A design method for high-efficiency and low-vibration and low-noise airfoil blades for axial flow pumps based on pseudo-vortex energy and pressure pulsation intensity

Abstract

The present invention relates to the field of pump design and manufacturing technology, and more specifically, to a method for designing high-efficiency, low-vibration and low-noise airfoil blades for axial flow pumps based on pseudo-vortex energy and pressure pulsation intensity. The design method is to design the airfoil structure of the blade, mainly including the chord length l, the blade thickness τ at the hub, and the blade thickness τ at the hub. hmax , blade thickness at the wheel rim #imgabs0# blade inlet angle β1 and blade outlet angle β2. The present invention realizes a high-efficiency impeller design that can ensure various performance requirements by improving several main parameters of the blade airfoil, including the diameter of the impeller, the head of the water pump, the chord length, the blade inlet angle, and the blade outlet angle, thereby improving efficiency, reducing vibration and noise, further broadening the range of the high-efficiency zone, and improving the operating reliability of the axial flow pump.

Description

Technical Field

[0001] The invention relates to the technical field of pump design and manufacturing, in particular to a design method for high-efficiency, low-vibration and low-noise airfoil blades of an axial flow pump based on pseudo-vortex energy and pressure pulsation intensity. Background Art

[0002] Axial flow pumps are widely used, covering many aspects such as farmland irrigation, large hydropower units, and water jet propulsion of ships. The stability of axial flow pumps during operation has always been a focus of attention. Poor unit stability will cause large vibrations and noise, affecting the performance of the water pump, and in severe cases even leading to major safety accidents.

[0003] Axial flow pumps are high-flow, low-head pumps. As a key component of an axial flow pump, the performance of the axial flow pump impeller directly affects its operating performance. The impeller design methods currently used on the market are still traditional. With the development of the East Route of the South-to-North Water Diversion Project, the demand for high-performance axial flow pumps continues to increase. However, due to the low terrain in different regions and high flow rates during flood season, the axial flow pumps in most pumping stations have problems with "irrational operating conditions" during operation. In addition, the original model's design problems, such as unreasonable blade airfoil selection, severe secondary flow in the impeller flow channel, and a narrow high-efficiency zone, have also become shackles on pump performance in actual operation. The contradiction between the demand for high-specific-speed axial flow pumps with lower head and greater flow and the existing axial flow pumps has become increasingly prominent.

[0004] Therefore, in order to solve the above problems, this application proposes a high-efficiency, low-vibration and low-noise airfoil blade design method for axial flow pumps based on pseudo-vortex energy and pressure pulsation intensity. By studying the changing patterns of water pump performance, vibration energy and sound pressure intensity with different axial flow pump blade thicknesses and blade back profile combinations, a reasonable pump blade thickness is given. Summary of the Invention

[0005] The purpose of this invention is to fill the gap in the prior art and provide a method for designing high-efficiency, low-vibration and low-noise airfoil blades for axial flow pumps based on pseudo-vortex energy and pressure pulsation intensity. By studying the variation of pump performance, vibration energy and sound pressure intensity with different axial flow pump blade thicknesses and blade back profile combinations, a reasonable pump blade thickness is given.

[0006] In order to achieve the above object, the present invention provides a method for designing an axial flow pump airfoil with high efficiency and low vibration and noise based on pseudo-vortex energy and pressure pulsation intensity. The design method is to design the airfoil structure of the blade, mainly including the chord length l, the blade thickness τ at the hub, and the blade thickness τ at the hub. λmax , blade thickness at the rim The blade inlet angle β1 and the blade outlet angle β2 are specifically:

[0007]

[0008]

[0009] β1≤β′1+Δβ1

[0010]

[0011]

[0012]

[0013]

[0014] β2=β′2+Δβ2

[0015]

[0016] v u2 =ξv′ u2

[0017] ξ=0.9~1.1

[0018]

[0019]

[0020] in:

[0021] τ hmax is the airfoil thickness at the impeller hub;

[0022] D is the impeller diameter;

[0023] H is the pump head;

[0024] l is the chord length;

[0025] is the blade thickness at the rim section;

[0026] β1 is the blade inlet angle;

[0027] β1′ is the inlet flow angle;

[0028] Δβ1 is the inlet angle of attack;

[0029] v m1 is the inlet shaft speed;

[0030] u is the circumferential velocity of each section;

[0031] is the lift coefficient;

[0032] β2 is the blade outlet angle;

[0033] Δβ2 is the exit angle of attack;

[0034] β2′ is the outlet liquid flow angle;

[0035] v m2 is the outlet axial velocity;

[0036] v a2 is the corrected component velocity of each section;

[0037] η h is the impeller hydraulic efficiency;

[0038] η is the pump efficiency.

