Shock Boundary Layer Interaction and Aero-Optical Effects in a Transonic Flow over Hemisphere-on-Cylinder Turrets

Hemisphere-on-cylinder turrets are the main airborne optical platform structure. However, an unsteady shock boundary layer interaction (SBLI) would act on flow separation and turbulent wake, which causes serious aero-optical effects with high spatial and temporal frequency characteristics. In this p...

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Bibliographic Details
Published in:International journal of aerospace engineering 2022-11, Vol.2022, p.1-19
Main Authors: Ren, Xiang, Yu, Huahua, Yao, Xianghong, Su, Hua, Hu, Peng
Format: Article
Language:English
Subjects:
Aerospace engineering
Boundary layer interaction
Cylinders
Detached eddy simulation
Distortion
Experiments
Flow separation
Fluid dynamics
Lasers
Mach-Zehnder interferometers
Optics
Peak frequency
Pressure distribution
Proper Orthogonal Decomposition
R&D
Ray tracing
Research & development
Research methodology
Reynolds number
Simulation
Subsonic flow
Transonic flow
Turbulence models
Velocity
Vortices
Wave fronts
Wind tunnels
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Summary:Hemisphere-on-cylinder turrets are the main airborne optical platform structure. However, an unsteady shock boundary layer interaction (SBLI) would act on flow separation and turbulent wake, which causes serious aero-optical effects with high spatial and temporal frequency characteristics. In this paper, the SBLI phenomenon of a hemisphere-on-cylinder turret is recorded in a wind tunnel at Ma=0.7 using shadowing and Mach-Zehnder interferometer measurements. Its wavefront distortion is measured using the Shack-Hartmann measurement. The detached eddy simulation (DES) based on SST k-ω turbulence model and ray-tracing methods are used to reproduce the transonic flow and optical aberration. Experiments and simulations suggest that the SBLI causes the flow to separate earlier relative to a subsonic flow over the turret. The time-averaged root-mean-square of optical path difference (OPD) over the beam aperture is 0.56 λ∼0.59 λ with λ as the wavelength, while the root-mean-square of the time-averaged OPD is about 0.45 λ. The local shock and wavefront distortion have dual peak frequencies at StD=fD/U∞=0.24 and 0.34, different from the single-peak-frequency phenomenon of a subsonic flow over turrets. Fast model decomposition of wavefront can be performed by proper orthogonal decomposition (POD) of its Zernike coefficients. The first two modes contain the shock’s reciprocating motion.
ISSN:1687-5966
1687-5974
DOI:10.1155/2022/3397763