Experimental investigation of the effect of transpiration cooling on second mode instabilities in a hypersonic boundary layer
| Autor: | Giannino Ponchio Camillo, Leroy Benjamin, Jens Neumann, Alexander Wagner, Rüdiger Hink, Christian Dittert, Viola Wartemann |
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| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Hypersonic speed
hypersonic boundary layer Materials science Mass flow Expansion tunnel Computational Mechanics Raumfahrzeuge GO General Physics and Astronomy transition delay Raumfahrt - System - Integration 02 engineering and technology Aeroelastische Simulation 01 natural sciences 010305 fluids & plasmas symbols.namesake 0203 mechanical engineering Schlieren 0103 physical sciences Mass flow rate porous surface Transpiration Fluid Flow and Transfer Processes 020301 aerospace & aeronautics HEG second mode instability Reynolds number transpiration cooling Raumfahrzeuge BS Boundary layer hypersonic transition Mechanics of Materials symbols Atomic physics gas injection |
| Popis: | Abstract The influence of localized nitrogen transpiration on second mode instabilities in a hypersonic boundary layer is experimentally investigated. The study is conducted using a $$7^\circ$$ 7 ∘ half-angle cone with a length of 1100 mm and small nose bluntness at $$0^\circ$$ 0 ∘ angle-of-attack. Transpiration is realized through a porous Carbon/Carbon patch of $$44 \times 82$$ 44 × 82 mm located near the expected boundary layer transition onset location. Transpiration mass flow rates in the range of 0.05–1% of the equivalent boundary layer edge mass flow rate were used. Experiments were conducted in the High Enthalpy Shock Tunnel Göttingen (HEG) at total enthalpies around 3 MJ/kg and unit Reynolds numbers in the range of $$1.4 \cdot 10^6 \,$$ 1.4 · 10 6 to $$6.4 \cdot 10^6 \, {\text {m}}^{-1}$$ 6.4 · 10 6 m - 1 . Measurements were conducted by means of coaxial thermocouples, Atomic Layer Thermopiles (ALTP), pressure transducers and high-speed schlieren. The present study shows that the most amplified second mode frequencies were shifted to lower values as nitrogen is transpired into the boundary layer. In some cases the instability amplitudes were found to be significantly reduced. The observed frequency reduction was verified to correlate with the change of the relative sonic line height in the boundary layer. The amplitude damping was observed to occur only until the most amplified frequencies were reduced to around 50% of their undisturbed values. When transpiration within this limit was performed shortly upstream of the natural boundary layer transition onset, a transition delay of approximately 17% could be observed. Graphic abstract |
| Databáze: | OpenAIRE |
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