Design method of semi-open type low-vibration single-blade impeller

Abstract

The invention relates to a semi-open type low-vibration single-blade impeller design method which comprises the following steps: 1, determining the diameter of an impeller inlet, 2, determining the outer diameter of an impeller outlet, 3, determining the thicknesses of blades, a cover plate and a hub, 4, determining a blade wrap angle, 5, establishing an impeller three-dimensional centroid calculation model, marking a de-weight position, and 6, determining the impeller inlet diameter and the impeller outlet diameter. And sixthly, dynamic balance and weight removal of the impeller are carried out. According to the semi-open type low-vibration single-blade impeller designed by the invention, due to the single-blade wide flow channel design, the maximum particle size can be increased, and the high-impurity medium conveying requirement in the sewage treatment industry can be met. The impeller designed by the design method is stable in operation and excellent in vibration performance.

Description

Technical Field

[0001] This invention relates to an impeller design method, specifically to a semi-open, low-vibration single-blade impeller design method that provides stable impeller operation and excellent vibration performance. Background Technology

[0002] In oil and gas mixed-transport pumps used in oil extraction, semi-open single-blade impellers can adapt to complex media containing gas, liquid, and solid particles, preventing blockages and ensuring efficient oil and gas transport. In chemical process pumps used to transport various corrosive and high-viscosity chemical media, semi-open single-blade impellers, through reasonable structural design and material selection, can ensure stable operation under harsh conditions, meeting the requirements of continuous and efficient chemical production.

[0003] In wastewater treatment, semi-open single-blade impellers offer significant advantages in wastewater pumps, effectively addressing the complex characteristics of wastewater media. Wastewater typically contains various solid impurities, fibrous materials, and suspended solids of different properties. Ordinary impellers are prone to clogging and entanglement, affecting the normal operation of the pump. However, semi-open single-blade impellers, with their fewer blades and lack of cover plate restrictions, provide a wide and unobstructed flow channel, allowing solid particles and fibrous materials to pass through the impeller more smoothly, greatly reducing the probability of clogging and entanglement.

[0004] The most significant characteristic of a semi-open single-blade impeller is that it has only one blade and, unlike a closed impeller, it does not have a closed structure with front and rear cover plates. This open design allows one side of the impeller to directly contact the fluid, reducing the constraint of the cover plates on the fluid and allowing the fluid to move more freely in and out of the impeller. This reduces the risk of clogging when conveying complex media containing impurities, fibers, etc.

[0005] Centrifugal force is generated when the rotor rotates with unbalanced mass (eccentricity). This force increases quadratically with the rotational speed, causing periodic vibration of the impeller and pump body. In semi-open single-blade impellers, the blade is integrated with the hub, and the hub drives the blade's rotation. However, due to the single blade and structural asymmetry, the center of mass naturally deviates from the center of rotation. Furthermore, uneven density during material casting and processing, as well as blade profile machining errors (such as surface roughness Ra > 1.6 μm leading to localized mass deviations), further exacerbate the imbalance. Therefore, the impeller experiences uneven forces during rotation, making it more prone to unbalanced forces compared to multi-blade impellers, thus inducing vibration. This not only reduces the impeller's efficiency and service life but can also lead to equipment failure and even serious safety accidents. This necessitates precise calculations and dynamic balancing adjustments during design and manufacturing to reduce vibration and noise, ensuring stable impeller operation. Existing impeller design methods have limited effectiveness in reducing vibration and cannot meet the growing demand for high performance. Therefore, a design method that effectively reduces vibration in semi-open single-blade impellers is urgently needed. Summary of the Invention

[0006] To address the aforementioned problems, the main objective of this invention is to provide a design method for a semi-open, low-vibration single-blade impeller that exhibits stable impeller operation and excellent vibration performance.

