High-efficiency guide vane type diffuser

Abstract

The invention discloses a high-efficiency guide vane type diffuser which comprises a diffuser body, a speed diffusion section and a pressure increasing section. Wherein an impeller mounting hole is formed in the center of the diffuser body and is used for mounting a diffuser impeller; the speed diffusion section is communicated with the pressure increasing section to form a diffuser flow channel which is arranged on the inner wall face of the diffuser body. According to the high-efficiency guide vane type diffuser, the flow channel is designed in the mode that the speed diffusion section and the pressure increasing section are combined, uniform diffusion of the speed can be guaranteed, advanced conversion from the speed to the pressure can be guaranteed, and therefore energy loss is effectively reduced.

Description

Technical Field

[0001] This invention belongs to the field of fluid machinery technology, and in particular relates to a high-efficiency guide vane diffuser. Background Technology

[0002] In the field of centrifugal pumps with low flow rate and high head, characterized by low specific speed and ultra-low specific speed, high-speed pumps have higher efficiency than ordinary centrifugal pumps. High-speed pumps typically use an inducer, a semi-open straight-blade impeller, a diffuser, and a cylindrical inner and outer casing to form the flow passage. The work is mainly completed in the inducer and impeller sections; the conversion of fluid velocity energy into pressure energy is completed in the diffuser section.

[0003] Since high-speed pumps are generally modular in design, the external dimensions of the diffuser remain basically unchanged. In traditional diffuser design, the inlet and outlet areas of the guide vanes are determined first, and the intermediate flow channel is designed by optimization. Under low flow conditions, the inlet and outlet areas of the guide vanes are small, which makes the flow channel too narrow and long. The fluid contacts the wall surface at high speed over a long distance, which increases flow loss and reduces the energy conversion efficiency in the diffuser. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a high-efficiency guide vane diffuser, which can effectively reduce high-speed flow losses in the flow channel, improve the energy conversion efficiency in the diffuser, thereby improving the overall efficiency of the high-speed pump and achieving the purpose of energy saving and consumption reduction.

[0005] To solve the above-mentioned technical problems, the present invention discloses a high-efficiency guide vane diffuser, comprising: a diffuser body, a velocity diffusion section, and a pressure boosting section; wherein, the diffuser body has an impeller mounting hole in the center for mounting a diffuser impeller; the velocity diffusion section is connected to the pressure boosting section to form a diffuser flow channel, which is disposed on the inner wall of the diffuser body.

[0006] In the aforementioned high-efficiency guide vane diffuser, the throat of the velocity diffusion section is a straight section with the same length as the throat diameter.

[0007] In the aforementioned high-efficiency guide vane diffuser, the inlet angle of the throat of the velocity diffusion section is 3~8°.

[0008] In the aforementioned high-efficiency guide vane diffuser, the pressure boosting section reduces the liquid velocity by expanding the flow cross-sectional area in the radial direction, thereby converting velocity energy into pressure energy.

[0009] In the aforementioned high-efficiency guide vane diffuser, the flow curve of the diffuser channel was determined through CFD simulation.

[0010] In the aforementioned high-efficiency guide vane diffuser, the inner wall of the diffuser channel outlet is treated with a "precision polishing + plasma ceramic spraying" process to ensure that the surface roughness Ra≤0.8μm.

[0011] In the aforementioned high-efficiency guide vane diffuser, the cross-sectional area of ​​the velocity diffusion section is smaller than that of the pressure boosting section.

[0012] In the aforementioned high-efficiency guide vane diffuser, the cross-sectional area of ​​the pressure boosting section satisfies the requirement that the liquid flow velocity be kept below 6 m / s.

[0013] The present invention has the following advantages: (1) This invention discloses a high-efficiency guide vane diffuser, which adopts a combination of velocity diffusion section and pressure boosting section to design the flow channel, which can ensure uniform velocity diffusion and early conversion of velocity to pressure, thereby effectively reducing energy loss.

