分布式边界层吸入推进系统的建模与分析

机体后部边界层吸入技术可显著改善飞机的燃油经济性，但目前尚未建立推进系统设计与分析方法。针对类似N3-X飞机的分布式边界层吸入推进系统，采用基于边界层积分方程的数值分析方法，引入功推比参数，详细分析边界层状态和推进系统参数对系统性能的影响，从而为推进系统设计提供理论和数据支撑。通过基准状态与N3-X的对比，验证了计算方法的可靠性。分析表明，当吸入边界层占比为50%左右时推进系统能耗可降低4%，边界层形状因子越小或者动量厚度越大，能耗降低越多；进气道扩张比对功推比的影响不大；随着进气道入口马赫数增大、风扇压比降低、风扇效率增大、风扇损失降低或者喷流速度降低，功推比都会下降。

Modeling and analysis of distributed boundary layer ingesting propulsion system

The aft body boundary layer ingesting technology can significantly improve the fuel economy of aircraft. However, the design and analysis methods for such a propulsion system have not been developed yet. To provide supportive theories and data on the distributed boundary layer ingesting propulsion system of N3-X aircraft, the numerical analysis method based on integral boundary layer equations is used and the power-thrust ratio is introduced to analyze the effect of boundary layer conditions and propulsion system parameters on the system performance. The computational model and procedure are validated through a comparison between the benchmark condition and N3-X. Analyses show that 50% boundary layer ingestion can improve the fuel consumption efficiency by 4%. The smaller the shape factor is or the larger the momentum thickness is, the less the fuel consumption is. The power-thrust ratio is weakly relevant to the inlet area ratio, but the ratio decreases with the increase of the inlet Mach number or fan efficiency, or with the decrease of the fan pressure ratio, fan loss or jet velocity.