A high-efficiency and low-noise airfoil blade design method for centrifugal pumps based on internal flow and pressure pulsation

Abstract

This invention discloses a design method for high-efficiency, low-noise airfoil blades for centrifugal pumps based on internal flow and pressure pulsation. CFD simulations are performed on the designed centrifugal pump airfoil blades, and the results of the preliminary numerical simulations are analyzed to improve the geometric parameters of the airfoil blades. Based on the original model, several different blade profiles are determined by improving parameters such as the blade inlet and outlet angles and maximum thickness. Finally, the optimal selection between the internal flow distribution, head, and other performance parameters of the centrifugal pump and the key geometric parameters of the airfoil blades is obtained, resulting in centrifugal pump airfoil blade performance parameters that combine high efficiency and low noise. Experimental verification is then conducted. This design method, from the perspective of centrifugal pump noise control, can effectively reduce the dynamic and static interference between the impeller and the volute, ensuring the external characteristics of the pump, reducing internal noise, improving the overall quietness of the centrifugal pump, and simultaneously improving the flow field.

Description

Technical Field

[0001] This invention relates to the field of centrifugal pump blade noise reduction design technology, and in particular to a method for designing high-efficiency, low-noise airfoil blades for centrifugal pumps based on internal flow and pressure pulsation. Background Technology

[0002] Centrifugal pumps are a type of rotary hydraulic machinery with small flow rate and large head, and are widely used not only in pumping stations, farmland irrigation, and urban water supply and drainage, but also in national defense, aerospace, navigation, and energy fields.

[0003] Ensuring efficient, safe, and stable operation of centrifugal pumps has always been the ultimate design goal. Although centrifugal pumps in these practical engineering applications have already achieved excellent performance, we have also discovered their shortcomings during actual use. During operation, the centrifugal pump experiences strong dynamic and static interference at the impeller and volute tongue, resulting in a very complex flow field. In particular, significant flow separation occurs near the trailing edge of the blade working surface, leading to wake-jet flow, which further exacerbates the pressure pulsation at the volute tongue, causing considerable noise. Centrifugal pumps are often accompanied by loud noise during operation.

[0004] Against this technological backdrop and in light of the problems encountered in actual production, and addressing the common issue of loud noise during the operation of current centrifugal pumps, the inventors have made some technical improvements and optimizations, and have invented a design method for centrifugal pump airfoil blades. Summary of the Invention

[0005] To address the aforementioned problems, this invention aims to provide a high-efficiency, low-noise airfoil blade design method for centrifugal pumps based on internal pump flow and pressure pulsation, thereby solving the noise problem in the operation of existing centrifugal pump units.

[0006] To achieve the above objectives, the technical solution adopted by this invention is as follows: a method for designing high-efficiency, low-noise airfoil blades for centrifugal pumps based on internal flow and pressure pulsation, characterized by comprising the following steps:

[0007] S1. Determine the operating parameters of the centrifugal pump: This includes the design flow rate, design head, design efficiency, design speed, and performance parameters of the pumped medium. The impeller, volute, and inlet / outlet sections are hydraulically designed using traditional methods. The geometric parameters of the impeller, volute, and inlet / outlet components are also determined, including:

[0008] Impeller inlet and outlet diameters, number of blades, blade inlet and outlet angles, blade width, blade wrap angle, ratio of impeller outlet to inlet flow area, volute base circle diameter, ratio of volute base circle to impeller outer diameter, volute cross-sectional area and shape;

[0009] S2. Centrifugal pump airfoil blades and hydraulic components modeling: Geometric modeling is performed by designing the geometric parameters of the airfoil blades, the inlet and outlet sections of the centrifugal pump, and the volute, to establish a three-dimensional model, and numerical simulation analysis is conducted using CFD methods.

[0010] S3. Determine the blade profile: The numerical simulation includes flow calculation, pressure pulsation calculation and flow noise calculation of the entire flow field of the centrifugal pump. The results of the preliminary numerical simulation calculation are analyzed, and the geometric parameters of the centrifugal pump airfoil blades are improved to determine several different blade profiles.

