涵道比(bypass ratio),也称旁通比,是涡扇发动机外涵道与内涵道空气流量的比值。内涵道的空气进入燃烧室与燃料混合,燃烧做功,外涵道的空气不进入燃烧室,而是与内涵道流出的燃气相混合后排出。外涵道的空气只通过风扇,流速较慢,且是低温,内涵道排出的是高温燃气,两种气体混合后降低了喷嘴平均流速与温度,较低的流速带来了较高的推进效率和较低的噪声,而根据热机原理,较低的温度能带来较高的热力学效率。两种因素共同作用,使涡扇发动机在相同油耗的情况下能获得比涡喷发动机更大的推力。
陶瓷合成材料、纳米技术和外形记忆合金卓越地体现于其机体和超高涵道比的推进系统结构。
Ceramic composites, nanotechnology and shape memory alloys figure prominently in the airframe and ultra high bypass ratio propulsion system construction.
通过一个高涵道比涡扇发动机故障诊断的实例分析,验证了三层逆传播网络的可行性。
The case study of a high bypass ratio turbofan engine has verified the feasibility of a three-layer back propagation network.
与现行设计趋势相反,麻省的概念通过最小化发动机总体直径的尺度以及相应缩小喷气排放直径来增加涵道比。
In a reversal of current design trends the MIT concept increases the bypass ratio by minimizing expansion of the overall diameter of the engine and shrinking the diameter of the jet exhaust instead.
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