An axial flow pump inlet pipe structure with vortex prevention guide structure

Abstract

The application belongs to the technical field of fluid machinery, and discloses an inlet pipe structure of an axial flow pump with an anti-vortex flow guide structure, which comprises a horn pipe in a tapered structure, a large end of the horn pipe being a water inlet, and a small end of the horn pipe being a water outlet; a conical anti-vortex device is arranged in the middle of the horn pipe, a top of the conical anti-vortex device faces the water inlet direction of the horn pipe, a surface of the conical anti-vortex device is provided with a spiral groove, and the spiral groove extends spirally along the surface of the conical anti-vortex device; a plurality of flow guide ribs are arranged on the inner wall of the horn pipe at equal intervals in the circumferential direction and are fixedly connected with the outer side wall of the conical anti-vortex device, the flow guide ribs have a streamlined cross section, and the bending direction of the cross section is consistent with the water flow direction. The application effectively reduces the energy loss, vortex intensity and pressure pulsation of the inlet flow field, significantly improves the hydraulic efficiency and operation stability of the axial flow pump, and meets the requirements of high efficiency, energy saving, low noise and environmental protection.

Description

Technical Field

[0001] This invention belongs to the field of fluid machinery technology, and in particular relates to an inlet pipe structure for an axial flow pump with an anti-vortex guiding structure. Background Technology

[0002] Axial flow pumps, as a common type of bladed fluid machinery, are widely used in agricultural irrigation, urban drainage, water conservancy projects, and industrial circulating water systems due to their large flow rate and low head. The inlet pipe of an axial flow pump is a key flow-through component that guides water flow into the impeller, and its structural design directly affects the pump's hydraulic efficiency, operational stability, and energy consumption.

[0003] In the actual operation of axial flow pumps, the flow state within the inlet pipe is quite complex. On the one hand, when water flows from the inlet pool into the bell-shaped pipe, eddies of various sizes are easily formed within the inlet pipe due to factors such as uneven velocity distribution, boundary layer separation, or pre-swirl in the incoming flow. These eddies not only increase local hydraulic losses but also lead to uneven velocity distribution at the impeller inlet, affecting the impeller's energy conversion efficiency and, in severe cases, even causing vibration and noise. On the other hand, when the pump operates outside of its design conditions (such as low-flow conditions), a backflow zone may appear before the impeller inlet, accompanied by strong vortex motion. These vortices, after propagating downstream, exacerbate the dynamic and static interference effect between the impeller and the guide vanes, resulting in a significant increase in pressure pulsation and affecting the pump's operational reliability.

[0004] To suppress vortices within the inlet pipe, existing technologies include vortex-resistant devices. Common examples include cross-shaped vortex-resistant plates and conical vortex-resistant covers, which break up large-scale vortices through physical obstruction. However, these devices have limitations in practical applications. First, the devices themselves introduce additional flow resistance, and some structures can disrupt the uniformity of the inlet velocity field, thus negating their vortex-resistant effect to some extent. Second, the connection structure between traditional vortex-resistant devices and the inlet pipe often only serves a fixing function, failing to fully utilize the guiding function of the connecting components and lacking the ability to actively optimize the flow state. Therefore, how to effectively suppress inlet vortices while simultaneously reducing flow resistance, improving inlet velocity distribution, and synergistically reducing pressure pulsation has become a key technical problem to be solved in the design of the axial flow pump inlet pipe structure.

[0005] Therefore, there is an urgent need for an axial flow pump inlet pipe structure with an anti-vortex guiding structure to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide an axial flow pump inlet pipe structure with an anti-vortex guiding structure to solve the problems existing in the prior art.

[0007] To achieve the above objectives, the present invention provides the following solution: The present invention provides an axial flow pump inlet pipe structure with an anti-vortex guiding structure, comprising: The horn tube has a tapered structure, with the large end of the horn tube being the water inlet and the small end being the water outlet. A conical anti-vortex device is installed in the middle of the horn tube, with the cone tip of the conical anti-vortex device facing the water inlet direction of the horn tube. The surface of the conical anti-vortex device is provided with a spiral groove, which extends spirally along the surface of the conical anti-vortex device. Multiple flow guide ribs are evenly spaced along the circumference on the inner wall of the trumpet tube and are fixedly connected to the outer wall of the conical anti-vortex device. The flow guide ribs have a streamlined cross-section, and the bending direction of the cross-section is consistent with the direction of water flow.

[0008] Preferably, the streamlined cross-section of the guide rib is airfoil-shaped or teardrop-shaped, with a rounded front end and a sharp rear end.

