A stage-by-stage hydraulic design method for the impeller of a multi-stage gas-liquid mixed transmission pump

Abstract

The present invention provides a method for the step-by-step hydraulic design of a multi-stage gas-liquid mixed flow pump impeller, comprising the following steps: determining the design parameters of the multi-stage gas-liquid mixed flow pump; determining the boost coefficients of different boosting stages of the multi-stage mixed flow pump, and determining the hydraulic design parameters of the different boosting stages step-by-step based on the boost coefficients of the different boosting stages, including the volume flow rate and boost value of the different boosting stages; determining the parameters of the impellers of each stage based on the gas void fraction of the impellers of the different boosting stages; and establishing an impeller model of the multi-stage gas-liquid mixed flow pump based on the parameters of the impellers of each stage. The present invention can obtain the impeller structures of different boosting stages and thereby determine the hydraulic model of the multi-stage mixed flow pump impeller.

Description

Technical Field

[0001] The present invention relates to the field of fluid machinery design, and in particular to a step-by-step hydraulic design method for an impeller of a multi-stage gas-liquid mixed transmission pump. Background Art

[0002] Traditional oil and gas transportation often begins with gas-liquid separation, followed by separate pressurization of the gas-liquid and liquid phases via compressors and oil pumps before transport. However, this method requires more equipment and longer pipelines. A more advanced method now uses a mixed gas-liquid pump to pressurize the two phases, then transports the mixture through a single mixed pipeline. This method requires far less pipeline laying and maintenance costs than traditional separate oil and gas transportation. Consequently, mixed oil and gas transportation is being adopted by more and more oil and gas fields, and the demand for mixed gas-liquid pumps is increasing.

[0003] Gas-liquid mixed flow pumps generally have high boost pressures and often exist in a multi-stage form. The transport medium is a gas-liquid two-phase fluid with a high gas content. Therefore, unlike the design method of conventional multi-stage pumps that transport pure liquids, the design of multi-stage gas-liquid mixed flow pumps needs to consider the total volume compression of the gas during the pump's stage-by-stage boost process, the reduction of the flow rate at each stage, and the reduction of the gas content. Therefore, the structural parameters of each stage impeller should be adjusted to adapt to the gradually changing incoming flow conditions. However, a mature hydraulic design method for multi-stage gas-liquid mixed flow pumps has not yet been formed at home and abroad. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a step-by-step hydraulic design method for the impeller of a multi-stage gas-liquid mixed transmission pump. By correcting the impeller hydraulic design between different boosting stages step by step and determining the structural parameters of the impellers at different stages, the hydraulic design of the multi-stage impeller can be carried out more conveniently, saving design time.

[0005] The present invention achieves the above technical objectives through the following technical means.

[0006] A method for hydraulically designing a multi-stage gas-liquid mixed pump impeller step by step includes the following steps:

[0007] Determine the design parameters of the multi-stage gas-liquid mixed transmission pump;

[0008] Determine the boost coefficient of different boosting stages of multi-stage mixed pumps,

[0009] Determine the hydraulic design parameters of different boosting stages step by step according to the boosting coefficients of different boosting stages, including the volume flow rate and boosting value of different boosting stages;

[0010] According to the air content of the impellers of different boosting stages, the parameters of the impellers at each stage are determined;

[0011] A multi-stage gas-liquid mixed pump impeller model is established based on the parameters of each stage impeller.

[0012] Furthermore, the design parameters of the multi-stage gas-liquid mixed flow pump include the inflow pressure P0, the mixed flow pump boost pressure P T , volume flow rate Q, gas content α and total number of pressurization stages n,

[0013] Where, volume flow rate Q = Q l +Q g , Q l is the liquid flow rate, Q g is the gas flow rate;

[0014] Gas content α = Q g / Q.

