CFD simulation and pattern recognition analysis of the chugging condensation regime

Tanskanen, Vesa; Jordan, A.; Puustinen, Markku; Kyrki-Rajamäki, Riitta

doi:10.1016/j.anucene.2013.12.007

Cited by 57 publications

(15 citation statements)

References 10 publications

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“…Pressure oscillation was thought to be induced by the balance action between the supply of steam to steam cavity and its condensation on the steam-water interface. Tanskanen et al (2014) simulated steam condensation for chugging regime, the information of bubble size and chugging frequency was revealed. Youn et al (2003) found that when the steam bubble detached from the nozzle exit with the necking phenomenon, high pressure pulses with relatively low frequency were observed.…”

Section: Introductionmentioning

confidence: 99%

Pressure oscillation and steam cavity during the condensation of a submerged steam jet

Zhao

Chen

Yuan

et al. 2015

Annals of Nuclear Energy

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a b s t r a c tSteam jet condensation is important in many industrial applications. In this work, the pressure oscillation and steam jet patterns during submerged jet condensation in quiescent water is investigated experimentally. Firstly, it is found that even at stable condensation region, the steam cavity length varies all the time and steam bubbles separate from the steam cavity periodically. With the variation of steam cavity length and separated bubble oscillation, condensation also undergoes oscillation. Along the axial direction, the pressure oscillation intensity increases first and then decreases gradually. There is an distinct pressure oscillation peak, and the peak position varies over a length-to-diameter ratio range of X/D = 2 to X/D = 7. The axial position of pressure oscillation peak corresponds to the end of steam cavity. Moreover, oscillation energy analysis shows that the oscillation energy generated by separated steam bubble is much higher than that generated by the steam cavity length variation. Finally, based on the relationship between the axial distribution of pressure oscillation and the steam cavity, a method is proposed to determine the maximum steam cavity length by measuring the pressure oscillation distributions. The predicted deviation is only in range of ±16% for the test conditions.

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Section: Introductionmentioning

confidence: 99%

Pressure oscillation and steam cavity during the condensation of a submerged steam jet

Zhao

Chen

Yuan

et al. 2015

Annals of Nuclear Energy

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“…As shown in the frequency spectrograms, when X/D is small, such as X/D≤6, only one dominant frequency exists in frequency spectrograms. This dominant frequency is called the first dominant frequency and it is generated by the variations of steam jet length [16,17]. Experimental results show that with rise of water temperature and steam mass flux, the first dominant frequency decreases monotonously.…”

Section: Resultsmentioning

confidence: 99%

“…Youn et al [15] proved that pressure oscillation was caused by steam bubble necking and detached process by synchronizing the high speed CCD camera and pressure transducer. Tanskanen et al [16] simulated steam condensation for chugging regime. They also simulated and identified the characteristics of bubble size and chugging frequency.…”

Section: Introductionmentioning

confidence: 99%

Characteristic of pressure oscillation caused by turbulent vortexes and affected region of pressure oscillation

Chen

Zhao

Wang

et al. 2016

Experimental Thermal and Fluid Science

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Submerged steam jet condensation is widely applied in various fields because of its high heat transfer efficiency. Condensation oscillation is a major character of submerged steam turbulent jet, and it significantly affects the design and safe operation of industrial equipment. This study is designed to reveal the mechanism of the low-frequency pressure oscillation of steam turbulent jet condensation and determine its affected region. First, pressure oscillation signals with low frequency are discovered in the downstream flow field through oscillation frequency spectrogram and power analysis. The oscillation frequency is even lower than the first dominant frequency. Moreover, the critical positions, where the low-frequency pressure oscillation signals appear, move downstream gradually with radial distance and water temperature. However, these signals are little affected by the steam mass flux. Then, the regions with low-frequency pressure oscillation occurring are identified experimentally. The affected width of the low-frequency pressure oscillation is similar to the turbulent jet width. Turbulent jet theory and the experiment results collectively indicate that the low-frequency pressure oscillation is generated by turbulent jet vortexes in the jet wake region. Finally, the angular coefficients of the low-frequency affected width are obtained under different water temperatures. Angular coefficients, ranging from 0.2268 to 0.2887, decrease with water temperature under test conditions.

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“…Recently, CFD analysis was applied to the chugging phenomenon to validate proposed models. Tanskanen [26,27,28,29,30] performed a comprehensive CFD study of two-phase flow for the prediction of the direct contact condensation employing two-fluid model. Their work focused on the description of the heat transfer coefficient given by the turbulent flow around the bubble surface as the main parameter characterizing the bubble implosion.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Experimental study on steam chugging phenomenon in a vertical sparger

Gregu

Takahashi

Pellegrini

et al. 2017

International Journal of Multiphase Flow

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Unstable direct contact condensation called ``Chugging'’ that occurs in certain conditions in the pressure suppression pool of Primary Containment Vessel of Boiling Water Reactors (BWRs) was studied experimentally. The mechanisms of every phase of the chugging was described, and experimental results useful for the development and validation of more accurate CFD models were provided. The experiment was conducted with a transparent pool and a transparent polycarbonate pipe or a stainless steel pipe with inner diameter of 27 mm under the conditions of the steam mass flux of 5.5–19.5 kg/m2s and the pool temperature of 19–46.5 °C. Pressure pulses were measured and synchronized with a high speed video camera for images acquisition. It was identified that the bubble implosion occurred while the pressure in the bubble quickly decreased. This condition might establish instability in the interfacial area which grew abruptly causing the implosion. Moreover the transparent apparatus allowed to interpret and relate internal condensations, generating pressure spikes of around 1.2 MPa because of the condensation-induced water hammer. Finally, the chugging condensation regime map was created from the experimental data

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CFD simulation and pattern recognition analysis of the chugging condensation regime

Cited by 57 publications

References 10 publications

Pressure oscillation and steam cavity during the condensation of a submerged steam jet

Pressure oscillation and steam cavity during the condensation of a submerged steam jet

Characteristic of pressure oscillation caused by turbulent vortexes and affected region of pressure oscillation

Experimental study on steam chugging phenomenon in a vertical sparger

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