Vortex pump hydraulic performance evaluation method based on internal flow

Abstract

Disclosed in the present invention is a vortex pump hydraulic performance evaluation method based on internal flow, comprising the following steps: S1, carrying out vortex pump full-flow-domain CFD numerical simulation calculation; S2, calculating a head coefficient NH* and a hydraulic efficiency η of a vortex pump; S3, calculating a slope sl of a curve in a linear acceleration section; S4, calculating a longitudinal vortex position coefficient lv *; S5, calculating a momentum exchange coefficient It *; S6, calculating a dissipation loss coefficient Ndep*; and S7, calculating a flow separation coefficient Nssv*. According to the present invention, starting with an internal flow mechanism of a vortex pump, feature extraction is carried out on a three-dimensional numerical simulation flow field of the vortex pump, and the hydraulic performance of the vortex pump is systematically evaluated from two aspects of work done and flow loss, thereby fully reflecting the internal exchange flow pattern of the vortex pump and covering the shortage that internal flow is ignored in existing vortex pump hydraulic performance evaluation methods.

Description

Hydraulic performance evaluation method of vortex pump based on internal flow Technical Field

[0001] The present invention relates to the technical field of vortex pumps, and in particular to a method for evaluating the hydraulic performance of a vortex pump based on internal flow. Background Art

[0002] A vortex pump, a vane-type pump based on momentum exchange between the impeller and the pump casing, boasts the ability to achieve high head at extremely low flow rates. Its simple structure, consisting primarily of an impeller, pump chamber, and pump cover, makes it widely used in industries such as the chemical industry, automotive, construction, and fire protection. However, the internal flow within a vortex pump is highly complex. The liquid flows in a three-dimensional spiral pattern, accompanied by intense momentum exchange and vortex interaction, resulting in relatively high energy losses. Consequently, its efficiency is low, typically below 50%. Due to the specific nature of their operating principle, vortex pumps lack a specific theoretical design method. Designers often rely on their own experience and experimental prototype testing during the design optimization process, which undoubtedly increases the design and optimization cycle and difficulty, leading to increased design costs. The mature development of computational fluid dynamics (CFD) technology has provided strong support for solving complex three-dimensional flows within vortex pumps. This method has been widely adopted by scholars and has been experimentally validated.

[0003] There are many types of vortices in a vortex pump. The development and shedding of vortices have extremely strong dynamic characteristics, and the interaction between the vortices causes the vortex motion and its evolution to have complex spatiotemporal characteristics. These factors lead to the particularity of the working principle of the vortex pump, which is also an important flow characteristic that distinguishes the vortex pump from other vane pumps. Therefore, the evaluation of the hydraulic performance of the vortex pump must fully consider the influence of the internal flow of the pump. Using CFD to carry out numerical simulation of the hydraulic performance and internal flow of the vortex pump can not only extract the performance results of the vortex pump, but also obtain rich flow field information. However, the existing evaluation methods of vortex pumps usually use indicators such as head and hydraulic efficiency. This is an evaluation of the macroscopic performance of the vortex pump. There is a lack of evaluation of the internal flow of the vortex pump, making it difficult to reveal the differences in the hydraulic performance of the vortex pump from the perspective of internal flow.

[0004] Summary of the Invention

[0005] The technical problem to be solved by the present invention is: in order to solve the technical problem that it is difficult to evaluate the hydraulic performance differences of existing vortex pumps from the perspective of internal flow, the present invention provides a vortex pump hydraulic performance evaluation method based on internal flow, which can systematically evaluate the hydraulic performance of a vortex pump from the perspective of internal flow.

[0006] The technical solution adopted by the present invention to solve the technical problem is: a method for evaluating the hydraulic performance of a vortex pump based on internal flow, comprising the following steps:

[0007] S1. Construct a three-dimensional model of the vortex pump using its impeller, pump chamber, and pump cover, and perform flow domain extraction. The flow domain model of the vortex pump is divided into: inlet pump casing flow channel, impeller flow domain, outlet pump casing flow channel, inlet axial clearance, outlet axial clearance, and radial clearance. Grids are divided for each flow domain, and CFD numerical simulation calculations are performed on the entire flow domain of the vortex pump.