[0015] Furthermore, the boost coefficients of different boosting stages of the multi-stage mixed pump are determined as follows:

[0016] Assume that the pressure coefficient of the i-th stage impeller is a i , i∈(1,2,…,n), then the corresponding multi-stage mixed pump's boosting capacity at each stage satisfies the relationship:

[0017]

[0018] in:

[0019] P i = boost value of the i-th stage impeller;

[0020] a1,a2,a3,…,a n is the boost coefficient, and satisfies the relationship:

[0021] The boost value of the i-th stage impeller is:

[0022] The boost coefficient of the i+1th stage satisfies a i+1 =a i *b i , b i is the pressure ratio of the i-th stage impeller, ranging from 1.0 to 1.8;

[0023] Obtain the boost value of the i+1th stage impeller

[0024] The gas fraction α at the i+1 stage impeller inlet is obtained i+1 , the air volume fraction α of the i+1th stage impeller i+1 The expression is:

[0025]

[0026] Determine whether the boost coefficient of each stage meets the requirements If it is not satisfied, adjust the pressure coefficient of the first stage impeller and the pressure ratio of each stage until the pressure coefficient of each stage meets the requirements.

[0027] Furthermore, the pressure ratio b of the i-th stage impeller is i The value range is 1.0 to 1.8; the pressure coefficient a1 of the first-stage impeller ranges from 0.6 to 0.9; the higher the air content at the inlet of the i-th stage impeller, the greater the corresponding i-th stage pressure ratio.

[0028] Furthermore, according to the boost coefficient a of the i-th impeller i Determine the hydraulic design parameters of different boosting stages step by step, including the volume flow and boosting value of different boosting stages, specifically:

[0029] The boost value P of the i-th stage impeller i for:

[0030] Volume flow rate Q of the i-th stage impeller i , satisfying the following relationship:

[0031] Furthermore, when the air volume fraction α of the i-th stage impeller is i When the air volume fraction α of the i-th stage impeller is less than or equal to 10%, the parameters of each stage impeller are determined by the i-th stage impeller specific speed; when the i-th stage impeller gas volume fraction α i When it is greater than 10%, the structural parameters of the first-stage impeller are determined first, and then the structural parameters of each stage impeller are corrected.

[0032] Furthermore, when the air volume fraction α of the i-th stage impeller is i When it is less than or equal to 10%, the specific speed of the i-th stage impeller is calculated by the following formula:

[0033]

[0034] Where: n s_i is the specific speed of the i-th stage impeller; n rotating is the impeller speed; ρ l is the density of the liquid in the pump;

[0035] Then, the pump model is selected according to the obtained specific speed of the i-th stage impeller, and the structural parameters of the i-th stage impeller are determined.

[0036] Furthermore, when the air volume fraction α of the i-th stage impeller is i When it is greater than 10%, the structural parameters of the first-stage impeller are determined as follows:

[0037] The first-stage impeller structural parameters are calculated based on the first-stage impeller pressure value P1, volume flow rate Q and the first-stage impeller gas fraction α1, including the first-stage impeller inlet and outlet diameters D s_1, Equivalent diameter of the first stage impeller hub D h_1 、First stage impeller inlet placement angle β j_1 、First stage impeller rim outlet placement angle β c_1 , first stage impeller hub cone angle θ1, first stage blade wrap angle The details are as follows:

[0038] The first stage impeller inlet and outlet diameter D s_1 :

[0039] Where: k0 is the first coefficient; n rotating is the impeller speed;

[0040] Equivalent diameter of the first stage impeller hub D h_1 :D h_1 =d sh D s_1 ;

[0041] where d sh is the hub ratio;

[0042] The first stage impeller rim inlet placement angle β j_1 :

[0043] Where: k1 is the second coefficient;

[0044] The first stage impeller rim outlet placement angle β c_1 :

[0045]

[0046] Where k2 is the third coefficient; ρmix is ​​the gas-liquid mixture density, ρ mix =ρ l (1-α1)+ρ g α1; Δβ is the angle of attack;

[0047] The cone angle of the first stage impeller hub θ1 = 6°~12°;

[0048] First stage blade angle

[0049] Furthermore, when the air volume fraction α of the i-th stage impeller is i When it is greater than 10%, the structural parameters of each stage impeller are modified, specifically:

[0050] Each stage uses the same impeller inlet and outlet diameters and hub ratio;

[0051] The inlet placement angle of the i-th stage impeller rim β j_i The correction method satisfies the following formula:

[0052] The outlet placement angle of the i-th stage impeller rim β c_i The correction method satisfies the following formula:

[0053] The correction method of the i-th level hub cone angle satisfies the following formula: Where k3 is the fourth coefficient;

[0054] The i-th level blade wrap angle As the gas holdup of each stage decreases step by step, Gradually decrease.

