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1
Content available New gas-liquid two-phase flow pattern maps based on the energy ratio of pressure fluctuation through a Venturi tube
Sun Zhiqiang, Chen Luyang, Yao Fengyan
Metrology and Measurement Systems
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2019
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Vol. 26, nr 2
241--252
EN
To find effective and practical methods to distinguish gas-liquid two-phase flow patterns, new flow pattern maps are established using the differential pressure through a classical Venturi tube. The differential pressure signal was first decomposed adaptively into a series of intrinsic mode functions (IMFs) by the ensemble empirical mode decomposition. Hilbert marginal spectra of the IMFs showed that the flow patterns are related to the amplitude of the pressure fluctuation. The cross-correlation method was employed to sift the characteristic IMF, and then the energy ratio of the characteristic IMF to the raw signal was proposed to construct flow pattern maps with the volumetric void fraction and with the two-phase Reynolds number, respectively. The identification rates of these two maps are verified to be 91.18% and 92.65%. This approach provides a cost-effective solution to the difficult problem of identifying gas-liquid flow patterns in the industrial field.
2
Content available Analiza wpływu parametrów siatki obliczeniowej na wynik symulacji przepływomierza
Jurkowski Sławomir, Janisz Karina
Autobusy : technika, eksploatacja, systemy transportowe
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2019
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R. 20, nr 12
129--134
PL
W artykule przedstawiono analizę wpływu parametrów siatki na wynik symulacji przepływu gazu przez zwężkę Venturiego. Rozważono wpływ rodzaju siatki, algorytmu siatkowania i wielkości komórek obliczeniowych. Analizą objęto siatkę całego układu pomiarowego włącznie z przewodami impulsowymi. Wyniki symulacji odniesiono do wyników obliczeń przepływu wg. normy PN-EN ISO 5167-4:2005. Wybrano optymalne rozwiązanie biorąc pod uwagę jakość siatki i czas symulacji. Symulację przeprowadzono z wykorzystaniem programu Ansys 2019 R2.
EN
The article presents the analysis of the influence of grid parameters on the result of gas flow simulation through a Venturi. The influence of the grid type, netting algorithm and element size were considered. The analysis covered the grid of the entire measurement system including with impulse lines. The results of the simulation were referred to the results of flow calculations according to standards PN-EN ISO 5167-4: 2005. Optimal solution was chosen considering the grid quality and simulation time. The simulation was carried out using the Ansys 2019 R2 program.
3
Content available Experimental investigations of cavitating flows in a Venturi tube
Niedźwiedzka A., Sobieski W.
Technical Sciences / University of Warmia and Mazury in Olsztyn
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2016
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nr 19(2)
151--164
EN
This article presents results of the experimental measurements of the cavitation phenomena in a Venturi tube with water as the working medium. Three variants of such tube were tested. Angles of converging and diverging sections are equal to 45o and 45o, 30o and 60o, 45o and 60o, respectively. In every case the throat diameter is equal to 3 mm and the throat length to 6 mm. The average flow velocity ranges from 0.1 to 0.5 m/s. During measurements, the average flow velocity, upstream and downstream pressure and water temperature were recorded. Additionally, by the use of a high-speed camera and a simple digital camera, information about the size and the shape of the bubble clouds for different flow conditions was collected. The aim of the article is data acquisition for the further numerical analyses. The experimental runs executed for this paper are to help provide more information about this type of flow, since numerical modeling of the cavitation phenomena in Venturi tubes is still very difficult and in many cases even quantitative agreement is impossible to obtain.
4
Content available Analytical analysis of cavitating flow in Venturi tube on the basis of experimental data
Niedźwiedzka A., Sobieski W.
Technical Sciences / University of Warmia and Mazury in Olsztyn
|
2016
|
nr 19(3)
215--229
EN
The content of this article is a direct continuation of the prior experimental works on the topic of cloud cavitation in Venturis. The results of the experimental tests were used to create a set of characteristics for three types of Venturis. The article has two aims: 1) verification of the similarity between the characteristics obtained and reported in the literature, 2) verification of the range of the obtained characteristics with respect to parallel diagrams. Both aims were achieved, which confirms that the quality of the prior results of the experimental measurements is at least sufficient to realize the main objective of the whole project: creation of numerical models of cavitating flow in Venturis. The literature overview showed that the issue has been not solved until today, even at the qualitative level. This reason was the motivation for the undertaken research, including contents of the article.
5
Content available Erosive impact of vapor-gas phase on the working surface in hydrodynamic type cavitation mode
Vitenko T., Droździel P., Horodyskyi N.
Diagnostyka
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2016
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Vol. 17, No. 1
3--8
EN
In this article is analyzed the possible mechanism of cavitation bubbles erosive impact on the working surfaces of equipment. The volume and the size of vapor-gas phase generated in hydrodynamic type mode was theoretically determined and experimentally verified. Here are presented the results of studies of cavitation-erosion resistance of food steel, in particular, that the process of destruction has cyclical pattern.
PL
W artykule przedstawiono oddziaływanie erozji na powierzchnię elementów maszynowych powstałej pod wpływem pęcherzyków kawitacyjnych. Ilość oraz wielkość fazy gazowej w stanie hydrodynamicznym została teoretycznie obliczona oraz doświadczalnie zweryfikowana. Artykuł prezentuje wyniki badań odporności na erozję kawitacyjną stali stosowanej przy produkcji żywności, że szczególnym uwzględnieniem cyklicznego procesu jej destrukcji.
6
Content available Efficiency Increase of Wet Gas Cleaning from Dispersed Admixtures by the Application of Ultrasonic Fields
Khmelev V. N., Shalunov A. V., Golykh R. N., Dorovskikh R. S, Nesterov V. A., Khmelev S. S., Shalunova K. V.
Archives of Acoustics
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2016
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Vol. 41, No. 4
757--771
EN
The article presents the results of research aimed at increase of the efficiency of gas cleaning equipment based on the Venturi tube using high-intensity ultrasound. The model based on known laws of hydrodynamics of multiphase mediums of dust-extraction in Venturi scrubbers was proposed. Modification of this model taking into account ultrasonic field allows evaluating optimum modes (sound pressure level) and conditions (direction of ultrasonic field, square and number of ultrasonic sources) of ultrasonic influence. It is evaluated that optimum for efficient gas cleaning is the mode of ultrasonic action at the frequency of 22 kHz with sound pressure level of 145…155 dB at the installation of two radiators with area of 0.14 m2, four radiators with area of 0.11 m2 or six radiators with area of 0.08 m2 at the angle of 45 degrees to the axis of Venturi tube. Numerical calculations showed that realization of ultrasonic action is the most efficient for the reduction (up to 15 times) of the content of fine-dispersed fraction (2 µm and less), which is impossible to extract without ultrasonic action. The received theoretical results were confirmed by industrial testing by typical dust-extraction plant and used as foundations of development of apparatuses with the radiators of various sizes.
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