[0014] (2) This invention discloses a high-efficiency guide vane diffuser. The throat of the velocity diffusion section is a straight section with the same length as the throat diameter, and the inlet angle of the throat is 3~8°. This section is used to control the design flow rate. The curvature optimization of the velocity diffusion section is achieved through CFD (Computational Fluid Dynamics) simulation. Based on different design objectives, such as maximum efficiency, steep performance curve, and high cavitation resistance, the curvature variation law of the central axis of the flow channel is determined to ensure that the boundary layer is not easily separated when the fluid flows along the curve in the flow channel, thereby reducing eddy current losses.

[0015] (3) This invention discloses a high-efficiency guide vane diffuser, which can more precisely process the flow channel hole compared with traditional drilling. Different surface treatment processes can be conveniently adopted according to the working conditions. For example, by using the "precision polishing + plasma ceramic spraying" process, the surface roughness Ra of the flow channel is ensured to be ≤0.8μm, which is suitable for harsh working conditions such as high corrosion and high particle content.

[0016] (4) This invention discloses a high-efficiency guide vane diffuser, which is suitable for low specific speed and ultra-low specific speed high-speed pumps. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a high-efficiency guide vane diffuser in an embodiment of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments disclosed in the present invention will be described in further detail below with reference to the accompanying drawings.

[0019] Conventional high-speed pump guide vane diffusers achieve the conversion of liquid velocity into pressure by machining a diffusion section within the diffuser body. However, for low specific speed centrifugal pumps, due to the small flow channel diameter, a diffusion section of 5-7 times the flow rate is sufficient for the conversion. But due to diffuser structural limitations, the diffusion may require a diffusion section of 10 times or even higher, increasing liquid flow losses. Therefore, this application proposes a novel structural design for a high-efficiency guide vane diffuser.

[0020] Reference Figure 1 In this embodiment, the high-efficiency guide vane diffuser includes: a diffuser body 1, a velocity diffusion section 3, and a pressure boosting section 4. The diffuser body 1 has an impeller mounting hole 2 at its center for mounting a diffuser impeller; the velocity diffusion section 3 communicates with the pressure boosting section 4 to form a diffuser flow channel, and is disposed on the inner wall of the diffuser body 1.

[0021] In this embodiment, the throat of velocity diffusion section 3 is a straight section with the same length as the throat diameter, and the throat inlet angle is 3~8°. This design aims to control the design flow rate and uses a variable curvature smooth transition to reduce the high-speed liquid velocity at the impeller outlet, thus preparing for subsequent pressure increases. The core design includes three parts: the rectangular cross-sectional shape design of the velocity diffusion section 3 flow channel, the flow channel curvature optimization, and the flow channel surface treatment.

[0022] In this embodiment, the pressure boosting section 4 reduces the liquid velocity by expanding the flow cross-sectional area in the radial direction, thereby converting velocity energy into pressure energy. Specifically, after the velocity diffusion section 3 completes the theoretically calculated diffusion length, the cross-section of the pressure boosting section 4 is smoothly expanded to a larger cross-section. The area of ​​this larger cross-section satisfies the following conditions: ensuring that the liquid velocity is within 6 m / s, ensuring that the liquid already has a high pressure head before entering the pipe, thereby reducing the flow path of the high-speed fluid and reducing losses. That is, the cross-sectional area of ​​the velocity diffusion section 3 is smaller than the cross-sectional area of ​​the pressure boosting section 4, and the cross-sectional area of ​​the pressure boosting section 4 satisfies the condition: able to keep the liquid velocity within 6 m / s.

[0023] In this embodiment, the curve 5 of the diffuser channel is determined by CFD simulation: based on different design objectives, such as maximum efficiency, steep performance curve, and high cavitation resistance, the curvature variation law of the channel center axis is determined to ensure that the boundary layer is not easily separated when the fluid flows along the curve in the channel, thereby reducing eddy current losses.

