Abstract
The physical characteristics of self-sustain shock oscillation and the key factors that affect the shock oscillation in turbine-based combined-cycle(TBCC) inlet were investigated through unsteady numerical simulation method in this paper. The terminal shock oscillation in the throat was caused by the separation bubble appeared in the lower wall of the turbojet flowpath. The angle of the splitter and the offset of the diffuser were the main factors which affect the characteristics of the shock oscillation. When the angle of the splitter increased from 0 deg to 12 deg, the frequency of terminal shock increased from 100Hz to 133Hz; while when it was greater than 18 deg the terminal shock oscillation phenomenon disappeared. Different offset of the turbojet diffuser affect the motion of terminal shock in the inlet. When the y-coordinate value of the control point (ym) in the turbojet diffuser was smaller than 1.5, the shock oscillated in the inlet; when ym was greater than 2.0, the shock oscillation disappeared. The bleed in the diffuser was able to control the oscillation of the terminal shock.
Funding statement: Funding for Outstanding Doctoral Dissertation in NUAA (No.BCXJ16-01) support by the Fundamental Research Funds for the Central Universities. Foundation of Graduate Innovation Center in NUAA (No.kfjj20160204) support by the Fundamental Research Funds for the Central Universities. the Fundamental Research Funds for the Central Universities (No. NS2015025)
Nomenclature
- f
frequency of pressure fluctuation (Hz)
- Ma
Mach number
- PSD
power spectral density ((Pa)2/Hz)
- t
time (ms)
- T
non-dimensional time
- u
shock oscillation velocity (m/s)
- x
x-coordinate (m)
- xm
x-coordinate value of control point
- y
y-coordinate (m)
- ym
y-coordinate value of control point
- θ
angle of splitter (deg)
- π
static pressure ratio
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