[0008] S2, extract the flow field data of the characteristic position of the vortex pump, and calculate the head coefficient NH of the vortex pump * and hydraulic efficiency η;

[0009] S3. Extract the pressure values ​​p at each monitoring point in the circumferential direction of the impeller, the inlet pump casing flow channel, or the outlet pump casing flow channel from the internal flow field of the vortex pump, plot a growth curve of the pressure coefficient p* after processing, and calculate the slope sl of the curve in the linear acceleration region;

[0010] S4, extracting the velocity cloud map and streamline map of the longitudinal section of the vortex pump from the internal flow field of the vortex pump, and finding the axial position h of the longitudinal vortex on the section al , and using the impeller height h ab After processing, the longitudinal vortex position coefficient l is obtained v * ;

[0011] S5. Extract the exchange flow cloud diagram of any one of the impeller, the inlet pump casing flow channel or the outlet pump casing flow channel on the axial section from the internal flow field of the vortex pump, and calculate the exchange momentum p ex , the momentum p on the cross section sf , after processing, the momentum exchange coefficient I is obtained t * ;

[0012] S6, extracting entropy generation distribution data from the internal flow field of the vortex pump, and obtaining the dissipation loss coefficient Ndep after processing * ;

[0013] S7, extracting the velocity vortex intensity ssv of any one of the impeller, the inlet pump casing flow channel or the outlet pump casing flow channel from the internal flow field of the vortex pump, and obtaining the flow separation coefficient Nssv in the vortex pump after processing *Therefore, starting from the internal flow mechanism of the vortex pump, the characteristics of the three-dimensional numerical simulation flow field of the vortex pump are extracted, and the hydraulic performance of the vortex pump is systematically evaluated from the two perspectives of work and flow loss. This fully reflects the internal exchange flow law of the vortex pump and makes up for the deficiency of ignoring the internal flow in the existing vortex pump hydraulic performance evaluation method. At the same time, the mapping relationship and analysis model between "vortex pump model-internal flow-hydraulic performance" are established, which links the internal flow and external characteristics of the vortex pump and realizes the evaluation of the hydraulic performance of the vortex pump.

[0014] Furthermore, in step S2, the pressure p at the inlet of the vortex pump is obtained. out , outlet pressure p in , fluid density ρ, speed n, fluid flow Q, torque M, the outer diameter D of the impeller out , the inner diameter D of the impeller in ;

[0015] The lift of the vortex pump

[0016] The median diameter of the impeller

[0017] The fluid velocity at the blade mid-diameter

[0018] The head coefficient of the vortex pump

[0019] The shaft power of the vortex pump

[0020] The hydraulic efficiency of the vortex pump

[0021] Where: g represents the acceleration due to gravity, and its unit is m / s 2 , pressure p out , pressure p in The unit of density is Pa, and the unit of density ρ is kg / m 3 , the unit of speed n is rpm, the unit of flow Q is m 3 / s, the unit of torque M is Nm, u m The unit is m / s. Therefore, through the head coefficient NH * And the hydraulic efficiency η can evaluate the hydraulic performance of the vortex pump from a macro perspective.

[0022] Furthermore, in step S3, the pressurization process of the vortex pump is divided into a flow development region and a linear acceleration region according to the flow conditions, and the pressure coefficient

[0023] Select the starting point A and the end point B from the flow acceleration area, and the slope

[0024] The unit of pressure value p is Pa. Therefore, in the flow development area, stable energy exchange has not yet been formed, and the pressure p does not increase significantly. However, the fluid pressurization effect in the linear acceleration area is significant. The slope sl of the pressure p curve in this area can reflect the vortex pump's ability to increase fluid pressure. The larger the slope sl, the faster the pressure growth of the vortex pump, the stronger the vortex pump's work capacity, and the higher the vortex pump's head H.

[0025] Furthermore, in step S4, the longitudinal vortex position coefficient is calculated

[0026] Where: axial position h al , the height h of the impeller ab The unit of the vortex pump is mm. Therefore, it can reflect the intensity of the fluid exchange driven by the longitudinal vortex, and is a characterization of the longitudinal vortex strength. At the same time, it comes from the internal flow of the vortex pump and is also a concrete manifestation of the vortex pump's functional capacity.

[0027] Furthermore, in step S5, the mass flow rate m exchanged by the vortex pump is obtained. ex , the selected axial mass flow rate m sf , fluid velocity v;

[0028] The momentum exchange value p ex =m ex v;

[0029] The momentum value p on the cross section sf =m sf v;

[0030] Where: exchange mass flow rate m ex , select the axial mass flow rate m sf The unit of is kg / s, the unit of fluid velocity v is m / s, and the momentum exchange value p ex , the momentum value p on the cross section sf The unit is kgm / s 2 . Thus, by exchanging the momentum value p ex It can measure the degree of momentum exchange inside the vortex pump by the momentum value p on the axial section. sf It can measure the momentum on this cross section.

[0031] Furthermore, in step S5, the momentum exchange coefficient

[0032] Therefore, the momentum exchange coefficient l v* It indicates the intensity of the fluid momentum exchange in the vortex pump. The larger the value, the more intense the energy transfer between the inlet pump casing flow channel, the outlet pump casing flow channel and the impeller fluid.

[0033] Furthermore, in step S6, the total dissipated entropy production DEP is calculated according to the Reynolds time-averaged method. sum Direct dissipative entropy production (DEP) d and turbulent dissipated entropy production (DEP) t ; Among them, the total dissipated entropy production DEP sum , direct dissipation of entropy production DEP d , turbulent dissipated entropy production DEP t The unit is kg / ms 3 K. Therefore, entropy generation, as a measure of adiabatic mechanical dissipation losses, is crucial for locating and evaluating flow losses inside vortex pumps.