[0007] This invention solves the above-mentioned technical problems through the following technical solution: a semi-open low-vibration single-blade impeller design method, the semi-open low-vibration single-blade impeller design method comprising the following steps:

[0008] Step 1: Determine the impeller inlet diameter:

[0009] The flow velocity at the impeller inlet is Vs = 3-5 m / s; Where D j Let Q be the impeller inlet diameter and Q be the pump flow rate, where the unit of pump flow rate is meters (m³). 3 / s;

[0010] Step 2: Determine the impeller outlet outer diameter: Where D2 is the impeller outlet outer diameter, Q is the pump flow rate, and n is the pump speed, with n in r / min. s The specific speed n of the water pump s =3.65nQ 0.5 / H 0.75 .

[0011] Step 3: Determine the thickness of the blades, cover plate, and hub:

[0012] The impeller blades have a uniform thickness from inlet to outlet along the streamline direction, when D j Between 100mm and 250mm, excluding the 100mm and 250mm endpoints, the thickness D at the leading streamline of the blade is 5-12mm.

[0013] Where D j =For diameters of 100mm and below, the value of D is taken as 5; D j =For diameters of 250mm and above, the value of D is 12;

[0014] The thickness at the rear streamline of the blade is C = 1.5D, the thickness of the impeller rear cover plate is B = 1.5C, and the thickness of the impeller hub is A = 1.4~1.8B.

[0015] Step 4: Determine the blade wrap angle:

[0016] The wrap angle of a single-blade impeller is between 360° and 540°, the inlet edge of the trailing streamline extends forward, and the wrap angle difference between the trailing streamline and the forward streamline is 15° to 60°.

[0017] Step 5: Establish a three-dimensional centroid calculation model of the impeller and mark the deduplication locations:

[0018] Step 6: Dynamic balancing of the impeller and weight reduction:

[0019] A dynamic balancing test was conducted on the single-blade impeller, and a counterweight groove was opened on the back of the impeller hub to eliminate material inhomogeneity and the inherent imbalance of the single-blade structure.

[0020] In a specific embodiment of the present invention, the counterweight groove removes mass from the back of the hub to counteract the centrifugal couple generated by eccentricity, thereby controlling the remaining imbalance of the impeller within a safe threshold. The counterweight groove is located in a 180° symmetrical region directly opposite the blade along the circumferential direction of the back of the hub.

[0021] In a specific embodiment of the present invention, the counterweight groove in the sixth step is an arc-shaped or rectangular groove.

[0022] In a specific embodiment of the present invention, when the counterweight groove in the sixth step is a rectangular groove, it is a rectangular groove with a width range of 5-8mm and a depth range of 3-5mm.

[0023] In a specific embodiment of the present invention, the counterweight groove further includes 2-3 auxiliary grooves, the width of which ranges from 2-3 mm and the depth ranges from 1-2 mm.

[0024] The positive and progressive effects of this invention are as follows: The semi-open, low-vibration single-blade impeller design method provided by this invention has the following advantages: The semi-open, low-vibration single-blade impeller provided by this invention features a wide flow channel design (the cross-sectional area of ​​the flow channel is more than 40% larger than that of traditional multi-blade impellers), which also increases the maximum particle size that can be handled, meeting the needs of conveying high-impurity media in the wastewater treatment industry. The vibration suppression mechanism optimizes the thickness ratio of the blade, cover plate, and hub at the front and rear streamlines (e.g., A:B:C:D≈1.6:1.5:1.5:1), controlling the impeller's center of mass offset to be close to the center of rotation. The forward extension design of the rear streamline inlet edge balances the pressure distribution on the front and rear streamlines of the blade inlet. Integrated CNC milling eliminates the stress concentration problem of traditional welding and the local quality deviation problem caused by casting, extending the impeller's fatigue life; at the same time, the improved machining accuracy controls the surface roughness of the blades, ensuring a smooth flow channel, reducing hydraulic losses, and minimizing impeller imbalance. Attached Figure Description

[0025] Figure 1 This is a axial view of the impeller of the present invention.

[0026] Figure 2 This is a cross-sectional view of the impeller front view of the present invention.

[0027] Figure 3 This is a top view of the impeller of the present invention.

