Flow-guiding diffusion type impeller balance hole structure

Abstract

The utility model relates to a kind of flow-guiding diffusion type impeller balance hole structure, which is located on the rear cover plate of the impeller, comprising a balance hole, a spiral flow guide groove is formed on the inner wall of the inlet end of the balance hole, and the spiral direction of the spiral flow guide groove is the same as the rotation direction of the impeller; an inclined conical diffusion section is provided at the outlet end of the balance hole; the inclined conical diffusion section starts from the end of the spiral flow guide groove of the balance hole, and the flow cross section gradually expands towards the low-pressure side of the impeller, forming a horn-shaped outlet structure. The utility model greatly reduces the axial impact speed of the leakage flow and optimizes its outflow direction, greatly reduces the mixing loss with the main flow, and improves the operating efficiency of the pump. The outlet jet velocity is reduced, the suction effect on the low-pressure inlet area is weakened, the high-speed jet effect on the low-pressure inlet area is eliminated, which helps to maintain the inlet pressure and improve the anti-cavitation ability. The gentle fusion mode stabilizes the inlet flow field, which can reduce the vibration and noise level of the pump.

Description

Technical Field

[0001] This utility model relates to an impeller balance hole structure, specifically a flow-guiding and diffusion type impeller balance hole structure that is highly efficient and energy-saving, improves cavitation performance, operates smoothly, and has a simple and reliable structure. Background Technology

[0002] As a general-purpose fluid transport device, the centrifugal pump's core component, the impeller, experiences uneven liquid pressure on its front and rear cover plates during high-speed rotation, generating a significant axial force pointing towards the pump inlet. This unbalanced axial force significantly increases the load on the pump bearings, leading to accelerated bearing wear, increased temperature, shortened lifespan, and even equipment failure.

[0003] Balancing holes are a common and economical means of balancing axial forces. Existing technology uses several straight cylindrical through-holes (usually equal in number to the number of blades) evenly distributed along the circumference of the impeller's rear cover plate, axially penetrating the rear cover plate with their axis parallel to the impeller's centerline. This structure connects the high-pressure chamber at the rear of the impeller with the low-pressure zone at the impeller inlet, allowing some of the liquid on the high-pressure side to flow back to the low-pressure side, effectively reducing the pressure difference across the impeller and thus balancing the axial force.

[0004] Existing balancing orifice technology uses straight cylindrical through-holes, causing the high-pressure leakage flow ejected through the orifice to impact the low-pressure mainstream flow at the impeller inlet in a high-speed jet form. This generates strong eddies and turbulence, disrupting the uniformity and stability of the flow field at the impeller inlet and potentially inducing vibration. Slowing down, mixing, and aligning this jet with the mainstream flow requires a significant amount of energy, resulting in substantial hydraulic losses. Furthermore, the high-pressure leakage flow from the balancing orifice reduces the effective pressure at the impeller inlet, increasing the pump's required net positive suction head (NPSH) and worsening cavitation performance. This is extremely detrimental to pumps operating under low suction pressure conditions. Utility Model Content

[0005] To address the aforementioned problems, the main objective of this utility model is to provide a flow-guiding and diffusion impeller balance hole structure that is highly efficient and energy-saving, improves cavitation performance, operates smoothly, and has a simple and reliable structure.

[0006] This utility model solves the above-mentioned technical problems through the following technical solution: a flow-guiding and diffusion type impeller balance hole structure, wherein the flow-guiding and diffusion type impeller balance hole structure is located on the impeller rear cover plate, the flow-guiding and diffusion type impeller balance hole structure includes: a balance hole, and a spiral flow guide groove is provided at the inlet end of the balance hole, the spiral flow guide groove is formed on the inner wall of the inlet end, and the spiral direction of the spiral flow guide groove is the same as the rotation direction of the impeller.

[0007] An inclined conical diffuser section is provided at the outlet end of the balance hole; the inclined conical diffuser section starts from the end of the spiral guide groove of the balance hole, and its flow cross section gradually expands towards the low-pressure side of the impeller, forming a funnel-shaped outlet structure.

[0008] In specific embodiments of this utility model, the spiral guide groove includes 2-5 grooves.

[0009] In specific embodiments of this utility model, the cross-sectional shape of the spiral groove is arc-shaped, rectangular, or triangular.

[0010] In a specific embodiment of this utility model, the helix angle α of the spiral groove is between 10° and 30°.

[0011] In a specific embodiment of this utility model, the cone angle β of the inclined conical diffusion section is between 8° and 15°.