[0034] Furthermore, in step S6, the dynamic viscosity μ of the vortex pump fluid, the thermodynamic temperature T of the fluid, the velocity component u of the x-axis, the velocity component v of the y-axis, the velocity component w of the z-axis of the fluid in the Cartesian coordinate system, and the dissipation rate ε of the fluid are obtained;

[0035] The total dissipated entropy production DEP sum =DEP d +DEP t ;

[0036] Direct dissipation of entropy production

[0037] The turbulence dissipates entropy production

[0038] The unit of fluid dynamic viscosity μ is Pas, the unit of fluid thermodynamic temperature T is K, the unit of fluid x-axis velocity component u, y-axis velocity component v, and z-axis velocity component w are all m / s, and the unit of fluid dissipation rate ε is m 2 / s 2 Therefore, the total dissipated entropy production DEP sum , direct dissipation of entropy production DEP d and turbulent dissipated entropy production (DEP) t The internal flow loss of the vortex pump is systematically measured from the overall and partial perspectives, which directly affects the performance of the vortex pump. The size of the loss in the vortex pump can be evaluated by comparing these three indicators.

[0039] Furthermore, in step S6, the total dissipated entropy production DEP is extracted from the internal flow field of the vortex pump. sum , after processing, the total dissipation loss coefficient is obtained

[0040] Extracting Direct Dissipated Entropy Production (DEP) from the Internal Flow Field of the Vortex Pump d , after processing, the direct dissipation loss coefficient is obtained

[0041] Extracting turbulent dissipated entropy production (DEP) from the internal flow field of the vortex pump t , after processing, the turbulent dissipation loss coefficient is obtained

[0042] Therefore, the total dissipation loss coefficient Ndep sum * , direct dissipation loss Ndep d * and turbulent dissipation loss coefficient Ndep t * The larger it is, the more flow loss there is in the vortex pump, and the greater the energy dissipation of the vortex pump.

[0043] Furthermore, in step S7, the velocity swirl intensity ssv and flow separation coefficient of the fluid are obtained.

[0044] The unit of the velocity swirl intensity ssv is 1 / s. Therefore, the velocity swirl intensity ssv indicates the intensity of the fluid rotating around the local center, and the flow separation coefficient Nssv * It indicates the severity of flow separation inside the vortex pump, the flow separation coefficient Nssv * The larger it is, the more obvious the fluid flow separation is.

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

[0046] 1. Starting from the internal flow mechanism of the vortex pump, the present invention extracts the characteristics of the three-dimensional numerical simulation flow field of the vortex pump, and systematically evaluates the hydraulic performance of the vortex pump from the two perspectives of work and flow loss. It fully reflects the internal exchange flow law of the vortex pump, and makes up for the deficiency of ignoring the internal flow in the existing vortex pump hydraulic performance evaluation method. At the same time, a mapping relationship and analysis model between "vortex pump model-internal flow-hydraulic performance" are established, which links the internal flow and external characteristics of the vortex pump, and realizes the evaluation of the hydraulic performance of the vortex pump.

[0047] 2. The present invention is based on numerical simulation data and does not require experiments, which greatly shortens the cycle and cost of vortex pump performance evaluation. At the same time, it facilitates designers to evaluate the performance of vortex pumps in multiple dimensions, improves the comprehensiveness and rationality of vortex pump performance evaluation, and can also provide design ideas for performance optimization of vortex pumps from a flow perspective. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The present invention will be further described below with reference to the accompanying drawings and examples.

[0049] FIG1 is a flow chart of a method for evaluating the hydraulic performance of a vortex pump based on internal flow according to the present invention;

[0050] FIG2 is a schematic structural diagram of a vortex pump according to the present invention;

[0051] FIG3 is a schematic structural diagram of the vortex pump flow region of the present invention;

[0052] FIG4 is a schematic diagram of monitoring point positions of a vortex pump according to the present invention;

[0053] FIG5 is a comparison diagram of the pressure growth curves of the vortex pumps of Example 1 and Example 2;

[0054] FIG6 is a comparison diagram of the longitudinal vortices of the vortex pumps of Example 1 and Example 2;

[0055] FIG7 is a comparison diagram of the exchange flow of the vortex pumps of Example 1 and Example 2

[0056] FIG8 is a comparison diagram of the dissipated entropy generation loss of the vortex pumps of Example 1 and Example 2;

[0057] FIG9 is a comparison diagram of the flow separation of the vortex pumps of Example 1 and Example 2.