[0011] S4. Airfoil blade performance parameters: Improve the geometric parameters of the pump airfoil blade and perform numerical simulation calculations. Based on the optimal selection between the internal performance parameters of the centrifugal pump and the geometric parameters of the pump airfoil blade, obtain the centrifugal pump airfoil blade performance parameters based on the combination of high efficiency and low noise.

[0012] S5. Experimental Verification: The obtained high-efficiency and low-noise blades are processed and subjected to actual experimental verification, including testing of external characteristics, pressure pulsation, and noise. The test results are re-verified to ensure the uncontrollability of the experiment. Airfoil blades that do not meet the design requirements are redesigned, and the final design scheme of high-efficiency and low-noise airfoil blades for centrifugal pumps is determined.

[0013] Furthermore, in step S2, the airfoil blade is modeled as a NACA airfoil blade by changing the conventional cylindrical blade with varying thickness. The structural geometric parameters of the airfoil blade include: number of blades, blade inlet and outlet angles, blade thickness, blade inlet and outlet placement angles, and blade profile.

[0014] Furthermore, in step S2, boundary conditions are set using Fluent software to perform numerical simulation on the three-dimensional water model of the centrifugal pump. The rotational speed, flow rate, and inlet pressure conditions are set according to the design conditions of the centrifugal pump, and monitoring points are set to monitor pressure pulsation. Noise simulation is performed using the acoustic analogy integral module in Fluent.

[0015] Furthermore, in step S4, based on the initial blade simulation, the optimal combination of blade thickness and blade back profile is found, balancing the relationship between efficiency and vibration noise. The thickness of the airfoil blade inlet section is reduced within a small range to make it closer to a streamlined shape.

[0016] The thickness of the airfoil blade outlet interface is gradually increased in a linear manner, which improves the flow separation generated at the trailing edge of the blade working surface, reduces the pressure pulsation and noise of the centrifugal pump, and at the same time ensures the head and efficiency of the centrifugal pump.

[0017] The blade inlet angle is appropriately increased to reduce blade bending and improve its noise reduction performance, while the blade outlet angle is slightly increased.

[0018] Furthermore, in step S4, the head, efficiency, sound pressure level and related parameters of centrifugal pumps with different airfoil blades are analyzed using range analysis, and the internal flow of the centrifugal pump and the pressure pulsation at the monitoring point are analyzed using post-processing software.

[0019] The beneficial effects of this invention are: This invention provides a novel design method for centrifugal pump airfoil blades to control the noise of centrifugal pumps. Through CFD simulation design and experimental verification, the designed airfoil blades can improve the flow conditions of the centrifugal pump impeller channel, reduce flow separation at the blade outlet, reduce pressure pulsation in the volute, and achieve noise control of the centrifugal pump while ensuring the head and efficiency of the centrifugal pump. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating a high-efficiency, low-noise airfoil blade design method for centrifugal pumps based on internal pump flow and pressure pulsation, according to the present invention.

[0021] Figure 2 NACA airfoil design for centrifugal pumps.

[0022] Figure 3 This is a cross-sectional view of the airfoil blade of an unmodified centrifugal pump.

[0023] Figure 4 This is a 3D diagram of the airfoil blade of an unmodified centrifugal pump.

[0024] Figure 5 This is a cross-sectional view of an efficient and low-noise airfoil blade for a centrifugal pump based on internal flow and pressure pulsation, according to the present invention.

[0025] Figure 6 This is a three-dimensional diagram of a high-efficiency, low-noise airfoil blade for a centrifugal pump based on internal pump flow and pressure pulsation, according to the present invention.

[0026] Figure 7 Comparison cloud map of pressure distribution in the flow channel of a centrifugal pump using modified blades and unmodified blades.