[0055] A multi-stage gas-liquid mixed flow pump impeller is an impeller determined by using the multi-stage gas-liquid mixed flow pump impeller step-by-step hydraulic design method.

[0056] The beneficial effects of the present invention are:

[0057] The present invention aims at the step-by-step changing incoming flow conditions in a multi-stage mixed flow pump and proposes a step-by-step hydraulic design method for multi-stage pump impellers. Through this method, when designing the mixed flow pump, the changes in the incoming flow parameters of each stage can be fully considered, and the structural parameters of each stage of the mixed flow pump can be designed step by step, so that the impeller of each stage can better match the incoming flow conditions of each stage, ensuring that the impeller of each stage of the mixed flow pump operates in the high-efficiency zone. This design method can ensure the design of a multi-stage gas-liquid mixed flow pump with more efficient operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. The drawings described below are some embodiments of the present invention. For ordinary technicians in this field, it is obvious that other drawings can be obtained based on these drawings without paying any creative work.

[0059] Figure 1 This is a flow chart of the step-by-step hydraulic design method for the impeller of a multi-stage gas-liquid mixed transmission pump according to the present invention.

[0060] Figure 2 This is an axial cross-sectional view of an impeller of a mixed flow pump provided by an embodiment of the present invention.

[0061] Figure 3 A schematic diagram of the inlet and outlet angles of the impeller rim of a mixed pump provided in an embodiment of the present invention.

[0062] Figure 4 A schematic diagram of the blade wrap angle of a mixed flow pump impeller provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0063] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0064] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "axial", "radial", "vertical", "horizontal", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention 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 limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0065] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0066] like Figure 1 As shown, the step-by-step hydraulic design method of the multi-stage gas-liquid mixed pump impeller of the present invention includes the following steps:

[0067] S01: Determine the design parameters of the multi-stage gas-liquid mixed transfer pump, including volume flow rate, mixed transfer pump boost pressure, and gas holdup;

[0068] The hydraulic design parameters of the multi-stage gas-liquid mixed flow pump include the inflow pressure P0, the mixed flow pump boost pressure P T , volume flow rate Q, gas content α and total number of pressurization stages n, where volume flow rate Q = Q l +Q g , Q l is the liquid flow rate, Q g is the gas flow rate; gas content α=Q g / Q. The air content α here can be understood as the air content of the first-stage impeller, that is, α1.

[0069] S02: Determine the boosting coefficients of different boosting stages of the multi-stage mixed pump, as follows:

[0070] Assume that the pressure coefficient of the i-th stage impeller is a i , i∈(1,2,…,n), then the corresponding multi-stage mixed pump's boosting capacity at each stage satisfies the relationship:

[0071]

[0072] in:

[0073] P i = boost value of the i-th stage impeller;

[0074] a1,a2,a3,…,a n is the boost coefficient, and satisfies the relationship:

[0075] The boost coefficient of the i+1th stage satisfies a i+1 =a i *b i , b i is the pressure ratio of the i-th stage impeller, ranging from 1.0 to 1.8;

[0076] Generally, the pressure coefficient a1 of the first-stage impeller is 0.6~0.9. The higher the gas content, the smaller the a1 value should be. The higher the gas content at the boosting stage inlet, the greater the corresponding pressure ratio. When the gas content is lower than 0.1, the pressure ratio is closer to 1.

[0077] The boost value of the first stage impeller is:

[0078] The gas holdup at the second stage inlet can be calculated based on the first stage impeller pressure value. The calculation method is:

[0079]

[0080] Then, according to the second stage inlet gas content α2, the corresponding pressure ratio b2 is preliminarily selected to calculate the second stage pressure coefficient a2; the pressure value P2 of the second stage can be calculated by a2, and the pressure value P of the i+1 stage impeller can be obtained by analogy. i+1 and the air volume fraction α of the i+1th stage impeller i+1 ,

[0081] The air volume fraction α of the i+1th stage impeller i+1 The expression is:

[0082]

[0083] Select the boost ratio of each stage and calculate the boost coefficient of each stage in turn, and finally determine whether the boost coefficient of each stage meets the requirements. If it is not satisfied, fine-tune the pressure coefficient of the first stage impeller and the pressure ratio of each stage until the pressure coefficient of each stage meets the requirements.