[0009] Preferably, the thickness of the guide rib gradually decreases from the side connected to the inner wall of the horn tube to the side connected to the conical anti-vortex device.

[0010] Preferably, the spiral direction of the spiral groove is opposite to the rotation direction of the axial flow pump impeller.

[0011] Preferably, the depth of the spiral groove gradually increases from the top to the bottom of the conical anti-vortex device.

[0012] Preferably, the bottom diameter of the conical anti-vortex device is smaller than the minimum inner diameter of the horn tube, and an annular flow channel is formed between the bottom of the conical anti-vortex device and the inner wall of the horn tube.

[0013] Preferably, the cone apex angle of the cone-shaped anti-vortex device is 60°.

[0014] Preferably, the height of the conical anti-vortex device is the same as the height of the horn tube.

[0015] Preferably, the starting end of the flow guide rib is 0.1L away from the water inlet end face of the horn tube, and the end of the flow guide rib extends to 0.1L away from the cone bottom of the conical anti-vortex device.

[0016] Preferably, the number of the flow guide ribs is 3-6.

[0017] Compared with the prior art, the present invention has the following advantages and technical effects: This invention provides an axial flow pump inlet pipe structure with an anti-vortex guiding structure. The tapered structure allows the water flow to accelerate smoothly before entering the impeller, avoiding boundary layer separation and vortex generation caused by sudden changes in flow velocity. It provides initial rectification, reduces local hydraulic losses, and the cone apex faces the inlet direction, effectively cutting and breaking the central vortex core, suppressing the formation of the backflow zone, and reducing hydraulic losses and pressure pulsations caused by vortices. The spiral groove guides the water flow to form a secondary vortex opposite to the impeller rotation direction, counteracting the pre-swirl induced by impeller suction, making the inlet water flow closer to pure axial inflow, reducing vortex losses and pressure pulsations, dividing the main flow into multiple uniform sub-flows, suppressing circumferential pre-swirl and boundary layer separation. At the same time, the conical anti-vortex device is stably fixed at the center of the trumpet tube to ensure the symmetry of the flow field. The consistency of the streamlined cross-section and bending direction significantly reduces the flow resistance and the additional hydraulic losses caused by the guide ribs themselves, while guiding the water flow smoothly. This invention effectively reduces energy loss, eddy current intensity, and pressure pulsation in the inlet flow field, significantly improves the hydraulic efficiency and operational stability of axial flow pumps, and meets the requirements of high efficiency, energy saving, low noise, and environmental protection. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a perspective view of the horn tube of the present invention; Figure 3 This is a front view of the horn tube of the present invention; Figure 4 This is a perspective view of the conical anti-vortex device of the present invention; Figure 5 This is a front view of the conical anti-vortex device of the present invention; Figure 6 This is a schematic diagram of the water interception ditch of the guide ribs of the present invention; Figure 7 This is a schematic diagram of the pump's performance characteristics before and after performance optimization under different operating conditions according to the present invention. Among them: 1. Trumpet tube; 2. Conical anti-vortex device; 3. Guide rib; 4. Spiral groove. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] In related technologies, the inlet pipe of an axial flow pump, as a key flow channel component for fluid entering the impeller, has a decisive influence on the overall performance of the pump unit due to its internal flow state. Traditional axial flow pump inlet pipes often employ a single trumpet-shaped structure. In actual operation, this structure is prone to a series of technical defects due to problems such as uneven inlet flow field, central vortex accumulation, circumferential pre-swirl, and local backflow. On the one hand, vortices and backflow generate significant hydraulic losses, leading to a decrease in axial flow pump operating efficiency, especially under variable operating conditions, where the efficiency reduction can reach 5%-8%. On the other hand, pressure pulsations caused by unsteady flow exacerbate unit vibration and generate high-frequency noise. The noise caused by inlet pipe vortices accounts for more than 35% of the total pump noise, with a significant peak in the 1000-2500Hz frequency band, seriously affecting equipment reliability and environmental comfort. Existing improvement methods, such as simply increasing the trumpet length, optimizing the trumpet profile, or adding a single guide structure, can alleviate the vortex problem to some extent, but it is difficult to achieve an effective balance between hydraulic losses and flow field stability.

