# Experimental Determination Influence of Flow Disturbances behind the Knife Gate Valve on the Indications of the Ultrasonic Flow Meter with Clamp-On Sensors on Pipelines

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## Abstract

**:**

## 1. Introduction

_{A}) as well as components connected to the accuracy of the measuring instrument installation and the conditions of performing a measurement (components of the uncertainty type B u

_{B}) [1,2,3]. Apart from the above-mentioned classic method for the determination of the uncertainty budget based on the uncertainty propagation law, there is a possibility to determine the uncertainty budget with the use of the numerical Monte Carlo method [4,5]. The possibility of mounting during the uninterrupted work continuity in the system, influence on the processes occurring in the system (non-invasiveness) and economic factors are the most important elements which determine the use of a measuring device. There are several highly desirable features of flow meters:

- High measurement accuracy—high sensitivity and resolution;
- Non-invasiveness during operation;
- Non-contact;
- Service life—long-term operation;
- Independence from environmental conditions/system operation conditions;
- Low cost of investment and of operation.

## 2. Measurements

- With the valve placed in the position of closure of 1/3 of the knife gate valve’s height, one obtains P
_{1/3}= 78.09% of the active flow area; - With the valve placed in the position of closure of 1/2 of the knife gate valve’s height, one obtains P
_{1/2}= 60.89% of the active flow area.

_{v}(8).

## 3. Results

_{ref,}at a straight section of the pipeline in front of the knife gate valve. The Endress+Hausser Prosonic Flow 93T flow meter was used to measure the velocity, v

_{mes,}in the area of the disturbed flow behind the knife gate valve. A subsequent series of measurements were run in following distances from the knife gate valve in the range of 3D–15D.

_{ref,}and behind the valve, v

_{mes,}were calculated for each measurement series. In order to determine an actual dimensionless factor describing the level of flow distortion, a ratio of the average speeds, v

_{ref}and v

_{mes,}was used (9). The K* factor is a dimensionless parameter reflecting changes in the velocity distribution on the section between the ultrasonic sensors. The K* factor is used by the authors in many articles on ultrasonic flow measurement [7,9,11,12].

#### 3.1. Measurement Results—½ Closure of the Knife Gate Valve’s Height, Re = 35,000

#### 3.2. Measurement Results—½ of Closure of the Knife Gate Valve’s Height, Re = 70,000

#### 3.3. Measurement Results—1/3 of the Knife Gate Valve’s Height Closed, Re = 35,000

#### 3.4. Measurement Results—1/3 of the Knife Gate Valve’s Height Closed, Re = 70,000

#### 3.5. Comparison of Results from All of the Measurement Series

#### 3.6. Treatment of Results of Laser Anemometry Test

## 4. Conclusions

- In the measurement series conducted for the ½ closure of the knife gate valve, much larger flow disturbances occurred than in the measurement series conducted for the 1/3 closure of the valve. These observations were also confirmed by the laser anemometry LDA tests. Graphic analysis of the velocity profiles showed an analogy in the flow disturbance structure for both levels of the closure of the valve.
- In the course of the correlation of the K* factor (α) for the series with Re = 35,000 and Re = 70,000, analogies can be noticed. It can be assumed that this correlation is universal for Reynolds numbers in the range of the turbulent flow.

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

## Abbreviation

Symbols | |

C | velocity of ultrasonic wave, m/s |

D | diameter of the pipeline, mm |

…D | measurement cross sections at a distance |

… | pipeline diameters from the knife gate valve, mm |

K* | correction factor |

l | path length of the ultrasonic wave, mm |

L | distance between ultrasonic sensors, mm |

q_{v} | volume flow rate, m^{3}/s |

t | transit time of the ultrasonic wave, s |

Δt | time difference between the flow upstream and downstream, s |

Re | Reynolds number |

V | flow velocity, m/s |

v_{mes} | velocity measured behind the knife gate valve, m/s |

v_{ref} | velocity measured in front of the knife gate valve, m/s |

α | angle of the ultrasonic heads setting, ° |

u_{A} | component of the type A uncertainty of the flow velocity measurement, m/s |

u_{B} | component of the type B uncertainty of the flow velocity measurement, m/s |

