A design method for mixed flow pump

Abstract

The present application discloses a design method for a mixed flow pump. The blade includes an integrated axial flow section and a centrifugal section; the outlet end of the axial flow section is connected to the inlet end of the centrifugal section, and the design flow rates of the axial flow section and the centrifugal section are equal; the design method for the mixed flow pump includes: amplifying the operating parameters by the amplification factor and the gas content to obtain the design flow rate and the design head; calculating the head of the axial flow section according to the gas content and the design head, and calculating the head of the centrifugal section according to the head of the axial flow section; calculating the inlet diameter of the impeller, and calculating the inlet diameter and outlet diameter of the mixed flow pump respectively; calculating the outer diameter of the impeller; calculating the outlet width of the impeller; determining the number of blades; calculating the inlet placement angle of each blade, and determining the outlet placement angle of each blade, and determining the fracture position of the impeller. The present application improves the ability of the mixed flow pump in conveying high gas content media, ensuring that the mixed flow pump can exhibit strong boosting performance even under large gas content ratio conditions.

Description

Technical Field

[0001] The present application relates to the technical field of mixed flow pumps, and in particular to a design method of a mixed flow pump. Background Art

[0002] Gas-liquid two-phase mixed pump, as a special pump equipment that can handle gas and liquid at the same time, is widely used in petrochemical, environmental protection, food and mining fields. However, in the process of conveying gas-liquid two-phase mixed medium, the pump head and efficiency will decrease to varying degrees. This phenomenon is closely related to the retention state of the bubble group in the impeller.

[0003] Specifically, since the gas and liquid phases have different physical properties and flow rates, they are prone to phase separation when transported in the pump. The bubbles accumulated in the impeller due to phase separation directly reduce the effective flow area of ​​the medium, thereby increasing energy loss and further reducing the pump head and efficiency; at the same time, the accumulation of bubbles may also cause the pump to operate in an unstable state, and in severe cases, even cause flow interruption, causing the pump to fail to work properly.

[0004] At present, the main challenge facing the application of mixed flow pumps under two-phase conditions is that their head and efficiency are far from meeting the design requirements. The root of this problem is that the design method of mixed flow pumps has long been based on the design concept of clean water pumps, which is mainly based on the working characteristics of blades under single-phase conditions. However, in actual gas-liquid two-phase mixed flow applications, due to the strong interaction between the gas and liquid phases caused by the inlet gas content, more stringent requirements are placed on the performance of gas-liquid two-phase mixed flow pumps. Therefore, mixed flow pumps designed by traditional design methods often cannot meet the requirements for head and efficiency under gas-containing conditions. Summary of the invention

[0005] The embodiment of the present application provides a design method for a mixed flow pump, thereby solving the technical problem that a mixed flow pump designed by a traditional design method cannot meet the requirements for head and efficiency under gas-containing conditions.

[0006] The embodiment of the present application provides a design method for a mixed flow pump, wherein the impeller of the mixed flow pump comprises a hub and blades; the blades are arranged on the outer peripheral surface of the hub and spirally extend along the axial direction of the hub; the blades comprise an integrated axial flow section and a centrifugal section; the outlet end of the axial flow section is connected to the inlet end of the centrifugal section, and the design flow rates of the axial flow section and the centrifugal section are equal;

[0007] The design methods of mixed flow pumps include:

[0008] The design flow and design head are obtained by amplifying the operating parameters through the amplification factor and the gas content;

[0009] The lift of the axial flow section is calculated based on the air void fraction and the design lift, and the lift of the centrifugal section is calculated based on the lift of the axial flow section;

[0010] Calculate the inlet diameter of the impeller, and calculate the inlet diameter and outlet diameter of the mixed flow pump respectively;

[0011] Calculate the outer diameter of the impeller;

[0012] Calculate the impeller outlet width;

[0013] Determine the number of leaves;

[0014] Calculate the inlet placement angle of each blade and determine the outlet placement angle of each blade;

[0015] Determine the fracture position of the impeller, which is located at the position where gas is likely to gather in the impeller flow channel.