[0084] S03: According to the boost coefficient a of the i-th impeller i Determine the hydraulic design parameters of different boosting stages step by step, including the volume flow and boosting value of different boosting stages:

[0085] The boost value P of the i-th stage impeller i for:

[0086] Volume flow rate Q of the i-th stage impeller i , satisfying the following relationship:

[0087] S04: Determination of parameters of impellers at each level

[0088] S04.1: When the air volume fraction α of the i-th stage impeller i When it is less than or equal to 10%, the specific speed of the i-th stage impeller can be calculated by the following formula:

[0089]

[0090] Where: n s_i is the specific speed of the i-th stage impeller; n rotating is the impeller speed; ρ l is the density of the liquid in the pump;

[0091] Then, the pump model is selected according to the obtained specific speed of the i-th stage impeller, and the parameters such as the impeller diameter, hub ratio, blade inlet and outlet angles, hub cone angle, and blade wrap angle of the i-th stage impeller are determined.

[0092] S04.2: When the air volume fraction α of the i-th stage impeller i When it is greater than 10%, first determine the first-stage impeller structural parameters, and then modify the structural parameters of each stage impeller, as follows:

[0093] S04.2.1: Calculate the first-stage impeller structural parameters based on the first-stage impeller pressure value P1, volume flow rate Q, and the first-stage impeller gas fraction α1, including the first-stage impeller inlet and outlet diameters D. s_1 , Equivalent diameter of the first stage impeller hub D h_1 、First stage impeller inlet placement angle β j_1 、First stage impeller rim outlet placement angle β c_1 , first stage impeller hub cone angle θ1, first stage blade wrap angle The details are as follows:

[0094] The first stage impeller inlet and outlet diameter D s_1 :

[0095] Where: k0 is the first coefficient, k0 = 7 to 10; n rotating is the impeller speed; the selection of k0 is related to the flow rate and gas content.

[0096] Equivalent diameter of the first stage impeller hub D h_1 :D h_1 =d sh D s_1 ;

[0097] where d sh is the hub ratio; d sh =0.75~0.9, the higher the gas content, the larger the value;

[0098] The first stage impeller rim inlet placement angle β j_1 :

[0099] Where: k1 is the second coefficient, k1 = 0.6 ~ 1.0;

[0100] The first stage impeller rim outlet placement angle β c_1 :

[0101]

[0102] Where k2 is the third coefficient, k2 = 1.0 ~ 2.0; ρmix is ​​the gas-liquid mixture density, ρ mix =ρ l (1-α1)+ρ g α1; Δβ is the attack angle, 0°~3°.

[0103] After obtaining the outlet placement angle of the first-stage impeller rim, the inlet and outlet placement angles of different blade heights are calculated using the formula dtanβ=constant.

[0104] The cone angle of the first-stage impeller hub is θ1 = 6°~12°. The higher the air content, the larger the cone angle θ1.

[0105] First stage blade angle This value is related to the number of blades and the air content. The greater the air content, the larger the blade wrap angle.

[0106] S04.2.2: Use the step-by-step correction method to correct the structural parameters of the impellers of different booster stages, specifically:

[0107] Each stage uses the same impeller inlet and outlet diameters and hub ratio;

[0108] The inlet placement angle of the i-th stage impeller rim βj_i The correction method satisfies the following formula:

[0109] The outlet placement angle of the i-th stage impeller rim β c_i The correction method satisfies the following formula:

[0110] The correction method of the i-th level hub cone angle satisfies the following formula:

[0111] Wherein k3 is the fourth coefficient, k3 = 0.8 ~ 1.2;

[0112] The selection method of the i-th level blade wrap angle meets the following criteria: As the gas holdup of each stage decreases step by step, Gradually decrease.

[0113] S05: Determine the hydraulic model of the multi-stage mixed flow pump impeller based on the structural parameters of the impellers at different boosting stages.

[0114] Example

[0115] Take the design parameters of a multi-stage pump as an example: the inflow pressure is 100000Pa and the design flow rate is 150m 3 / h, gas content 0.5, speed 3000r / min, required boost pressure 500000Pa, pump boost stage 4.

