End wall jet device for clearing axial flow pump impeller tip blockage and its parameter determination method

Abstract

The present invention discloses an end wall jet device for unblocking the tip blockage of an axial flow pump and a method for determining its parameters. The end wall jet device provided by the present invention can suppress unstable flows such as unsteady breakup of the tip leakage vortex, thereby unblocking the blockage of the impeller tip channel. In this way, the problems of sudden drop in head, increased noise and rotational stall caused by tip blockage in the axial flow pump under low flow conditions are solved. At the same time, since the device does not require external energy input, it can effectively reduce the difficulty of specific implementation. Therefore, the device has broad development prospects and is suitable for large-scale application and promotion in the field of impeller expansion stabilization technology.

Description

Technical Field

[0001] The invention belongs to the technical field of impeller machinery, and particularly relates to an end wall jet device for clearing impeller tip blockage in an axial flow pump and a parameter determination method thereof. Background Art

[0002] An axial flow pump is a vane pump with the characteristics of large flow and low head. Among them, high efficiency and high operating stability are important indicators for the design of axial flow pumps. However, in actual operation, when the axial flow pump works under low flow conditions, its blade tip leakage vortex will show unstable flow such as unsteady breakage. This will cause a large amount of low-energy fluid to gather in the blade tip channel, thereby causing serious blade tip blockage. Based on this, the axial flow pump will experience problems such as a sudden drop in head, increased pump body vibration and noise. At the same time, if the axial flow pump operates in this working condition for a long time, it is also easy to cause major safety accidents due to blade fatigue and fracture. Therefore, how to provide a device that can clear the blockage of the blade tip of an axial flow pump has become an urgent problem to be solved. Summary of the Invention

[0003] The purpose of the present invention is to provide an end wall jet device for clearing the blockage of the blade tips of axial flow pumps and a method for determining its parameters, so as to solve the problem in the prior art that when the axial flow pump works under low flow conditions, its blade tip leakage vortex will exhibit unstable flow such as unsteady breakup, resulting in a large amount of low-energy fluid gathering in its blade tip channel, thereby causing serious blade tip blockage.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] In a first aspect, an end wall jet device for clearing blockage in the tip of an axial flow pump is provided, comprising:

[0006] A jet bridge, wherein a jet channel is provided in the jet bridge;

[0007] Suction base and jet base;

[0008] The suction base and the jet base are both hollow structures, wherein one end of the jet bridge is connected to the suction base, and the other end of the jet bridge is connected to the jet base, and when the jet bridge is connected to the suction base and the jet base respectively, the suction base and the jet base are connected to the jet channel to form a fluid jet bridge;

[0009] The suction base and the jet base are respectively fixed on the circumferential surface of the impeller of the axial flow pump at one end away from the jet bridge, wherein the suction base and the jet base are respectively arranged in sequence along the axial direction of the impeller, a suction port is provided on the end surface of the suction base connected to the impeller, and a jet port is provided on the end surface of the jet base connected to the blade, and the pressures between the suction port and the jet port are different.

[0010] Based on the above-disclosed content, the present invention provides a jet bridge with a jet channel inside, and one end of the jet bridge is installed on the circumferential surface of the impeller of an axial flow pump through a suction base, and the other end is installed on the circumferential surface of the impeller through a jet base; wherein, in a specific implementation, a suction port is provided on the contact surface between the suction base and the impeller, and a jet port is provided on the contact surface between the jet base and the impeller, and the suction base and the jet base are both hollow structures. In this way, when the three are connected, a fluid jet bridge can be formed inside; at the same time, the pressure of the suction port and the jet port is different (the pressure at the suction port is lower than that at the jet port). Based on this, the pressure difference between the suction port and the jet port can be utilized to form a suction-injection flow cycle of the fluid in the fluid jet bridge, thereby suppressing unstable flows such as unsteady breakup of the blade tip leakage vortex, thereby achieving the purpose of unblocking the blade tip channel, improving the rotational stall of the axial flow pump and ensuring the stable operation of the axial flow pump.

[0011] Through the above design, the end wall jet device provided by the present invention can suppress unstable flows such as unsteady breakup of blade tip leakage vortex, thereby unblocking the blockage of the impeller blade tip channel. In this way, the problems of sudden drop in head, increased noise and rotational stall caused by blade tip blockage in axial flow pumps under low flow conditions are solved. At the same time, since the device does not require external energy input, it can effectively reduce the difficulty of specific implementation. Therefore, the device has broad development prospects and is suitable for large-scale application and promotion in the field of impeller stabilization technology.

[0012] In one possible design, the jet bridge includes: a first hollow plate, a second hollow plate, and a third hollow plate, wherein the first hollow plate is a rectangular plate, and the second hollow plate and the third hollow plate are both arc-shaped plates;

[0013] One end of the first hollow plate is connected to the second hollow plate, and the other end of the first hollow plate is connected to the third hollow plate. When the first hollow plate is respectively connected to the second hollow plate and the third hollow plate, the first hollow plate, the second hollow plate and the third hollow plate are interconnected to form the jet channel.