[0016] In a possible implementation, the operating parameters are amplified by the amplification factor and the gas content to obtain the design flow rate and the design head, including:

[0017] The specific speed is calculated as follows:

[0018]

[0019] In the formula, is the specific speed, n is the speed, Q is the operating flow rate, and H is the operating head;

[0020] The calculation formula of the amplification factor is as follows:

[0021]

[0022] In the formula, k is the amplification factor, is the specific speed;

[0023] The design flow rate is calculated as follows:

[0024]

[0025] In the formula, is the design flow rate, k is the amplification factor, λ is the gas content, and Q is the operating flow rate;

[0026] The calculation formula for the design head is as follows:

[0027]

[0028] In the formula, is the design head, k is the amplification factor, λ is the gas content, It is the working head.

[0029] In a possible implementation, the head of the axial flow section is calculated according to the air void fraction and the design head, and the head of the centrifugal section is calculated according to the head of the axial flow section, including:

[0030] The calculation formula of the head of the axial flow section is as follows:

[0031]

[0032] In the formula, is the head of the axial flow section, is the design head, λ is the air void fraction;

[0033] The calculation formula of the centrifugal head is as follows:

[0034]

[0035] In the formula, is the head of the centrifugal section, is the head of the axial flow section, To design the lift.

[0036] In a possible implementation, calculating the inlet diameter of the impeller includes:

[0037] The impeller inlet diameter is set equal to the outer diameter of the axial flow section. The calculation formula for the impeller inlet diameter is as follows:

[0038]

[0039] In the formula, is the impeller inlet diameter, For the design flow rate, is the first correction coefficient, The value range is 300-350;

[0040] Calculate the inlet and outlet diameters of the mixed flow pump separately, including:

[0041] The inlet diameter of the mixed flow pump is equal to the inlet diameter of the impeller. The calculation formula of the inlet diameter of the mixed flow pump is as follows:

[0042]

[0043] In the formula, is the inlet diameter of the mixed flow pump, is the inlet diameter of the impeller;

[0044] The calculation formula of the outlet diameter of the mixed flow pump is as follows:

[0045]

[0046] In the formula, is the outlet diameter of the mixed flow pump, k is the magnification factor, is the second correction coefficient, The value range is 3.5-4.5. is the design flow rate and n is the rotation speed.

[0047] In a possible implementation, calculating the outer diameter of the impeller includes:

[0048] The calculation formula of the impeller outer diameter is as follows:

[0049]

[0050] In the formula, is the outer diameter of the impeller, is the specific speed, is the design flow rate and n is the rotation speed.

[0051] In a possible implementation, calculating the outlet width of the impeller includes:

[0052] The calculation formula of the impeller outlet width is as follows:

[0053]

[0054] In the formula, is the outlet width of the impeller, is the third correction coefficient, is the specific speed, is the design flow rate and n is the rotation speed.

[0055] In one possible implementation, The calculation formula is as follows:

[0056]

[0057] In the formula, is the third correction coefficient, is the specific speed.

[0058] In a possible implementation, the number of blades is 7-12.

[0059] In a possible implementation, calculating the inlet placement angle of each blade includes:

[0060] The inlet placement angle of the axial flow section is equal to the inlet placement angle of the blade, and the outlet placement angle of the axial flow section is equal to the inlet placement angle of the centrifugal section;

[0061] Calculate the inlet placement angle of the corresponding blade through the liquid flow angle and angle of attack of each blade streamline;

[0062] The calculation formula of the blade inlet placement angle is as follows:

[0063]

[0064] In the formula, is the blade inlet placement angle, is the flow angle of the blade streamline, is the attack angle, The value range is 5-15°;

[0065] The calculation formula of the liquid flow angle of the blade streamline is as follows:

[0066]

[0067] In the formula, is the peripheral velocity of the liquid point, is the circular velocity of the liquid point, is the axial velocity of the liquid at a point;

[0068] The outlet placement angle of the centrifugal section is equal to the outlet placement angle of the blades, and the outlet placement angle of the blades is 22-30°.

[0069] In a possible implementation, the fracture position of the impeller is determined, and the fracture position is located at a position in the impeller flow channel where gas is likely to gather, including: performing fracture cutting between 40% and 60% of the impeller outer diameter to form an effective gas channel.

