Experimental research of multiphase flow with cavitation in the nozzle

Kozubková, Milada; Bojko, Marián; Jablonská, Jana; Homa, D.; Tůma, Jiří

doi:10.1051/epjconf/201611402058

Cited by 4 publications

(4 citation statements)

References 5 publications

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“…To investigate the properties of cavitation (especially noise), three similar hydraulic elements typical for the formation of hydraulic cavitation were chosen: I -converging -diverging nozzle of circular cross section [14], II -converging -diverging nozzle of rectangular cross-section [15] III -Venturi tube [16] All elements are transparent and have the same inlet flow area corresponding to an inlet diameter of 50 mm, resp. rectangular cross section (50 x 12) mm.…”

Section: Circuit Description and Measurementmentioning

confidence: 99%

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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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Section: Circuit Description and Measurementmentioning

confidence: 99%

“…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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“…Air is dissolved in water or can be added into the stream either upstream of the element being tested (e.g. hydrofoil, nozzle) (Kozubkova et al , 2016) or at a certain location on the hydrofoil surface (Sun et al , 2020). Presence of air influences the dynamics of cavitation and air injection can be used to control cavitation (Sun et al , 2020; Bin et al , 2010).…”

Section: Introductionmentioning

confidence: 99%

Numerical study of cavitating flow over hydrofoil in the presence of air

Wróblewski

Bochon

Majkut

et al. 2021

HFF

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Purpose The presence of air in the water flow over the hydrofoil is investigated. The examined hydrofoil is ClarkY 11.7% with an angle of attack of 8 deg. The flow simulations are performed with the assumption of different models. The Singhal cavitation model and the models which resolve the non-condensable gas including 2phases and 3phases are implemented in the numerical model. The calculations are performed with the uRANS model with assumption of the constant temperature of the mixture. The two-phase flow is simulated with a mixture model. The dynamics and structures of cavities are compared with literature data and experimental results. Design/methodology/approach The cavitation regime can be observed in some working conditions of turbomachines. The phase transition, which appears on the blades, is the source of high dynamic forces, noise and also can lead to the intensive erosion of the blade surfaces. The need to control this process and to prevent or reduce the undesirable effects can be fulfilled by the application of non-condensable gases to the liquid. Findings The results show that the Singhal cavitation model predicts the cavity structure and related characteristics differently with 2phases and 3phases models at low cavitation number where the cavitating flow is highly dynamic. On the other hand, the impact of dissolved air on the cloud structure and dynamic characteristic of cavitating flow is gently observable. Originality/value The originality of this paper is the evaluation of different numerical cavitation models for the prediction of dynamic characteristics of cavitating flow in the presence of air.

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“…On the suction side, the significant negative vacuum is generated due to running at maximum operating parameters. The pumps are therefore extensively stressed by cavitation (aeration) erosion, resulting in a shorter service life and serviceability of the pump, noise level and vibration are increased and performance parameters are also reduced [1,2].…”

Section: Introductionmentioning

confidence: 99%

Mathematical simulation of temperature influence on pressure drop at pump suction line

2019

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The article is focused on mathematical simulation of the temperature influence on the pressure drop at the pump suction line. It is evaluated pressure drop depending on mineral oil flow rate. The courses of individual dependencies are determined by mathematical simulation using the ANSYS CFD computing software. The temperature affects significantly physical properties of the flowing mineral oil. In a paper is also described the experimental measurement of a mineral oil sample and determination of its physical properties depending on temperature.

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Experimental research of multiphase flow with cavitation in the nozzle

Cited by 4 publications

References 5 publications

Identification of Cavitation by Noise

Identification of Cavitation by Noise

Numerical study of cavitating flow over hydrofoil in the presence of air

Mathematical simulation of temperature influence on pressure drop at pump suction line

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