[0028] The following are the names corresponding to the reference numerals in this invention:

[0029] In the diagram: 1. Impeller blades; 2. Impeller back cover plate; 3. Impeller hub; 4. Hub thread. Detailed Implementation

[0030] The preferred embodiments of the present invention are given below with reference to the accompanying drawings to illustrate the technical solution of the present invention in detail.

[0031] Figure 1 This is a axial view of the impeller of the present invention. Figure 2 This is a sectional view of the impeller front view of the present invention. Figure 3 This is a top view of the impeller of the present invention. Figure 1-3 As shown: The semi-open low-vibration single-blade impeller provided by the present invention includes: impeller blade 1, impeller rear cover plate 2, impeller hub 3, and hub thread 4. The impeller rear cover plate, hub, and impeller blade structure are integrally machined by CNC milling. Through optimized design of impeller structural parameters and control of the thickness of each part, the vibration of the impeller during operation is reduced, and the working efficiency and reliability of the impeller are improved.

[0032] The impeller hub and shaft are connected by a thread. The impeller hub is machined with an internal thread, and the thread direction is opposite to the impeller rotation direction, ensuring that it tends to become tighter as the impeller rotates.

[0033] The thickness of the blades, cover plates, and hubs is selected according to a certain proportion to control the center of gravity of the entire impeller to be close to the center of rotation, thereby avoiding or reducing vibration caused by imbalance when the impeller rotates.

[0034] This invention proposes a design method for a semi-open, low-vibration single-blade impeller. The design method includes the following steps: Step 1: Determine the impeller inlet diameter:

[0035] Ensure the flow velocity Vs at the impeller inlet is 3-5 m / s; Where D j Where Q is the impeller inlet diameter and Q is the pump flow rate (unit: m³ / s). 3 / s);

[0036] Step 2: Determine the impeller outlet outer diameter: Where D2 is the impeller outlet outer diameter, n is the pump speed (in r / min), and ns is the pump specific speed. s =3.65nQ 0.5 / H 0.75 ;

[0037] Step 3: Determine the thickness of the blades, cover plate, and hub:

[0038] The impeller blades have a uniform thickness from inlet to outlet along the streamline direction, when D j Between 100mm and 250mm, excluding the 100mm and 250mm endpoints, the thickness D at the leading streamline of the blade is 5-12mm.

[0039] Where D j =For diameters of 100mm and below, the value of D is taken as 5; D j =For diameters of 250mm and above, the value of D is 12;

[0040] The thickness at the blade trailing streamline is C = 1.5D, the thickness of the impeller rear cover plate is B = 1.5C, and the thickness of the impeller hub is A = 1.4~1.8B;

[0041] Step 4: Determine the blade wrap angle:

[0042] The wrap angle of a single-blade impeller is between 360° and 540°, with the trailing streamline of the blade extending forward from the inlet edge, and the difference in wrap angle between the trailing and forward streamlines being approximately 15° to 60°.

[0043] Step 5: Establish a three-dimensional centroid calculation model of the impeller and mark the deduplication locations:

[0044] The blades are designed with a non-uniform thickness, being thinner at the front and thicker at the rear. This shifts the blade's center of mass towards the hub, offsetting some of the centrifugal force eccentricity. By adjusting the thickness ratio of each component, precise positioning of the center of mass is achieved, making the distribution of rotational inertia closer to the axis of rotation and reducing radial vibration intensity.

[0045] Step 6: Dynamic balancing of the impeller and weight reduction:

[0046] A dynamic balancing test was conducted on the single-blade impeller, and a counterweight groove (5-8 mm wide and 3-5 mm deep) was opened on the back of the impeller hub to eliminate material inhomogeneity and the inherent imbalance of the single-blade structure.

[0047] The counterweight groove removes mass from the back of the hub (the side symmetrical to the blades), counteracting the centrifugal couple caused by eccentricity and keeping the remaining imbalance of the impeller within a safe threshold. The counterweight groove is located along the circumference of the back of the hub in a 180° symmetrical region directly opposite the blades (e.g.,...). Figure 1 (The back of hub 3 in the axle plane diagram) ensures that the line of action of the counterweight passes through the center of rotation.