[0070] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects:

[0071] The blades of the present application include an integrated axial flow section and a centrifugal section. The medium first performs preliminary work through the axial flow section to obtain a certain amount of energy and pressure. This process effectively suppresses the separation tendency of the gas-liquid two-phase medium in a low-pressure environment and ensures a more uniform mixing of the two-phase medium. Subsequently, the medium flows smoothly into the centrifugal section to further obtain higher kinetic energy, thereby effectively solving the problem that the gas-liquid two-phase medium is easy to gather and block the flow channel at the impeller inlet (i.e., the lowest pressure point). In addition, this design introduces the concepts of amplification factor and gas content to accurately amplify the operating parameters and then determine the design flow rate and design head. Based on the calculation results of the gas content and the design head, the heads required for the axial flow section and the centrifugal section can be calculated respectively. This refined design method improves the ability of the mixed pump to transport high-gas content media, ensuring that the mixed pump can exhibit strong pressurization performance even under large gas content ratio conditions, and enhances its adaptability and stability under different working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following is a brief introduction to the drawings required for use in the description of the embodiments of the present application. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0073] Figure 1 A flow chart of a design method for a mixed flow pump provided in an embodiment of the present application;

[0074] Figure 2 An axial projection diagram of an impeller provided in an embodiment of the present application;

[0075] Figure 3 A schematic structural diagram of the cutting position of the impeller provided in an embodiment of the present application;

[0076] Figure 4 A schematic diagram of the structure of a mixed flow pump provided in an embodiment of the present application;

[0077] Figure 5a and Figure 5b The gas distribution diagrams inside the mixed pump of the control group and the test group provided in the embodiments of the present application respectively;

[0078] Figure 6a and Figure 6b The pressure distribution diagrams of the impellers at the same gas content for the control group and the test group provided in the embodiments of the present application are shown respectively;

[0079] Figure 7 This is a distribution diagram of the gas volume fraction inside the impeller without cutting the impeller outer diameter of the test group provided in the embodiments of the present application. DETAILED DESCRIPTION

[0080] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0081] In the description of the embodiments of the present application, it should be noted that the orientation or positional relationship indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. The terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. In addition, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0082] The present application embodiment provides a design method for a mixed flow pump, such as Figures 1 to 7 The impeller of the mixed flow pump includes a hub and blades; the blades are arranged on the outer peripheral surface of the hub and spirally extend along the axial direction of the hub; the blades include an integrated axial flow section and a centrifugal section; the outlet end of the axial flow section is connected to the inlet end of the centrifugal section, and the design flow rates of the axial flow section and the centrifugal section are equal.

[0083] It should be noted that the blades of the present application are designed to be an integrated combination of an axial flow section and a centrifugal section, wherein the outlet end of the axial flow section is seamlessly connected to the inlet end of the centrifugal section to achieve smooth transition and efficient transmission of the medium.

[0084] Specifically, in view of the actual working condition that the impeller inlet area is a low-pressure area and gas is easy to gather there, the front blades of the impeller are designed as axial flow sections in this application to better adapt to and handle complex working conditions containing gas. The rear blades are designed as centrifugal sections to further increase the pressure and kinetic energy of the medium, thereby meeting the needs of efficient mixed transportation. Therefore, this application not only solves the problem that the gas-liquid two-phase medium is easy to separate and clog at the impeller inlet, but also improves the head and efficiency of the mixed transportation pump under gas-containing working conditions.

[0085] The design methods of mixed flow pumps include:

[0086] S1: The design flow and design head are obtained by amplifying the operating parameters through the amplification factor and the gas content;

[0087] S2: Calculate the head of the axial flow section based on the air void fraction and the design head, and calculate the head of the centrifugal section based on the head of the axial flow section;

[0088] S3: Calculate the inlet diameter of the impeller, and calculate the inlet diameter and outlet diameter of the mixed pump respectively;

[0089] S4: Calculate the outer diameter of the impeller;

[0090] S5: Calculate the outlet width of the impeller;

[0091] S6: determine the number of leaves;

[0092] S7: Calculate the inlet placement angle of each blade, and determine the outlet placement angle of each blade;

[0093] First, based on the principles of medium mechanics and the design requirements of the mixed pump, the inlet placement angle of each blade is calculated. The selection of this angle is crucial to the mixing effect and initial work of the gas-liquid two-phase medium in the axial flow section. Then, according to the design requirements of the centrifugal section, the outlet placement angle of each blade is determined. The design of the outlet placement angle must ensure that the medium can smoothly transition from the axial flow section to the centrifugal section and further obtain higher kinetic energy and pressure in the centrifugal section.

