Zberovskyi V.V., Zhulai Yu.A., Myrnyi S.S. Evaluation of the cavitation generator efficiency in the hydro impulsive loosening of a coal-bed

Details
Parent Category: Geo-Technical Mechanics, 2019
Category: Geo-Technical Mechanics, 2019, № 148

Geoteh. meh. 2019, 148, 49-58

https://doi.org/10.1051/e3sconf/201910900123

Evaluation of the cavitation generator efficiency in the hydro impulsive loosening of a coal-bed

1Zberovskyi V.V., 2Zhulai Yu.A., 2Myrnyi S.S.

1Institute of Geotechnical Mechanics named by N. Poljakov of National Academy of Sciences of Ukraine, 2Institute of Transport Systems and Technologies of National Academy of Sciences of Ukraine

UDC 621.313.12-752.001.5:532.528

Language: English

Abstract.

The paper presents the results of mining and experimental work, bench tests and theoretical studies of the energy characteristics of the stationary and pulsating fluid flow, which allow to estimate the efficiency of the cavitation generator in the hydro impulsive loosening of an outburst-prone coal-bed.

The generator is the Venturi tube of special geometry in the flow part of which high-frequency self-oscillations of fluid pressure occur. The advantage of this device is the absence of additional energy sources and moving mechanical parts. Generator is installed in the filtrational part of the well. That's why all energy of cavitational self-oscillations is spent to hydro impulsive loosening of a coal-bed. The active stage of the hydro impulsive loosening and the effective range of the amplitude-frequency (AF) spectrum of the generator operation acoustic signal have been established by the AF spectrum of the sound accompaniment of the hydro impulse impact and the backup pressure of the liquid in the well. The active stage of hydro impulsive loosening of the bed occurs within 6-7 minutes at the backup pressure of the liquid in the well from 1.2 MPa to 7.5 MPa. The frequency response of the generator in this range is from 1.5 kHz to 6.3 kHz. The range of the AF sound spectrum is from 1.4 kHz to 2.8 kHz.  Maximum values of the energy level - f≈2.0 kHz that corresponds to the frequency of 1.6-2.4 kHz. By calculation for this range the energy characteristics of the static and dynamic components of the pulsating fluid flow were determined. This made it possible to determine that the efficiency of the cavitation generator, all other conditions of the coal-bed hydro loosening being equal, is 4.8–1.2 times higher than the efficiency of the static impact. That leads to a decrease of energy consumption by about 50%.

The proposed method for evaluating the effectiveness of the device for hydro-impulsive action on a coal bed is of practical importance. It allows to evaluate the effectiveness of the operation of cavitation generators in the technological process of hydro impulsive action without additional experimental studies.

Keywords: coal bed, hydro impulsive loosening, cavitational generator, sound spectrum.

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About the authors

ZberovskyiVasylVladislavovych, Doctor of Technical Sciences (D. Sc.), Senior Researcher in Department of Underground Coal Mining Technology, Institute of Geotechnical Mechanics named by N. Poljakov of National Academy of Sciences of Ukraine (IGTM, NAS of Ukraine), Dnipro, Ukraine, This email address is being protected from spambots. You need JavaScript enabled to view it.

Zhulay Yuriy Alekseevich, Philosophy Doctor, Senior Researcher, Institute of Transport Systems and Technologies of National Academy of Sciences of Ukraine (ITST NAS of Ukraine), Dnipro, Ukraine.

Myrnyi Serhii Serhiyovych, Junior Researcher, Institute of Transport Systems and Technologies of National Academy of Sciences of Ukraine (ITST NAS of Ukraine), Dnipro, Ukraine.