[0048] Use either arc-shaped or rectangular grooves, with rectangular grooves preferred (better manufacturability). Groove width should be 5-8mm (related to the wheel hub thickness A; for example, if A = 18mm, use 6mm), and depth 3-5mm (not exceeding 1 / 3 of the wheel hub thickness to avoid weakening structural strength). The counterweight groove consists of one main counterweight groove; for fine-tuning, 2-3 auxiliary grooves (2-3mm wide, 1-2mm deep) can be added.

[0049] Below is a specific example:

[0050] This invention provides a design method for a semi-open, low-vibration single-blade impeller, using "design of a semi-open single-blade impeller for a sewage pump" as an example:

[0051] The parameters of the sewage pump are as follows: pump flow rate Q = 0.03 m³ / h 3 / s=108m 3 / h, pump speed n=2950r / min, pump head H=18m.

[0052] Design steps:

[0053] Step 1: Determine the impeller inlet diameter:

[0054] Take the impeller inlet velocity Vs = 4 m / s; The impeller inlet diameter Dj = 100 mm;

[0055] Step 2: Determine the impeller outlet outer diameter:

[0056] pump specific speed n s =3.65nQ 0.5 / H 0.75 =213.4;

[0057] Impeller outlet outer diameter Select an impeller outer diameter of 180mm.

[0058] Step 3: Determine the thickness of the blades, cover plate, and hub:

[0059] The impeller blades have a uniform thickness from the inlet to the outlet along the streamline direction. The thickness at the front streamline of the blade is D = 5 mm; the thickness at the rear streamline of the blade is C = 1.5 and D = 7.5 mm. The thickness of the impeller rear cover plate is B = 1.5 and C = 11.3 mm. The thickness of the impeller hub is A = 1.4 to 1.8 and B = 18 mm.

[0060] Step 4: Determine the blade wrap angle:

[0061] The wrap angle of a single-blade impeller is 500°, the inlet edge of the trailing streamline extends forward, and the wrap angle difference between the trailing and forward streamlines is about 30°.

[0062] Step 5: Establish a three-dimensional centroid calculation model of the impeller and mark the deduplication locations:

[0063] The blades are designed with a non-uniform thickness, being thinner at the front and thicker at the back. This shifts the blade's center of mass towards the hub, offsetting some of the centrifugal force eccentricity. By adjusting the thickness ratio of each component, precise positioning of the center of mass is achieved, initially eliminating the imbalance of the individual blade impeller itself. This makes the distribution of rotational inertia closer to the axis of rotation, resulting in a reduction in measured radial vibration intensity.

[0064] Through the above steps, the following single-blade impeller is obtained. The impeller is made of 304 stainless steel and weighs approximately 3.36 kg. The actual shaft center offset from the theoretical shaft center is ΔX = 0.458 mm and ΔY = 2.355 mm. The radial eccentricity is e = (ΔX) / (ΔY). 2 +ΔY2 )^0.5=2.4mm.

[0065] Step 6: Dynamic balancing of the impeller and weight reduction:

[0066] A dynamic balancing test was conducted on the single-blade impeller, and a counterweight groove (5-8 mm wide and 3-5 mm deep) was opened on the back of the impeller hub to eliminate material inhomogeneity and the inherent imbalance of the single-blade structure.

[0067] The counterweight groove is located along the circumferential direction of the back of the hub, in a 180° symmetrical area directly opposite the blade (e.g., Figure 1 (See the back of hub 3 in the axle view), ensuring the line of action of the counterweight passes through the center of rotation. A rectangular groove is used, with a width of 5-8mm (related to the hub thickness A; for example, if A = 18mm, use 6mm) and a depth of 3-5mm. There is one main counterweight groove.

[0068] Through the above design methods, the non-uniform thickness design of "thin front and thick back", dynamic balancing test and weight removal of the balance counterweight groove can effectively solve the inherent imbalance problem of semi-open single blade impeller. Combined with the optimization of blade thickness ratio (A:B:C:D≈1.6:1.5:1.5:1) and integrated processing technology, the technical effect of accurately offsetting the eccentric mass of single blade and reducing vibration intensity can be achieved.