[0012] In a specific embodiment of this utility model, the angle γ between the central axis of the inclined conical diffuser section and the impeller axis is between 15° and 40°.

[0013] The positive and progressive effects of this utility model are as follows: The flow-guiding and diffusion type impeller balance hole structure provided by this utility model has the following advantages: 1. High efficiency and energy saving: By significantly reducing the axial impact velocity of the leakage flow and optimizing its outflow direction, the mixing loss with the mainstream is greatly reduced, improving the pump's operating efficiency, especially under partial load conditions.

[0014] 2. Improved Cavitation: The reduced outlet jet velocity weakens the "suction" effect on the low-pressure inlet area, eliminating the entrainment effect of the high-speed jet on the low-pressure inlet area. This helps maintain inlet pressure, effectively reducing the pump's required net positive suction head (NPSH) and improving cavitation resistance. Cavitation itself drastically reduces efficiency; therefore, avoiding cavitation is protecting efficiency.

[0015] 3. Smooth operation: The gentle fusion method stabilizes the inlet flow field, which can reduce the vibration and noise level of the pump.

[0016] 4. Simple and reliable structure: The entire structure is composed of simple geometric features with no moving parts. It can be achieved through one-time machining with forming tools or precision casting, resulting in low manufacturing cost and high reliability. Attached Figure Description

[0017] Figure 1 This is a cross-sectional view of an impeller with balancing holes in the existing technology.

[0018] Figure 2 This is an enlarged view of the location of the balance hole in the prior art.

[0019] Figure 3 This is a schematic diagram of the overall structure of this utility model.

[0020] Figure 4 This is an enlarged view of the position of the balance hole in this utility model.

[0021] The following are the names corresponding to the reference numerals in this utility model: In the figure: impeller rear cover plate 1, balance hole 2, impeller 3, inlet end 201, spiral guide groove 202, outlet end 203, inclined conical diffuser section 204. Detailed Implementation

[0022] The preferred embodiments of this utility model are given below with reference to the accompanying drawings to illustrate the technical solution of this utility model in detail.

[0023] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a simple and effective optimized structure for the centrifugal pump impeller balancing hole. This structure features a spiral guide groove at the inlet end of the balancing hole and an inclined conical diffuser section at the outlet end. Through the synergistic effect of inlet guidance and outlet diffusion, it minimizes impact losses, turbulent dissipation, and cavitation risks caused by leakage flow mixing with the mainstream, thereby ensuring axial force balance while minimizing the negative impact of the balancing hole on pump efficiency.

[0024] This invention, without significantly increasing manufacturing costs, completely changes the outflow state of the leakage flow by designing a spiral guide groove at the inlet end of the balance hole and an inclined conical diffuser section at the outlet end through synergistic optimization of the two aspects.

[0025] The flow-guiding and diffusion-type impeller balance hole structure proposed in this utility model is located on the impeller rear cover plate 1. Figure 3 This is a schematic diagram of the overall structure of this utility model. Figure 4 This is an enlarged view of the position of the balance hole in this utility model, as shown below. Figure 3 and 4 As shown: This invention designs a spiral guide groove 202 at the inlet end 201 of the balance hole 2. The spiral guide groove 202 is formed on the inner wall of the inlet section 201 of the balance hole 2, and its spiral direction is the same as the rotation direction of the impeller 3. At least 2 to 5 continuous spiral guide grooves 202 should be provided. The cross-sectional shape of the spiral guide groove 202 is arc-shaped, rectangular, or triangular, and the helix angle α is between 10° and 30° to adapt to the flow requirements under different working conditions. When the impeller rotates, the fluid on the high-pressure side is given tangential velocity along the spiral guide groove, forming a forced vortex within the hole, reducing its effective axial velocity, and creating conditions for downstream diffusion.

[0026] This invention features an inclined conical diffuser section 204 at the outlet end 203 of the balance hole 2. This diffuser section begins at the end of the spiral guide groove of the balance hole, and its flow cross-section gradually expands towards the low-pressure side of the impeller, forming a funnel-shaped outlet structure. The cone angle β of the inclined conical diffuser section 204 is between 8° and 15°, and the angle γ between its central axis and the impeller axis is between 15° and 40° to achieve optimal flow diffusion and prevent flow separation. This structure effectively reduces the velocity of the fluid flowing out and guides the fluid in a direction more consistent with the main flow direction of the impeller, greatly mitigating the impact on the main flow at the impeller inlet, reducing mixing losses, and helping to suppress cavitation.

[0027] In this invention, the overall number and diameter of the balance holes 2 are conventionally determined based on the impeller model and the designed axial force. The improvement of this invention lies in the local structure of its inlet and outlet.