[0014] In a possible design, a plurality of end wall jet devices are provided, and the plurality of end wall jet devices are circumferentially arranged on the circumferential surface of the impeller.

[0015] In a second aspect, a method for determining parameters of an end wall jet device for clearing a blockage in an axial flow pump blade tip according to the first aspect of the embodiment or any possible design of the first aspect is provided, comprising:

[0016] Obtaining a simulation geometric model and a model parameter set, wherein the simulation geometric model is a geometric model of an end wall jet device installed on the circumferential surface of an impeller of an axial flow pump, and the model parameter set includes multiple sets of model parameters, and any model parameter includes installation structure parameters of the end wall jet device, and structural parameters of a suction port, a jet bridge, and a jet port in the end wall jet device;

[0017] Using the model parameter set, performing end jet numerical simulation processing on the simulation geometric model to obtain numerical simulation results corresponding to the simulation geometric model when the numerical simulation processing is performed using each set of model parameters as simulation parameters;

[0018] An optimal numerical simulation result is selected from a number of numerical simulation results, and the model parameters corresponding to the optimal numerical simulation result are used as the optimal structural parameters of the end wall jet device.

[0019] In a possible design, the best numerical simulation result is selected from several numerical simulation results, including:

[0020] Calculating, based on each numerical simulation result, a blocking coefficient of the simulation geometric model when performing numerical simulation processing using each model parameter as a simulation parameter;

[0021] The numerical simulation result corresponding to the minimum blocking coefficient is taken as the optimal numerical simulation result.

[0022] In one possible design, any one of the plurality of numerical simulation results includes: a first fluid density of the target fluid on the impeller, a second fluid density of the target fluid in the end wall jet device, a first flow velocity of the target fluid on the impeller, and a second flow velocity of the target fluid in the end wall jet device, wherein the target fluid is the fluid used in the end jet numerical simulation process;

[0023] The blocking coefficient of the simulated geometric model is calculated based on the numerical simulation results when the numerical simulation is performed using the model parameters as simulation parameters, including:

[0024] For any numerical simulation result, based on the first fluid density, the second fluid density, the first flow velocity, and the second flow velocity in the numerical simulation result, and using the following formula (1), the blockage coefficient of the simulation geometric model is calculated when the numerical simulation is performed using any model parameter as the simulation parameter;

[0025] B e =A b / A (1)

[0026]

[0027] In the above formula (1), B e It represents the blocking coefficient of the simulation geometric model when the numerical simulation is performed with any of the model parameters as simulation parameters, A b is an intermediate parameter, A represents the circumferential cross-sectional area of ​​the impeller corresponding to the blade tip;

[0028] In the above formula (2), ρ represents the first fluid density in any numerical simulation result, ρ cr represents the second fluid density in any numerical simulation result, v m represents the first streamwise velocity in any numerical simulation result, v cr represents the second stream velocity in any of the numerical simulation results.

[0029] In a possible design, the structural parameters include the axial length and circumferential width of the suction port, and the structural parameters of the jet port include the axial distance between the jet port and the leading edge of the impeller blade tip, the throat height of the jet port, the jet angle of the jet port, and the connection height between the jet base and the jet bridge;

[0030] The installation structure parameters include the circumferential coverage angle of the end wall jet device; and

[0031] The structural parameters of the jet bridge include the length and width of the jet channel.

[0032] In one possible design, the optimal structural parameters include: an optimal axial length and an optimal circumferential width of the suction port, wherein the optimal axial length is 0.15Ca, the optimal circumferential width is 0.24Ca, and Ca represents the axial chord length of the impeller corresponding to the blade tip.

[0033] In a possible design, the optimal structural parameters include: an optimal axial distance between the jet port and the leading edge of the impeller blade tip, an optimal throat height of the jet port, an optimal jet angle of the jet port, and an optimal connection height between the jet base and the jet bridge;

[0034] Among them, the optimal axial distance is 0.04Ca, the optimal throat height is 4h1, the optimal jet angle is 20°, the optimal connection height is 0.07Ca, and Ca and h1 respectively represent the axial chord length of the impeller corresponding to the blade tip and the clearance of the blade tip.

[0035] In one possible design, the optimal circumferential coverage angle of the end wall jet device, and the optimal length and optimal width of the jet channel, wherein the optimal circumferential coverage angle is 40°, the optimal length and optimal width of the jet channel are 0.18Ca and 0.07Ca respectively, and Ca represents the axial chord length of the impeller corresponding to the blade tip.

[0036] In a third aspect, a storage medium is provided, on which instructions are stored. When the instructions are run on a computer, a parameter determination method for an end wall jet device for unblocking a blockage in an axial flow pump blade tip as described in the first aspect or any possible design of the first aspect is executed.

