Abstract The interaction of an impinging shock and a supersonic helium cooling film is investigated experimentally by high-speed particle-image velocimetry. A laminar helium jet is tangentially injected into a turbulent air freestream at a freestream Mach number $$\mathrm{Ma}_\infty =2.45$$ Ma ∞ = 2.45 . The helium cooling film is injected at a Mach number $$\mathrm{Ma}_{\mathrm{i}}=1.30$$ Ma i = 1.30 at a total temperature ratio $$T _{0,\mathrm {i}}/ T _{0,\infty }=0.75$$ T 0 , i / T 0 , ∞ = 0.75 . A deflection $$\beta =8^\circ$$ β = 8 ∘ generates a shock that impinges upon the cooling film. A shock interaction case and a reference case without shock interaction are considered. The distributions of the turbulent mass flux and the turbulent Schmidt number are determined qualitatively. The results are compared with large-eddy simulation (LES) data by Konopka et al. (Phys Fluids 25(10):106101, 2013. https://doi.org/10.1063/1.4823745 ) for a comparable flow configuration. The streamwise and wall-normal turbulent mass fluxes are in qualitative agreement with the LES solutions. The turbulent Schmidt number differs significantly from unity. Without shock interaction, the turbulent Schmidt number is in the range $$0.5 \le {\mathrm {Sc}}_{\mathrm{t}}\le 1.5$$ 0.5 ≤ Sc t ≤ 1.5 which is in agreement with the literature. With shock interaction, the turbulent Schmidt number varies drastically in the vicinity of the shock interaction. Thus, the experimental results confirm the numerical data showing a massively varying turbulent Schmidt number in supersonic film cooling flows, i.e., the standard assumption of a constant turbulent Schmidt number is valid neither without nor with shock interaction. Graphic abstract

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带激波相互作用的超音速气膜冷却湍流施密特数的实验研究

摘要 通过高速粒子图像测速法实验研究了冲击激波和超音速氦冷却膜的相互作用。层流氦射流以自由流马赫数 $$\mathrm{Ma}_\infty =2.45$$ Ma ∞ = 2.45 切向注入湍流自由流中。氦冷却膜以马赫数 $$\mathrm{Ma}_{\mathrm{i}}=1.30$$ Ma i = 1.30 注入，总温度比 $$T _{0,\mathrm {i} }/ T _{0,\infty }=0.75$$ T 0 , i / T 0 , ∞ = 0.75 。偏转 $$\beta =8^\circ$$ β = 8 ∘ 产生冲击冷却膜的冲击。考虑冲击相互作用情况和没有冲击相互作用的参考情况。湍流质量通量和湍流施密特数的分布被定性地确定。结果与 Konopka 等人的大涡模拟 (LES) 数据进行了比较。（Phys Fluids 25(10):106101, 2013. https://doi.org/10.1063/1.4823745 ）用于类似的流动配置。流向和壁法向湍流质量通量与 LES 解定性一致。湍流施密特数与 1 显着不同。在没有激波相互作用的情况下，湍流施密特数在 $$0.5 \le {\mathrm {Sc}}_{\mathrm{t}}\le 1.5$$ 0.5 ≤ Sc t ≤ 1.5 的范围内，这与文献一致。对于激波相互作用，湍流施密特数在激波相互作用附近剧烈变化。因此，实验结果证实了数值数据显示在超音速薄膜冷却流中大量变化的湍流施密特数，即，恒定湍流施密特数的标准假设在没有或有激波相互作用的情况下都是有效的。图形摘要