Method and system for calculating water flow velocity value and flow velocity deflection angle in water pump flow channel

Abstract

The present invention relates to a method and system for calculating the water flow velocity value and flow velocity deflection angle of a water pump flow channel, and belongs to the technical field of calculating the water flow measurement distance based on the water flow direction. The calculation method comprises the following steps: S1, at least two pairs of transducers are horizontally installed on both sides of the flow channel; the transducers include transducer A forming the direction of the sound channel A and transducer B forming the direction of the sound channel B, the transducers A and the transducers B are cross-arranged on the same horizontal plane, and the intersection O of the direction of the sound channel A and the direction of the sound channel B is located on the longitudinal center plane of the flow channel; wherein the parameter sound channel length is L , the sound channel angle is, is the average axial flow velocity on the sound channel line, and is the sound speed of ultrasonic wave in still water.

Description

Technical Field

[0001] The present invention relates to the technical field of calculating water flow measurement distance based on water flow orientation, and in particular to a method and system for calculating water flow velocity value and flow velocity deflection angle in a water pump flow channel. Background Art

[0002] Under ideal conditions, the water in the water flow channel in front of the water pump flows in the same direction as the central axis. However, in reality, due to the rotation of the water pump blades on the downstream side of the flow channel, the interaction between the rotating blades and the water transfers energy to lift the water from a low place to a high place, so the flow distribution in the upstream water flow channel becomes more complex and chaotic, resulting in errors in the actual theoretical calculations and the inability to truly reproduce the actual situation. How to grasp the water flow velocity and actual flow direction in the on-site flow channel is of guiding significance for the subsequent analysis and research on the operating status of the water pump, and provides a reference basis for improving the analysis of water pump efficiency. This is also not proposed in the prior art.

[0003] There is a lack of actual measurement technology for the analysis of the water flow velocity and direction in the on-site flow channel. Currently, we rely on CFD (Computational Fluid Dynamics) simulation, which uses numerical solutions to the differential equations that control the flow of water fluids to obtain the discrete distribution of the flow field of water fluids in a continuous area, thereby approximately simulating the fluid flow. This technology uses a computer to do a "virtual" experiment to simulate the actual fluid flow. When using this software analysis method, some boundary conditions need to be preset. If the boundary conditions are slightly different from those on site, the simulation results will be quite different. Therefore, the flow velocity and flow direction simulated by CFD simulation can only be used as a reference and cannot be considered to be completely consistent with the actual situation. Summary of the invention

[0004] The technical problem to be solved by the present invention is generally to provide a method and system for calculating the water flow velocity value and flow velocity deflection angle of a water pump flow channel. The purpose is to provide a method that can obtain the real-time changing flow velocity and flow direction in the on-site flow channel by measurement and calculation, which can be applied to the analysis of the water flow velocity value and deflection angle in the water flow channel before the water pump in the pump station.

[0005] To solve the above problems, the technical solution adopted by the present invention is:

[0006] A method for calculating the water flow velocity value and flow velocity deflection angle of a water pump flow channel, the calculation method comprising the following steps;

[0007] S1, at least two pairs of transducers are installed horizontally on both sides of the flow channel;

[0008] The transducer includes a transducer A forming the direction of the sound channel A and a transducer B forming the direction of the sound channel B. The transducer A and the transducer B are arranged crosswise on the same horizontal plane. The intersection point O of the direction of the sound channel A and the direction of the sound channel B is located on the longitudinal center plane of the flow channel. Among them, the parameter sound channel length is L , the channel angle is , is the average axial velocity on the sound channel line, is the speed of ultrasound in still water;

[0009] S2, the actual water speed Axial velocity decomposed into axial components and the transverse velocity of the transverse component perpendicular to the axial direction ; Analyze the velocity vector in the direction of channel A and channel B respectively:

[0010] S2.1, analyze the direction of channel A, axial flow velocity Corresponding to the axis flow velocity , lateral flow velocity Corresponding to the lateral flow velocity ;

[0011] Analyze the direction of channel B, the axial flow velocity Corresponding to the axis flow velocity , lateral flow velocity Corresponding to the lateral flow velocity ;

[0012] According to the axial flow velocity value in the direction of the sound channel A Axial velocity value in the direction of channel B The direction of the lateral flow velocity is determined by the size relationship between them;

[0013] when When , there is a transverse flow component, and the transverse flow velocity is calculated as:

[0014] S2.2, for the direction of channel A, calculate the lateral flow velocity ;

[0015] when When the lateral flow velocity Projected flow velocity and axial flow velocity in the direction of channel A The projected flow velocity in the direction of channel A is in the opposite direction, and the lateral flow velocity is calculated according to the following formula ;

[0016]

[0017]

[0018] but Formula (1);

[0019] when When, the lateral flow velocity Projected flow velocity and axial flow velocity in the direction of channel A The projected flow velocity in the direction of the sound channel A is in the same direction, and the lateral flow velocity is calculated according to the following formula ;

[0020]

[0021]

[0022] but Formula (2);

[0023] S2.3, calculate the lateral velocity in the direction of channel B ;

[0024] when When the lateral flow velocity Projected flow velocity and axial flow velocity in the direction of channel B The projected flow velocity in the direction of channel B is in the same direction, and the lateral flow velocity is calculated according to the following formula ;

[0025] ;

[0026] ;

[0027] but Formula (3);

[0028] when When the transverse flow velocity Projected flow velocity and axial flow velocity in the direction of channel B The projected flow velocity in the direction of channel B is in the opposite direction, and the lateral flow velocity is calculated according to the following formula ;

[0029] ;

[0030] ;

[0031] but Formula (4);

[0032] S2.4, based on the calculated lateral velocity , The arithmetic mean of the lateral flow velocity is .

[0033] when , then there is no transverse velocity .

[0034] Transducer A and transducer B are arranged symmetrically, and the direction of channel A is equidistant from and perpendicular to the direction of channel B.

[0035] To obtain the axial velocity, S2.5, solve for the two axial velocity values , ;

[0036] ;

[0037] ;

[0038] Formula (5);

[0039] The actual velocity component on the axis is ,

[0040] Formula (6);

[0041] in, , ——are the channel angles of transducer channels A and B, ——The deflection angle of flow direction relative to the axial direction.

[0042] In order to achieve velocity synthesis, S2.6, the axial velocity obtained by combining equation (6) and lateral velocity , and synthesize to get the actual water flow rate and the deflection angle of the flow direction to the axial direction :

[0043] ;

[0044] Formula (7).

[0045] Furthermore, in order to realize flow calculation, according to the actual flow velocity and the deflection angle of the flow direction to the axial direction , the ultrasonic time difference method measurement is corrected and the flow rate of the flow channel is calculated.

[0046] A system for calculating the water flow velocity value and flow velocity deflection angle of a water pump flow channel comprises a water pump; a transducer is installed on the water pump flow channel for use in the above algorithm.

[0047] The invention collects information about the propagation of ultrasonic signals in the water body in the flow channel, processes the collected information using software, and automatically calculates the flow rate and flow angle, without the need for subsequent manual processing. Relevant water pump researchers can improve the efficiency of the on-site water pump by adjusting the blade angle and other methods based on the actual flow rate and flow direction on site, combined with the operating rules of the water pump itself, which indirectly saves energy and can also accumulate a large amount of actual analysis data for subsequent research work. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a top view of the ultrasonic sound channel propagation of the present invention.

[0049] Figure 2 It is a top view of the cross-channel ultrasonic channel propagation of the present invention.

[0050] Figure 3 It is a top view of the propagation direction of the sound channel A of the present invention.

[0051] Figure 4 It is a top view of the propagation in the direction of channel B of the present invention.

[0052] Figure 5 It is the actual flow rate synthesis diagram of the present invention. DETAILED DESCRIPTION

[0053] like Figure 1-5 The ultrasonic propagation time method is a method for calculating the velocity of each layer based on the forward and reverse propagation time of ultrasonic waves in the fluid. Since the velocities overlap, in order to more clearly represent the technical solution of the present invention, color distinction is used. In this embodiment, a pair of transducers A1 and A2 are arranged, and the length of the sound channel is L , the channel angle is , installed horizontally on both sides of the flow channel, is the average axial velocity on the sound channel line, is the speed of ultrasound in still water, such as Figure 1 shown.

[0054] For a pair of transducers in the same channel, the propagation time of ultrasonic waves from the downstream to the upstream transducer , the propagation time from the upstream to the downstream transducer , due to the projection of water velocity on the sound channel line The influence of the two propagation times in the same channel is different, and the ultrasonic propagation process obtains the following set of equations:

[0055] ;

[0056] Where: ——Voice tract length, m; ——Sound speed, in m / s; ——projected velocity of the acoustic channel, in m / s; ——The propagation time of ultrasound in the reverse direction, in seconds; ——The propagation time of ultrasound in the downstream direction, in seconds; ——Voice channel angle, in degrees.