[0027] Figure 8 This is a comparison chart of pressure pulsation at monitoring points on modified and unmodified blades. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0029] See attached document Figures 1-8As shown, a method for designing high-efficiency, low-noise airfoil blades for centrifugal pumps based on internal flow and pressure pulsation is described, and the method includes the following steps:

[0030] S1. Determine the operating parameters of the centrifugal pump: including the design flow rate, design head, design operating efficiency, design speed, and performance parameters of the conveyed medium. Perform hydraulic design on the impeller, volute, and inlet / outlet flow components using traditional methods. Also, determine the geometric parameters of the impeller, volute, and inlet / outlet components, including: impeller inlet / outlet diameter, number of blades, blade inlet / outlet angle, blade width, blade wrap angle, ratio of impeller outlet to inlet flow area, volute base circle diameter, ratio of volute base circle to impeller outer diameter, and volute cross-sectional area and shape.

[0031] The formula for calculating the head of a centrifugal pump is as follows:

[0032] H=(p2-p1) / ρg+(c2-c1) / 2g+z2-z1

[0033] In the formula: p1 and p2 represent the pressure of the liquid at the pump inlet and outlet, c1 and c2 represent the flow velocity of the fluid at the pump inlet and outlet, z1 and z2 represent the installation height of the inlet and outlet, ρ is the density of the fluid medium, and g is the local gravitational acceleration.

[0034] The formula for calculating the efficiency of a centrifugal pump is:

[0035]

[0036] In the formula: ρ is the density of the fluid medium, g is the local gravitational acceleration, Q is the inlet flow rate, H is the head of the centrifugal pump, and P represents the output power of the motor.

[0037] The formula for calculating the sound pressure level of a centrifugal pump is:

[0038]

[0039] In the formula: P is the actual pressure, P0 = 0.00002 N / m 2 This is the reference pressure.

[0040] S2. Centrifugal pump airfoil blades and hydraulic components modeling: Geometric modeling of centrifugal pump airfoil blades, centrifugal pump inlet and outlet sections, and volute. The conventional cylindrical blades with varying thickness are replaced with NACA airfoil blades. The structural geometric parameters of the airfoil blades include: number of blades, blade inlet and outlet angles, blade thickness, blade inlet and outlet placement angles, and blade profile.

[0041] Establishing a 3D model: Boundary conditions were set using Fluent software to perform numerical simulation on the 3D water model of the centrifugal pump. Rotation speed, flow velocity, and inlet pressure conditions were set according to the centrifugal pump's design operating conditions, and monitoring points were set to monitor pressure fluctuations. Noise simulation was performed using the acoustic analogy integral module in Fluent, and numerical simulation analysis was conducted using CFD methods. Specifically:

[0042] A two-dimensional hydraulic model of the centrifugal pump impeller was created using CAD. Then, a three-dimensional model of the centrifugal pump impeller was created using Pro / E modeling software based on the two-dimensional hydraulic model. After rotating the blade outline one revolution along the axial direction, complete and accurate three-dimensional blades could be cut out. All blades were arrayed according to the blade geometry, and then the inlet edges of the blades were rounded to obtain the solid model of the blades.

[0043] After rotating the impeller water profile by 360° using Pro / E software, the complete impeller water body is obtained. Then, the .stp file of the blade entity is imported, and the part of the flow channel occupied by the blade entity is cut off to obtain the three-dimensional model of the impeller flow channel.

[0044] The created models of the impeller and other fluid domain components of the pump were used to optimize the structural design of the impeller blades through 3D CFD calculations, specifically:

[0045] The impeller and other fluid domains of the pump were meshed and interactive surfaces were set using ICEM software. Boundary conditions were set using Fluent software for numerical simulation. Conditions such as rotational speed, flow rate, and inlet pressure were set according to the design conditions of the centrifugal pump. Monitoring points were set to monitor pressure pulsation. Noise simulation was performed using the acoustic analogy integral module in Fluent.