[0023] Numerical simulations and experimental tests revealed that the generation of vortices, backflow, and pre-swirl within the inlet pipe of an axial flow pump mainly stems from three core factors: First, the inlet water flow lacks effective guidance after entering the trumpet-shaped pipe, easily forming a concentrated vortex core; second, uneven circumferential velocity distribution generates pre-swirl, which, when superimposed on the impeller rotation direction, exacerbates flow turbulence; and third, an unreasonable transition in the flow channel cross-section leads to boundary layer separation, triggering secondary vortices. Based on flow stability theory and hydraulic design principles, a multi-stage synergistic control approach of "pre-guidance - vortex core breaking - secondary swirl compensation - velocity homogenization" is proposed. An integrated anti-vortex guiding structure is designed to overcome the technical bottlenecks of limited vortex suppression range and difficulty in balancing hydraulic loss and flow field stability in single structures, forming a composite flow field control scheme to optimize the inlet flow field of the axial flow pump.

[0024] Reference Figures 1-7 This invention provides an axial flow pump inlet pipe structure with an anti-vortex guiding structure, comprising: The trumpet tube 1 has a tapered structure, with the large end of the trumpet tube 1 being the water inlet and the small end of the trumpet tube 1 being the water outlet. A conical anti-vortex device 2 is installed in the middle of the horn tube 1. The cone tip of the conical anti-vortex device 2 faces the water inlet direction of the horn tube 1. A spiral groove 4 is provided on the surface of the conical anti-vortex device 2. The spiral groove 4 extends spirally along the surface of the conical anti-vortex device 2. Multiple guide ribs 3 are evenly spaced along the circumference on the inner wall of the trumpet tube 1 and are fixedly connected to the outer wall of the conical anti-vortex device 2. The guide ribs 3 have a streamlined cross section, and the bending direction of the cross section is consistent with the direction of water flow.

[0025] In one embodiment of the present invention, the tapered structure allows the water flow to accelerate smoothly before entering the impeller, avoiding boundary layer separation and vortex generation caused by sudden changes in flow velocity, thus achieving preliminary rectification and reducing local hydraulic losses. The cone apex faces the inlet direction, effectively cutting and breaking the central vortex core, suppressing the formation of the backflow zone, and reducing hydraulic losses and pressure pulsations caused by vortices. The spiral groove 4 guides the water flow to form a secondary vortex opposite to the impeller rotation direction, counteracting the pre-swirl induced by impeller suction, making the inlet water flow approach pure axial inflow, reducing vortex losses and pressure pulsations, dividing the main flow into multiple uniform sub-flows, suppressing circumferential pre-swirl and boundary layer separation, and simultaneously fixing the conical anti-vortex device 2 stably at the center of the trumpet tube 1 to ensure flow field symmetry. The consistency of the streamlined cross-section and bending direction significantly reduces flow resistance and reduces the additional hydraulic losses caused by the guide ribs 3 themselves, while guiding the water flow smoothly.

[0026] In one embodiment of the present invention, the base circle radius of the horn tube 1 is R, the inlet diameter of the horn tube 1 is D1, the outlet diameter is D2, the axial length is L, the cone apex angle of the conical anti-vortex device 2 is θ, and the cone base diameter is D. c The diameter of the spiral groove 4 is 0.4D2-0.6D2, the included angle between two adjacent guide ribs 3 is α, the height H (radial extension length) of the guide rib 3 is 0.25-0.35R, the thickness gradually decreases from the outside to the inside, and the helix angle β of the spiral groove 4 is... s The angle is 15°-25°, and the groove depth h gradually increases from the apex to the bottom of the cone. (z represents the axial coordinate of the conical anti-vortex device). All structural parameters are precisely calculated using hydraulic design formulas to ensure a balance between the synergistic vortex suppression effect and hydraulic performance.

[0027] The contraction ratio of the horn tube 1 The ratio of inlet diameter D1 to outlet diameter D2 is controlled within the range of 1.2-1.5. This range has been determined through extensive numerical simulations and experimental verification. This ratio ensures smooth acceleration of the water flow within the funnel-shaped tube, avoiding boundary layer separation caused by excessive adverse pressure gradients. It also avoids both excessively small contraction ratios leading to excessively long flow channels and increased hydraulic losses, and excessively large contraction ratios leading to sudden velocity changes and intensified eddies. The formula for calculating the contraction ratio is: ; In the formula: D1 is the bell tube shrinkage ratio, ranging from 1.2 to 1.5; D2 is the bell tube inlet diameter (mm); D2 is the bell tube outlet diameter (mm), which matches the impeller inlet diameter of the axial flow pump and is usually equal to the impeller inlet diameter.

[0028] Further optimization of the design involves controlling the ratio of the axial length L of the trumpet pipe 1 to the outlet diameter D2 within the range of 0.9-1.4, i.e., L = (0.9-1.4)D2. This ratio ensures sufficient transition distance for the water flow within the trumpet pipe, achieving a uniform increase in flow velocity and avoiding sudden changes in local flow velocity. The determination of the axial length also needs to consider the overall installation space of the axial flow pump to ensure a compact inlet pipe structure while meeting the requirements for hydraulic rectification.

