摘要:
为排除来流空气对含硼燃气的掺混效应,研究等离子体对含硼富燃料推进剂在补燃室二次燃烧过程的影响,建立了含硼两相流平行进气扩散燃烧物理模型。利用高速摄影仪拍摄了含硼燃气在补燃室二次燃烧的火焰图像,分析了该物理模型的扩散燃烧特性和硼颗粒的二次点火距离。采用硼颗粒的King点火模型、有限速度/涡耗散模型、颗粒轨道模型和RNG k-ε模型以及等离子体模型,模拟了一定条件下等离子体对含硼两相流扩散燃烧过程的影响。结果表明,依据含硼燃气二次燃烧图像得到的硼颗粒二次点火距离,与数值模拟结果基本一致,保证了该物理模型和计算方法的可靠性。含硼两相流经过等离子体区域后,硼颗粒在运动轨迹上颗粒温度明显增加,颗粒直径明显减小, B2O3的质量分数分布区域明显扩增,70%的硼颗粒在到达补燃室2/3尺寸前燃烧效率已达到100%,硼颗粒充分燃烧释放出更多热量导致中心流线区域温度增加近1/2,可见等离子体可以明显强化含硼两相流的燃烧过程,提高硼颗粒的燃烧效率。
关键词:
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等离子体
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硼颗粒
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两相流
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扩散燃烧
Abstract:
A parallel intake diffusion combustion physical model is designed to study the influence of plasma on the secondary combustion of boron-based gas in the after-burning chamber, with excluding mixing effects of the intake air. The flame images of the diffusion combustion of the boron-based gas in the after-burning chamber are obtained by a high-speed photographic apparatus. The diffusion combustion characteristics of the physical model and the secondary ignition distance of boron particles are analyzed. The King ignition model, finite-rate/eddy-dissipation model, particle-trajectory model, RNG k-εmodel, and plasma model are adopted to simulate the influence of plasma on the diffusion combustion of boron-based two-phase flow in a certain condition. The results show that the secondary ignition distance of boron particles, which is based on the boron-based flame image, is consistent well with the numerical simulation result, which verifies the accuracy of the boron-based two-phase flow diffusion combustion numerical model and the calculation method. When the boron-based gas passes through the plasma area, the temperature of the boron particles increases while the diameter decreases significantly on their trajectory. The distribution area of the B2O3 mass fraction increases significantly, and more than 70% boron particles reach a 100% combustion e?ciency before they arrive at the area of the two-thirds after-burning chamber. More heat is released by fully burning the boron particles under the influence of plasma, which results in a half increase of the central area. It can be indicated that plasma can obviously enhance the combustion process of the boron-based gas, which improves the combustion e?ciency of boron particles and releases more energy.
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