Application of Color Fluorescent Oil Flow Visualization Technique in Tests of Space Capsule at Atmospheric Condition

Before re-entry flight or parachute deployment landing in low-altitude escape lifesaving flight, spaceship re-entry capsule will experience a low-supersonic, transonic and subsonic speed flight stage. In order to ensure successful parachute deployment and safe landing in this stage, it is necessary to accurately predict the re-entry capsule high-speed aerodynamic characteristics to ensure its stable flight. Conventional wind tunnel force test can only obtain macroscopic aerodynamic characteristics such as drag, lift, trim and static stability of re-entry capsules, but cannot achieve detailed flow structure. For having a better understanding of re-entry capsule high-speed flow characteristics and providing more detailed experimental data used for validating CFD tools and methods, the complex surface flow structure of a re-entry capsule at the atmospheric condition and the flow M 0.6-1.5 are visualized using color fluorescent oil flow visualization technique in this paper. The experimental result shows that: by well controlling oil viscosity and wind tunnel blowing time, color fluorescent oil flow visualization technique provides an ability to achieve distinguishing re-entry capsule high-speed surface flow structure including flow separation and flow mixing. In the next step, we will continuously optimize the oil flow viscosity and thickness distribution. Moreover, the dynamic color fluorescent oil flow visualization technique will be applied to obtain digital streamlines through real-time oil flow image post-processing techniques and provide better experimental data used for developing and verifying numerical simulation methods.