[0058] In the figure: 1, vortex pump; 101, impeller; 102, pump chamber; 103, pump cover; 104, inlet pump casing flow channel; 105, impeller flow field; 106, outlet pump casing flow channel; 107, inlet axial clearance; 108, outlet axial clearance; 109, radial clearance. DETAILED DESCRIPTION

[0059] The present invention will now be described in further detail with reference to the accompanying drawings, which are simplified schematic diagrams that illustrate the basic structure of the present invention in a schematic manner.

[0060] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply 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, features defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0061] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and 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 the specific circumstances.

[0062] As shown in FIG1 to FIG9 , which are the best embodiments of the present invention, the method for evaluating the hydraulic performance of a vortex pump based on internal flow in this embodiment includes the following steps:

[0063] S1. Construct a three-dimensional model of the vortex pump 1 using its impeller 101, pump chamber 102, and pump cover 103, and perform flow domain extraction. The flow domain model of the vortex pump 1 is divided into: inlet pump casing flow channel 104, impeller flow domain 105, outlet pump casing flow channel 106, inlet axial gap 107, outlet axial gap 108, and radial gap 109. Grids are divided for each flow domain, and CFD numerical simulation calculations of the entire flow domain of the vortex pump 1 are performed.

[0064] S2. Extract the flow field data of the characteristic position of the vortex pump 1 to calculate the head coefficient NH of the vortex pump 1 * and hydraulic efficiency η;

[0065] S3. Extract the pressure value p of each monitoring point in the circumferential direction of the impeller 101, the inlet pump casing flow channel 104, or the outlet pump casing flow channel 106 from the internal flow field of the vortex pump 1, and after processing, draw a growth curve of the pressure coefficient p*, and calculate the slope sl of the curve in the linear acceleration region;

[0066] S4. Extract the velocity cloud map and streamline map of the longitudinal section of the vortex pump 1 from the internal flow field of the vortex pump 1, and find the axial position h of the longitudinal vortex on the section. al , and using the impeller 101 height h ab After processing, the longitudinal vortex position coefficient l is obtained v * ;

[0067] S5. Extract the exchange flow cloud diagram of any one of the impeller 101, the inlet pump casing flow channel 104 or the outlet pump casing flow channel 106 on the axial section from the internal flow field of the vortex pump 1, and calculate the exchange momentum p ex , the momentum p on the cross section sf , after processing, the momentum exchange coefficient I is obtained t * ;

[0068] S6. Extract the entropy generation distribution data from the internal flow field of the vortex pump 1 and obtain the dissipation loss coefficient Ndep after processing. * ;

[0069] S7, extract the velocity vortex intensity ssv of any one of the impeller 101, the inlet pump casing flow channel 104 or the outlet pump casing flow channel 106 from the internal flow field of the vortex pump 1, and obtain the flow separation coefficient Nssv in the vortex pump 1 after processing * Therefore, starting from the internal flow mechanism of the vortex pump 1, the characteristics of the three-dimensional numerical simulation flow field of the vortex pump 1 are extracted, and the hydraulic performance of the vortex pump 1 is systematically evaluated from the two perspectives of work and flow loss. This fully reflects the internal exchange flow law of the vortex pump 1, and makes up for the deficiency of ignoring the internal flow in the existing hydraulic performance evaluation method of the vortex pump 1. At the same time, the mapping relationship and analysis model between "vortex pump 1 model-internal flow-hydraulic performance" are established, which links the internal flow and external characteristics of the vortex pump 1 and realizes the evaluation of the hydraulic performance of the vortex pump 1.

[0070] Specifically, when dividing the impeller 101 flow domain into grids, the single blade can be gridded first, and then the array can be rotated according to the number of blades to obtain the grids of the entire impeller 101. In addition, since the axial size of the axial gap and the radial size of the radial gap 109 are relatively small, a sufficient number of grid layers must be divided to ensure the accuracy of the simulation calculation.

[0071] For example, Fluent software is used to carry out CFD numerical simulation calculations of the entire flow basin of vortex pump 1.

[0072] For example, the dark area indicates that the fluid flows from the inlet pump casing flow channel 104 into the impeller 101 flow domain at the inner diameter of the impeller 101, and the light area indicates that the fluid flows from the impeller 101 flow domain into the inlet pump casing flow channel 104 at the outer diameter of the impeller 101 (as shown in Figure 7).

[0073] In this embodiment, in step S2, the pressure p at the inlet of the vortex pump 1 is obtained. out , outlet pressure p in , fluid density ρ, speed n, fluid flow rate Q, torque M, outer diameter D of impeller 101 out , the inner diameter D of the impeller 101 in ;

[0074] Head of vortex pump 1

[0075] The median diameter of the impeller 101

[0076] Fluid velocity at the mid-diameter of impeller 101

[0077] Head coefficient of vortex pump 1

[0078] Shaft power of vortex pump 1

[0079] Hydraulic efficiency of vortex pump 1

[0080] Where: g represents the acceleration due to gravity, and its unit is m / s 2 , pressure p out , pressure p in The unit of density is Pa, and the unit of density ρ is kg / m 3 , the unit of speed n is rpm, the unit of flow Q is m 3 / s, the unit of torque M is Nm, u m The unit is m / s. Therefore, through the head coefficient NH * The hydraulic efficiency η and the hydraulic performance of the vortex pump 1 can be evaluated from a macroscopic perspective.