[0094] S8: Determine the fracture position of the impeller. The fracture position is located at the position where the gas is easy to gather in the impeller flow channel.

[0095] Specifically, the axial flow section design of the present application is insensitive to gas. During the high-speed rotation of the impeller, the axial flow section can effectively stir and break up the bubbles gathered at the impeller inlet, thereby preventing the gas from gathering and clogging at the inlet, and ensuring that the gas-liquid two-phase medium enters the impeller smoothly. However, after entering the impeller, due to the difference in force between the gas-liquid two-phase medium, they will gradually separate from each other over time, and may gather in the subsequent flow channel of the impeller, thereby causing the risk of blockage. In order to address this problem, fractures are set at the parts of the impeller where the gas is prone to gather and blockage in the rear section. The fracture allows the gas to flow freely in the flow channel of the rear section of the impeller. At the same time, the high-pressure liquid on the pressure surface of the blade can flow to the suction surface through these fractures, producing an impact and crushing effect on the gathered gas, further preventing the occurrence of blockage.

[0096] It should be noted that the blades of the present application include an integrated axial flow section and a centrifugal section. The medium first performs preliminary work through the axial flow section to obtain a certain amount of energy and pressure. This process effectively suppresses the separation tendency of the gas-liquid two-phase medium in a low-pressure environment and ensures a more uniform mixing of the two-phase medium. Subsequently, the medium flows smoothly into the centrifugal section to further obtain higher kinetic energy, thereby effectively solving the problem that the gas-liquid two-phase medium is easy to gather and block the flow channel at the impeller inlet (i.e., the lowest pressure point). In addition, this design introduces the concepts of amplification factor and gas content to accurately amplify the operating parameters and then determine the design flow rate and design head. Based on the calculation results of the gas content and the design head, the heads required for the axial flow section and the centrifugal section can be calculated respectively. This refined design method improves the ability of the mixed pump to transport high-gas content media, ensuring that the mixed pump can exhibit strong boosting performance even under large gas content ratio conditions, and enhances its adaptability and stability under different working conditions.

[0097] In the embodiment of the present application, the operating parameters are amplified by the amplification factor and the gas content to obtain the design flow rate and the design head, including:

[0098] The specific speed is calculated as follows:

[0099]

[0100] In the formula, is the specific speed, n is the speed, Q is the operating flow rate, and H is the operating head.

[0101] It should be noted that, since the flow passage of the low specific speed impeller is narrow and long, it is more likely to get clogged when conveying gas-liquid two-phase medium, so a larger amplification factor is used in the design to improve the flow characteristics. On the contrary, the flow passage of the high specific speed impeller is relatively spacious and not easy to get clogged, so a smaller amplification factor is used.

[0102] The calculation formula of the amplification factor is as follows:

[0103]

[0104] In the formula, k is the amplification factor, is the specific speed.

[0105] It should be noted that the specific speed of the pump is an important similarity discriminant number, which directly reflects the shape characteristics of the impeller flow channel. Specifically, the smaller the specific speed, the thinner the impeller flow channel is designed. This structure usually corresponds to a smaller flow rate and a higher head. In order to further optimize the performance of the pump, technicians introduced the concept of amplification factor, which is determined based on the size of the specific speed.

[0106] Through a large number of simulation calculations in the early stage, the technicians systematically studied the specific effects of different amplification factors on pump performance under different specific speeds, and successfully found the optimal amplification factor corresponding to each specific speed. Subsequently, the technicians fitted these optimal amplification factors and obtained an equation describing the relationship between the amplification factor and the specific speed.

[0107] After preliminary calculations and summaries, the technicians found that the optimal value of the amplification factor is not fixed, but varies according to different ranges of specific speed. Therefore, they summarized the corresponding amplification factor calculation formulas according to the range of different specific speeds. Especially when the specific speed is small, the flow channel is designed to be narrower, and the gas is more likely to block the flow channel. In order to improve this situation, the technicians found that the value of the amplification factor needs to be increased accordingly to optimize the gas-liquid mixed transmission performance and efficiency of the pump.

