氢与碳氢燃料超声速气膜冷却和减阻规律及其影响机制

Cooling and friction reduction performance and mechanism of supersonic film cooling using hydrogen and hydrocarbon

  • 摘要: 在超燃冲压发动机燃烧室中应用燃料气膜冷却可以有效降低发动机壁面严峻的力热载荷,本文对有望应用于超燃冲压发动机的氢和碳氢燃料气膜进行大涡模拟研究。结果表明,氢气膜与碳氢燃料气膜的防热和减阻性能有显著差异,该差异来源于燃料气膜与主流之间混合层中的湍流状态不同。氢气膜与主流之间的湍流输运过程远弱于碳氢燃料气膜,因此氢气膜在惰性情况下具有极其优异的冷却和减阻性能;但当发生边界层燃烧时,由于近壁释热剧烈,氢气膜的冷却性能急剧恶化。相反,当碳氢燃料发生边界层燃烧时,碳氢燃料气膜的冷却和减阻性能可以从惰性时较差的水平提升至与氢气膜相当的水平。

     

    Abstract: The essential difference of the turbulent state in the mixing layer contributes to the totally different behavior of the cooling and wall friction reduction performances of the hydrogen and hydrocarbon fuel films. The turbulent transport processes between the hydrogen film and the mainstream are much weaker than that of the hydrocarbon film making inert hydrogen to be rather superior in cooling and friction reduction applications. However, the film cooling performance severely deteriorates when the hydrogen film burns due to the severe heat release sources presented near the wall. On the other hand, the boundary layer combustion of hydrocarbon film can remarkably improve its original barely satisfactory cooling and friction reduction performance to be comparable to that of the hydrogen film due to the suppression of turbulent transport processes in the mixing layer and presence of heat absorption sources near the wall.

     

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