Flow of Oil and Water through the Nozzle and Cavitation

Jablonská, Jana; Kozubková, Milada; Bojko, Marián

doi:10.3390/pr9111936

Cited by 4 publications

(4 citation statements)

References 20 publications

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“…The P cav of PAO, PDMS, and POE all showed larger values than their vapor pressure estimated from the values shown in Table 2. Although there is no data on the vapor pressure of the tested PAG in Table 2, the saturated vapor pressure of the oil is generally very low [9], and this should be the case with other oils. PAG with polarity showed the highest P cav , but POE with polarity showed the lowest P cav , suggesting that the polarity had little effect in this study.…”

Section: Measurement Of Cavitation Pressure -Experimentsmentioning

confidence: 97%

Variation of Cavitation Pressure with Liquid and Operating Conditions in Mechanical Seals

Makishima,

Itadani,

Tokunaga

et al. 2023

Tribology Online

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A series of experiments is conducted to investigate the cavitation pressure P cav in the sealing film of a mechanical seal. To generate negative pressure, a reversed Rayleigh step is produced on the sliding surface, and the formation of cavities in the sealing film is observed. The pressure in the cavitation region is directly measured using a pressure sensor installed under a pinhole on the sliding surface. Various lubricating oils with similar kinematic viscosities are used as sealing fluid. The results show that pressure in the cavitation region is related to the operating conditions. P cav decreases with increasing sliding speed in all oils and all sealing gap, i.e. minimum distance between two sliding surfaces of mechanical seal. When the sealing gap is the same, P cav at each sliding speed is slightly different depending on the type of lubricating oils. When the lubricating oil is the same, small dissolved air results in low P cav . In addition, two sealing gap are tested under the same sliding speed and the same oil, revealing that thin sealing gap results in low P cav . Further, a model of cavitation in the reversed Rayleigh step is proposed based on the experimental results.

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Section: Measurement Of Cavitation Pressure -Experimentsmentioning

confidence: 97%

Variation of Cavitation Pressure with Liquid and Operating Conditions in Mechanical Seals

Makishima,

Itadani,

Tokunaga

et al. 2023

Tribology Online

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show abstract

“…Measurements that have been published in the literature [13,14,15,16] are used for evaluation. For each measurement variant, pressures and volume flow rates were recorded with a time step of 0.001 s and subsequently the average values were evaluated.…”

Section: Evaluation Of Basic Hydraulic Parametersmentioning

confidence: 99%

Identification of Cavitation by Noise

et al. 2022

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The identification of cavitation is very important in technical practice for operational and especially economic reasons. The article deals with the use of another way to measure noise during cavitation. The current approach of measuring noise with an intensity probe is used in practice for identification, but it does not immediately address the position of the cavitation source for a given frequency range. Measurement by an acoustic camera is not entirely common in practice, but it allows to determine the location of the noise source for a given frequency range. To test the acoustic camera, the authors focused on the cavitating flow in a hydraulic circuit with three previously tested nozzles. Noise was measured for these nozzles using an acoustic intensity probe with two microphones. The results were evaluated by statistical methods and compared with measurements using an acoustic camera. The aim of the article is to point out the advantages of using this approach for accurate area identification of the problem. Research background: The work is focused on the issue of cavitation and its identification in the hydraulic circuit. For cavitation research, a variant of cavitation identification by noise was chosen. However, this measurement brings problems that are only revealed through more sophisticated and accurate measurements. Purpose of the article: The purpose of the article is to point out other possibilities of measuring cavitation noise using modern technologies and subsequently verify the results. Methods: Metody: A common way of measuring noise is to measure it with a suitably located acoustic intensity probe. A more modern approach is area noise measurement. Measurement methodology and benefits are described. Findings & Value added: The commonly used way of measuring noise using an acoustic intensity probe has proved to be insufficient, as it is not possible to distinguish the location of sources in the case of complex measurements. When using an acoustic camera, there are more sources of noise in a given circuit and they are detected according to the required frequencies in different places than expected. The article points out the specific identification of noise sources using the frequency spectrum of noise for selected elements.

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“…While the vapour cavitation is accompanied by the phase change between liquid and gas phases, gas cavitation is associated with diffusion processes in the liquid [2,11]. Liquids are affected by both processes [6][7][8][9], and both significantly affect the hydraulic mechanisms.…”

Section: Introductionmentioning

confidence: 99%

“…The hydraulic oils also exhibit both gaseous and vapour cavitation [8][9][10][11], but the conditions for the release of oil vapour bubbles are more difficult to achieve in comparison to the release of water vapour bubbles. This is due to the different properties of the liquids, which are manifested, among other things, by the very low saturation vapour pressure of the oil.…”

Section: Introductionmentioning

confidence: 99%

Experimental Analysis of Flow Through Throttle Valve During Gaseous Cavitation

et al. 2022

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The multiphase flow in oil hydraulic systems has a very significant effect on the correct operation of the hydraulic system. Air can be found in various states in hydraulic systems, while free entrained air in the form of bubbles has the potential to be the most problematic. It especially affects the compressibility of the hydraulic liquid resulting in reduced stiffness of the hydraulic system. The actuators of the hydraulic mechanisms then do not achieve the fast response and the precision of movements depending on the input control signals. One possibility for the contamination of hydraulic fluid by air bubbles is through a phenomenon known as gaseous cavitation. This is a phenomenon in which gas is released when the pressure drops below the saturation pressure of the dissolved gas in the liquid. This article focuses on the experimental analysis of the flow through the throttle valve which is affected by the formation of air bubbles at the throttle edge of the valve. The regions of gaseous cavitation were observed at the different flow cross-section of the throttle valve. The throttle valve was placed into the block of transparent material to provide visualization of the individual measurements. The article is supplemented with photographs of the individual measurements showing the gaseous cavitation inception. Research background: flow cross-section, cavitation phenomenon, discharge coefficient. Purpose of the article: Effect of flow cross-section size and flow velocity on cavitation development. Methods: Experimental measurements. Findings & Value added: The investigation of the gaseous cavitation inception, Visualization of the individual measurements.

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Flow of Oil and Water through the Nozzle and Cavitation

Cited by 4 publications

References 20 publications

Variation of Cavitation Pressure with Liquid and Operating Conditions in Mechanical Seals

Variation of Cavitation Pressure with Liquid and Operating Conditions in Mechanical Seals

Identification of Cavitation by Noise

Experimental Analysis of Flow Through Throttle Valve During Gaseous Cavitation

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