[0057] Furthermore, the average axial velocity of the water flow is obtained ,

[0058] ;

[0059] Where: ——The difference between the propagation time of ultrasound in the downstream direction and the upstream direction, in seconds;

[0060] As a further improvement, the transducer channels A and B are arranged in a cross-symmetrical manner, and two axial flow velocity values ​​are obtained by distribution. , ,like Figure 2 ,get:

[0061] ;

[0062] ;

[0063] ;

[0064] Therefore, the actual velocity component on the axis is ,

[0065] ;

[0066] in, , ——are the channel angles of transducer channels A and B, ——the deflection angle of flow direction to the axial direction; is the actual water flow rate;

[0067] The present invention utilizes cross-channels to eliminate the cross-flow effect and obtains the actual water flow rate. The above method can be used to preliminarily measure the axial velocity component, but the disadvantage is that the actual flow direction and velocity value cannot be obtained. As a creative further improvement, in order to obtain the real-time actual flow direction and velocity value, the two axial velocity values ​​obtained are used according to the above cross-arranged sound channels. , As the judgment basis and known parameters, it is further deduced and obtained.

[0068] Furthermore, assuming that the actual water flow velocity is not parallel to the axis of the flow channel, the velocity vector is analyzed in the direction of channel A and channel B respectively. The actual water velocity Can be decomposed into axial flow velocity and the transverse velocity perpendicular to the axial direction .

[0069] First, according to the two axial flow velocity values ​​obtained and The direction of the lateral flow velocity is determined by the size relationship between them;

[0070] Analyze the direction of channel A, assuming that there is an actual water flow velocity in the direction of channel A that is not parallel to the channel axis. , axis flow velocity Corresponding to the axis flow velocity , lateral flow velocity Corresponding to the lateral flow velocity ;

[0071] Analyze the direction of channel B, assuming that there is an actual water flow velocity in the direction of channel B that is not parallel to the channel axis. , axis flow velocity Corresponding to the axis flow velocity , lateral flow velocity Corresponding to the lateral flow velocity ;

[0072] Specifically, if , then there is no transverse flow component;

[0073] when When , there is a transverse flow component, and the transverse flow velocity is calculated according to the following two situations :

[0074] (1) , lateral flow velocity Projected flow velocity and axial flow velocity in the direction of channel A The projected flow velocity in the direction of channel A is in the opposite direction, and the lateral flow velocity is calculated according to the following formula , (see Figure 3 );

[0075] ;

[0076] ;

[0077] so, ;

[0078] (2) , lateral flow velocity Projected flow velocity and axial flow velocity in the direction of channel A The projected flow velocity in the direction of the sound channel A is in the same direction, and the lateral flow velocity is calculated according to the following formula ;

[0079] ;

[0080] ;

[0081] so, ;

[0082] when When , there is a transverse flow component, and the transverse flow component is calculated according to the following two cases ;

[0083] (1) , lateral flow velocity Projected flow velocity and axial flow velocity in the direction of channel B The projected flow velocity in the direction of channel B is in the same direction, and the lateral flow velocity is calculated according to the following formula (See Figure 4 );

[0084] ;

[0085] ;

[0086] so, ;

[0087] (2) , lateral flow velocity Projected flow velocity and axial flow velocity in the direction of channel B The projected flow velocity in the direction of channel B is in the opposite direction, and the lateral flow velocity is calculated according to the following formula ,

[0088] ;

[0089] ;

[0090] so: ;

[0091] According to the above analysis of the A and B channels, the lateral flow velocities of the two components are calculated respectively. , In theory, the two are equal, but due to the existence of measurement errors, there may be differences between the two. In order to improve accuracy, further, take the lateral flow velocity , The arithmetic mean of the lateral velocity is ; ;

[0092] Combined axial flow rate and lateral velocity , for synthesis, see Figure 5 , get the real flow velocity and the deflection angle of the flow direction to the axial direction :

[0093] ;

[0094] .

[0095] The invention is based on the time-difference ultrasonic flowmeter arranged in a cross-channel arrangement. The two axial flow velocity values ​​measured in real time by the flowmeter are used as the basis for judgment and as known parameters. The real-time actual flow velocity and flow direction are further derived in combination with the formula of the present invention. The implementation method can be implemented using a software program without the need for human participation in the calculation.