[0081] In this embodiment, in step S3, the pressurization process of the vortex pump 1 is divided into a flow development region and a linear acceleration region according to the flow conditions, and the pressure coefficient

[0082] Select the starting point A(θ A , p A *) and end point B(θ B , p B *), slope

[0083] The unit of the pressure value p is Pa. Therefore, in the flow development region, stable energy exchange has not yet been formed, and the pressure p does not increase significantly. However, the fluid pressurization effect in the linear acceleration region is significant. The slope sl of the pressure p curve in this region can reflect the fluid pressurization ability of the vortex pump 1. The larger the slope sl, the faster the pressure growth of the vortex pump 1, the stronger the work capacity of the vortex pump 1, and the higher the head H of the vortex pump 1.

[0084] Specifically, a series of monitoring points are set in the circumferential direction of the inlet pump casing flow channel 104 , and the pressure at each monitoring point is extracted along the rotation direction of the impeller 101 .

[0085] In this embodiment, in step S4, the longitudinal vortex position coefficient is calculated

[0086] Where: axial position h al , the height h of the impeller 101 ab The unit of is mm. Therefore, it can reflect the strength of the longitudinal vortex driving the fluid exchange, and is a characterization of the longitudinal vortex strength. At the same time, it comes from the internal flow of the vortex pump 1 and is also a specific embodiment of the functional capacity of the vortex pump 1.

[0087] Specifically, the longitudinal vortex is a very important flow feature in the vortex pump 1 and an important factor that distinguishes the working process of the vortex pump 1 from other vane pumps. Extracting and characterizing the longitudinal vortex is a key link in the evaluation of the internal flow and hydraulic performance of the vortex pump 1.

[0088] In this embodiment, in step S5, the mass flow rate m exchanged by the vortex pump 1 is obtained. ex , the selected axial mass flow rate m sf , fluid velocity v;

[0089] Momentum exchange value p ex =m ex v;

[0090] The momentum value p on this section sf =m sf v;

[0091] Momentum exchange coefficient

[0092] Where: exchange mass flow rate m ex , select the axial mass flow rate m sf The unit of is kg / s, the unit of fluid velocity v is m / s, and the momentum exchange value p ex , the momentum value p on the cross section sf The unit is kgm / s 2 . Thus, by exchanging the momentum value pex The degree of momentum exchange inside the vortex pump 1 can be measured by the momentum value p on the axial section. sf It can measure the momentum on the cross section; the momentum exchange coefficient l v * It indicates the intensity of the fluid momentum exchange in the vortex pump 1. The larger the value, the more intense the energy transfer between the inlet pump casing flow channel 104, the outlet pump casing flow channel 106 and the impeller 101 fluid.

[0093] Specifically, the vortex pump 1 transfers energy to the fluid in the flow channel through the blades of the impeller 101. This process of transferring energy through three-dimensional momentum exchange is repeated many times in the vortex pump 1, so that the vortex pump 1 has a high head that is difficult to achieve with other vane pumps.

[0094] In this embodiment, in step S6, the total dissipated entropy production DEP is calculated according to the Reynolds time-averaged method. sum Direct dissipative entropy production (DEP) d and turbulent dissipated entropy production (DEP) t , obtain the dynamic viscosity μ of the fluid in the vortex pump 1, the thermodynamic temperature T of the fluid, the velocity component u of the x-axis, the velocity component v of the y-axis, the velocity component w of the z-axis of the fluid in the Cartesian coordinate system, and the dissipation rate ε of the fluid;

[0095] Total dissipated entropy production DEP sum =DEP d +DEP t ;

[0096] Direct dissipation of entropy production

[0097] Turbulent dissipation entropy production

[0098] Extracting the total dissipated entropy production (DEP) from the internal flow field of vortex pump 1 sum , after processing, the total dissipation loss coefficient is obtained

[0099] Extracting Direct Dissipated Entropy Production (DEP) from the Internal Flow Field of a Vortex Pump 1 d , after processing, the direct dissipation loss coefficient is obtained

[0100] Extracting Turbulent Dissipated Entropy Production (DEP) from the Internal Flow Field of a Vortex Pump 1 t , after processing, the turbulent dissipation loss coefficient is obtained

