Dynamic characteristics of a cryogenic nitrogen swirl injector under supercritical conditions

作者：Kang Jeongseok; Heo Junyoung; Sung Hong Gye^*; Yoon Youngbin

来源：Aerospace Science and Technology, 2017, 67: 398-411.

DOI：10.1016/j.ast.2017.04.010

• Supercritical condition
• Cryogenic nitrogen
• Injector instability
• Large eddy simulation
• Swirl injector
• Gaseous core vibration

A three dimensional large eddy simulation (LES) is conducted to investigate the dynamic characteristics of a cryogenic nitrogen swirl injector operating in supercritical high pressure conditions. To predict the precise thermodynamic properties under supercritical conditions, various real gas equations are validated by comparing them with extended corresponding states (ECS) data. The numerical results are also validated with 50-bar experimental data in terms of the spray angle and instability frequency behind the injector post. Various flow structures and swirl injector dynamics are observed and examined. They include the liquid film, gaseous core, spray angle, toroidal recirculation and the dominant unstable frequencies related with acoustic modes and flow oscillations induced by the helical vortex, Kelvin Helmholtz instability. The unstable motions of the acoustics and flow are investigated using power spectrum densities (PSDs), proper orthogonal decomposition (POD) and band-pass filter methods. The inlet mass flow rate fluctuation causes liquid film and gaseous core instability. The gaseous core oscillates along the centerline at a low frequency of about the 100-Hz order. The pressure increases from 50 bar to 90 bar cause the surface boundary of the liquid film and gaseous core to become fainter and the gaseous core depth to become shorter. This results in a decrease of spray angle.

• 出版日期2017-8