[0037] In a fourth aspect, a computer program product comprising instructions is provided, which, when executed on a computer, causes the computer to execute a method for determining parameters of an end wall jet device for unblocking axial flow pump blade tip blockage as described in the first aspect or any possible design of the first aspect.

[0038] Beneficial effects:

[0039] (1) The end wall jet device provided by the present invention can suppress unstable flows such as unsteady breakup of blade tip leakage vortex, thereby clearing the blockage of the impeller blade tip channel. In this way, the problem of sudden drop in head, increased noise and rotational stall caused by blade tip blockage in axial flow pumps under low flow conditions is solved. At the same time, since the device does not require external energy input, it can effectively reduce the difficulty of specific implementation. Therefore, the device has broad development prospects and is suitable for large-scale application and promotion in the field of impeller expansion stabilization technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A structural diagram of an end wall jet device for clearing axial flow pump impeller tip blockage provided by an embodiment of the present invention;

[0041] Figure 2 A schematic diagram of the circumferential distribution of the end wall jet device provided by an embodiment of the present invention;

[0042] Figure 3 A flow chart of the steps of a method for determining parameters of an end wall jet device for clearing a clogged blade tip of an axial flow pump provided by an embodiment of the present invention;

[0043] Figure 4 An internal streamline distribution diagram of an end wall jet device provided by an embodiment of the present invention;

[0044] Figure 5 A comparison diagram of the external characteristic curves of the end wall jet device model provided by an embodiment of the present invention;

[0045] Figure 6 A comparative schematic diagram of the static pressure contour lines, relative velocity, streamlines, and axial reversal zone distribution at 0.99 times the blade height of the endwall jet device provided by an embodiment of the present invention under low flow conditions;

[0046] Figure 7 A schematic diagram of the distribution of blockage coefficients at different sections of the impeller flow channel of the end wall jet device provided by an embodiment of the present invention;

[0047] Figure 8 A schematic structural diagram of an electronic device provided by an embodiment of the present invention.

[0048] Reference numerals: 10 - jet bridge; 20 - suction base; 30 - jet base; 40 - impeller; 11 - first hollow plate; 12 - second hollow plate; 13 - third hollow plate; 50 - end wall jet device. DETAILED DESCRIPTION

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the present invention will be briefly introduced below in conjunction with the drawings and the description of the embodiments or the prior art. Obviously, the following description of the structure of the drawings is only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention.

[0050] It should be understood that although the terms "first," "second," etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element can be referred to as a second element, and similarly, a second element can be referred to as a first element without departing from the scope of the exemplary embodiments of the present invention.

[0051] It should be understood that the term "and / or" that may appear in this document is merely a description of the association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B may indicate three situations: A exists alone, B exists alone, and A and B exist at the same time. The term " / and" that may appear in this document describes another type of association object relationship, indicating that two relationships may exist. For example, A / and B may indicate two situations: A exists alone, and A and B exist alone. In addition, the character " / " that may appear in this document generally indicates that the previous and subsequent associated objects are in an "or" relationship.

[0052] Example:

[0053] See also Figures 1-2As shown, the end wall jet device for unblocking the impeller tip of an axial flow pump provided in this embodiment may include, but is not limited to: a jet bridge 10, a suction base 20 and a jet base 30, wherein, for example, a jet channel is provided in the jet bridge 10 so that the fluid at the top of the impeller 40 flows through the jet channel; further, for example, the suction base 20 and the jet base 30 are both hollow structures, and in a specific implementation, one end of the jet bridge 10 is connected to the suction base 20, and the other end of the jet bridge 10 is connected to the jet base 30, so that when the jet bridge 10 is respectively connected to the suction base 20 and the jet base 30, the suction base 20 and the jet base 30 can be connected to the jet channel, thereby forming a fluid jet bridge.

[0054] In addition, in this embodiment, for example, the ends of the suction base 20 and the jet base 30 away from the jet bridge 10 are respectively fixed on the circumferential surface of the impeller 40 of the axial flow pump, wherein the suction base 20 and the jet base 30 are respectively arranged in sequence along the axial direction of the impeller 40, and the end surface of the suction base 20 connected to the impeller 40 is provided with a suction port, and the end surface of the jet base 30 connected to the impeller 10 is provided with a jet port, and the pressure between the suction port and the jet port is different; based on this, due to the different pressures between the suction port and the jet port, there will be a pressure difference in the fluid jet bridge of the end wall jet device, so that the fluid on the impeller 40 can enter the end jet device from the suction port and be accelerated to eject the end jet device from the jet port, and under the action of the pressure difference, a suction-injection flow cycle can be formed inside the end wall jet device, thereby suppressing unstable flows such as the unsteady breakup of the blade tip leakage vortex, thereby clearing the blockage of the blade tip channel through the suction-injection process.