[0046] S3. Determine the blade profile: The numerical simulation is used to calculate the flow, pressure pulsation, and flow noise of the entire flow field of the centrifugal pump. The results of the preliminary numerical simulation are analyzed, and the geometric parameters of the centrifugal pump airfoil blades are improved. Based on the original model, several different blade profiles are determined by improving parameters such as the blade inlet and outlet angles and the maximum blade thickness.

[0047] S4. Airfoil blade performance parameters: Numerical simulation calculations were performed on blades with different improved outlet angles and outlet thicknesses, as well as other hydraulic components of the centrifugal pump. Based on centrifugal pumps with different airfoil blades, the range analysis method was used to analyze parameters such as head, efficiency, and sound pressure level of centrifugal pumps with different blades. Post-processing software such as Tecplot and Origin were used to analyze the internal flow of the centrifugal pump and the pressure pulsation at the monitoring points.

[0048] Based on the initial blade simulation, the optimal combination of blade thickness and blade back profile is determined to balance the relationship between efficiency and vibration noise. The thickness of the airfoil blade inlet section is reduced within a small range to make it closer to a streamlined shape, reducing flow separation and noise. The thickness of the airfoil blade outlet interface is gradually increased in a linear manner to improve the large flow separation generated at the trailing edge of the blade working surface, reduce pressure pulsation and noise of the centrifugal pump, while ensuring the head and efficiency of the centrifugal pump. The blade inlet placement angle is appropriately enlarged to reduce blade bending and improve its noise reduction performance. The blade outlet angle is appropriately increased within a small range to reduce flow loss of the centrifugal pump and improve overall efficiency.

[0049] Ultimately, by optimizing the selection between performance parameters such as internal flow distribution, head, efficiency, pressure pulsation, and sound pressure level of the centrifugal pump and the key geometric parameters of the airfoil blades, performance parameters for centrifugal pump airfoil blades combining high efficiency and low noise were obtained. The designed blades can effectively reduce unstable flow within the impeller channel of the centrifugal pump. The pressure distribution near the impeller outlet on the modified impeller blades is more uniform than that of the unmodified airfoil blades, reducing flow separation at the trailing edge outlet of the blade working surface. Furthermore, the modified blades show a significant reduction in pulsation amplitude at the main frequency (blade frequency) compared to the original blades, effectively reducing pressure pulsation and flow noise within the centrifugal pump.

[0050] S5. Experimental Verification: The obtained high-efficiency and low-noise blades are processed and subjected to actual experimental verification, including testing of external characteristics, pressure pulsation, and noise. After the tests are completed, the test results are re-verified to ensure the uncontrollability of the experiment. Airfoil blades that do not meet the design requirements are redesigned, and finally the design scheme of high-efficiency and low-noise airfoil blades for centrifugal pumps is determined, namely, the design method of high-efficiency and low-noise airfoil blades for centrifugal pumps based on internal flow and pressure pulsation of the pump.

[0051] The principle of this invention is as follows: by optimizing the selection between performance parameters such as internal flow distribution, head, efficiency, pressure pulsation, and sound pressure level of the centrifugal pump and the key geometric parameters of the airfoil blade, performance parameters of the centrifugal pump airfoil blade based on a combination of high efficiency and low noise are obtained. The designed blade can effectively reduce unstable flow in the impeller channel of the centrifugal pump. The pressure distribution of the modified impeller blade near the impeller outlet is more uniform than that of the unmodified airfoil blade, reducing flow separation at the trailing edge outlet of the blade working surface. Furthermore, the pulsation amplitude of the modified blade at the main frequency (blade frequency) is significantly reduced compared to the original blade, effectively reducing pressure pulsation and flow noise inside the centrifugal pump.

