CN115076085A - Pressure pulsation identification method for flow state in suction pipe of water pump station - Google Patents
Pressure pulsation identification method for flow state in suction pipe of water pump station Download PDFInfo
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- CN115076085A CN115076085A CN202210651624.4A CN202210651624A CN115076085A CN 115076085 A CN115076085 A CN 115076085A CN 202210651624 A CN202210651624 A CN 202210651624A CN 115076085 A CN115076085 A CN 115076085A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B51/00—Testing machines, pumps, or pumping installations
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The invention discloses a pressure pulsation identification method of the flow state in a suction pipe of a water pump station, which comprises the following steps: obtaining a pressure pulsation signal p (t) of a suction pipe of a water pump station, and carrying out dimensionless processing on the pressure pulsation signal p (t) to obtain a pressure pulsation time domain signal C p (t); obtaining a pressure pulsation signal frequency domain signal G (j omega) by adopting fast Fourier transform, and extracting 0.1f n The amplitude A and 0-1 f of the pressure pulsation n In-range pressure pulsation frequency domain signal G 1 (j ω); for pressure pulsation frequency domain signal G 1 (j omega) performing inverse Fourier transform to obtain 0-1 f n Pressure pulsation time domain signal C p1 (t); calculating to obtain 0-1 f n Pressure pulsation time domain signal C p1 Energy E and power P of (t); calculated to give 0.1f n Pressure pulsation amplitude A, 0-1 f n Threshold value T of pressure pulsation signal energy E and power P A 、T E And T P (ii) a According to a threshold value T A 、T E And T P And judging whether a bad flow state appears in the suction pipe or not. The method can be used for the suction pipe of the water pump stationAccurate identification is made to the mobile state of portion, thereby avoids water pump unit to move under the too low condition of intake pool water level and leads to the interior bad flow state that appears of suction pipe.
Description
Technical Field
The invention belongs to the technical field of hydraulic engineering, and particularly relates to a method for identifying the flow state in a suction pipe of a water pump station through a pressure pulsation signal.
Background
In the operation of the water pump station, whether the water pump can safely and efficiently operate is closely related to the flow state of water flow of the pump station. As a key device for connecting a water inlet pool of a pump station with a water pump, the flow state of water flow in a suction pipe influences the running state of the whole water pump unit to a great extent. The flow state of the water in the suction pipe is affected by the water level of the water inlet pool, the process of numerical simulation is carried out on the water level flow fields of different water inlet pools of the water pump station system, when the water level of the water inlet pool is reduced to a certain critical value, the submerging depth of the inlet of the suction pipe is lower than the critical submerging depth, the occurrence of suction vortex of the water inlet pool can be caused, air enters the suction pipe, the flow state of the water in the suction pipe can be deteriorated, the phenomenon of blocking of the water flow of the pipe wall below the suction pipe occurs, namely, the flow rate is lower, the flow line is bent, at the moment, the inflow condition of the water pump can be seriously affected, the running stability of the water pump is further affected, even the cavitation erosion and the vibration of the water pump can be caused, and the normal running of the water pump can be avoided. Therefore, a method for identifying the flow state inside the suction pipe of the water pump station is very necessary, and has very important significance on the safe, stable and efficient operation of the water pump station.
Disclosure of Invention
The invention aims to provide a method for identifying the flow state in a suction pipe of a water pump station, which avoids the phenomenon of flow state deterioration in the suction pipe caused by too low water level of a water inlet pool and provides guidance for safe operation of the pump station.
The technical scheme adopted by the invention is as follows:
the pressure pulsation identification method of the flow state in the suction pipe of the water pump station is implemented according to the following steps:
Step 2, aiming at the dimensionless pressure pulsation time domain signal C in the step 1 p (t), obtaining a pressure pulsation signal frequency domain signal G (j omega) by adopting fast Fourier transform, and extracting 0.1f n The amplitude A and 0-1 f of the pressure pulsation n In-range pressure pulsation frequency domain signal G 1 (jω)，f n Frequency conversion is carried out on the water pump;
step 3, carrying out extraction on 0-1 f extracted in the step 2 n Pressure pulsation frequency domain signal G 1 (j omega) performing inverse Fourier transform to obtain 0-1 f n Pressure pulsation time domain signal C p1 (t)；
Step 4, calculating 0-1 f according to a calculation formula of the signal energy E and the signal power P n Pressure pulsation time domain signal C p1 Energy E and power P of (t);
step 5, extracting 0.1f according to step 2 n The amplitude A of the pressure pulsation and 0-1 f obtained in the step 4 n The energy E and the power P of the pressure pulsation signal are calculated to obtain 0.1f n Pressure pulsation amplitude A, 0-1 f n Threshold T of pressure pulsation signal energy E and power P A 、T E And T P ；
Step 6, obtaining the threshold value T according to the step 5 A 、T E And T P And judging whether the suction pipe has a bad flow state or not.