[0108] The design flow rate is calculated as follows:

[0109]

[0110] In the formula, is the design flow rate, k is the amplification factor, λ is the gas content, and Q is the operating flow rate;

[0111] The calculation formula for the design head is as follows:

[0112]

[0113] In the formula, is the design head, k is the amplification factor, λ is the gas content, It is the working head.

[0114] In the embodiment of the present application, the lift of the axial flow section is calculated according to the air void fraction and the design lift, and the lift of the centrifugal section is calculated according to the lift of the axial flow section, including:

[0115] The calculation formula of the head of the axial flow section is as follows:

[0116]

[0117] In the formula, is the head of the axial flow section, is the design head, and λ is the air void fraction.

[0118] The calculation formula of the centrifugal head is as follows:

[0119]

[0120] In the formula, is the head of the centrifugal section, is the head of the axial flow section, To design the lift.

[0121] It should be noted that the following operating parameters are used as an example for explanation:

[0122] Working flow Q=600 , working head H=70m, gas content λ=10%, speed n=2950rpm. The corresponding design parameters are as follows:

[0123] K=1.48, , .

[0124] Therefore, this application takes =977 , =114m design the mixed flow pump. The mixed flow pump is actually similar to a series of axial flow pumps and centrifugal pumps, so the design flow of the two is the same, both of which are ,

[0125] In the embodiment of the present application, the calculation of the inlet diameter of the impeller includes:

[0126] The impeller inlet diameter is set equal to the outer diameter of the axial flow section. The calculation formula for the impeller inlet diameter is as follows:

[0127]

[0128] In the formula, is the impeller inlet diameter, For the design flow rate, is the first correction coefficient, The value range is 300-350.

[0129] It should be noted that, considering the overall structural dimensions, =300mm. At the same time, in order to increase the inlet size of the mixed flow pump, the technicians introduced the first correction coefficient. By appropriately reducing the value of the first correction coefficient relative to the design of the traditional ordinary axial flow pump, a larger inlet diameter can be obtained, thereby increasing the inlet flow area and effectively avoiding gas accumulation at the inlet.

[0130] Calculate the inlet and outlet diameters of the mixed flow pump separately, including:

[0131] The inlet diameter of the mixed flow pump is equal to the inlet diameter of the impeller. The calculation formula of the inlet diameter of the mixed flow pump is as follows:

[0132]

[0133] In the formula, is the inlet diameter of the mixed flow pump, is the impeller inlet diameter.

[0134] Specifically,

[0135] The calculation formula of the outlet diameter of the mixed flow pump is as follows:

[0136]

[0137] In the formula, is the outlet diameter of the mixed flow pump, k is the magnification factor, is the second correction coefficient, The value range is 3.5-4.5. is the design flow rate and n is the rotation speed.

[0138] It should be noted that

[0139] In the embodiment of the present application, calculating the outer diameter of the impeller includes:

[0140] The calculation formula of the impeller outer diameter is as follows:

[0141]

[0142] In the formula, is the outer diameter of the impeller, is the specific speed, is the design flow rate and n is the rotation speed.

[0143] It should be noted that the outer diameter of the impeller is equal to the outlet diameter of the impeller, and the outlet diameter of the impeller is equal to the outer diameter of the centrifugal section, that is, the outer diameter of the impeller is equal to the outer diameter of the centrifugal section.

[0144]

[0145] In the embodiment of the present application, calculating the outlet width of the impeller includes:

[0146] The calculation formula of the impeller outlet width is as follows:

[0147]

[0148] In the formula, is the outlet width of the impeller, is the third correction coefficient, is the specific speed, is the design flow rate and n is the rotation speed.

[0149] In the embodiment of the present application, The calculation formula is as follows:

[0150]

[0151] In the formula, is the third correction coefficient, is the specific speed.

[0152] It should be noted that the technicians have enlarged the k value of the design parameters in the early stage. When calculating the outlet width of the impeller here, the third correction coefficient is introduced. At different specific speeds, The values ​​are different.

[0153] In the embodiment of the present application, the number of blades is 7-12.

[0154] It should be noted that as the number of blades increases, the constraints on the flow of the gas-liquid two-phase medium in the impeller gradually increase, which helps to reduce the phase separation between the gas-liquid two-phase medium, thereby increasing the gas content. However, when the number of blades increases to a certain extent, the flow area of ​​the impeller will decrease accordingly, resulting in an increase in the rejection coefficient, which in turn causes a significant decrease in the efficiency of the mixed pump. Therefore, in the design process, these factors should be comprehensively considered and the number of blades should be reasonably selected to balance the relationship between gas content and efficiency.