## References

- ISO. Guide to the Expression of Uncertainty in Measurement; ISO: Geneva, Switzerland, 1995. [Google Scholar]
- JCGM 200:2012; International Vocabulary of Metrology—Basic and General Concepts and Associated Terms (VIM). 2012. Available online: https://www.bipm.org/documents/20126/2071204/JCGM_200_2012.pdf/f0e1ad45-d337-bbeb-53a6-15fe649d0ff1 (accessed on 1 May 2023).
- Joint Committee for Guides in Metrology. Evaluation of Measurement Data—Guide to the Expression of Uncertainty in Measurement; International Bureau of Weights and Measures (BIPM): Sèvres, France, 2008.
- JCGM 101:2008; Evaluation of Measurement Data—Supplement 1 to the Guide—Propagation of Distribution Using a Monte Carlo Method. 2008. Available online: https://www.bipm.org/documents/20126/2071204/JCGM_101_2008_E.pdf/325dcaad-c15a-407c-1105-8b7f322d651c (accessed on 8 May 2023).
- Joint Committee for Guides in Metrology. Evaluation of Measurement Data—Supplement 1 to the “Guide to the Expression of Uncertainty in Measurement”—Propagation of Distributions Using a Monte Carlo Method; International Bureau of Weights and Measures (BIPM): Sèvres, France, 2008. [Google Scholar]
- AlSaqoor, S.; Alahmer, A.; Andruszkiewicz, A.; Piechota, P.; Synowiec, P.; Beithu, N.; Wędrychowicz, W.; Wróblewska, E.; Jouhara, H. Ultrasonic technique for measuring the mean flow velocity behind a throttle: A metrological analysis. Therm. Sci. Eng. Prog.
**2022**, 34, 101402. [Google Scholar] [CrossRef] - Synowiec, P.; Andruszkiewicz, A.; Wędrychowicz, W.; Piechota, P.; Wróblewska, E. Influence of flow disturbances behind the 90° bend on the indications of the ultrasonic flow meter with clamp-on sensors on pipelines. Sensors
**2021**, 21, 868. [Google Scholar] [CrossRef] [PubMed] - Awad, A.S.; Abulghanam, Z.; Fayyad, S.M.; AlSaqoor, S.; Alahmer, A.; Aljabarin, N.; Piechota, P.; Andruszkiewicz, A.; Wędrychowicz, W.; Synowiec, P. Measuring the fluid flow velocity and its uncertainty using Monte Carlo method and ultrasonic technique. WSEAS Trans. Fluid Mech.
**2020**, 15, 172–182. [Google Scholar] [CrossRef] - Piechota, P.; Synowiec, P.; Andruszkiewicz, A.; Wędrychowicz, W. Analysis of the accuracy of liquid flow measurements by the means of ultrasonic method in non-standard measurements conditions. In Methods and Techniques of Signal Processing in Physical Measurements; Hanus, R., Mazur, D., Kreischer, C., Eds.; Springer: Cham, Switzerland, 2019; pp. 275–285. [Google Scholar]
- Synowiec, P.; Andruszkiewicz, A.; Wędrychowicz, W.; Regucki, P. Badania możliwości pomiaru strumienia objętości czynnika dwufazowego przepływomierzem ultradźwiękowym. Prz. Elektrotechniczny
**2015**, 10, 181–184. [Google Scholar] [CrossRef] - Salami, L.A. Errors in the velocity area method of measuring asymetric flows in circular pipes. Mod. Dev. Flow Meas.
**1971**, 10, 381–399. [Google Scholar] - Moore, P.I.; Brown, G.J.; Stimpson, B.P. Ultrasonic transit-time flowmeters modelled with theoretical velocity profiles: Methodology. Measurement Sci. Technol.
**2000**, 11, 1802–1810. [Google Scholar] [CrossRef] - Pistun, Y.; Roman, V.; Matiko, F. Investigating the Ultrasonic Flowmeter Error in Conditions of Distorted Flow Using Multipeaks Salami Functions. Errors Uncertain.
**2019**, 24, 14–19. [Google Scholar] [CrossRef] - Waluś, S. Mathematical modelling of an ultrasonic flowmeter primary device. Arch. Acoust.
**1998**, 23, 429–442. [Google Scholar] - Piechota, P.; Synowiec, P.; Andruszkiewicz, A.; Wędrychowicz, W. Selection of the relevant turbulence model in a CFD simulation of a flow disturbed by hydraulic elbow: Comparative analysis of the simulation with measurements results obtained by the ultrasonic flowmeter. J. Therm. Sci.
**2018**, 27, 413–420. [Google Scholar] [CrossRef] - Ekambara, K.; Sanders, R.S.; Nandakumar, K.; Masliyah, J.H. Hydrodynamic Simulation of Horizontal Slurry Pipeline Flow Using ANSYS-CFX. Ind. Eng. Chem. Res.
**2009**, 48, 8159–8171. [Google Scholar] [CrossRef] - Hu, L.; Fang, Z.; Qin, L.; Mao, K.; Chen, W.; Fu, X. Modelling of received ultrasonic signals based on variable frequency. Flow Meas. Instrum.