[0116] S01: Determine the design parameters of the multi-stage gas-liquid mixed transfer pump, including volume flow rate, mixed transfer pump boost pressure, and gas holdup, specifically:

[0117] Inflow pressure P0 = 1atm; Mixing pump boost pressure P T =5atm; volume flow rate Q = Q l +Q g =150m 3 / h; gas content α=0.5=α1; total number of boosting stages n=4; impeller speed n rotating =3000r / min. Volume flow Q is generally the volume flow Q1 of the first stage;

[0118] S02: Determine the boosting coefficients of different boosting stages of the multi-stage mixed pump, as follows:

[0119] Since the incoming flow has a high gas content of α = 0.5, a smaller first-stage boost coefficient a1 = 0.7 is selected, and the corresponding first-stage boost value is:

[0120]

[0121] The corresponding gas content at the second stage inlet is:

[0122]

[0123] At this time, the gas content at the second stage inlet is still relatively high. If the second stage pressure ratio b2 = 1.5 is selected, the corresponding second stage pressure coefficient a2 is: 1.05. Therefore, the second stage pressure value can be calculated as:

[0124]

[0125] The gas content at the third stage entrance can be obtained as follows:

[0126]

[0127] The gas fraction at the third stage inlet is reduced to 0.239. The third stage pressure ratio b3 is selected as 1.2, and the corresponding third stage pressure coefficient a3 is 1.26. Therefore, the third stage pressure value can be calculated as:

[0128]

[0129] The gas content at the fourth stage entrance can be obtained as follows:

[0130]

[0131] The gas content at the fourth stage inlet is reduced to 0.174. Considering that the total number of boosting stages is 4 and the total boosting value must be 500,000 Pa, the fourth stage boosting value P4 can be calculated to be 124,000 Pa, and the fourth boosting ratio b4 is 0.787, which is not within the boosting range of 1 to 1.5. Therefore, according to the above steps, the first stage boosting coefficient a1 and the boosting ratios of each stage are revised, so that the boosting coefficient, boosting ratio and total boosting value of each stage can meet their restrictions.

[0132] Through the above steps, the first-stage boost coefficient is adjusted to a1=0.6, b2=1.5, b3=1.3, b4=1.14, and the calculated boost coefficients of each stage are a2=0.9, a3=1.17, and a4=1.33 respectively.

[0133] Each stage of the boost coefficient meets

[0134] S03: According to the boost coefficient a of the i-th impeller i Determine the hydraulic design parameters of different boosting stages step by step, including the volume flow and boosting value of different boosting stages:

[0135] The boost value P of the i-th stage impeller i for:

[0136] Volume flow rate Q of the i-th stage impeller i , satisfying the following relationship:

[0137] The calculation is shown in Table 1:

[0138] Table 1: Hydraulic design parameters of multistage pumps

[0139] Boost stage Boost coefficient Pressure increase value (Pa) <![CDATA[Flow rate (m 3 / h)]]> Gas content 1 0.6 75000 150.00 0.50 2 0.9 112500 117.86 0.36 3 1.17 146250 101.09 0.26 4 1.33 166250 92.29 0.19

[0140] S04: Determination of parameters of impellers at each level

[0141] As shown in Table 1, the air volume fraction α of each impeller stage is i The impeller structure parameters of the first stage are determined first, and then the impeller structure parameters of each stage are modified as follows:

[0142] The design parameters of the first stage impeller are: P1 = 75000Pa; Q = 150m 3 / h; α1=0.5; n rotating =3000r / min;

[0143] First, as Figure 2 、 Figure 3 and Figure 4 As shown, according to the volume flow rate and gas content, the first k0=8.32 is selected to calculate the inlet and outlet diameters D of the first-stage impeller. s_1 :

[0144]

[0145] Next, select d sh =0.875, then the impeller hub equivalent diameter D can be obtained h_1 :

[0146] D h_1 =d sh D s_1 =0.875×200mm=175mm

[0147] Select k1 = 0.75, and you can get the first stage impeller rim inlet placement angle β j_1 =6°;

[0148] Select k2 = 1.8, outlet angle of attack Δβ = 2°, and obtain the outlet angle β of the first-stage impeller rim. c_1 =13°;

[0149] The first stage impeller hub cone angle θ1=8°, the first stage blade wrap angle

[0150] S04.2.2: Use the step-by-step correction method to correct the structural parameters of the impellers of different booster stages, specifically:

[0151] Each stage uses the same impeller inlet and outlet diameters and hub ratio;

[0152] According to the volume flow rate Q2 of the second-stage impeller, the inlet angle of the second-stage impeller rim is obtained:

[0153]

[0154] Similarly, the inlet angle β of the third-stage impeller rim can be calculated in sequence j_3 =4.9°, fourth stage impeller rim inlet angle β j_4 =4.7°.