[0155] In the embodiment of the present application, the inlet placement angle of each blade is calculated, including:

[0156] The inlet placement angle of the axial flow section is equal to the inlet placement angle of the blade, and the outlet placement angle of the axial flow section is equal to the inlet placement angle of the centrifugal section;

[0157] Calculate the inlet placement angle of the corresponding blade through the liquid flow angle and angle of attack of each blade streamline;

[0158] The calculation formula of the blade inlet placement angle is as follows:

[0159]

[0160] In the formula, is the blade inlet placement angle, is the flow angle of the blade streamline, is the attack angle, The value range is 5-15°;

[0161] The calculation formula of the liquid flow angle of the blade streamline is as follows:

[0162]

[0163] In the formula, is the peripheral velocity of the liquid point, is the circular velocity of the liquid point, is the axial velocity of the liquid at a point;

[0164] The outlet placement angle of the centrifugal section is equal to the outlet placement angle of the blades, and the outlet placement angle of the blades is 22-30°.

[0165] In an embodiment of the present application, the fracture position of the impeller is determined, and the fracture position is located at a position where gas is easily gathered in the impeller flow channel, including: performing fracture cutting between 40%-60% of the impeller outer diameter to form an effective gas channel.

[0166] It should be noted that if Figure 7 As shown in the figure, after the gas enters the impeller flow channel, it will gather significantly in the range of 40% to 60% of its outer diameter. This phenomenon has an adverse effect on the performance of the mixed flow pump. To solve this problem, the technicians adopted the following Figure 3 The cutting method shown is to precisely cut off the impeller in this specific area, so that the blade is divided into two parts at this position, but the front and rear parts are still firmly fixed on the hub. This structural design opens up a direct gas channel, allowing the gas to flow smoothly from the high-pressure side of the blade working surface to the low-pressure side of the back, thereby effectively alleviating the problem of gas accumulation.

[0167] Example 1 - A mixed infusion pump according to the prior art was used as a control group.

[0168] Example 2: A mixed flow pump designed according to the design method in this application is used as a test group.

[0169] Figure 5a The mixed flow pump of the control group is in operation. The red part in the figure represents gas. It can be seen from the figure that the gas obviously gathers at the impeller inlet, causing the impeller to be blocked, thus affecting the normal operation of the mixed flow pump.

[0170] Figure 5b This is the state of the mixed flow pump of the test group during operation. The red part in the figure also represents gas. It can be seen from the figure that the gas inside the impeller flow channel is evenly distributed without large-scale accumulation, which effectively avoids the problem of impeller blockage and ensures that the mixed flow pump can work continuously and stably.

[0171] Figure 6a and Figure 6b The following are the pressure distribution diagrams of the impeller under the same gas content for the control group and the test group. Figure 6a It can be seen that there is no pressure gradient from the inlet to the outlet inside the impeller flow channel, indicating that the impeller has almost no work capacity and the performance of the mixed flow pump is limited. Figure 6b There is an obvious and gradually increasing pressure gradient from the inlet to the outlet inside the impeller flow channel, which not only ensures the normal operation of the mixed flow pump, but also promotes a more uniform mixing of the gas-liquid two-phase medium, and improves the overall efficiency and performance of the mixed flow pump.

[0172] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other. Each embodiment focuses on the differences from other embodiments.

[0173] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present application.