The invention is also characterized in that:
defining the pressure pulsation coefficient formula in the step 1 as follows:
in formula (1): u. of 2 ＝ωR＝2πnR (2)
In formulae (1) and (2): p is static pressure of a monitoring point and has a unit of Pa;
is the average static pressure in Pa; ρ is the flowBulk density in kg/m 3 ；u 2 Is the impeller exit peripheral velocity in m/s; r is the radius of the outlet position of the impeller and is expressed in m; and n is the rotating speed of the water pump and has the unit of r/s.
The inverse fourier transform formula in step 3 is:
in the formula (3), ω is a signal angular frequency.
The calculation formula of the signal energy E in the step 4 is as follows:
the calculation formula of the signal power P is:
0.1f in step 5 n Pressure pulsation amplitude A, 0-1 f n Threshold T of pressure pulsation signal energy E and power P A 、T E And T P The specific determination process comprises the following steps:
step 5.1, calculating the mean value of the pressure pulsation amplitude A of different water inlet pool water levels of the water pump station
And standard deviation S A ，0.1f n The threshold value of the pressure pulsation amplitude is
Step 5.2, calculating 0-1 f of different water inlet pond water levels of the water pump station n Mean value of the energy E of the pressure pulsation signal
And standard deviation S E ，0～1f n Pressure pulsationThe threshold of the signal energy is
Step 5.3, calculating 0-1 f of different water inlet pond water levels of the water pump station n Mean value of the power P of the pressure pulsation signal
And standard deviation S P ，0～1f n The threshold value of the power of the pressure pulsation signal is
Wherein a, b and c are coefficients.
The standard for judging whether the suction pipe has bad flow state in the step 6 is as follows:
under a certain water level of the water inlet pool, the pressure pulsation signal simultaneously meets the following three conditions:
0.1f n amplitude of pressure pulsation A>T A ；
0～1f n Energy E of pressure pulsation signal>T E ；
0～1f n Power P of pressure pulsation signal>T P ；
The poor flow regime in the suction pipe of the water pumping station is considered to be present at this time.
The invention has the beneficial effects that: the invention relates to a pressure pulsation identification method of a suction pipe of a water pump station, which comprises the steps of respectively extracting a pressure pulsation amplitude corresponding to 0.1 time of frequency conversion under the water level of each water inlet tank and a pressure pulsation signal within a frequency conversion range of 0-1 time after carrying out fast Fourier transform on an acquired pressure pulsation signal of the suction pipe, calculating the energy and power of the pressure pulsation signal within the frequency conversion range of 0-1 time, and identifying the flow state inside the suction pipe of the water pump station through the pressure pulsation amplitude corresponding to 0.1 time of frequency conversion and the energy and power of the pressure pulsation signal within the frequency conversion range of 0-1 time. The method can accurately identify the flowing state in the suction pipe of the water pump station, and avoids the poor flow state in the suction pipe caused by the running of the water pump unit under the condition that the water level of the water inlet pool is too low.
Drawings
FIG. 1 is a flow chart of a method for identifying pressure pulsations in the flow conditions inside a suction pipe of a water pumping station according to the present invention;
FIG. 2 is a schematic view of the position of a monitoring point of a suction pipe of the water pumping station in the embodiment of the invention;
FIG. 3 shows the measured values of 0.1f at different water levels of the intake pool according to the embodiment of the present invention n Pressure pulsation amplitude A, 0-1 f n A graph of pressure pulsation signal energy E and power P;
fig. 4 and 5 are schematic diagrams of the bad flow state of the suction pipe under the water level of the low water inlet pool of the water pumping station discovered by the invention.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
The invention relates to a pressure pulsation identification method of the flow state in a suction pipe of a water pump station, which extracts the characteristics of the obtained pump station pressure pulsation signal, judges the flow state of the suction pipe through a threshold value and identifies the occurrence of poor flow state in the suction pipe, such as the flow retardation phenomenon occurring below the suction pipe. The steps are shown in figure 1, and specifically comprise:
step 1: obtaining a pressure pulsation signal p (t) of a suction pipe of a water pump station, wherein the positions of a collection point, a water pump station structure and a suction pipe measuring point in the embodiment are shown in fig. 2, the water level of a water intake pool is h, and the sampling frequency f s Obtaining a pressure pulsation signal p (t) of a suction pipe of a water pumping station (2000 Hz), and carrying out dimensionless processing on the pressure pulsation signal p (t) by using a pressure pulsation coefficient formula to obtain a dimensionless pressure pulsation time domain signal C p (t), defining a pressure pulsation coefficient formula as:
in formula (1): u. u 2 ＝ωR＝2πnR (2)
In formulae (1) and (2): p is static pressure of a monitoring point and has a unit of Pa;
is the average static pressure in Pa; rho is the fluid density in kg/m 3 ；u 2 Is the impeller exit peripheral velocity in m/s; r is the radius of the outlet position of the impeller and the unit is m; n is the rotating speed of the water pump, and the unit is r/s;
step 2: aiming at the pressure pulsation time domain signal C after dimensionless processing in the step 1 p (t), obtaining a pressure pulsation signal frequency domain signal G (j omega) by adopting Fast Fourier Transform (FFT), and extracting 0.1f n The amplitude A and 0-1 f of the pressure pulsation n In-range pressure pulsation frequency domain signal G 1 (j ω), water pump frequency f n ＝20Hz；
And step 3: for 0-1 f extracted in the step 2 n Frequency domain signal G of pressure pulsations in the range 1 (j omega) performing inverse Fourier transform to obtain 0-1 f n In-range pressure pulsation time domain signal C p1 (t), the inverse fourier transform formula is:
in the formula (3), ω is the signal angular frequency;
and 4, step 4: calculating 0-1 f according to a calculation formula of signal energy E and signal power P n Pressure pulsation time domain signal C p1 Energy E and power P of (t):
the formula for the signal energy E is:
the calculation formula of the signal power P is:
and 5: 0.1f extracted according to step 2 n The amplitude A of the pressure pulsation and 0-1 f obtained in the step 4 n Pressure pulsation signal energy E and power P meterCalculated to yield 0.1f n Pressure pulsation amplitude A, 0-1 f n Threshold T of pressure pulsation signal energy E and power P A 、T E And T P ：
0.1f n Pressure pulsation amplitude A, 0-1 f n Threshold T of pressure pulsation signal energy E and power P A 、T E And T P The specific determination process comprises the following steps:
step 5.1: in this embodiment, the coefficients a, b and c are all 1, and the water level of different water intake pools of the water pump station is calculated to be 0.1f n Mean value of the amplitude A of the pressure pulsations
Standard deviation S A 0.1f when 0.00552 is satisfied n A pressure pulsation amplitude threshold of
When the collected pressure pulsation signal is 0.1f n The amplitude A of the pressure pulsation is less than or equal to T A When A exceeds the threshold value, the poor flow state is considered to possibly occur;
step 5.2: calculating the water level 0-1 f of different water inlet pools of the water pump station n Mean value of the energy E of the pressure pulsation signal
Standard deviation S E 0 to 1f when 0.00023 is satisfied n The threshold value of the energy of the pressure pulsation signal is
When the collected pressure pulsation signal is 0-1 f n Component energy E is less than or equal to T E When E exceeds the threshold value, the poor flow state is considered to possibly occur;
step 5.3: calculating the water level 0-1 f of different water inlet pools of the water pump station n Mean value of the power P of the pressure pulsation signal
Standard deviation S P 0 to 1f when the average value is 0.00012 n The threshold value of the power of the pressure pulsation signal is
When the collected pressure pulsation signal is 0-1 f n Component power P is less than or equal to T P When P exceeds the threshold value, the poor flow state is considered to possibly occur;
step 6: obtaining the threshold value T according to the step 5 A 、T E And T P Judging whether a bad flow state appears in the suction pipe:
if the pressure pulse signal under a certain water level of the water inlet pool simultaneously meets the following three conditions:
0.1f n amplitude of pressure pulsation A>T A ；
0～1f n Energy E of pressure pulsation signal>T E ；
0～1f n Power P of pressure pulsation signal>T P ；
The pump station suction line is considered to have a poor flow pattern at this time.
In this embodiment, when the intake pool water level h of the water pumping station is 0.9566m, a is 0.0165, E is 0.00063, and P is 0.00032, all of which satisfy the above conditions, and therefore, the flow state in the suction pipe deteriorates at this intake pool water level, and a defective flow state occurs. In order to verify the reliability of the method, the numerical simulation is carried out on the working condition that the water level h of the water inlet pool is 0.9566m, the obtained result is shown in fig. 4 and fig. 5, and the phenomenon that a poor flow state occurs on the lower pipe wall of the suction pipe and the water flow is blocked, namely the flow speed is low and the flow line is bent, can be obviously seen.