[0101] The unit of fluid dynamic viscosity μ is Pas, the unit of fluid thermodynamic temperature T is K, the unit of fluid x-axis velocity component u, y-axis velocity component v, and z-axis velocity component w are all m / s, and the unit of fluid dissipation rate ε is m 2 / s 2 , total dissipated entropy production DEP sum , direct dissipation of entropy production DEP d , turbulent dissipated entropy production DEP t The unit is kg / ms 3 K. Therefore, entropy production, as a measure of adiabatic mechanical dissipation loss, is crucial for locating and evaluating flow losses inside the vortex pump 1; total dissipated entropy production DEP sum , direct dissipation of entropy production DEP d and turbulent dissipated entropy production (DEP) t The internal flow loss of the vortex pump 1 is systematically measured from the overall and partial perspectives, which directly affects the performance of the vortex pump 1. The size of the loss in the vortex pump 1 can be evaluated by comparing these three indicators; the total dissipation loss coefficient Ndep sum * , direct dissipation loss Ndep d * and turbulent dissipation loss coefficient Ndep t * The larger the value is, the greater the flow loss in the vortex pump 1 is, and the greater the energy dissipation of the vortex pump 1 is.

[0102] Specifically, since the heat transfer inside the vortex pump 1 is negligible, the entropy generation caused by it is also negligible, and the entropy generation loss inside the vortex pump 1 is mainly caused by the change of turbulent flow. Therefore, the entropy generation loss inside the vortex pump 1 can ignore the heat transfer, so the internal flow loss of the vortex pump 1 is measured only by comparing the entropy generation caused by viscous dissipation.

[0103] In this embodiment, in step S7, the velocity swirl intensity ssv and flow separation coefficient of the fluid are obtained.

[0104] The unit of the velocity swirl intensity ssv is 1 / s. Therefore, the velocity swirl intensity ssv indicates the intensity of the fluid rotating around the local center, and the flow separation coefficient Nssv * It indicates the severity of flow separation inside the vortex pump 1, the flow separation coefficient Nssv * The larger it is, the more obvious the fluid flow separation is.

[0105] In this embodiment, the head coefficient NH * The processing method of the pressure coefficient p*, the processing method of the longitudinal vortex position coefficient l v *The processing method and momentum exchange coefficient I t * Treatment method, dissipation loss coefficient Ndep * Treatment method and flow separation coefficient Nssv * The processing method is normalization. Therefore, different vortex pumps 1 have different sizes, and their hydraulic performance and internal flow also have different degrees of difference. If the absolute value of each indicator is directly used for evaluation, erroneous results may be obtained. Normalization is a simplified calculation method that converts the absolute value of a numerical value into a relative value, ultimately obtaining a certain degree of irrelevance. It can eliminate the size differences of different vortex pumps 1, and thus avoid the influence of the size of the vortex pump 1 on its internal flow and hydraulic performance evaluation results, thereby improving the accuracy of the hydraulic performance evaluation of the vortex pump 1.

[0106] Specifically, the density of the corresponding fluid is selected according to the type and temperature of the fluid conveyed by the vortex pump. That is, the conveyed fluid is water, whose density at room temperature of 25°C is 998.2 kg / m 3 .

[0107] Example 1:

[0108] The impeller 101 of the vortex pump 1 has a height of 4.8 mm, a blade outer diameter of 24 mm, a blade inner diameter of 14.4 mm, a blade number of 33 mm, a pump casing flow passage outer diameter of 24 mm, and a pump casing flow passage inner diameter of 14.4 mm.

[0109] Example 2:

[0110] The difference from Example 1 is that the outer diameter of the blades of the vortex pump 1 is 28.8 mm, the inner diameter of the blades is 19.2 mm, the outer diameter of the pump casing flow channel is 28.8 mm, and the inner diameter of the pump casing flow channel is 19.2 mm.

[0111] The calculation formula of lift coefficient is:

[0112] The calculation formula of hydraulic efficiency is:

[0113] The calculation formula of slope sl is:

[0114] The calculation formula of vortex position coefficient is:

[0115] The calculation formula of momentum exchange coefficient is:

[0116] The calculation formula of the total dissipation loss coefficient is:

[0117] The calculation formula of direct dissipation loss coefficient is:

[0118] The calculation formula of turbulent dissipation loss coefficient is:

[0119] Calculation formula for flow separation coefficient

[0120] Example 1 and Example 2 adopt the above calculation method and use water (the density of water is 998.2kg / m 3 ) as the medium and the data are shown in Table 1.