**2019**, 65, 141–149. [Google Scholar] [CrossRef] - Papathanasiou, P.; Kissling, B.; Berberig, O.; Kumar, V.; Rohner, A.; Bezděk, M. Flow disturbance compensation calculated with flow simulations for ultrasonic clamp-on flowmeters with optimized path arrangement. Flow Meas. Instrum.
**2022**, 85, 102167. [Google Scholar] [CrossRef] - Bopp, S.; Durst, F.; Holweg, J.; Weber, H. A laser—Doppler sensor for flowrate measurements. Flow Meas. Instrum.
**1989**, 1, 31–38. [Google Scholar] [CrossRef] - Waluś, S. The use of the ultrasonic flowmeter in the conditions other than normal. Int. Conf. Flow Meas. Melb.
**1985**, 20–23, 171–176. [Google Scholar] - Stoker, D.; Barfuss, S.; Johnson, M.C. Ultrasonic Flow Measurement for Pipe Installations with Non-Ideal Conditions. J. Irrig. Drain. Eng.
**2012**, 138, 993–998. [Google Scholar] [CrossRef] - Sejong, C.; Byung-Ro, Y.; Woong, K.; Hyu-Sang, K. Assessment of combined V/Z clamp-on ultrasonic flow metering. J. Mech. Sci. Technol.
**2014**, 28, 2169–2177. [Google Scholar] - Martins, R.S.; Andrade, J.R.; Ramos, R. On the effect of the mounting angle on single-path transit-time ultrasonic flow measurement of flare gas. J. Braz. Soc. Mech. Sci. Eng.
**2020**, 42, 13. [Google Scholar] [CrossRef] - Kumar, K.; Farande, K.; Sahoo, G. Installation effects of a clamp-On transit time ultrasonic flow metery. Int. J. Fluid Mech.
**2011**, 2011, 489–498. [Google Scholar] [CrossRef] - Zhang, H.; Guo, C.; Lin, J. Effects of Velocity Profiles on Measuring Accuracy of Transit-Time Ultrasonic Flowmeter. Appl. Sci.
**2019**, 9, 1648. [Google Scholar] [CrossRef] - Sakhavi, N.; Nouri, N.M. Generalized velocity profile evaluation of multipath ultrasonic phased array flowmeter. Measurement
**2021**, 187, 110302. [Google Scholar] [CrossRef] - Waluś, S. Some guidelines for ultrasonic flowmeter sensors installation for distorted velocity profiles. Mol. Quantum Acoust.
**1998**, 19, 91–102. [Google Scholar] - Wada, S.; Furuichi, N. Influence of obstacle plates on flowrate measurement uncertainty based on ultrasonic Doppler velocity profile method. Flow Meas. Instrum.
**2016**, 48, 81–89. [Google Scholar] [CrossRef] - Waluś, S. The Compensation of Sensitivity Changes and the Influence of Liquid Temperature in the Microprocessor-Based Multi-Path Ultrasonic Flowmeter; Wissenschaftliche Tage: Magdeburg, Germany, 1989; pp. 214–218. [Google Scholar]
- Tawackolian, K.; Büker, O.; Hogendoorn, J.; Lederer, T. Calibration of an ultrasonic flow meter for hot water. Flow Meas. Instrum.
**2013**, 30, 166–173. [Google Scholar] [CrossRef] - Utsumi, H. An Ultrasonic Velocitymeter for Use of Calibration of Waste-Water Flowmeter. Fluid Control and Measurement, tom Volume 2, M. Harada, Red.; Pergamon Press: Tokyo, Japan, 1985; pp. 997–1002. [Google Scholar]
- Endress+Hauser, Manual Proline Prosonic Flow 93T HART-Portable Ultrasonic Flowmeter. Available online: https://portal.endress.com/wa001/dla/5000255/6790/000/02/BA00136DEN_1311.pdf (accessed on 20 January 2021).
- Micronics Ltd. User Manual of Portable Ultrasonic Flow Meter Micronics Portaflow PF330; Micronics Ltd.: Loudwater, UK, 2012. [Google Scholar]
- Guo, S.; Xiang, N.; Li, B.; Wang, F.; Zhao, N.; Zhang, T. Integration method of multipath ultrasonic flowmeter based on velocity distribution. Measurement
**2023**, 207, 112388. [Google Scholar] [CrossRef] - Sakhavi, N.; Nouri, N.M. Performance of novel multipath ultrasonic phased array flowmeter using Gaussian quadrature integration. Appl. Acoust.
**2022**, 199, 109004. [Google Scholar] [CrossRef] - Kurniadi, D.; Trisnobudi, A. A Multi-Path Ultrasonic Transit Time Flow Meter Using a Tomography Method for Gas Flow Velocity Profile Measurement. Part. Part. Syst. Charact.
**2006**, 23, 330–338. [Google Scholar] [CrossRef] - Tang, X.-Y.; Yang, Q.; Sun, Y. Gas flow-rate measurement using a transit-time multi-path ultrasonic flow meter based on PSO-SVM. In Proceedings of the 2017 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), Turin, Italy, 22–25 May 2017; pp. 1–6. [Google Scholar] [CrossRef]