[0052] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for high efficiency and low noise airfoil blade design of centrifugal pumps based on internal flow and pressure pulsations in the pump, characterized by, The method comprises the following steps: S1, determining the working condition parameters of the centrifugal pump: including the design flow rate, design head, design working condition efficiency, design rotating speed, performance parameters of the conveying medium of the centrifugal pump, and performing hydraulic design on the impeller, volute, inlet and outlet sections according to the traditional method, and determining the geometric parameters of the impeller, volute and inlet and outlet section components of the centrifugal pump, including: The impeller inlet and outlet diameters, the number of blades, the blade inlet and outlet angles, the blade width, the blade wrap angle, the ratio of the impeller outlet to inlet flow area, the volute base circle diameter, the ratio of the volute base circle to the impeller outer diameter, the volute cross-sectional area and shape; S2, modeling of the centrifugal pump airfoil blade and hydraulic components: geometric modeling is performed by designing the geometric parameters of the airfoil blade and the geometric parameters of the inlet and outlet sections and the volute of the centrifugal pump, a three-dimensional model is established, and numerical simulation analysis is performed by using the CFD method; S3, determining the blade profile: numerical simulation includes flow calculation, pressure pulsation calculation and flow noise calculation of the whole flow field of the centrifugal pump, the results of the preliminary numerical simulation calculation are analyzed, the geometric parameters of the pump airfoil blade are improved, and a plurality of different blade profiles are determined; S4, performance parameters of the airfoil blade: the geometric parameters of the pump airfoil blade are improved and numerical simulation calculation is performed, the optimal selection between the internal performance parameter indexes of the centrifugal pump and the geometric parameters of the pump airfoil blade is obtained, and the performance parameters of the centrifugal pump airfoil blade based on high efficiency and low noise are obtained; In step S4, on the basis of the initial blade simulation, the best combination of the blade thickness and the blade back profile is found out, the relationship between the efficiency and the vibration noise is balanced, the airfoil blade inlet cross-sectional thickness is thinned in a small range, so that it is closer to the streamline type; The airfoil blade outlet cross-sectional thickness is gradually increased in a linear manner, the flow separation generated at the tail edge outlet of the blade working surface is improved, the pressure pulsation and noise of the centrifugal pump are reduced, and the head and efficiency of the centrifugal pump are ensured; The blade inlet setting angle is appropriately expanded, the blade bending is reduced, the noise reduction performance is improved, and the blade outlet angle is increased in a small range; S5, experimental verification: the high-efficiency and low-noise blade obtained is processed, actual experimental verification is performed, including the test of external characteristics, pressure pulsation and noise, the test results are re-verified, the uncontrollability of the experiment is ensured, the airfoil blade that does not meet the design requirements is re-designed, and finally the design scheme of the high-efficiency and low-noise airfoil blade of the centrifugal pump is determined.

2. A method for designing high efficiency and low noise airfoil vanes for centrifugal pumps based on internal flow and pressure pulsations in the pump according to claim 1, characterized in that: In step S2, the modeling of the airfoil blade is to change the conventional thickness-changing cylindrical blade into a NACA airfoil blade, and the structural geometric parameters of the airfoil blade include: the number of blades, the blade inlet and outlet angles, the blade thickness, the blade inlet and outlet setting angles, and the blade profile.

3. A method of designing high efficiency and low noise airfoil vanes for a centrifugal pump based on internal flow and pressure pulsations in the pump as claimed in claim 2, wherein: In step S2, the modeling uses the Fluent software to set the boundary conditions, performs numerical simulation on the three-dimensional water model of the centrifugal pump, sets the monitoring points to monitor the pressure pulsation according to the design working condition conditions of the rotating speed, flow rate and inlet pressure, and performs noise simulation by using the sound analogy integral module in Fluent.

4. The method for designing high efficiency and low noise airfoil vanes of a centrifugal pump based on internal flow and pressure pulsations of the pump according to claim 1, characterized in that: In step S4, the different blade centrifugal pump is analyzed by range analysis method according to different airfoil blades, the head, efficiency, sound pressure level and related parameters of different blade centrifugal pumps are analyzed, the internal flow of the centrifugal pump and the pressure fluctuation of the monitoring point are analyzed by post-processing software.

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