Claims

1. A design method for a mixed flow pump, characterized in that: The impeller of the mixed flow pump includes a hub and blades; the blades are arranged on the outer peripheral surface of the hub and extend spirally along the axial direction of the hub; the blades include an integrated axial flow section and a centrifugal section; the outlet end of the axial flow section is connected to the inlet end of the centrifugal section, and the design flow rates of the axial flow section and the centrifugal section are equal; The design methods of mixed flow pumps include: The design flow and design head are obtained by amplifying the operating parameters through the amplification factor and the gas content; The lift of the axial flow section is calculated based on the air void fraction and the design lift, and the lift of the centrifugal section is calculated based on the lift of the axial flow section; Calculate the inlet diameter of the impeller, and calculate the inlet diameter and outlet diameter of the mixed flow pump respectively; Calculate the outer diameter of the impeller; Calculate the impeller outlet width; Determine the number of leaves; Calculate the inlet placement angle of each blade and determine the outlet placement angle of each blade; Determine the fracture position of the impeller, which is located at the part of the impeller flow channel where gas is likely to gather; The design flow and design head are obtained by amplifying the operating parameters through the amplification factor and gas content, including: The specific speed is calculated as follows: In the formula, is the specific speed, n is the speed, Q is the operating flow rate, and H is the operating head; The calculation formula of the amplification factor is as follows: In the formula, k is the amplification factor, is the specific speed; The design flow rate is calculated as follows: In the formula, is the design flow rate, k is the amplification factor, λ is the gas content, and Q is the operating flow rate; The calculation formula for the design head is as follows: In the formula, is the design head, k is the amplification factor, λ is the gas content, It is the working head; The lift of the axial flow section is calculated based on the air void fraction and the design lift, and the lift of the centrifugal section is calculated based on the lift of the axial flow section, including: The calculation formula of the head of the axial flow section is as follows: In the formula, is the head of the axial flow section, is the design head, λ is the air void fraction; The calculation formula of the centrifugal head is as follows: In the formula, is the head of the centrifugal section, is the head of the axial flow section, To design the lift.

2. The design method of the mixed flow pump according to claim 1, characterized in that: Calculate the impeller inlet diameter, including: The impeller inlet diameter is set equal to the outer diameter of the axial flow section. The calculation formula for the impeller inlet diameter is as follows: In the formula, is the impeller inlet diameter, For the design flow rate, is the first correction coefficient, The value range is 300-350; Calculate the inlet and outlet diameters of the mixed flow pump separately, including: The inlet diameter of the mixed flow pump is equal to the inlet diameter of the impeller. The calculation formula of the inlet diameter of the mixed flow pump is as follows: In the formula, is the inlet diameter of the mixed flow pump, is the inlet diameter of the impeller; The calculation formula of the outlet diameter of the mixed flow pump is as follows: In the formula, is the outlet diameter of the mixed flow pump, k is the magnification factor, is the second correction coefficient, The value range is 3.5-4.

5. is the design flow rate and n is the rotation speed.

3. The design method of the mixed flow pump according to claim 1, characterized in that: Calculate the outer diameter of the impeller, including: The calculation formula of the impeller outer diameter is as follows: In the formula, is the outer diameter of the impeller, is the specific speed, is the design flow rate and n is the rotation speed.

4. The design method of the mixed flow pump according to claim 1, characterized in that: Calculate the impeller outlet width, including: The calculation formula of the impeller outlet width is as follows: In the formula, is the outlet width of the impeller, is the third correction coefficient, is the specific speed, is the design flow rate and n is the rotation speed.

5. The design method of the mixed flow pump according to claim 4, characterized in that: The calculation formula is as follows: In the formula, is the third correction coefficient, is the specific speed.

6. The design method of the mixed flow pump according to claim 1, characterized in that: The number of leaves is 7-12.

7. The design method of the mixed flow pump according to claim 1, characterized in that: Calculate the inlet placement angle of each blade, including: The inlet placement angle of the axial flow section is equal to the inlet placement angle of the blade, and the outlet placement angle of the axial flow section is equal to the inlet placement angle of the centrifugal section; Calculate the inlet placement angle of the corresponding blade through the liquid flow angle and angle of attack of each blade streamline; The calculation formula of the blade inlet placement angle is as follows: In the formula, is the blade inlet placement angle, is the flow angle of the blade streamline, is the attack angle, The value range is 5-15°; The calculation formula of the liquid flow angle of the blade streamline is as follows: In the formula, is the peripheral velocity of the liquid point, is the circular velocity of the liquid point, is the axial velocity of the liquid at a point; The outlet placement angle of the centrifugal section is equal to the outlet placement angle of the blades, and the outlet placement angle of the blades is 22-30°.

8. The design method of the mixed flow pump according to claim 1, characterized in that: Determine the fracture position of the impeller. The fracture position is located in the part of the impeller flow channel where gas is likely to gather, including: The fracture cutting is performed between 40% and 60% of the impeller outer diameter to form an effective gas channel.

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