**Figure 1.**(

**a**) Wafer knife gate valve PVC DN50, (

**b**) valve closed in 1/3 of the valve’s height, (

**c**) valve closed in 1/2 of the valve’s height.

**Figure 2.**(

**a**) Scheme of the ultrasonic wave transition in the system of V-shaped heads. (

**b**) Measurement system diagram: 1—ultrasonic flow meter (reference flow meter) Micronics PortaFlow 330, 2—knife gate valve DN50, 3—ultrasonic flow meter Endress+Hausser Prosonic Flow 93T, 3D–15D—measurement cross sections.

**Figure 3.**Positions (angles) of the flow meter installation behind the valve at individual 3D–15D measurement cross sections.

**Figure 4.**Graph showing values of velocity measured in front of the valve, v

_{ref,}and at 3D distance from the valve, v

_{mes,}with ½ of the knife gate valve’s height closed and Reynolds number, Re = 35,000.

**Figure 5.**Graph showing values of velocity measured in front of the valve, v

_{ref,}and at 6D distance from the valve, v

_{mes,}with ½ of the knife gate valve’s height closed and Reynolds number, Re = 35,000.

**Figure 6.**Graph showing values of velocity measured in front of the valve, v

_{ref,}and at 9D distance from the valve, v

_{mes,}with ½ of the knife gate valve’s height closed and Reynolds number, Re = 35,000.

**Figure 7.**Graph showing values of velocity measured in front of the valve, v

_{ref,}and at 12D distance from the valve, v

_{mes,}with ½ of the knife gate valve’s height closed and Reynolds number, Re = 35,000.

**Figure 8.**Graph showing values of velocity measured in front of the valve, v

_{ref,}and at 15D distance from the valve, v

_{mes,}with ½ of the knife gate valve’s height closed and Reynolds number, Re = 35,000.

**Figure 9.**Graph showing values of the K* factor determined for the measured values of velocity, v

_{ref}and v

_{mes,}with ½ of the knife gate valve’s height closed and Reynolds number, Re = 35,000.

**Figure 10.**Graph showing values of velocity measured in front of the valve, v

_{ref,}and at 3D distance from the valve, v

_{mes,}with ½ of the knife gate valve’s height closed and Reynolds number, Re = 70,000.