[0155] According to the gas content of the second-stage impeller, the boost value of the second-stage impeller and the first-stage impeller rim outlet angle, the second-stage impeller rim outlet angle β is obtained. c_2 :

[0156]

[0157] Similarly, the third-stage impeller rim outlet angle β can be calculated in sequence c_3 =11.8°, the fourth stage impeller rim outlet angle β j_4 =11.1°.

[0158] According to the gas content of each stage and the selection of appropriate k3, the hub cone angles of each stage can be calculated as follows: the second stage hub cone angle θ2 = 6.5°, the third stage hub cone angle θ3 = 5.5°, and the fourth stage hub cone angle θ4 = 4.5°;

[0159] The blade wrap angles of the second, third and fourth levels are: Third level blade wrap angle Fourth-level blade angle

[0160] The hydraulic structural parameters of the impellers of all booster stages in the multistage pump were determined, and the results are shown in Table 2.

[0161] Table 2: Structural parameters of multistage pump impellers

[0162]

[0163] S05: Determine the hydraulic model of the multi-stage mixed flow pump impeller based on the structural parameters of the impellers at different boosting stages.

[0164] A multi-stage gas-liquid mixed flow pump impeller is an impeller determined by using the multi-stage gas-liquid mixed flow pump impeller step-by-step hydraulic design method described in the present invention.

[0165] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0166] The series of detailed descriptions listed above are only specific descriptions of feasible embodiments of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent embodiments or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A step-by-step hydraulic design method for a multi-stage gas-liquid mixed pump impeller, characterized in that: The following steps are involved: Determine the design parameters of the multi-stage gas-liquid mixed transmission pump, including the inflow pressure P0, the mixed transmission pump boost pressure P T , volume flow rate Q, gas content α and total number of pressurization stages n, where volume flow rate Q=Q l +Q g , Q l is the liquid flow rate, Q g is the gas flow rate; gas content α = Q g / Q; Determine the boost coefficients of different boost stages of the multi-stage mixed pump as follows: Assume that the pressure coefficient of the i-th stage impeller is a i , , then the corresponding multi-stage mixed pump's boosting capacity at each stage satisfies the relationship: ， in: P i = boost value of the i-th stage impeller; a1,a2,a3,…,a n is the boost coefficient, and satisfies the relationship: ; The boost value of the i-th stage impeller is: ; The boost coefficient of the i+1th stage satisfies a i+1 =a i *b i , b i is the pressure ratio of the i-th stage impeller, ranging from 1.0 to 1.8; Obtain the boost value of the i+1th stage impeller ; The gas fraction α at the i+1 stage impeller inlet is obtained i+1 , the air volume fraction α of the i+1th stage impeller i+1 The expression is: ； Determine whether the boost coefficient of each stage meets the requirements If it is not satisfied, adjust the pressure coefficient of the first stage impeller and the pressure ratio of each stage until the pressure coefficient of each stage meets ; Determine the hydraulic design parameters of different boosting stages step by step according to the boosting coefficients of different boosting stages, including the volume flow rate and boosting value of different boosting stages; Determine the structural parameters of each impeller according to the air void fraction of the impeller at different boosting stages; A multi-stage gas-liquid mixed pump impeller model is established based on the structural parameters of each stage impeller.

2. The step-by-step hydraulic design method for the impeller of a multi-stage gas-liquid mixed transfer pump according to claim 1 is characterized in that: The pressure ratio b of the i-th stage impeller i The value range is 1.0~1.8; the pressure coefficient a1 of the first-stage impeller ranges from 0.6~0.9; the higher the air content at the inlet of the i-th stage impeller, the greater the corresponding i-th stage pressure ratio.