[0029] ; The inner wall of the horn tube 1 is constructed using a cubic polynomial curve, and the diameter D(x) at the axial position x satisfies: ; In the formula: The inlet diameter of the horn tube is (mm). L is the outlet diameter of the horn tube (mm); L is the axial length of the horn tube (mm); x is the axial coordinate (mm), with the inlet end face of the horn tube as the origin. The inlet end face of horn tube 1 is rounded, with a rounding radius R1 of 0.05-0.08D1. This rounding avoids water flow separation caused by sharp inlet edges, allowing water to enter the horn tube smoothly and reducing eddy currents at the inlet. The value of the rounding radius needs to balance structural strength and flow guiding effect. Through flow field simulation, it was verified that when R1=0.06-0.07D1, the inlet water flow separation area is minimized and the flow guiding effect is optimal.

[0030] The cone apex angle θ of the conical anti-vortex device 2 is controlled within the range of 55°-65°, preferably θ=60°. This cone angle range is determined through analysis of the vortex core breaking mechanism and flow resistance: if the cone angle is too small, the cutting and breaking effect of the cone apex on the vortex core is weak, making it difficult to effectively destroy the central vortex core, resulting in poor vortex suppression; if the cone angle is too large, the blocking ratio of the conical anti-vortex device increases, leading to increased flow resistance and hydraulic losses. The formula for calculating the cone apex angle is related to the slope of the generatrix of the cone surface as follows: ; In the formula: θ is the cone apex angle of the conical anti-vortex device, ranging from 55° to 65°; Rc is the cone base radius (mm) of the conical anti-vortex device; H c The axial height (mm) of the conical anti-vortex device.

[0031] Further optimize the design by adjusting the axial height H of the conical anti-vortex device 2. c The axial length L of the horn tube 1 is equal to or approximately equal to that of the horn tube 1, i.e., H c≈L, so that the conical anti-vortex device covers the entire internal area of ​​the trumpet tube along the axial direction, realizing vortex core breaking and backflow suppression throughout the entire flow channel, and avoiding vortex residue caused by local areas not being covered. When At this time, the bottom of the cone-shaped anti-vortex device is flush with the outlet end face of the trumpet tube, ensuring that the water flows directly and smoothly into the impeller after being guided by the cone-shaped anti-vortex device, avoiding flow disturbances caused by sudden changes in the flow channel.

[0032] The diameter D of the cone base of the cone-shaped anti-vortex device 2 c The ratio of the blocking ratio β to the outlet diameter D2 of the horn tube is controlled within the range of 0.28-0.33, i.e. The range of blocking ratios can balance the vortex core breaking effect and flow capacity: if the blocking ratio is too small, the size of the conical anti-vortex device will be too small and the vortex suppression effect will be insufficient; if the blocking ratio is too large, the flow channel will be severely blocked, the flow resistance will increase, and the flow capacity of the axial flow pump will be affected.

[0033] The cone bottom of the conical anti-vortex device 2 forms an annular flow channel between itself and the inner wall of the horn tube 1, and the flow area A of this channel is... ring The calculation formula is: ; In the formula: A ring D1 is the flow area of ​​the annular flow channel (m²); D2 is the outlet diameter of the horn tube (mm). The diameter (mm) of the cone base of the conical anti-vortex device. This annular flow channel allows water to flow uniformly between the conical anti-vortex device and the inner wall of the trumpet tube, achieving velocity homogenization, reducing velocity gradient, and minimizing turbulence losses.

[0034] The cone tip of the conical anti-vortex device 2 is rounded, with a rounding radius R2 of 0.02-0.03D. c This treatment avoids localized low-pressure zones caused by sharp cone apex, suppresses cavitation, and ensures smooth water flow over the cone apex, reducing vortex shedding at the apex. The radius of the cone apex's blunt radius needs to be verified through cavitation simulation to ensure that the pressure at the cone apex is not lower than the saturated vapor pressure of the working medium under both rated and variable operating conditions. The vortex suppression mechanism of the conical anti-vortex device 2 is mainly based on vortex core breaking and backflow suppression; the strength of the central vortex core can be determined using vorticity. Characterized by the formula for calculating vorticity: ; Where: Ω is vorticity ( V represents the water flow velocity vector (m / s). The conical anti-vortex device breaks the central vortex core into multiple small-scale vortices through cone apex cutting and cone surface compression. These small-scale vortices decay rapidly under the influence of water flow, thereby reducing the overall vortex volume and minimizing hydraulic losses and pressure pulsations caused by vortices.