**Figure 11.**Graph showing values of velocity measured in front of the valve, v

_{ref,}and at 6D distance from the valve, v

_{mes,}with ½ of the knife gate valve’s height closed and Reynolds number, Re = 70,000.

**Figure 12.**Graph showing values of velocity measured in front of the valve, v

_{ref,}and at 9D distance from the valve, v

_{mes,}with ½ of the knife gate valve’s height closed and Reynolds number, Re = 70,000.

**Figure 13.**Graph showing values of velocity measured in front of the valve, v

_{ref,}and at 12D distance from the valve, v

_{mes,}with ½ of the knife gate valve’s height closed and Reynolds number, Re = 70,000.

**Figure 14.**Graph showing values of velocity measured in front of the valve, v

_{ref,}and at 15D distance from the valve, v

_{mes,}with ½ of the knife gate valve’s height closed and Reynolds number, Re = 70,000.

**Figure 15.**Graph showing values of the K* factor determined for the measured values of velocity, v

_{ref}and v

_{mes,}with ½ of the knife gate valve’s height closed and Reynolds number, Re = 70,000.

**Figure 16.**Graph showing values of velocity measured in front of the valve, v

_{ref,}and at 3D distance from the valve, v

_{mes,}with 1/3 of the knife gate valve’s height closed and Reynolds number, Re = 35,000.

**Figure 17.**Graph showing values of velocity measured in front of the valve, v

_{ref,}and at 6D distance from the valve, v

_{mes,}with 1/3 of the knife gate valve’s height closed and Reynolds number, Re = 35,000.

**Figure 18.**Graph showing values of velocity measured in front of the valve, v

_{ref,}and at 9D distance from the valve, v

_{mes,}with 1/3 of the knife gate valve’s height closed and Reynolds number, Re = 35,000.

**Figure 19.**Graph showing values of velocity measured in front of the valve, v

_{ref,}and at 12D distance from the valve, v

_{mes,}with 1/3 of the knife gate valve’s height closed and Reynolds number, Re = 35,000.

**Figure 20.**Graph showing values of velocity measured in front of the valve, v

_{ref,}and at 15D distance from the valve, v

_{mes,}with 1/3 of the knife gate valve’s height closed and Reynolds number, Re = 35,000.

**Figure 21.**Graph showing values of the K* factor determined for the measured values of velocity, v

_{ref}and v

_{mes,}with 1/3 of the knife gate valve’s height closed and Reynolds number, Re = 35,000.

**Figure 22.**Graph showing values of velocity measured in front of the valve, v

_{ref,}and at 3D distance from the valve, v

_{mes,}with 1/3 of the knife gate valve’s height closed and Reynolds number, Re = 70,000.

**Figure 23.**Graph showing values of velocity measured in front of the valve, v

_{ref,}and at 6D distance from the valve, v

_{mes,}with 1/3 of the knife gate valve’s height closed and Reynolds number, Re = 70,000.

**Figure 24.**Graph showing values of velocity measured in front of the valve, v

_{ref,}and at 9D distance from the valve, v

_{mes,}with 1/3 of the knife gate valve’s height closed and Reynolds number, Re = 70,000.

**Figure 25.**Graph showing values of velocity measured in front of the valve, v

_{ref,}and at 12D distance from the valve, v

_{mes,}with 1/3 of the knife gate valve’s height closed and Reynolds number, Re = 70,000.

**Figure 26.**Graph showing values of velocity measured in front of the valve, v

_{ref,}and at 15D distance from the valve, v

_{mes,}with 1/3 of the knife gate valve’s height closed and Reynolds number, Re = 70,000.

**Figure 27.**Graph showing values of the K* factor determined for the measured values of velocity, v

_{ref}and v

_{mes,}with 1/3 of the knife gate valve’s height closed and Reynolds number, Re = 70,000.

**Figure 28.**Graph showing values of the K* factor determined for the measured values of velocity, v

_{ref}and v

_{mes,}at 3D distance with different levels of the knife gate valve’s opening and Reynolds number.

**Figure 29.**Graph showing values of the K* factor determined for the measured values of velocity, v

_{ref}and v

_{mes,}at 6D distance with different levels of the knife gate valve’s opening and Reynolds number.

**Figure 30.**Graph showing values of the K* factor determined for the measured values of velocity, v

_{ref}and v

_{mes,}at 9D distance with different levels of the knife gate valve’s opening and Reynolds number.