[0028] As the impeller rotates, the fluid on the high-pressure side is given tangential velocity along the spiral guide groove, forming a forced vortex within the orifice and reducing its effective axial velocity. After pre-swirling through the guide groove, the fluid enters the inclined conical diffuser, where its outlet velocity is significantly reduced, converting remaining kinetic energy into pressure energy. Furthermore, the direction of the leakage flow is closer to the mainstream flow direction within the impeller, optimizing the flow direction and reducing impact losses caused by abrupt changes in flow direction, greatly mitigating interference with the low-pressure zone at the impeller inlet. This allows the fluid to enter the impeller inlet at a lower velocity and in a gentler manner. This not only compensates for the hydraulic losses in the balance orifice circuit but also effectively improves the pump's cavitation resistance, resulting in smoother and more reliable pump operation.

[0029] This invention changes the way fluid enters the balance hole by designing a spiral guide groove at the high-pressure side inlet, transforming it from the traditional "direct flow" to "spiral entry." Utilizing the kinetic energy of the impeller rotation, the liquid is guided smoothly into the balance hole, converting impact energy into kinetic energy, thereby significantly reducing inlet eddies and impact losses.

[0030] This invention changes the state of the fluid after it flows out of the balance hole by designing an inclined conical diffuser section at the outlet end of the balance hole, transforming it from "high-speed jetting" to "stable diffusion". By increasing the cross-sectional area, kinetic energy is converted into pressure energy, reducing the flow velocity and allowing the outflowing fluid to better blend with the mainstream at the impeller inlet, thus reducing the impact and interference on the mainstream.

[0031] The spiral guide at the inlet and the conical diffusion at the outlet work together to optimize the flow inside the balance hole from the "inlet" to the "outlet", creating a "1+1>2" effect. This significantly reduces the impact loss, cavitation and vibration caused by the balance hole, improves the pump's efficiency and operational stability, and features a simple structure with no moving parts and high reliability.

[0032] This invention significantly reduces the axial impact velocity of the leakage flow and optimizes its outflow direction, thereby greatly reducing mixing losses with the mainstream and improving the pump's operating efficiency, especially under partial load conditions.

[0033] This invention reduces the outlet jet velocity, weakens the "suction" effect on the low-pressure inlet area, eliminates the entrainment effect of the high-speed jet on the low-pressure inlet area, helps maintain inlet pressure, effectively reduces the pump's required net positive suction head (NPSH), and improves cavitation resistance. Cavitation itself drastically reduces efficiency; therefore, avoiding cavitation is protecting efficiency.

[0034] The gentle fusion method of this invention stabilizes the inlet flow field, which can reduce the vibration and noise level of the pump.

[0035] The entire structure of this utility model is composed of simple geometric features, with no moving parts. It can be achieved through one-time machining with forming tools or precision casting, resulting in low manufacturing cost and high reliability.

[0036] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection of this utility model as defined by the appended claims and their equivalents.

Claims

1. A flow-guiding and diffusion-type impeller balancing hole structure, characterized in that: The flow-guiding and diffusion type impeller balance hole structure is located on the impeller rear cover plate. The flow-guiding and diffusion type impeller balance hole structure includes: a balance hole, and a spiral flow guide groove is provided at the inlet end of the balance hole. The spiral flow guide groove is formed on the inner wall of the inlet end, and the spiral direction of the spiral flow guide groove is the same as the rotation direction of the impeller. An inclined conical diffuser section is provided at the outlet end of the balance hole; the inclined conical diffuser section starts from the end of the spiral guide groove of the balance hole, and its flow cross section gradually expands towards the low-pressure side of the impeller, forming a funnel-shaped outlet structure.

2. The flow-guiding and diffusion type impeller balance hole structure according to claim 1, characterized in that: The spiral guide channel consists of 2-5 channels.

3. The flow-guiding and diffusion type impeller balance hole structure according to claim 1, characterized in that: The cross-sectional shape of the spiral groove can be arc-shaped, rectangular, or triangular.

4. The flow-guiding and diffusion type impeller balance hole structure according to claim 1, characterized in that: The helix angle α of the spiral groove is between 10° and 30°.

5. The flow-guiding and diffusion type impeller balance hole structure according to claim 1, characterized in that: The cone angle β of the inclined conical diffusion section is between 8° and 15°.

6. The flow-guiding and diffusion type impeller balance hole structure according to claim 1, characterized in that: The angle γ between the central axis of the inclined conical diffuser section and the impeller axis is between 15° and 40°.

Images