Abstract
Pre-breakdown phenomenon in dielectric
liquids, also called streamer, has been widely investigated to
understand the breakdown mechanism of dielectric liquids.
The possibility of streamer initiation due to electrostrictive
force induced cavitation formation under fast-rising voltage
waveform is studied in this paper. The finite element method
(FEM) based modelling is conducted by coupling Poisson
equation and Navier-stoke equations in COMSOL
Multiphysics. The pressure threshold of cavitation formation
in cyclohexane and rapeseed oil is estimated to be -6 MPa and -
9.31 MPa, respectively, which are 3-5 times smaller than that
in deionized water (-30 MPa). This is mainly due to smaller
surface tension coefficients of oils than deionized water. A
detailed description on the dynamics of cavitation formation in
deionized water is first presented and then compared with
those in cyclohexane and rapeseed oil. Results showed that the
electrostrictive pressure increases with the increasing applied
voltage, which pushes local liquid towards the needle tip at tens
of m/s and leads to large negative pressure in the vicinity of
needle tip. Cavitation appears in the area where local negative
pressure reaches the threshold. The electrostrictive pressure in
deionized water is around 100 and 60 times larger than that in
cyclohexane and rapeseed oil, respectively, under the same
conditions due to the larger relative permittivity of deionized
water. Therefore, it is much harder to initiate cavitation in
cyclohexane and rapeseed oil than in deionized water. In
addition, the voltage magnitude thresholds for cavitation
formation are comparable between cyclohexane and rapeseed
oil under different voltage rising rates.
liquids, also called streamer, has been widely investigated to
understand the breakdown mechanism of dielectric liquids.
The possibility of streamer initiation due to electrostrictive
force induced cavitation formation under fast-rising voltage
waveform is studied in this paper. The finite element method
(FEM) based modelling is conducted by coupling Poisson
equation and Navier-stoke equations in COMSOL
Multiphysics. The pressure threshold of cavitation formation
in cyclohexane and rapeseed oil is estimated to be -6 MPa and -
9.31 MPa, respectively, which are 3-5 times smaller than that
in deionized water (-30 MPa). This is mainly due to smaller
surface tension coefficients of oils than deionized water. A
detailed description on the dynamics of cavitation formation in
deionized water is first presented and then compared with
those in cyclohexane and rapeseed oil. Results showed that the
electrostrictive pressure increases with the increasing applied
voltage, which pushes local liquid towards the needle tip at tens
of m/s and leads to large negative pressure in the vicinity of
needle tip. Cavitation appears in the area where local negative
pressure reaches the threshold. The electrostrictive pressure in
deionized water is around 100 and 60 times larger than that in
cyclohexane and rapeseed oil, respectively, under the same
conditions due to the larger relative permittivity of deionized
water. Therefore, it is much harder to initiate cavitation in
cyclohexane and rapeseed oil than in deionized water. In
addition, the voltage magnitude thresholds for cavitation
formation are comparable between cyclohexane and rapeseed
oil under different voltage rising rates.
| Original language | English |
|---|---|
| Title of host publication | 2020 IEEE International Conference on High Voltage Engineering and Application |
| DOIs | |
| Publication status | Published - 15 Dec 2020 |
| Event | 2020 IEEE International Conference on High Voltage Engineering and Application - Tsinghua University, Beijing, China Duration: 6 Sept 2020 → 10 Sept 2020 |
Conference
| Conference | 2020 IEEE International Conference on High Voltage Engineering and Application |
|---|---|
| Abbreviated title | ICHVE 2020 |
| Country/Territory | China |
| City | Beijing |
| Period | 6/09/20 → 10/09/20 |