[0039] The design method also includes the following steps:

[0040] S1, establish a three-dimensional model of the entire flow field and the entire structural field;

[0041] S2, to determine the numerical simulation, which mainly focuses on the flow calculation of the entire flow field, the calculation of flow-coupled vibration and the calculation of flow noise;

[0042] S3, conduct analysis, focusing on the analysis of pseudo-vortex energy and flow loss; analysis of pressure pulsation, exciting force and vibration energy, analysis of noise time-frequency domain and sound pressure intensity;

[0043] S4, determine the quantitative correlation between the key geometric parameters of the airfoil blade and the vibration energy, sound pressure intensity and flow loss, and determine the design criteria for vibration and noise reduction of the airfoil blade based on high efficiency and low vibration and noise;

[0044] S5, conduct real-time measurement experiments to test noise, performance and vibration. After the test is completed, re-verify the test results to ensure the uncontrollability of the experiment, and redesign the airfoil blades that do not meet the design requirements through the method of claim 1.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] By improving several main parameters of the blade airfoil, including the impeller diameter, pump head, chord length, blade inlet angle, and blade outlet angle, a high-efficiency impeller design that can meet various performance requirements has been achieved, thereby improving efficiency, reducing vibration and noise, further broadening the range of the high-efficiency zone, and improving the operating reliability of the axial flow pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic diagram of the overall process of the present invention.

[0048] Figure 2This is a diagram of blade thickness values ​​according to the present invention, where the x-axis is dimensionless, with the rim being 0 and the hub being 1.

[0049] Figure 3 This is a diagram of the blade inlet and outlet angle values ​​of the present invention, where the x-axis is dimensionless, the inlet angle is 0, and the outlet angle is 1. DETAILED DESCRIPTION

[0050] The present invention will now be further described with reference to the accompanying drawings.

[0051] The cross-sectional thickness of the axial flow blade is a non-uniform structure, that is, the cross-sectional thickness of the axial flow blade increases linearly from the outer side of the blade to the root along the circumference, and the cross-sectional thickness of the axial flow blade from the edges on both sides to the inner radial direction also increases linearly.

[0052] By appropriately thickening the blade thickness at the hub, appropriately thinning the blade thickness at the rim within a small range, appropriately reducing the blade inlet angle, and appropriately expanding the blade outlet angle, and then analyzing the pseudo-vortex energy and entropy production of the internal flow field, we can further determine whether the blade design is reasonable.

[0053] See also Figures 1 to 3 The present invention proposes a method for designing high-efficiency and low-vibration-noise airfoil blades for axial flow pumps based on pseudo-vortex energy and pressure pulsation intensity. The design method is to design the airfoil structure of the blade, mainly including the chord length l, the blade thickness τ at the hub, and the blade thickness τ at the hub. hmax , blade thickness at the rim The blade inlet angle β1 and the blade outlet angle β2 are specifically:

[0054]

[0055]

[0056] β1=β′1+Δβ1

[0057]

[0058]

[0059]

[0060]

[0061] β2=β′2+Δβ2

[0062]

[0063] v u2 =ξv′ u2

[0064] ξ=0.9~1.1

[0065]

[0066]

[0067] in:

[0068] τ hmax is the airfoil thickness at the impeller hub;

[0069] D is the impeller diameter;

[0070] H is the pump head;

[0071] l is the chord length;

[0072] is the blade thickness at the rim section;

[0073] β1 is the blade inlet angle;

[0074] β′1 is the inlet flow angle;

[0075] Δβ1 is the inlet angle of attack;

[0076] v m1 is the inlet shaft speed;

[0077] u is the circumferential velocity of each section;

[0078] is the lift coefficient;

[0079] β2 is the blade outlet angle;

[0080] Δβ2 is the exit angle of attack;

[0081] β′2 is the outlet liquid flow angle;

[0082] v m2 is the outlet axial velocity;

[0083] v a2 is the corrected component velocity of each section;

[0084] η h is the impeller hydraulic efficiency;

[0085] η is the pump efficiency.