[0035] As an optional implementation, the streamlined cross-section of the guide rib 3 is airfoil-shaped or teardrop-shaped, with a rounded front end and a sharp rear end.

[0036] In one embodiment of the present invention, the airfoil or teardrop-shaped cross-section allows the water flow to be smoothly split at the leading edge and smoothly merge at the trailing edge, avoiding flow separation and eddy shedding, and further reducing drag and noise.

[0037] In one embodiment of the present invention, the guide rib 3 adopts a streamlined cross-section with an airfoil shape, featuring a rounded leading edge (inlet end) and a sharp trailing edge (outlet end). This cross-sectional shape minimizes the flow resistance coefficient C. d , making C d ≤0.03, reducing additional hydraulic losses caused by the guide ribs. The airfoil section profile equation is designed based on aerodynamic and fluid dynamics theories, specifically as follows: ; In the formula: y(x) is the y coordinate (mm) at any x position of the airfoil section; t is the maximum thickness of the airfoil (mm), t=0.1-0.15c; c is the chord length of the airfoil (mm), that is, the axial length of the guide rib; x is the chord coordinate of the airfoil (mm), with the leading edge of the airfoil as the origin and the direction along the chord towards the trailing edge as the positive direction.

[0038] As an alternative implementation, the thickness of the guide rib 3 gradually decreases from the side connected to the inner wall of the horn tube 1 to the side connected to the conical anti-vortex device 2.

[0039] In one embodiment of the present invention, the thickness of the guide rib 3 gradually decreases from the outer side (the end connected to the inner wall of the horn tube) to the inner side (the end connected to the conical anti-vortex device), forming a smoothly transitioning three-dimensional streamline shape to avoid flow disturbances caused by sudden expansion or contraction in certain areas. The thickness variation follows a linear decreasing relationship, and the calculation formula is as follows: ; In the formula: δ(r) is the thickness (mm) of the guide rib at radial position r; δ o δ represents the outer thickness of the guide rib (mm). o =0.04-0.06R; δ i δ is the inner thickness of the guide rib (mm). i =0.008-0.015R; r is the radial position (mm), with the central axis of the horn tube as the origin and the radial direction pointing towards the inner wall as the positive direction; Rc is the cone bottom radius of the conical anti-vortex device (mm); R2 is the outlet radius of the horn tube (mm).

[0040] Further optimization of the design resulted in the axial coverage length S of the guide rib 3 being 0.7-0.8 times that of the horn tube 1. This length range was determined through flow field simulation and experimental verification, ensuring sufficient guidance of the inlet flow field while avoiding unnecessary flow resistance due to excessively long ribs. The starting end of the guide rib is 0.1L from the inlet end face of the horn tube, and the end extends to 0.1L from the bottom of the conical anti-vortex device 2, and is fixedly connected by annular reinforcing ribs to maintain structural stability.

[0041] To further optimize the design, the outlet end of the guide rib 3 is rounded with a fillet radius R3 of 0.012-0.015R. This rounding allows for gradual flow separation when the water detaches from the guide rib, avoiding abrupt flow separation caused by sharp edges and reducing broadband noise caused by eddy shedding. The fillet radius must balance flow separation control and structural strength. Flow field simulations show that when R3 = 0.009R, the velocity gradient after the water detaches from the guide rib is the gentlest, and the eddy shedding intensity is the lowest.

[0042] Further optimization involves creating a guiding angle γ between the inlet tangent of the guide rib 3 and the inner wall tangent of the trumpet tube 1. This guiding angle is controlled within the range of 15°-18°. By controlling the water flow direction through this angle, the flow separation phenomenon caused by the water flow impacting the inner wall of the trumpet tube is reduced, thereby suppressing the generation of turbulent noise. The profile equation of the guide rib is defined with the central axis of the trumpet tube as the origin: ; In the formula: ξ is a dimensionless parameter, with a value range of 0-1. ξ=0 corresponds to the inlet end of the guide fin, and ξ=1 corresponds to the outlet end of the guide fin. Let ξ be the axial coordinate (mm) corresponding to the parameter ξ, representing the distance from a point on the guide rib to the inlet end face; For parameters The corresponding radial coordinate (mm) represents the distance from a point on the guide rib to the central axis of the horn tube; R1 is the inlet radius of the horn tube (mm), R1=D1 / 2; The initial guide angle (°) is taken as 15°-18°; δ(ξ) is the thickness (mm) of the guide rib corresponding to parameter ξ. This represents the change in the guide angle along the axial direction.