**Figure 31.**Graph showing values of the K* factor determined for the measured values of velocity, v

_{ref}and v

_{mes,}at 12D distance with different levels of the knife gate valve’s opening and Reynolds number.

**Figure 32.**Graph showing values of the K* factor determined for the measured values of velocity, v

_{ref}and v

_{mes,}at 15D distance with different levels of the knife gate valve’s opening and Reynolds number.

**Figure 33.**Velocity profiles created on the basis of LDA measurements performed with ½ opening of the knife gate valve and Reynolds number, Re = 35,000, at distances from the valve: (

**a**) 4D, (

**b**) 7D, (

**c**) 10D, (

**d**) 15D.

**Figure 34.**Velocity profiles created on the basis of LDA measurements performed with ½ opening of the knife gate valve and Reynolds number, Re = 70,000, at distances from the valve: (

**a**) 4D, (

**b**) 7D, (

**c**) 10D, (

**d**) 15D.

**Figure 35.**Velocity profiles created on the basis of LDA measurements performed with 1/3 opening of the knife gate valve and Reynolds number, Re = 35,000, at distances from the valve: (

**a**) 4D, (

**b**) 7D, (

**c**) 10D, (

**d**) 15D.

**Figure 36.**Velocity profiles created on the basis of LDA measurements performed with 1/3 opening of the knife gate valve and Reynolds number, Re = 70,000, at distances from the valve: (

**a**) 4D, (

**b**) 7D, (

**c**) 10D, (

**d**) 15D.

Name of Parameter | Parameter |
---|---|

Nominal diameter of the pipeline | DN 50 |

Measurement sections | 3D–15D |

Velocities | ca. 0.3 m/s for Re = 35,000 |

ca. 1.78 m/s for Re = 70,000 | |

The ultrasound wave path | V |

Sampling interval | 5 s |

Distance between sensors | ca. 90 mm |

Knife gate closing level | 1/3 valve height (ca. 22%) |

1/2 valve height (ca. 40%) |

Device | Brand | Model | Specification | Maximum Permissible Error (MPE) |
---|---|---|---|---|

Ultrasonic flow meter | Microsonic | Porta Flow 330 | Transit-time measurement, clamp-on sensors | 0.5% to 2% of velocity reading for v > 0.2 m/s |

Ultrasonic flow meter | Endress+Hausser | Prosonic Flow 93T | Transit-time measurement, clamp-on sensors | 0.5% to 2% of velocity reading for v > 0.3 m/s for Re > 10,000 |

Laser Doppler anemometer | Dantec | One-channel laser Doppler anemometer data | Power of laser: 10 mW Light wavelength: 632.8 nm-red Light focal length: 160 mm Measuring volume: 75 μm × 630 μm | - |

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## Share and Cite

**MDPI and ACS Style**

Piechota, P.; Synowiec, P.; Andruszkiewicz, A.; Wędrychowicz, W.; Wróblewska, E.; Mrowiec, A.
Experimental Determination Influence of Flow Disturbances behind the Knife Gate Valve on the Indications of the Ultrasonic Flow Meter with Clamp-On Sensors on Pipelines. *Sensors* **2023**, *23*, 4677.
https://doi.org/10.3390/s23104677

**AMA Style**

Piechota P, Synowiec P, Andruszkiewicz A, Wędrychowicz W, Wróblewska E, Mrowiec A.
Experimental Determination Influence of Flow Disturbances behind the Knife Gate Valve on the Indications of the Ultrasonic Flow Meter with Clamp-On Sensors on Pipelines. *Sensors*. 2023; 23(10):4677.
https://doi.org/10.3390/s23104677

**Chicago/Turabian Style**

Piechota, Piotr, Piotr Synowiec, Artur Andruszkiewicz, Wiesław Wędrychowicz, Elżbieta Wróblewska, and Andrzej Mrowiec.
2023. "Experimental Determination Influence of Flow Disturbances behind the Knife Gate Valve on the Indications of the Ultrasonic Flow Meter with Clamp-On Sensors on Pipelines" *Sensors* 23, no. 10: 4677.
https://doi.org/10.3390/s23104677