A serious problem in advancing ram accelerator technology is the very high in-tube heat transfer rate to the projectile. Herein, we examine a number of strategies for protecting the projectile from gasdynamic heating, Radiation cooling of the projectile and flying the projectile through alternating regions of fuel-oxidizer-diluent drive gas and pure hydrogen are found to be totally unworkable. The ablative cooling technique has serious problems with a substantial retreat of the projectile surface. A transpiration cooling technique using liquid ammonia is calculated to provide adequate protection of the projectile for ram accelerator missions from 3 to 7 or 8 km/sec. Techniques for flying the projectile in pure hydrogen are also examined. One may have a vortex arrangement with a pure hydrogen core surrounded by a fuel-oxidizer-diluent mixture. The projectile may also fly in pure hydrogen while the driving energy is supplied by a deflagrating or detonating solid coating on the tube wall or by electrical energy input. The techniques for flying the projectile in the pure hydrogen are judged to be extremely complex and expensive to implement. The transpiration technique appears to be the most viable way to protect projectiles flying in the 4 - 7 km/sec range.
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机译:推进冲压加速器技术的一个严重问题是管内向射弹的传热率很高。在本文中,我们研究了多种保护射弹免受气体动力加热的策略,发现射弹的辐射冷却以及通过燃料-氧化剂-稀释剂驱动气体和纯氢的交替区域飞行射弹是完全不可行的。烧蚀冷却技术具有严重的问题,使弹丸表面大量后退。计算出一种使用液氨的蒸腾冷却技术,可为3至7或8 km / sec的冲压加速器任务提供足够的射弹保护。还研究了在纯氢气中飞行弹丸的技术。一个人可能具有涡旋结构,其纯氢核被燃料-氧化剂-稀释剂混合物包围。当通过管壁上的爆燃或起爆固体涂层或通过电能输入来提供驱动能量时,弹丸也可能在纯氢中飞行。在纯氢气中飞行弹丸的技术被认为是极其复杂且实施昂贵。蒸腾技术似乎是保护在4-7 km / sec范围内飞行的弹丸的最可行方法。
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