[0055] In this embodiment, the suction base 20 and the jet base 20 may also be arc-shaped bases, see Figure 1 As shown, the area of ​​the suction port is larger than the area of ​​the jet port. In this way, it can be ensured that the pressure at the jet port is greater than the pressure at the suction port, thereby forming a pressure difference inside, so as to achieve the function of forming a suction-jet flow cycle of the fluid inside the end wall jet device; of course, in specific applications, when the suction base 20 and the jet base 30 are fixed on the impeller 40, a corresponding gap will be reserved between the two bases and the impeller 40, so that the fluid enters the suction port from the gap at the suction base 20 and is ejected from the device from the corresponding gap of the jet base 30.

[0056] Optionally, for example, multiple end wall jet devices may be provided on the circumferential surface of the impeller 40, see Figure 2 As shown, in this embodiment, there are preferably six end wall jet devices 50, and the six end wall jet devices 50 are evenly arranged along the circumferential direction.

[0057] In a specific implementation, the jet bridge 10 may include, but is not limited to: a first hollow plate 11, a second hollow plate 12, and a third hollow plate 13, wherein the first hollow plate 11 is a rectangular plate, and the second hollow plate 12 and the third hollow plate 13 are both arc-shaped plates. Figure 1 shown.

[0058] At the same time, the connection structure between the aforementioned components is: one end of the first hollow plate 11 is connected to the second hollow plate 12, and the other end of the first hollow plate 11 is connected to the third hollow plate 13, and when the first hollow plate 11 is respectively connected to the second hollow plate 12 and the third hollow plate 13, the first hollow plate 11, the second hollow plate 12 and the third hollow plate 13 are interconnected to form the jet channel; in this way, through the aforementioned structure, the entire jet bridge 10 can form an arched structure, which is more conducive to the suction and spraying of the fluid.

[0059] Therefore, through the above detailed explanation of the end wall jet device, this device uses the pressure difference effect to form a suction-injection flow cycle of the fluid inside the end wall jet device without the help of external force. In this way, unstable flows such as the unsteady breakup of the blade tip leakage vortex can be suppressed, thereby unblocking the channel blockage at the impeller blade tip, thereby achieving the purpose of improving the rotational stall of the axial flow pump and ensuring the stable operation of the axial flow pump.

[0060] See also Figure 3 As shown, the second aspect of this embodiment provides a method for determining the parameters of the end wall jet device for clearing the blockage of the blade tips of an axial flow pump as described in the first aspect of the embodiment, so as to determine the optimal structural parameters of the end wall jet device in the first aspect of the embodiment, thereby achieving the best blockage clearing effect.

[0061] In this embodiment, the parameter determination method mentioned above can be, but is not limited to, executed on the simulation end side. It can be understood that the aforementioned execution subject does not constitute a limitation on the embodiment of the present application. Accordingly, the operation steps of this method can be, but are not limited to, as shown in the following steps S1 to S3.

[0062] S1. Obtain a simulation geometric model and a model parameter set, wherein the simulation geometric model is a geometric model of an end wall jet device installed on the circumferential surface of an impeller of an axial flow pump, and the model parameter set includes multiple groups of model parameters, and any model parameter includes the installation structural parameters of the end wall jet device, and the structural parameters of the suction port, the structural parameters of the jet bridge, and the structural parameters of the jet port in the end wall jet device; in specific applications, the simulation geometric model and the model parameter set can be, but are not limited to, pre-stored on the simulation end side; at the same time, the aforementioned structural parameters can be, but are not limited to, the axial length and circumferential width of the suction port, and the structural parameters of the jet port can be, but are not limited to, the axial distance between the jet port and the leading edge of the impeller blade, the throat height of the jet port (which can be understood as the width inside the jet port), the jet angle of the jet port, and the connection height between the jet base and the jet bridge (see Figure 1 , Figure 1 The l 1 in the is the height of the connection).

[0063] Furthermore, exemplary installation structural parameters may include, but are not limited to, the circumferential coverage angle of the end wall jet device, see Figure 2 As shown, Figure 2 The θ2 in the equation represents the circumferential coverage angle, that is, the angle between the two ends of the entire device and the line connecting the center of the impeller. Similarly, the structural parameters of the jet bridge include the length and width of the jet channel ( Figure 1 Here, l2 represents the length and l3 represents the width).

[0064] In addition, for example, the aforementioned installation structural parameters, suction port structural parameters, jet bridge structural parameters, and jet port structural parameters are all set with corresponding value ranges; taking the suction port structural parameters as an example, the axial length of the suction port is in the range of 12% to 18% Ca, and the circumferential width of the suction port is in the range of 20% to 30% Ca; the axial distance between the jet port and the leading edge of the impeller blade is in the range of 0 to 20% Ca, and the throat height of the jet port is in the range of 4h. 1， The jet angle of the jet outlet ranges from 10° to 40°, and the connection height between the jet base and the jet bridge ranges from 5% to 9% of Ca. In this embodiment, Ca represents the axial chord length of the impeller corresponding to the blade tip, and h1 represents the clearance between the impeller and the blade tip. Of course, the value ranges of the remaining parameters are no longer listed one by one.