[0086] The design method also includes the following steps:

[0087] S1, establish a three-dimensional model of the entire flow field and the entire structural field;

[0088] S2, to determine the numerical simulation, which mainly focuses on the flow calculation of the entire flow field, the calculation of flow-coupled vibration and the calculation of flow noise;

[0089] S3, conduct analysis, focusing on the analysis of pseudo-vortex energy and flow loss; analysis of pressure pulsation, exciting force and vibration energy, analysis of noise time-frequency domain and sound pressure intensity;

[0090] S4, determine the quantitative correlation between the key geometric parameters of the airfoil blade and the vibration energy, sound pressure intensity and flow loss, and determine the design criteria for vibration and noise reduction of the airfoil blade based on high efficiency and low vibration and noise;

[0091] S5, conduct real-time measurement experiments to test noise, performance and vibration. After the test is completed, re-verify the test results to ensure the uncontrollability of the experiment, and redesign the airfoil blades that do not meet the design requirements through the method of claim 1.

[0092] The present invention solves as a whole the problem of "irrational operating conditions" in the operation of axial flow pumps in most pumping stations due to low terrain, large flow during flood season and other reasons in the prior art, as well as unreasonable blade airfoil selection, serious secondary flow in the impeller flow channel and narrow high-efficiency zone. By studying the variation law of water pump performance, vibration energy and sound pressure intensity with different axial flow pump blade thicknesses and blade back profile combinations, a reasonable pump blade thickness is given, the optimal position of the airfoil blade thickness and its combination with different blade back profiles are found, the optimal relationship between efficiency and vibration noise is balanced, and a high-efficiency impeller design with various performance requirements is achieved, efficiency is improved, vibration noise is reduced, the range of the high-efficiency zone is further broadened, and the operating reliability of the axial flow pump is improved.

Claims

1. A method for designing high-efficiency, low-vibration and low-noise airfoil blades for an axial flow pump based on pseudo-vortex energy and pressure pulsation intensity, characterized in that: The design method is to design the blade airfoil structure, including the chord length l, the blade thickness τ at the hub hmax , blade thickness at the rim The blade inlet angle β1 and the blade outlet angle β2 are specifically: β1=β1′+Δβ1 β2=β2′+Δβ2 v u2 =v′ u2 ξ=0.9~1.1 in: τ hmax is the airfoil thickness at the impeller hub; D is the impeller diameter; H is the pump head; l is the chord length; is the blade thickness at the rim section; β1 is the blade inlet angle; β1′ is the inlet flow angle; Δβ1 is the inlet angle of attack; v m1 is the inlet shaft speed; u is the circumferential velocity of each section; is the lift coefficient; β2 is the blade outlet angle; Δβ2 is the exit angle of attack; β2′ is the outlet liquid flow angle; v m2 is the outlet axial velocity; v u2 is the corrected component velocity of each section; η h is the impeller hydraulic efficiency; η is the pump efficiency.

2. The method for designing high-efficiency, low-vibration and low-noise airfoil blades for an axial flow pump based on pseudo-vortex energy and pressure pulsation intensity according to claim 1, characterized in that: The design method further comprises the following steps: S1, establish a three-dimensional model of the entire flow field and the entire structural field; S2, to determine the numerical simulation, which mainly focuses on the flow calculation of the entire flow field, the calculation of flow-coupled vibration and the calculation of flow noise; S3, conduct analysis, focusing on the analysis of pseudo-vortex energy and flow loss; analysis of pressure pulsation, exciting force and vibration energy, analysis of noise time-frequency domain and sound pressure intensity; S4, determine the quantitative correlation between the key geometric parameters of the airfoil blade and the vibration energy, sound pressure intensity and flow loss, and determine the design criteria for vibration and noise reduction of the airfoil blade based on high efficiency and low vibration and noise; S5, conduct real-time measurement experiments to test noise, performance and vibration. After the test is completed, re-verify the test results to ensure the uncontrollability of the experiment, and redesign the airfoil blades that do not meet the design requirements using the method of claim 1.

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