66, 68, and 70 can be defined with respect to a Cartesian coordinate system that is analogous to the cylindrical coordinate system defined by origin 72. Such a coordinate system has an origin that is collocated with origin 72 in which an x-axis extends radially at θ equal to 0 degrees, a y-axis extends radially at θ equal to 90 degrees, and a z-axis extends axially along axis 24.
Alternatively, first volute passage 88, second volute passage, 90, and diffuser 92 can be defined with respect to a Cartesian coordinate system that is analogous to the cylindrical coordinate system defined by origin 96. Such a coordinate system has an origin that is collocated with origin 96 in which an x-axis extends radially at θ equal to 0 degrees, a y-axis extends radially at θ equal to 90 degrees, and a z-axis extends axially along axis 24.
Alternatively, exit bend 94 can be defined with respect to a Cartesian coordinate system that is analogous to the cylindrical coordinate system defined by origin 100. Such a coordinate system has an origin that is collocated with origin 100 in which an x-axis extends radially at φ equal to 0 degrees, a y-axis extends radially at φ equal to 90 degrees, and a z-axis extends parallel to axis 24.
A method of making a centrifugal pump that has impeller 26 and volute collector 50 in accordance with the preceding description is also disclosed. The method includes forming impeller 26 with inducer section 58. As previously described, inducer section 58 has primary blades 62 and secondary blades 64 defined by a series of cross-sections. The method can further include forming impeller 26 with impeller section 60. Impeller section 60 has main blades 66, primary splitter blades 68, and secondary splitter blades 70. Blades 66, 68, and 70 are defined by a series of cross-sections. In each case, the cross-section can be represented by blade cross-section 74 having vertices 76, 78, 80, and 82.
The method can further include forming shroud 27 on the radially outward side of blades 66, 68, and 70. Additionally, the method can include forming a hub joining the inducer and impeller sections as previously shown and described above.
The method can further include forming housing 28 that includes walls defining first volute passage 88, second volute passage 90, and diffuser passage 92. Passages 88, 90, and 92 are defined by a series of cross-sectional areas as previously described. The walls of housing 28 can also define exit bend 94, similarly defined by a series of cross-sectional areas.
In some embodiments of the method, housing 28 can cooperate with center plate 30, each defining a portion of first volute passage 88, second volute passage 90, and diffuser passage 92. Housing 28 can have a facing relationship with center plate 30 such that each portion of passages 88, 90, and 92 cooperate to form a volute collector 50.
Tables 1-8 are provided below.
Tables 9-13 define blades 62, 64, 66, 68, and 70 in cylindrical coordinates (r, θ, z) for one embodiment of impeller 26. Tables 14-16 define first volute passage 88, second volute passage 90, and exit bend 94 for one embodiment of volute collector 50. In each embodiment, outer impeller diameter D equals 4.125 inches. Tables 9-16 are provided below.
Tables 17-21 define blades 62, 64, 66, 68, and 70 in Cartesian coordinates (x, y, z) for one embodiment of impeller 26 in which outer impeller diameter D equals 4.125 inches. Tables 17-21 are provided below.
Discussion of Possible Embodiments
An impeller according to an exemplary embodiment of this disclosure, among other possible things, includes an inducer section. The inducer section has first and second pluralities of blades, each having a plurality of polygonal cross-sections defined by a plurality of vertices. The vertices of the first plurality of blades can be defined by Table 1. The vertices of the second plurality of blades can be defined by Table 2. The z axis for the first and second pluralities of blades can be coincident with an axis of rotation of the impeller.
The impeller 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, wherein the impeller can include an impeller section fluidly connected downstream of the inducer section and having third, fourth, and fifth pluralities of blades, each having a plurality of polygonal cross-sections defined by a plurality of vertices. The vertices of the third plurality of blades can be defined by Table 3. The vertices of the fourth plurality of blades can be defined by Table 4. The vertices of the fifth plurality of blades can be defined by Table 5.
A further embodiment of any of the foregoing impellers, wherein the third, fourth, and fifth pluralities of blades can have a shroud.
A further embodiment of any of the foregoing impellers, wherein the inducer section and the impeller section can be joined by a hub.
A further embodiment of any of the foregoing impellers, wherein an outer diameter of the impeller can be greater than or equal to 4.115 inches and less than or equal to 4.135 inches.
A method of making a centrifugal pump according to an exemplary embodiment of this disclosure, among other possible things, includes forming an impeller having an inducer section. The inducer section has first and second pluralities of blades, each having a plurality of polygonal cross-sections defined by a plurality of vertices. The vertices of the first plurality of blades can be defined by Table 1. The vertices of the second plurality of blades can be defined by Table 2. The z axis for the first and second pluralities of blades can be coincident with an axis of rotation 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 forming a impeller includes an impeller section fluidly connected downstream of the inducer. The impeller can have third, fourth, and fifth pluralities of blades, each having a plurality of polygonal cross-sections defined by a plurality of vertices. The vertices of the third plurality of blades can be defined by Table 3. The vertices of the fourth plurality of blades can be defined by Table 4. The vertices of the fifth plurality of blades can be defined by Table 5.
A further embodiment of any of the foregoing methods can include forming a shroud joined to the third, fourth, and fifth pluralities of blades.
A further embodiment of any of the foregoing methods can include forming a hub joining the inducer section and the impeller section.
A further embodiment of any of the foregoing methods can include forming a housing. The housing can have walls defining a volute passage and a diffuser passage fluidly connected to a volute passage. The volute passage can have a first subsection with cross-sectional areas defined by Table 6 and a second subsection with cross-sectional areas defined by Table 7.
A further embodiment of any of the foregoing methods, wherein the walls can define an exit bend fluidly connected to the diffuser passage, and wherein the exit ben can have cross-sectional areas defined by Table 8.
A further embodiment of any of the foregoing methods, wherein the housing can have a first half defining a first portion of the volute and diffuser passages and a second half defining a second portion of the volute and diffuser passages. The first and second halves can mate in a facing relationship such that the first and second portions cooperate to form the volute and diffuser passages.
A further embodiment of any of the foregoing methods, wherein the diffuser passage has cross-sectional areas with continuously increasing area from an inlet to an outlet of the diffuser passage.
A further embodiment of any of the foregoing methods, wherein an outer diameter of the impeller is greater than or equal to 4.115 inches and less than or equal to 4.135 inches.
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.
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