[0043] As an optional implementation, the spiral direction of the spiral groove 4 is opposite to the rotation direction of the axial flow pump impeller.

[0044] In one embodiment of the present invention, the spiral direction of the spiral groove 4 is opposite to the rotation direction of the axial flow pump impeller: if the impeller rotates clockwise, the spiral groove is counterclockwise; if the impeller rotates counterclockwise, the spiral groove is clockwise. This design allows the secondary vortex formed by the water flow guided by the spiral groove to be opposite to the pre-vortex induced by the impeller, achieving pre-vortex cancellation and reducing the circumferential velocity of the inlet water flow. Approaching zero, meeting ideal inlet conditions, reducing swirl losses and pressure pulsation.

[0045] Further optimization of the scheme, the helix angle of helical groove 4 The helix angle is controlled within the range of 18°-22°. This range is determined through analysis of the pre-swirl compensation effect and flow resistance: if the helix angle is too small, the intensity of the generated secondary swirl is insufficient and cannot effectively offset the pre-swirl; if the helix angle is too large, the flow resistance of the spiral channel increases, leading to an increase in additional hydraulic losses. The formula for calculating the helix angle is: ; In the formula: The helix angle (°) ranges from 18° to 22°. Where is the diameter of the cone at the axial position. ; axial The radius of the conical anti-vortex device at the location; T is the pitch (mm), that is, the axial distance of the helical groove per revolution. In this embodiment... .

[0046] As an optional implementation, the depth of the spiral groove 4 gradually increases from the top of the cone to the bottom of the cone-shaped anti-vortex device 2.

[0047] In one embodiment of the present invention, the gradually increasing groove depth enhances the induced secondary swirling flow along the axial direction, creating a synergistic flow stabilization effect with the mainstream, preventing cavitation tendencies in local low-pressure areas, and simultaneously enhancing the destructive ability against axial vortices. The groove depth of the spiral groove 4 gradually increases from the cone apex to the cone bottom, matching the cone surface contraction law, thus gradually enhancing the induced compensating swirling flow along the axial direction, creating a synergistic flow stabilization effect with the mainstream, and preventing cavitation tendencies in local low-pressure areas. The groove depth variation follows a linear increasing relationship, and the calculation formula is: ; In the formula: The groove depth (mm) of the spiral groove at the axial x position; The depth of the cone apex groove is (mm). k is the slope of the trench depth increase. x is the axial coordinate (mm), with the apex of the cone as the origin and the direction from the axial direction to the bottom of the cone as the positive direction.

[0048] The groove width b of the spiral groove 4 is controlled within (0.015-0.025)D. cWithin the range, the ratio of groove width to groove depth This proportional relationship ensures the formation of a stable secondary flow within the spiral groove, while avoiding a decrease in the structural strength of the conical anti-vortex device due to excessive groove width, or insufficient secondary flow strength due to excessive groove width.

[0049] The working mechanism of the spiral groove 4 is mainly based on secondary swirling compensation and vortex core weakening. The spiral groove guides the water flow to form a weak reverse circumferential velocity, which cancels out the pre-swirl induced by the impeller, making the inlet flow closer to pure axial inflow. At the same time, the low-velocity secondary flow generated in the groove can destroy the axial vortex filaments, inhibit vortex stretching, reduce the central low pressure, and suppress the generation of cavitation. Pressure pulsation reduction rate The calculation formula is: ; In the formula: Pressure pulsation reduction rate (%); The pressure pulsation amplitude (MPa) of the traditional inlet pipe; The pressure pulsation amplitude (MPa) of the inlet pipe of this invention. It can achieve a reduction of 30%-60%, significantly reducing vibration and noise caused by pressure pulsation.

[0050] As an optional implementation, the bottom diameter of the conical anti-vortex device 2 is smaller than the minimum inner diameter of the horn tube 1, and an annular flow channel is formed between the bottom of the conical anti-vortex device 2 and the inner wall of the horn tube 1.

[0051] In one embodiment of the present invention, the annular flow channel enables the water to flow uniformly between the conical anti-vortex device and the inner wall of the trumpet tube, thereby achieving flow velocity homogenization, reducing velocity gradient, reducing turbulence loss, and improving the uniformity of the inlet flow field.

[0052] As an optional implementation, the cone apex angle of the cone-shaped anti-vortex device 2 is 60°.

[0053] In one embodiment of the present invention, a 60° cone angle achieves the optimal balance between the vortex core breaking effect and the flow resistance: it can effectively cut the central vortex core without significantly increasing the blockage ratio and additional hydraulic losses.