[0069] This invention provides a semi-open, low-vibration single-blade impeller with a wide flow channel design (the cross-sectional area of ​​the flow channel is more than 40% larger than that of traditional multi-blade impellers), which also improves the maximum particle size that can be handled, meeting the needs of conveying high-impurity media in the wastewater treatment industry. The vibration suppression mechanism optimizes the thickness ratio of the blade, cover plate, and hub at the front and rear streamlines (e.g., A:B:C:D≈1.6:1.5:1.5:1), controlling the impeller's center of mass offset to be close to the center of rotation. The forward extension design of the rear streamline inlet edge balances the pressure distribution on the front and rear streamlines of the blade inlet. Integrated CNC milling eliminates the stress concentration problems of traditional welding and the local quality deviation problems caused by casting, extending the impeller's fatigue life; at the same time, the improved machining accuracy controls the surface roughness of the blades, ensuring a smooth flow channel, reducing hydraulic losses, and minimizing impeller imbalance.

[0070] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as defined by the appended claims and their equivalents.

Claims

1. A design method for a semi-open, low-vibration single-blade impeller, characterized in that: The semi-open low-vibration single-blade impeller design method includes the following steps: Step 1: Determine the impeller inlet diameter: The flow velocity at the impeller inlet is Vs = 3-5 m / s; Where D j Let Q be the impeller inlet diameter and Q be the pump flow rate, where the unit of pump flow rate is meters (m³). 3 / s; Step 2: Determine the impeller outlet outer diameter: Where D2 is the impeller outlet outer diameter, Q is the pump flow rate, and n is the pump speed, with n in r / min. s The specific speed n of the water pump s =3.65nQ 0.5 / H 0.75 ; Step 3: Determine the thickness of the blades, cover plate, and hub: The impeller blades have a uniform thickness from inlet to outlet along the streamline direction, when D j Between 100mm and 250mm, excluding the 100mm and 250mm endpoints, the thickness D at the leading streamline of the blade is 5-12mm. Where D j =For diameters of 100mm and below, the value of D is taken as 5; D j =For diameters of 250mm and above, the value of D is 12; The thickness at the blade trailing streamline is C = 1.5D, the thickness of the impeller rear cover plate is B = 1.5C, and the thickness of the impeller hub is A = 1.4~1.8B; Step 4: Determine the blade wrap angle: The wrap angle of a single-blade impeller is between 360° and 540°, the inlet edge of the trailing streamline extends forward, and the wrap angle difference between the trailing streamline and the forward streamline is 15° to 60°. Step 5: Establish a three-dimensional centroid calculation model of the impeller and mark the deduplication locations: Step 6: Dynamic balancing of the impeller and weight reduction: A dynamic balancing test was conducted on the single-blade impeller, and a counterweight groove was opened on the back of the impeller hub to eliminate material inhomogeneity and the inherent imbalance of the single-blade structure.

2. The design method for a semi-open, low-vibration single-blade impeller according to claim 1, characterized in that: The counterweight groove removes mass from the back of the hub to counteract the centrifugal couple caused by eccentricity, thus keeping the remaining imbalance of the impeller within a safe threshold. The counterweight groove is located in a 180° symmetrical area directly opposite the blade along the circumferential direction of the back of the hub.

3. The design method for a semi-open, low-vibration single-blade impeller according to claim 1, characterized in that: In step six, the counterweight groove is either arc-shaped or rectangular.

4. The design method for a semi-open, low-vibration single-blade impeller according to claim 3, characterized in that: In step six, when the counterweight groove is a rectangular groove, it is a rectangular groove with a width range of 5-8mm and a depth range of 3-5mm.

5. The design method for a semi-open, low-vibration single-blade impeller according to claim 4, characterized in that: The counterweight groove also includes 2-3 auxiliary grooves, with a width of 2-3 mm and a depth of 1-2 mm.

Images