[0121] Table 1

[0122] According to Table 1, the slope s1 of Example 2 is higher than the slope s1 of Example 1, indicating that the pressure growth rate of Example 2 is higher than the pressure growth rate of Example 1, and the pressure boosting capability of the fluid conveyed by Example 2 is stronger; the longitudinal vortex position coefficient l of Example 2 is v * Lower than the longitudinal vortex position coefficient l of Example 1 v * The longitudinal vortex of Example 2 is more capable of driving the fluid in the impeller 101 and the pump casing flow channel to complete the exchange flow. The greater the strength of the longitudinal vortex, the stronger its ability to do work, and the higher the head coefficient NH* of the corresponding vortex pump 1; the momentum exchange coefficient I of Example 2 t * Higher momentum exchange coefficient I than that of Example 1 t * , corresponding to the more intense fluid energy transfer in the dark and light areas (as shown in Figure 8), the corresponding vortex pump 1 does more work, and the head coefficient NH * Higher; total dissipation loss coefficient Ndep of Example 2 sum * , direct dissipation loss coefficient Ndep d * , turbulent dissipation loss coefficient Ndep t * All of them are higher than the total dissipation loss coefficient Ndep of Example 1 sum * , direct dissipation loss coefficient Ndep d * , turbulent dissipation loss coefficient Ndep t * , indicating that the flow loss of the vortex pump 1 in Example 2 is larger, which is also an important reason why the hydraulic efficiency η of Example 2 is lower than that of Example 1; the flow separation coefficient Nssv of Example 2 * Higher flow separation coefficient Nssv than Example 1 *, indicating that the flow separation loss in Example 2 is greater, so its corresponding total dissipation loss coefficient Ndep sum * , direct dissipation loss coefficient Ndep d * , turbulent dissipation loss coefficient Ndep t * Bigger.

[0123] Comprehensive analysis shows that the slope sl of the pressure coefficient growth curve in the linear acceleration zone of Example 2 is larger, and the longitudinal vortex position coefficient l v * Small, momentum exchange coefficient I t * The vortex pump 1 has a stronger boosting capacity and a stronger longitudinal vortex, so the head coefficient NH of Example 2 is * Higher head coefficient NH than Example 1 * ; Total dissipation loss coefficient Ndep in Example 2 sum * , direct dissipation loss coefficient Ndep d * , turbulent dissipation loss coefficient Ndep t * Large, and the flow separation coefficient Nssv * is larger, resulting in more obvious internal flow loss of the vortex pump 1, so the hydraulic efficiency η of Example 2 is lower than the hydraulic efficiency η of Example 1.

[0124] To sum up, the present invention starts from the internal flow mechanism of the vortex pump 1, extracts the characteristics of the three-dimensional numerical simulation flow field of the vortex pump 1, and systematically evaluates the hydraulic performance of the vortex pump 1 from the two perspectives of work and flow loss, which fully reflects the internal exchange flow law of the vortex pump 1, and makes up for the deficiency of ignoring the internal flow in the existing hydraulic performance evaluation method of the vortex pump 1. At the same time, a mapping relationship and analysis model between "vortex pump 1 model-internal flow-hydraulic performance" are established, and the internal flow and external characteristics of the vortex pump 1 are linked to realize the evaluation of the hydraulic performance of the vortex pump 1; based on numerical simulation data, no experiment is required, which greatly shortens the cycle and cost of the performance evaluation of the vortex pump 1. At the same time, it is convenient for designers to evaluate the performance of the vortex pump 1 in multiple dimensions, improves the comprehensiveness and rationality of the performance evaluation of the vortex pump 1, and can also provide design ideas for the performance optimization of the vortex pump 1 from the flow perspective.

[0125] The above description is intended to serve as a guide for the preferred embodiments of the present invention. Based on the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of the present invention. The technical scope of the present invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A method for evaluating the hydraulic performance of a vortex pump based on internal flow, characterized in that: The following steps are involved: S1, constructing a three-dimensional model of the vortex pump (1) using the impeller (101), the pump chamber (102) and the pump cover (103) of the vortex pump (1) and performing flow domain extraction, and dividing the flow domain model of the vortex pump (1) into: an inlet pump casing flow channel (104), an impeller flow domain (105), an outlet pump casing flow channel (106), an inlet axial gap (107), an outlet axial gap (108) and a radial gap (109), dividing a grid for each flow domain, and carrying out CFD numerical simulation calculations of the entire flow domain of the vortex pump (1); S2, extracting the flow field data of the characteristic position of the vortex pump (1), thereby calculating the head coefficient NH of the vortex pump (1) * and hydraulic efficiency η; S3, extracting the pressure value p of each monitoring point in the circumferential direction of any one of the impeller (101), the inlet pump casing flow channel (104) or the outlet pump casing flow channel (106) from the internal flow field of the vortex pump (1), and drawing a growth curve of the pressure coefficient p* after processing, and calculating the slope sl of the curve in the linear acceleration region; S4. Extracting the velocity cloud map and streamline map of the longitudinal section of the vortex pump (1) from the internal flow field of the vortex pump (1), and finding the axial position h of the longitudinal vortex on the section. al , and using the impeller (101) height h ab After processing, the longitudinal vortex position coefficient l is obtained v * ; S5. Extracting the exchange flow cloud diagram of any one of the impeller (101), the inlet pump casing flow channel (104) or the outlet pump casing flow channel (106) on the axial section from the internal flow field of the vortex pump (1), and calculating the exchange momentum p ex , the momentum p on the cross section sf , after processing, the momentum exchange coefficient I is obtained t * ; S6. Extracting entropy generation distribution data from the internal flow field of the vortex pump (1), and obtaining the dissipation loss coefficient Ndep after processing. * ; S7. Extract the velocity vortex intensity ssv of any one of the impeller (101), the inlet pump casing flow channel (104) or the outlet pump casing flow channel (106) from the internal flow field of the vortex pump (1), and obtain the flow separation coefficient Nssv in the vortex pump (1) after processing. * .