[0054] As an optional implementation, the height of the conical anti-vortex device 2 is the same as the height of the horn tube 1.

[0055] In one embodiment of the present invention, the conical anti-vortex device 2 covers the entire internal area of ​​the horn tube 1 along the axial direction, thereby achieving vortex core breaking and backflow suppression throughout the entire flow channel range and avoiding vortex residue in local areas.

[0056] As an optional implementation, the starting end of the guide rib 3 is 0.1L away from the water inlet end face of the horn tube 1, and the end of the guide rib 3 extends to 0.1L away from the bottom of the cone-shaped anti-vortex device 2.

[0057] In one embodiment of the present invention, the axial coverage area accounts for about 70%-80% of the total length of the horn tube, which can ensure sufficient guidance of the inlet flow field, avoid unnecessary flow resistance caused by excessively long ribs, and maintain structural stability through annular reinforcing ribs.

[0058] As an optional implementation, the number of guide ribs 3 is 3-6.

[0059] In one embodiment of the present invention, the included angle α between two adjacent guide ribs 3 is preferably 90°, and the formula for calculating the included angle is: ; In the formula: α is the included angle between adjacent guide fins; n is the number of guide fins. In this embodiment, n=4, therefore α=90°. In practical applications, the number of guide fins can be adjusted according to the diameter of the horn tube, but it is necessary to ensure that the adjacent included angles are uniform and the number is controlled within the range of 3-6 fins to ensure a balance between the guiding effect and the flow capacity.

[0060] In one embodiment of the present invention, during use, after the water flows into the trumpet tube 1, it is first smoothly accelerated under the guidance of the gradually narrowing flow channel, and then divided into multiple uniform sub-flows by the guide ribs 3, effectively suppressing circumferential pre-swirl and boundary layer separation. When flowing through the conical anti-vortex device 2, the cone apex cuts and breaks the central vortex core, destroying the vortex accumulation conditions, and the cone surface guides the water flow to flow smoothly along the axial direction. At the same time, the spiral groove 4 guides the water flow to form a secondary vortex opposite to the impeller rotation direction, counteracting the pre-swirl generated by the impeller's suction, making the inlet water flow approach a pure axial inflow. Finally, the water flows through the annular flow channel between the conical anti-vortex device 2 and the inner wall of the trumpet tube 1, achieving velocity homogenization, and then smoothly enters the axial flow pump impeller. The synergistic effect of the various structures realizes the full-process flow field control from inlet pre-guidance, vortex core breaking to velocity homogenization, effectively suppressing vortices, backflow, and pressure pulsation, and reducing hydraulic losses and operating noise.

[0061] This application effectively solves the problems of high hydraulic loss, high noise, and unstable operation caused by unsteady flow in the inlet pipe of axial flow pumps. In rated operating condition tests, the guide ribs 3 reduce the circumferential pre-swirl velocity by 50%-75%, the conical anti-vortex device 2 weakens the central vortex core intensity by 60%-70%, the spiral groove 4 reduces the pressure pulsation amplitude by 25%-45%, and the annular flow channel reduces the velocity non-uniformity coefficient from 0.35 to 0.15-0.22. The synergistic effect of these structures reduces the hydraulic loss of the axial flow pump by 30%-50%, reduces operating noise by 4-6 dB(A), and increases pump efficiency by 1.5%-3.5%, while maintaining hydraulic efficiency fluctuations within ±1.2%, thus meeting the dual goals of high efficiency and energy saving, low noise and environmental protection, and equipment reliability.

[0062] Reference Figure 7 The results show that the axial flow pump with a composite anti-vortex guide structure inlet pipe performs significantly better than the prototype axial flow pump with a conventional inlet pipe. Comparative analysis reveals that the optimized pump exhibits significant improvements in both head and efficiency across all flow conditions, with an efficiency increase of approximately 8 percentage points and a head increase of approximately 7.7% under rated conditions. Simultaneously, it broadens the pump's stable operation and high-efficiency working range, achieving optimization of the axial flow pump's hydraulic external characteristics. This invention effectively regulates the inlet flow field and suppresses vortices and backflow by incorporating a composite anti-vortex guide structure within the axial flow pump inlet pipe.