Claims (6)
1. The pressure pulsation identification method of the flow state in the suction pipe of the water pump station is characterized by comprising the following steps:
step 1, obtaining a pressure pulsation signal p (t) of a suction pipe of a water pumping station, and carrying out dimensionless processing on the pressure pulsation signal p (t) by using a pressure pulsation coefficient formula to obtain a dimensionless pressure pulsation time domain signal C p (t)；
Step (ii) of2. Aiming at the dimensionless pressure pulsation time domain signal C in the step 1 p (t), obtaining a pressure pulsation signal frequency domain signal G (j omega) by adopting fast Fourier transform, and extracting 0.1f n The amplitude A and 0-1 f of the pressure pulsation n In-range pressure pulsation frequency domain signal G 1 (jω)，f n Frequency conversion is carried out on the water pump;
step 3, carrying out extraction on 0-1 f extracted in the step 2 n Pressure pulsation frequency domain signal G 1 (j omega) performing inverse Fourier transform to obtain 0-1 f n Pressure pulsation time domain signal C p1 (t)；
Step 4, calculating 0-1 f according to a calculation formula of the signal energy E and the signal power P n Pressure pulsation time domain signal C p1 Energy E and power P of (t);
step 5, extracting 0.1f according to step 2 n The amplitude A of the pressure pulsation and 0-1 f obtained in the step 4 n The energy E and the power P of the pressure pulsation signal are calculated to obtain 0.1f n Pressure pulsation amplitude A, 0-1 f n Threshold T of pressure pulsation signal energy E and power P A 、T E And T P ；
Step 6, obtaining the threshold value T according to the step 5 A 、T E And T P And judging whether a bad flow state appears in the suction pipe or not.
2. The method for recognizing the pressure pulsation of the flow state inside the suction pipe of the water pumping station according to claim 1, wherein the pressure pulsation coefficient formula in the step 1 is defined as follows:
in formula (1): u. of 2 2 pi nR (2) formula (1) and formula (2): p is static pressure of a monitoring point and has a unit of Pa;
is the average static pressure in Pa; rho is the fluid density in kg/m 3 ；u 2 Is leaf ofWheel exit peripheral speed in m/s; r is the radius of the outlet position of the impeller and the unit is m; and n is the rotating speed of the water pump and has the unit of r/s.
3. The method for recognizing the pressure pulsation of the flow state inside the suction pipe of the water pumping station according to claim 1, wherein the inverse Fourier transform formula in the step 3 is as follows:
in the formula (3), ω is a signal angular frequency.
4. The method for recognizing the pressure pulsation of the flow state inside the suction pipe of the water pumping station according to claim 1, wherein the calculation formula of the signal energy E in the step 4 is as follows:
the calculation formula of the signal power P is:
5. the method for recognizing the pressure pulsation in the flow state inside the suction pipe of the water pumping station according to claim 1, wherein 0.1f in the step 5 is n Pressure pulsation amplitude A, 0-1 f n Threshold T of pressure pulsation signal energy E and power P A 、T E And T P The specific determination process comprises the following steps:
step 5.1, calculating the mean value of the pressure pulsation amplitude A of different water inlet pool water levels of the water pump station
And standard deviation S A ，0.1f n The corresponding pressure pulsation amplitude threshold value is
Step 5.2, calculating 0-1 f of different water inlet pond water levels of the water pump station n Mean value of the energy E of the pressure pulsation signal
And standard deviation S E ，0～1f n The threshold value of the energy of the pressure pulsation signal is
Step 5.3, calculating 0-1 f of different water inlet pond water levels of the water pump station n Mean value of the power P of the pressure pulsation signal
And standard deviation S P ，0～1f n The threshold value of the power of the pressure pulsation signal is
Wherein a, b and c are coefficients.
6. The method for identifying the pressure pulsation of the flow state in the suction pipe of the water pumping station according to claim 1, wherein the standard for judging whether the poor flow state occurs in the suction pipe in the step 6 is as follows:
under a certain water level of the water inlet pool, the pressure pulsation signal simultaneously meets the following three conditions:
0.1f n amplitude of pressure pulsation A>T A ；
0～1f n Energy E of pressure pulsation signal>T E ；
0～1f n Power P of pressure pulsation signal>T P ；
The poor flow regime in the suction pipe of the water pumping station is considered to be present at this time.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2527563A1 (en) * | 2005-12-23 | 2006-03-10 | Westport Research Inc. | Apparatus and method for pumping a cryogenic fluid from a storage vessel and diagnosing cryogenic pump performance |
| CN108664710A (en) * | 2018-04-20 | 2018-10-16 | 江苏大学 | A kind of pump flow-induced vibration performance comprehensive evaluation method |
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- 2022-06-10 CN CN202210651624.4A patent/CN115076085B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2527563A1 (en) * | 2005-12-23 | 2006-03-10 | Westport Research Inc. | Apparatus and method for pumping a cryogenic fluid from a storage vessel and diagnosing cryogenic pump performance |
| CN108664710A (en) * | 2018-04-20 | 2018-10-16 | 江苏大学 | A kind of pump flow-induced vibration performance comprehensive evaluation method |
Non-Patent Citations (1)
| Title |
|---|
| 宋希杰;刘超;罗灿;: "轴流泵装置进水漩涡对压力脉动的影响", 农业机械学报, no. 02, pages 120 - 126 * |
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