[0065] In this embodiment, it is possible but not limited to adopting a preset interval value-taking method to take values ​​from the value range corresponding to each parameter, thereby combining different model parameters. The principle is a commonly used data value-taking technology and will not be repeated here.

[0066] After obtaining the simulation geometric model of the end wall jet device and its corresponding multiple model parameters, a simulation can be performed under a low flow rate condition, wherein the simulation process is shown in the following step S2.

[0067] S2. Using the model parameter set, perform end jet numerical simulation on the simulation geometric model to obtain the numerical simulation results corresponding to the simulation geometric model when the numerical simulation is performed with each set of model parameters as the simulation parameters; in this embodiment, for example, but not limited to, the fluid mechanics software ANSYS CFX can be used to perform numerical simulation on the aforementioned simulation geometric model; wherein, the fixed parameters of the simulation are: the inlet boundary condition is the total pressure, the outlet boundary condition is the mass flow rate, and the wall surface is set as an adiabatic no-slip boundary. Based on this, under the simulation of the aforementioned fixed parameters and model parameters, the numerical simulation results corresponding to each set of model parameters can be obtained.

[0068] Furthermore, any of the numerical simulation results may include, but is not limited to: the first fluid density of the target fluid on the impeller, the second fluid density of the target fluid in the end wall jet device, the first flow velocity of the target fluid on the impeller, and the second flow velocity of the target fluid in the end wall jet device, wherein the target fluid is the fluid used in the end jet numerical simulation processing; of course, any numerical simulation result may also include the external characteristic curve of the axial flow pump, the blade tip flow field distribution, etc.

[0069] After obtaining the numerical simulation results corresponding to the various model parameters, the optimal model parameters can be determined based on the numerical simulation results, and thus used as the optimal structural parameters of the device; wherein the determination process is shown in the following step S3.

[0070] S3. Select the optimal numerical simulation result from several numerical simulation results, and use the model parameters corresponding to the optimal numerical simulation result as the optimal structural parameters of the end wall jet device; in this embodiment, for example, but not limited to, the following steps S31 and S32 can be used to select the optimal numerical simulation result.

[0071] S31. Calculate the blockage coefficient of the simulation geometric model when the numerical simulation is performed with each model parameter as the simulation parameter based on the numerical simulation results; in specific applications, take any numerical simulation result as an example to specifically explain the calculation process of the blockage coefficient; wherein, for any numerical simulation result, it can be, but is not limited to, based on the first fluid density, the second fluid density, the first flow velocity and the second flow velocity in any numerical simulation result, and using the following formula (1), calculate the blockage coefficient of the simulation geometric model when the numerical simulation is performed with any model parameter as the simulation parameter.

[0072] B e =A b / A (1)

[0073]

[0074] In the above formula (1), B e It represents the blocking coefficient of the simulation geometric model when the numerical simulation is performed with any of the model parameters as simulation parameters, A b is an intermediate parameter, and A represents the circumferential cross-sectional area of ​​the impeller corresponding to the blade tip.

[0075] In the above formula (2), ρ represents the first fluid density in any numerical simulation result, ρ cr represents the second fluid density in any numerical simulation result, v m represents the first streamwise velocity in any numerical simulation result, v cr represents the second stream velocity in any of the numerical simulation results.

[0076] Thus, based on the aforementioned formulas (1) and (2), the blockage coefficient corresponding to the simulation geometric model can be calculated when numerical simulation processing is performed using each model parameter as the simulation parameter. Then, based on the blockage coefficient, the optimal numerical simulation result can be determined, as shown in the following step S32.

[0077] S32. The numerical simulation result corresponding to the minimum blockage coefficient is taken as the optimal numerical simulation result. In this embodiment, the minimum blockage coefficient indicates that the model parameters associated with the corresponding numerical simulation result can optimize the dredging effect of the end wall jet device. Therefore, the numerical simulation result corresponding to the minimum blockage coefficient can be taken as the optimal numerical simulation result, and the model parameters corresponding to the optimal numerical simulation result are the optimal structural parameters of the end wall jet device.