2. The method for evaluating the hydraulic performance of a vortex pump based on internal flow according to claim 1, characterized in that: In step S2, the pressure p at the inlet of the vortex pump (1) is obtained. out , pressure at the outlet p in , density ρ of the fluid, rotation speed n, flow rate Q of the fluid, torque M, outer diameter D of the impeller (101) out , the inner diameter D of the impeller (101) in ; The lift of the vortex pump (1) The median diameter of the impeller (101) The fluid velocity at the mid-diameter of the impeller (101) The lift coefficient of the vortex pump (1) The shaft power of the vortex pump (1) The hydraulic efficiency of the vortex pump (1) Where: g represents the acceleration due to gravity, and its unit is m / s 2 , pressure p out , pressure p in The unit of density is Pa, and the unit of density ρ is kg / m 3 , the unit of speed n is rpm, the unit of flow Q is m 3 / s, the unit of torque M is Nm, u m The unit is m / s.

3. The method for evaluating the hydraulic performance of a vortex pump based on internal flow according to claim 2, characterized in that: In step S3, according to the flow conditions, the pressurization process of the vortex pump (1) is divided into a flow development region and a linear acceleration region, and the pressure coefficient Select the starting point A(θ A , p A *) and end point B (θ B , p B *), the slope Wherein: the unit of pressure value p is Pa.

4. The method for evaluating the hydraulic performance of a vortex pump based on internal flow according to claim 1, characterized in that: In step S4, the longitudinal vortex position coefficient is calculated Where: axial position h al , the height h of the impeller (101) ab The unit is mm.

5. The method for evaluating the hydraulic performance of a vortex pump based on internal flow according to claim 1, characterized in that: In step S5, the mass flow rate m exchanged by the vortex pump (1) is obtained. ex , the selected axial mass flow rate m sf , fluid velocity v; The momentum exchange value p ex =m ex v; The momentum value on the cross section p sf =m sf v; Where: exchange mass flow rate m ex , select the axial mass flow rate m sf The unit of is kg / s, the unit of fluid velocity v is m / s, and the momentum exchange value p ex , the momentum value p on the cross section sf The unit is kgm / s 2 .

6. The method for evaluating the hydraulic performance of a vortex pump based on internal flow according to claim 5, characterized in that: In step S5, the momentum exchange coefficient 7. The method for evaluating the hydraulic performance of a vortex pump based on internal flow according to claim 2, characterized in that: In step S6, the total dissipated entropy production DEP is calculated according to the Reynolds time-averaged method. sum Direct dissipative entropy production DEP d and turbulent dissipated entropy production DEP t ; Among them, the total dissipated entropy production DEP sum , Direct dissipation of entropy production DEP d , turbulent dissipation entropy production DEP t The unit is kg / ms 3 K.

8. The method for evaluating the hydraulic performance of a vortex pump based on internal flow according to claim 7, characterized in that: In step S6, the dynamic viscosity μ of the fluid of the vortex pump (1), the thermodynamic temperature T of the fluid, the velocity component u of the x-axis, the velocity component v of the y-axis, the velocity component w of the z-axis of the fluid in the Cartesian coordinate system, and the dissipation rate ε of the fluid are obtained; The total dissipated entropy production DEP sum =DEP d +DEP t ; Direct dissipation of entropy production The turbulence dissipates entropy production The unit of fluid dynamic viscosity μ is Pas, the unit of fluid thermodynamic temperature T is K, the unit of fluid x-axis velocity component u, y-axis velocity component v, and z-axis velocity component w are all m / s, and the unit of fluid dissipation rate ε is m 2 / s 2 .

9. The method for evaluating the hydraulic performance of a vortex pump based on internal flow according to claim 8, characterized in that: In step S6, the total dissipated entropy production DEP is extracted from the internal flow field of the vortex pump (1). sum , after processing, the total dissipation loss coefficient is obtained Extracting direct dissipated entropy production (DEP) from the internal flow field of the vortex pump (1) d , after processing, the direct dissipation loss coefficient is obtained Extracting turbulent dissipated entropy production (DEP) from the internal flow field of the vortex pump (1) t , after processing, the turbulent dissipation loss coefficient is obtained 10. The method for evaluating the hydraulic performance of a vortex pump based on internal flow according to claim 2, characterized in that: In step S7, the velocity swirl intensity ssv and flow separation coefficient of the fluid are obtained. Where: the unit of fluid velocity swirl intensity ssv is 1 / s.

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