[0096] The present invention is fully described for a clearer disclosure, and the prior art is not listed one by one.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some of the technical features therein with equivalents; it is obvious for those skilled in the art to combine multiple technical solutions of the present invention. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention. The technical contents not described in detail in the present invention are all known technologies.

Claims

1. A method for calculating the water flow velocity value and flow velocity deflection angle of a water pump flow channel, characterized in that: The calculation method includes the following steps: S1, at least two pairs of transducers are installed horizontally on both sides of the flow channel; The transducer includes a transducer A forming the direction of the sound channel A and a transducer B forming the direction of the sound channel B. The transducer A and the transducer B are arranged crosswise on the same horizontal plane. The intersection point O of the direction of the sound channel A and the direction of the sound channel B is located on the longitudinal center plane of the flow channel. Among them, the parameter sound channel length is L , the channel angle is , is the average axial velocity on the sound channel line, is the speed of ultrasound in still water; S2, the actual water speed Axial velocity decomposed into axial components and the transverse velocity of the transverse component perpendicular to the axial direction ; Analyze the velocity vector in the direction of channel A and channel B respectively: In step S2, perform the following steps; S2.1, analyze the direction of channel A, axial flow velocity Corresponding to the axis flow velocity , lateral flow velocity Corresponding to the lateral flow velocity ; Analyze the direction of channel B, the axial flow velocity Corresponding to the axis flow velocity , lateral flow velocity Corresponding to the lateral flow velocity ; According to the axial flow velocity value in the direction of the sound channel A Axial velocity value in the direction of channel B The direction of the lateral flow velocity is determined by the size relationship between them; when When , there is a transverse flow component, and the transverse flow velocity is calculated as: S2.2, for the direction of channel A, calculate the lateral flow velocity ; when When the lateral flow velocity Projected flow velocity and axial flow velocity in the direction of channel A The projected velocity in the direction of the sound channel A is in the opposite direction. The lateral velocity is calculated according to the following formula (1): ; but Formula (1); when When the lateral flow velocity Projected flow velocity and axial flow velocity in the direction of channel A The projected flow velocity in the direction of the sound channel A is in the same direction, and the lateral flow velocity is calculated according to the following formula (2): ; but Formula (2); S2.3, calculate the lateral velocity in the direction of channel B ; when When the lateral flow velocity Projected flow velocity and axial flow velocity in the direction of channel B The projected flow velocity in the direction of channel B is in the same direction, and the lateral flow velocity is calculated according to the following formula (3): ; ； ； but Formula (3); when When the transverse flow velocity Projected flow velocity and axial flow velocity in the direction of channel B The projected velocity in the direction of channel B is in the opposite direction, and the lateral velocity is calculated according to the following formula (4): ; ； ； but Formula (4); S2.4, based on the calculated lateral velocity , The arithmetic mean of the lateral flow velocity is .

2. The method for calculating the water flow velocity value and flow velocity deflection angle of the water pump flow channel according to claim 1, characterized in that: when , then there is no transverse velocity .

3. The method for calculating the water flow velocity value and flow velocity deflection angle of the water pump flow channel according to claim 1, characterized in that: According to the actual flow rate and the deflection angle of the flow direction to the axial direction , correct the ultrasonic time difference method measurement and calculate the flow rate of the flow channel; Transducer A and transducer B are arranged symmetrically, and the direction of channel A is equidistant from and perpendicular to the direction of channel B.

4. The method for calculating the water flow velocity value and flow velocity deflection angle of a water pump flow channel according to claim 1, characterized in that: After step S2.4, execute S2.5 to solve the two axial flow velocity values , ; ； ； Formula (5); The actual velocity component on the axis is , Formula (6); in, , ——are the channel angles of transducer channels A and B, ——The deflection angle of flow direction relative to the axial direction.

5. The method for calculating the water flow velocity value and flow velocity deflection angle of a water pump flow channel according to claim 4, characterized in that: After step S2.5, execute S2.6 and combine the axial flow velocity obtained by formula (6) and lateral velocity , and synthesize to get the actual water flow rate and the deflection angle of the flow direction to the axial direction : ； Formula (7).

6. A system for calculating the water flow velocity value and flow velocity deflection angle of a water pump flow channel, characterized in that: It comprises a water pump; a transducer is installed on the flow channel of the water pump, and is used to execute the method described in any one of claims 1-5.

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