[0078] Furthermore, in this embodiment, the optimal structural parameters include: the optimal axial length and optimal circumferential width of the suction port, the optimal axial distance between the jet port and the leading edge of the impeller blade tip, the optimal throat height of the jet port, the optimal jet angle of the jet port and the optimal connection height between the jet base and the jet bridge, the optimal circumferential coverage angle of the end wall jet device, and the optimal length and optimal width of the jet channel; wherein, the optimal axial length is 0.15Ca, the optimal circumferential width is 0.24Ca, the optimal axial distance is 0.04Ca, the optimal throat height is 4h1, the optimal jet angle is 20°, the optimal connection height is 0.07Ca, the optimal circumferential coverage angle is 40°, and the optimal length and optimal width of the jet channel are 0.18Ca and 0.07Ca respectively; at the same time, the axial chord length of the blade tip is 54mm, and the clearance of the blade tip is 0.3mm.

[0079] Therefore, through the parameter determination method described in detail in the aforementioned steps S1 to S3, the present invention can obtain the blockage coefficient of the end wall jet device under different structural parameters through simulation. In this way, its optimal structural parameters can be determined based on the blockage coefficient, so as to achieve the maximum blockage unblocking effect.

[0080] See also Figures 4 to 7 As shown, the third aspect of this embodiment provides a simulation example of the end wall jet device described in the first aspect of the embodiment, and the simulation results are shown below.

[0081] This embodiment uses a closed axial flow pump circulation test bench as the research object. The design mass flow rate of the axial flow pump is 30.93 kg / s, the speed is 1710 rpm, the number of blades is 6, the blade tip axial chord length Ca = 54 mm, and the blade tip clearance is 0.3 mm. The distribution diagram of the blade tip leakage flow and the axial reversal flow zone corresponding to the near-stall condition of the axial flow pump without the end wall jet device is calculated by ANSYS CFX software, as shown in the figure. Figure 6 As shown in (a), Figure 6 As shown in (a), there is a large area of ​​flow blockage at the blade tip of the axial flow pump, which is induced by the unsteady breakup of the blade tip leakage vortex.

[0082] When the end wall jet device provided in the first aspect of this embodiment (the parameters are the optimal parameters provided in the second aspect of the embodiment) is installed on the impeller, a simulation is performed on it to obtain the corresponding streamline distribution diagram; see Figure 4 As shown by Figure 4 It can be seen that the blade tip fluid flows in from the suction port of the circulation loop, passes through the circulation bridge, is accelerated in the nozzle, and is injected into the blade tip channel at a high-speed flow of about 7.8 m / s. The high-speed jet is the main factor in eliminating blade tip blockage and widening the stable operating area of ​​the axial flow pump.

[0083] at the same time, Figure 5 The comparison diagram of the external characteristic curve of the end wall jet device model is given. Figure 5 (a) is a schematic diagram of head comparison. Figure 5 (b) is a schematic diagram of efficiency comparison, where Figure 5 It can be seen that under the action of the end wall jet device, the stall point of the axial flow pump shifts to the low flow rate. Under the low flow rate condition, the head is increased by 58.3% and the efficiency is increased by 12.41%. In this way, the blockage of the impeller blade tip can be unblocked without reducing the operating efficiency.

[0084] Furthermore, Figure 6 A comparative diagram of the static pressure contours, relative velocity, streamlines, and axial reversal zone distribution at 0.99 times the blade height of the endwall jet device under low flow conditions is given. Figure 6 (a) is a schematic diagram of the distribution when the device provided in this embodiment is not set. Figure 6 (b) is a schematic diagram of the distribution after the end wall jet device is set; Figure 6 As can be seen from the figure, the black dotted line is the static pressure chute, which represents the trajectory of the leakage vortex core; Figure 6 As can be seen from (a), the static pressure chute in the blade tip channel disappears under the influence of backflow, indicating that the blade tip leakage vortex undergoes complete unsteady breakup, forming a large area of ​​low-speed fluid, which aggravates the blade tip blockage.

[0085] Thus, after adding the end wall jet device, the fluid velocity in the entire blade tip channel is significantly increased under the action of its high-speed jet; the suction port draws the low-speed fluid into the bridge path, causing the originally chaotic static pressure contours to concentrate near the suction surface of the blade, and the static pressure chute appears at about 0.2 times the chord length from the leading edge of the blade and develops downstream, indicating that the tip leakage vortex has not been broken and is caused by Figure 6 (b) shows that under the suction-injection action of the end wall jet device, the area of ​​the shaded part representing the axial reversal zone is greatly reduced, and the high-speed jet guides the blade tip leakage streamline closer to the blade suction surface, reducing the possibility of the blade tip leakage vortex colliding with the adjacent blade and causing unsteady breakup, thereby aggravating the blade tip blockage. Therefore, from the above simulation results, it can be concluded that the end wall jet device can effectively clear the blade tip blockage caused by the unsteady breakup of the blade tip leakage vortex under low flow conditions of the axial flow pump, thereby widening the stable operation area of ​​the axial flow pump.

[0086] in addition, Figure 7 The schematic diagram of the blockage coefficient distribution at different sections of the impeller flow channel of the end wall jet device is given. Figure 7The peak value of the blockage coefficient is about 65%. Under the action of the end wall jet device, the overall blockage coefficient in the impeller flow channel is greatly reduced, with a reduction value of about 47%. Under the action of the high-speed jet, the device of the present invention almost completely eliminates the effect of blade tip blockage.