3. The step-by-step hydraulic design method for the impeller of a multi-stage gas-liquid mixed transfer pump according to claim 1 is characterized in that: According to the pressure coefficient a of the i-th impeller i Determine the hydraulic design parameters of different boosting stages step by step, including the volume flow and boosting value of different boosting stages, specifically: The boost value P of the i-th stage impeller i for: ; Volume flow rate Q of the i-th stage impeller i , satisfying the following relationship: , i>

1.

4. The step-by-step hydraulic design method for the impeller of a multi-stage gas-liquid mixed transfer pump according to claim 1 is characterized in that: When the air volume fraction α of the i-th stage impeller i When the air volume fraction α of the i-th stage impeller is less than or equal to 10%, the parameters of each stage impeller are determined by the i-th stage impeller specific speed; when the i-th stage impeller gas volume fraction α i When it is greater than 10%, the hydraulic design method of the mixed pump is used for stage-by-stage design.

5. The step-by-step hydraulic design method for the impeller of a multi-stage gas-liquid mixed transfer pump according to claim 4 is characterized in that: When the air volume fraction α of the i-th stage impeller i When it is less than or equal to 10%, the specific speed of the i-th stage impeller is calculated by the following formula: ， in: is the specific speed of the i-th stage impeller; is the impeller speed; ρ l is the density of the liquid in the pump; Then, the pump model is selected according to the obtained specific speed of the i-th stage impeller, and the structural parameters of the i-th stage impeller are determined.

6. The step-by-step hydraulic design method for the impeller of a multi-stage gas-liquid mixed transfer pump according to claim 4 is characterized in that: When the air volume fraction α of the i-th stage impeller i When it is greater than 10%, the structural parameters of the first-stage impeller are determined as follows: The first-stage impeller structural parameters are calculated based on the first-stage impeller pressure value P1, volume flow rate Q and the first-stage impeller gas fraction α1, including the first-stage impeller inlet and outlet diameters D s_1 , Equivalent diameter of the first stage impeller hub D h_1 、First stage impeller inlet placement angle β j_1 、First stage impeller rim outlet placement angle β c_1 , the first-stage impeller hub cone angle θ1, the first-stage blade wrap angle φ1, are as follows: The first stage impeller inlet and outlet diameter D s_1 : ; Where: k0 is the first coefficient; n rotating is the impeller speed; Equivalent diameter of the first stage impeller hub D h_1 : ; in is the hub ratio; The first stage impeller rim inlet placement angle β j_1 : ; Where: k1 is the second coefficient; The first stage impeller rim outlet placement angle β c_1 : ， Where k2 is the third coefficient; ρ mix is the gas-liquid mixture density, ; Δβ is the angle of attack; The cone angle of the first stage impeller hub is θ1=6 o ~12 o ; The first stage blade wrap angle φ1=100 o ~200 o .

7. The step-by-step hydraulic design method for the impeller of a multi-stage gas-liquid mixed transfer pump according to claim 4 is characterized in that: When the air volume fraction α of the i-th stage impeller i When it is greater than 10%, the structural parameters of each stage impeller are modified, specifically: Each stage uses the same impeller inlet and outlet diameters and hub ratio; The inlet placement angle of the i-th stage impeller rim β j_i The correction method satisfies the following formula: ; The outlet placement angle of the i-th stage impeller rim β c_i The correction method satisfies the following formula: ; i+1th level hub cone angle The correction method satisfies the following formula: , where k3 is the fourth coefficient; The wrap angle of the i-th blade i =100 o ~200 o , as the gas content of each stage decreases step by step, then φ i gradually decrease; Where: ρ mix is the gas-liquid mixture density; Q i is the volume flow rate of the i-th stage impeller; Q1 is the volume flow rate of the 1st stage impeller; P i is the boost value of the i-th stage impeller; P1 is the boost value of the 1st stage impeller; β j_1 β is the inlet placement angle of the first-stage impeller rim; c_1 The first stage impeller rim outlet placement angle; The cone angle of the i-th wheel hub; α i+1 is the air void fraction of the i+1th stage impeller.

8. A multi-stage gas-liquid mixed pump impeller, characterized in that: An impeller determined by the step-by-step hydraulic design method for a multi-stage gas-liquid mixed pump impeller according to any one of claims 1 to 7.

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