TY - JOUR
T1 - Effect of self-excited instability on single liquid swirl injector flow characteristics
AU - Jeong, Seokgyu
AU - Bae, Jinhyun
AU - Yoon, Sam S.
AU - Yoon, Youngbin
N1 - Funding Information:
This work was supported by the Advanced Research Center Program ( NRF-2013R1A5A1073861 ) through the National Research Foundation of Korea ( NRF ) grant funded by the Korean government ( MSIP ), contracted through the Advanced Space Propulsion Research Center at Seoul National University, and by the Korean Government ( NRF -2016-Fostering Core Leaders of the Future Basic Science Program/Global Ph.D. Fellowship Program).
Funding Information:
This work was supported by the Advanced Research Center Program (NRF-2013R1A5A1073861) through the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIP), contracted through the Advanced Space Propulsion Research Center at Seoul National University, and by the Korean Government (NRF-2016-Fostering Core Leaders of the Future Basic Science Program/Global Ph.D. Fellowship Program).
Publisher Copyright:
© 2020
PY - 2021/1
Y1 - 2021/1
N2 - Owing to their simple structure and high performance, swirl injectors have been used as propellant injectors for rocket engines in various countries, starting from Russia. However, when a swirl injector is used in combustion, flow instability becomes important because of its relation to combustion instability. Because the external flow of a swirl injector is a thin liquid sheet, wave-forming self-excited instability could occur. In this study, the effect of self-excited instability on the flow characteristics of a swirl injector was investigated. Moreover, through the use of a mechanical pulsator, the effect of self-excited instability frequency on the dynamic characteristics of the swirl injector was examined. As a result, self-excited instability was determined to cause the periodic breakup of the spray sheet. In addition, large droplets generated immediately after breakup are confirmed to be periodically concentrated with a specific frequency equal to the self-excited instability frequency. With external pulsation, breakup length was observed to be shortened with pulsation and had minimum value when pulsation of frequency equal to the self-excited instability frequency was applied. Droplet characteristics with pulsation were also investigated, and external pulsation was determined to cause mean droplet diameter (D10) and Sauter mean diameter (SMD) to be smaller. When SMDs at pulsations of different frequencies were compared, the SMD at pulsation with self-excited instability frequency was observed to be larger because this frequency causes droplet distribution to be more non-uniform. Through this study, self-excited instability was confirmed to be able to change the static and dynamic characteristics of a swirl injector. This result can serve as a reminder of the importance of the self-excited instability of a sheet in the design of a swirl injector.
AB - Owing to their simple structure and high performance, swirl injectors have been used as propellant injectors for rocket engines in various countries, starting from Russia. However, when a swirl injector is used in combustion, flow instability becomes important because of its relation to combustion instability. Because the external flow of a swirl injector is a thin liquid sheet, wave-forming self-excited instability could occur. In this study, the effect of self-excited instability on the flow characteristics of a swirl injector was investigated. Moreover, through the use of a mechanical pulsator, the effect of self-excited instability frequency on the dynamic characteristics of the swirl injector was examined. As a result, self-excited instability was determined to cause the periodic breakup of the spray sheet. In addition, large droplets generated immediately after breakup are confirmed to be periodically concentrated with a specific frequency equal to the self-excited instability frequency. With external pulsation, breakup length was observed to be shortened with pulsation and had minimum value when pulsation of frequency equal to the self-excited instability frequency was applied. Droplet characteristics with pulsation were also investigated, and external pulsation was determined to cause mean droplet diameter (D10) and Sauter mean diameter (SMD) to be smaller. When SMDs at pulsations of different frequencies were compared, the SMD at pulsation with self-excited instability frequency was observed to be larger because this frequency causes droplet distribution to be more non-uniform. Through this study, self-excited instability was confirmed to be able to change the static and dynamic characteristics of a swirl injector. This result can serve as a reminder of the importance of the self-excited instability of a sheet in the design of a swirl injector.
KW - Closed type swirl injector
KW - Hydraulic mechanical pulsatior
KW - Injector dynamics
KW - Self-excited instability
KW - Shear layer instability
UR - http://www.scopus.com/inward/record.url?scp=85091638406&partnerID=8YFLogxK
U2 - 10.1016/j.actaastro.2020.08.029
DO - 10.1016/j.actaastro.2020.08.029
M3 - Article
AN - SCOPUS:85091638406
VL - 178
SP - 452
EP - 462
JO - Acta Astronautica
JF - Acta Astronautica
SN - 0094-5765
ER -