[0087] To sum up, the present invention solves the problems of sudden drop in head, increased noise and rotational stall caused by blade tip blockage in axial flow pumps under low flow conditions, and has lower negative impact on the efficiency of axial flow pumps. At the same time, since the device does not require external energy input, it can effectively reduce the difficulty of specific implementation. Therefore, the device has broad development prospects and is suitable for large-scale application and promotion in the field of impeller stabilization technology.

[0088] like Figure 8 As shown, the fourth aspect of this embodiment provides an electronic device, wherein the electronic device includes: a memory, a processor and a transceiver that are communicatively connected in sequence, wherein the memory is used to store computer programs, the transceiver is used to send and receive messages, and the processor is used to read the computer program and execute the parameter determination method of the end wall jet device for unblocking the blade tip blockage of an axial flow pump as described in the second aspect of the embodiment.

[0089] For example, the memory may include, but is not limited to, random access memory (RAM), read-only memory (ROM), flash memory, first-in first-out memory (FIFO), and / or first-in last-out memory (FILO); specifically, the processor may include one or more processing cores, such as a quad-core processor, an octa-core processor, etc. The processor may be implemented in at least one hardware form selected from DSP (Digital Signal Processing), FPGA (Field-Programmable Gate Array), and PLA (Programmable Logic Array). Furthermore, the processor may include a main processor and a coprocessor. The main processor is a processor for processing data in an awake state, also known as a CPU (Central Processing Unit); and the coprocessor is a low-power processor for processing data in a standby state.

[0090] In some embodiments, the processor may be integrated with a GPU (Graphics Processing Unit), which is responsible for rendering and drawing the content to be displayed on the display screen. For example, the processor may be, but is not limited to, a microprocessor of the STM32F105 series, a reduced instruction set computer (RISC) microprocessor, an X86 architecture processor, or a processor with an integrated embedded neural network processing unit (NPU); the transceiver may be, but is not limited to, a wireless fidelity (WIFI) wireless transceiver, a Bluetooth wireless transceiver, a general packet radio service technology (GPRS) wireless transceiver, a ZigBee protocol (a low-power local area network protocol based on the IEEE802.15.4 standard, ZigBee) wireless transceiver, a 3G transceiver, a 4G transceiver, and / or a 5G transceiver. In addition, the device may also include, but is not limited to, a power module, a display screen, and other necessary components.

[0091] The working process, working details and technical effects of the electronic device provided in this embodiment can be found in the first and second aspects of the embodiment, and will not be repeated here.

[0092] The fifth aspect of this embodiment provides a storage medium that stores instructions for the method for determining parameters of an end wall jet device for unblocking a blockage in an axial flow pump blade tip as described in the second aspect of the embodiment, that is, the storage medium stores instructions, and when the instructions are run on a computer, the method for determining parameters of an end wall jet device for unblocking a blockage in an axial flow pump blade tip as described in the second aspect of the embodiment is executed.

[0093] The storage medium refers to a carrier for storing data, which may include but is not limited to a floppy disk, an optical disk, a hard disk, a flash memory, a USB flash drive and / or a memory stick, and the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device.

[0094] The working process, working details and technical effects of the storage medium provided in this embodiment can be found in the first and second aspects of the embodiment, and will not be repeated here.

[0095] A sixth aspect of this embodiment provides a computer program product comprising instructions, which, when executed on a computer, causes the computer to execute the parameter determination method for an end wall jet device for unblocking a blockage in an axial flow pump blade tip as described in the first aspect of the embodiment, wherein the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device.