[0024] In this embodiment, the inner wall of the outlet 6 of the diffuser channel can be treated with different surface treatment processes according to different working conditions. For example, it can be treated with "precision polishing + plasma ceramic spraying" to ensure that the surface roughness Ra≤0.8μm, so as to be suitable for harsh working conditions such as high corrosion and high particle content.

[0025] In summary, the high-efficiency guide vane diffuser of this invention employs a flow channel design combining a velocity diffusion section and a pressure boosting section. This ensures both uniform velocity diffusion and early velocity-to-pressure conversion, thereby effectively reducing energy loss. This high-efficiency guide vane diffuser has the following characteristics: The velocity diffusion section employs a smooth transition with varying curvature to reduce the high-speed liquid velocity at the impeller outlet, preparing for subsequent pressure increases. The core design includes three parts: rectangular cross-sectional shape design of the flow channel, flow channel curvature optimization, and flow channel surface treatment. The cross-sectional shape of the velocity diffusion section is a regular rectangle, with the varying length of the rectangle matching the impeller outlet width to ensure an error ≤0.2mm. This avoids sudden changes in local velocity within the velocity diffusion section while meeting the requirement for smooth diffusion.

[0026] The throat of the velocity diffusion section is a straight segment of equal length to the throat diameter, with an inlet angle of 3-8°. This segment controls the design flow rate. Subsequent optimization of the diffusion curve curvature is achieved through CFD simulation. Based on different design objectives, such as maximum efficiency, steep performance curve, and high cavitation resistance, the curvature variation law of the flow channel's central axis is determined to ensure that the boundary layer does not easily separate when the fluid flows along the curve within the flow channel, thus reducing eddy current losses.

[0027] The pressure boosting section mainly reduces the liquid velocity by expanding the flow cross-sectional area in the radial direction, thereby converting velocity energy into pressure energy. This ensures that the liquid has a high pressure head before entering the pipe, thus reducing the flow path of high-speed fluid and reducing friction loss.

[0028] The open guide vane diffuser structure design allows for more precise flow channel processing compared to traditional tapered orifices. Different surface treatment processes can be easily adopted according to the working conditions. For example, the "precision polishing + plasma ceramic spraying" process ensures that the surface roughness Ra of the flow channel is Ra≤0.8μm, making it suitable for harsh working conditions such as high corrosion and high particle content.

[0029] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

[0030] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A high-efficiency guide vane diffuser, characterized in that, include: The diffuser body (1), velocity diffusion section (3), and pressure boosting section (4) are provided. The diffuser body (1) has an impeller mounting hole (2) in the center for mounting the diffuser impeller. The velocity diffusion section (3) is connected to the pressure boosting section (4) to form a diffuser flow channel, which is located on the inner wall of the diffuser body (1).

2. The high-efficiency guide vane diffuser according to claim 1, characterized in that, The velocity diffusion section (3) has a straight section of the same length as the diameter of the throat.

3. The high-efficiency guide vane diffuser according to claim 1, characterized in that, The inlet angle of the throat of the velocity diffusion section (3) is 3~8°.

4. The high-efficiency guide vane diffuser according to claim 1, characterized in that, The pressure boosting section (4) reduces the liquid flow velocity by expanding the flow cross-sectional area in the radial direction, thereby converting velocity energy into pressure energy.

5. The high-efficiency guide vane diffuser according to claim 1, characterized in that, The diffuser flow path curve (5) was determined by CFD simulation.

6. The high-efficiency guide vane diffuser according to claim 1, characterized in that, The inner wall of the outlet (6) of the diffuser channel is treated with "precision polishing + plasma ceramic spraying" process to ensure that the surface roughness Ra≤0.8μm.

7. The high-efficiency guide vane diffuser according to claim 1, characterized in that, The cross-sectional area of ​​the velocity diffusion section (3) is smaller than that of the pressure boosting section (4).

8. The high-efficiency guide vane diffuser according to claim 1, characterized in that, The cross-sectional area of ​​the pressure boosting section (4) satisfies the requirement that the liquid flow velocity is within 6 m / s.

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