[0063] This invention addresses the shortcomings of traditional axial flow pumps. Without compromising the pump's original hydraulic performance and flow capacity, the traditional inlet pipe design, which lacks effective guidance for water flow within the flared tube, easily leads to central vortex formation, circumferential pre-swirl, and boundary layer separation, resulting in significant hydraulic losses and pressure pulsations. This not only reduces pump efficiency and increases energy consumption but also amplifies unit vibration and operating noise, negatively impacting equipment reliability, service life, and the working environment. This invention, however, constructs a composite anti-vortex guiding structure consisting of guide ribs, a conical anti-vortex device, spiral grooves, and annular flow channels. This structure enables precise, multi-dimensional control of the inlet flow field throughout the entire process, effectively overcoming the technical challenges of large vortices, high losses, and strong noise in traditional inlet pipes by improving flow stability, energy dissipation, and suppressing pressure pulsations. Specifically, the circumferentially distributed guide ribs divide the main flow into ordered sub-flows, significantly suppressing circumferential pre-swirl and boundary layer separation. The centrally arranged conical anti-vortex device, through cone apex cutting and cone surface guidance, powerfully breaks the central vortex core, eliminates local backflow and low-pressure areas. The spiral groove further counteracts the pre-swirl disturbance induced by impeller suction by generating reverse compensating swirl, making the inlet water flow approach pure axial inflow. Finally, the annular flow channel formed by the conical anti-vortex device and the inner wall of the trumpet tube can homogenize the flow velocity across the entire cross-section, reducing turbulence intensity and hydraulic losses. The synergistic effect of these structures realizes a complete flow field optimization system from inlet pre-guidance, vortex core breaking, swirl compensation to velocity homogenization, significantly improving the uniformity and stability of the axial flow pump inlet flow field, greatly reducing hydraulic losses and pressure pulsations. While maintaining efficient pump operation, it effectively reduces operating noise and unit vibration, delays cavitation risks, and has the engineering advantages of simple structure, high reliability, and wide adaptability.

[0064] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0065] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An inlet pipe structure for an axial flow pump with an anti-vortex guiding structure, characterized in that, include: The horn tube (1) has a tapered structure. The large end of the horn tube (1) is the water inlet, and the small end of the horn tube (1) is the water outlet. A conical anti-vortex device (2) is provided in the middle of the horn tube (1). The cone tip of the conical anti-vortex device (2) faces the water inlet direction of the horn tube (1). A spiral groove (4) is provided on the surface of the conical anti-vortex device (2). The spiral groove (4) extends spirally along the surface of the conical anti-vortex device (2). Multiple guide ribs (3) are arranged at equal intervals along the circumference on the inner wall of the trumpet tube (1) and fixedly connected to the outer wall of the conical anti-vortex device (2). The guide ribs (3) have a streamlined cross section, and the bending direction of the cross section is consistent with the direction of water flow.

2. The inlet pipe structure of an axial flow pump with an anti-vortex guiding structure according to claim 1, characterized in that: The streamlined cross-section of the guide rib (3) is airfoil-shaped or teardrop-shaped, with a rounded front end and a sharp rear end.

3. The inlet pipe structure of an axial flow pump with an anti-vortex guiding structure according to claim 1, characterized in that: The thickness of the guide rib (3) gradually decreases from the side connected to the inner wall of the horn tube (1) to the side connected to the conical anti-vortex device (2).

4. The inlet pipe structure of an axial flow pump with an anti-vortex guiding structure according to claim 1, characterized in that: The spiral direction of the spiral groove (4) is opposite to the rotation direction of the axial flow pump impeller.

5. The inlet pipe structure of an axial flow pump with an anti-vortex guiding structure according to claim 1, characterized in that: The depth of the spiral groove (4) gradually increases from the top of the cone to the bottom of the cone-shaped anti-vortex device (2).

6. The inlet pipe structure of an axial flow pump with an anti-vortex guiding structure according to claim 1, characterized in that: The bottom diameter of the conical anti-vortex device (2) is smaller than the minimum inner diameter of the horn tube (1), and an annular flow channel is formed between the bottom of the conical anti-vortex device (2) and the inner wall of the horn tube (1).

7. The inlet pipe structure of an axial flow pump with an anti-vortex guiding structure according to claim 1, characterized in that: The cone apex angle of the cone-shaped anti-vortex device (2) is 60°.

8. The inlet pipe structure of an axial flow pump with an anti-vortex guiding structure according to claim 1, characterized in that: The height of the conical anti-vortex device (2) is the same as the height of the horn tube (1).

9. The inlet pipe structure of an axial flow pump with an anti-vortex guiding structure according to claim 1, characterized in that: The starting end of the guide rib (3) is 0.1L away from the water inlet end face of the horn tube (1), and the end of the guide rib (3) extends to 0.1L away from the cone bottom of the cone-shaped anti-vortex device (2).

10. The inlet pipe structure of an axial flow pump with an anti-vortex guiding structure according to claim 1, characterized in that: The number of the flow guide ribs (3) is 3-6.

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