[0096] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A method for determining parameters of an end wall jet device for clearing a blockage in an axial flow pump blade tip, the method being applied to the end wall jet device for clearing a blockage in an axial flow pump blade tip, the end wall jet device for clearing a blockage in an axial flow pump blade tip comprising: A jet bridge (10), wherein a jet channel is provided in the jet bridge (10); A suction base (20) and a jet base (30); The suction base (20) and the jet base (30) are both hollow structures, wherein one end of the jet bridge (10) is connected to the suction base (20), and the other end of the jet bridge (10) is connected to the jet base (30), and when the jet bridge (10) is respectively connected to the suction base (20) and the jet base (30), the suction base (20) and the jet base (30) are connected to the jet channel to form a fluid jet bridge; The ends of the suction base (20) and the jet base (30) away from the jet bridge (10) are respectively fixed on the circumferential surface of the impeller (40) of the axial flow pump, wherein the suction base (20) and the jet base (30) are respectively arranged in sequence along the axial direction of the impeller (40), a suction port is provided on the end surface of the suction base (20) connected to the impeller (40), and a jet port is provided on the end surface of the jet base (30) connected to the impeller (40), and the pressures of the suction port and the jet port are different; The jet bridge (10) comprises: a first hollow plate (11), a second hollow plate (12) and a third hollow plate (13), wherein the first hollow plate (11) is a rectangular plate, and the second hollow plate (12) and the third hollow plate (13) are both arc-shaped plates; One end of the first hollow plate (11) is connected to the second hollow plate (12), and the other end of the first hollow plate (11) is connected to the third hollow plate (13), and when the first hollow plate (11) is respectively connected to the second hollow plate (12) and the third hollow plate (13), the first hollow plate (11), the second hollow plate (12) and the third hollow plate (13) are interconnected to form the jet channel; There are a plurality of end wall jet devices, and the plurality of end wall jet devices are circumferentially arranged on the circumferential surface of the impeller (40); The invention is characterized by comprising: Obtaining a simulation geometric model and a model parameter set, wherein the simulation geometric model is a geometric model of an end wall jet device installed on the circumferential surface of an impeller of an axial flow pump, and the model parameter set includes multiple sets of model parameters, and any model parameter includes installation structure parameters of the end wall jet device, and structural parameters of a suction port, a jet bridge, and a jet port in the end wall jet device; Using the model parameter set, performing end jet numerical simulation processing on the simulation geometric model to obtain numerical simulation results corresponding to the simulation geometric model when the numerical simulation processing is performed using each set of model parameters as simulation parameters; Selecting an optimal numerical simulation result from a plurality of numerical simulation results, and using the model parameters corresponding to the optimal numerical simulation result as the optimal structural parameters of the end wall jet device; The step of selecting the best numerical simulation result from a plurality of numerical simulation results comprises: Calculating, based on each numerical simulation result, a blocking coefficient of the simulation geometric model when performing numerical simulation processing using each model parameter as a simulation parameter; The numerical simulation result corresponding to the minimum blocking coefficient is taken as the optimal numerical simulation result; Any one of the plurality of numerical simulation results includes: a first fluid density of the target fluid on the impeller, a second fluid density of the target fluid in the end wall jet device, a first flow velocity of the target fluid on the impeller, and a second flow velocity of the target fluid in the end wall jet device, wherein the target fluid is the fluid used in the end jet numerical simulation process; The blocking coefficient of the simulated geometric model is calculated based on the numerical simulation results when the numerical simulation is performed using the model parameters as simulation parameters, including: For any numerical simulation result, based on the first fluid density, the second fluid density, the first flow velocity, and the second flow velocity in the numerical simulation result, and using the following formula (1), the blockage coefficient of the simulation geometric model is calculated when the numerical simulation is performed using any model parameter as the simulation parameter; B e =A b / A (1) In the above formula (1), B e It represents the blocking coefficient of the simulation geometric model when the numerical simulation is performed with any of the model parameters as simulation parameters, A b is an intermediate parameter, A represents the circumferential cross-sectional area of ​​the impeller corresponding to the blade tip; In the above formula (2), ρ represents the first fluid density in any numerical simulation result, ρ cr represents the second fluid density in any numerical simulation result, v m represents the first streamwise velocity in any numerical simulation result, v cr represents the second stream velocity in any of the numerical simulation results.

2. The method according to claim 1, characterized in that The structural parameters of the suction port include the axial length and circumferential width of the suction port, and the structural parameters of the jet port include the axial distance between the jet port and the leading edge of the impeller blade tip, the throat height of the jet port, the jet angle of the jet port, and the connection height between the jet base and the jet bridge; The installation structure parameters include the circumferential coverage angle of the end wall jet device; and The structural parameters of the jet bridge include the length and width of the jet channel.

3. The method according to claim 2, characterized in that The optimal structural parameters include: the optimal axial length and optimal circumferential width of the suction port, wherein the optimal axial length is 0.15Ca, the optimal circumferential width is 0.24Ca, and Ca represents the axial chord length of the impeller corresponding to the blade tip.

4. The method according to claim 2, characterized in that The optimal structural parameters include: the optimal axial distance between the jet port and the leading edge of the impeller blade tip, the optimal throat height of the jet port, the optimal jet angle of the jet port, and the optimal connection height between the jet base and the jet bridge; Among them, the optimal axial distance is 0.04Ca, the optimal throat height is 4h1, the optimal jet angle is 20°, the optimal connection height is 0.07Ca, and Ca and h1 respectively represent the axial chord length of the impeller corresponding to the blade tip and the clearance of the blade tip.

5. The method according to claim 2, characterized in that The optimal structural parameters also include: the optimal circumferential coverage angle of the end wall jet device, and the optimal length and optimal width of the jet channel, wherein the optimal circumferential coverage angle is 40°, the optimal length and optimal width of the jet channel are 0.18Ca and 0.07Ca respectively, and Ca represents the axial chord length of the impeller corresponding to the blade tip.

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