Aerodynamic shape optimization framework for engine installation in an unconventional airframe

未来20-30年，运输飞机行业面临的主要挑战是减少其运营中的二氧化碳排放。提高飞机能源效率的技术开发必须与将能源来源从化石燃料转换为氢或电等无碳能源的努力同时进行。单是飞机结构的改变对效率的提升就有很大的贡献，在混合翼体（BWB）的情况下，通过减少阻力可以达到30%。然而，在相关的技术障碍被清除之前，这种革命性的发展代表着重要的金融和技术风险。其中一个障碍是，尽管现代发动机也在一代又一代地改进，但它们的可操作性和高效率仍然容易受到发动机或风扇表面气流质量的影响。当风扇叶片在不断变化流动特性的间隙中旋转时，间隙之间的空间梯度过大可能会导致发动机的稳定性和结构完整性问题。非常规的配置，如飞翼或BWB，尤其当发动机集成（埋）在机身中时，会加剧这一问题。因此，提高这些非常规配置的成熟度以降低技术风险是非常重要的。如果在设计阶段没有对流动行为进行早期检查并充分稳定，那么飞机配置变得不切实际的风险很高，并且上述效率增益既不能得到保护也不能实现。提出了超越概念层面的高度集成推进系统的飞机配置，实现低阻力（高效率），并利用被动流动控制在苛刻的空间要求下保持发动机足够的流动均匀性。以现有文献中的非常规配置为例，建议审查、探索和确定其进气道（s -导管）和受发动机安装影响的外表面部分的气动形状，使其在任何飞行条件下都能令人满意地运行，从而消除与推进/机身集成（PAI）相关的技术障碍。将考虑代表实际飞机操作包线的多个约束。通过构建用于自动形状优化的设计框架，创建虚拟空气动力学实验室或试验台。例如，机身和进气道的气动造型的影响将被量化。安装在吊架上的机舱内的动力装置的效率将与嵌入机身的动力装置进行精确的比较。

The major challenge for the transport aircraft industry in the next 20-30 years is the reduction of its carbon dioxide emissions in operation. The development of technologies to increase the energy efficiency of the aircraft must continue in parallel with the efforts to switch the source of energy from fossil fuel to a carbon-free source, such as hydrogen or electricity. The contribution to the jump in efficiency from the change of aircraft configuration alone could be large, up to 30% in the case of the blended-wing body (BWB) through drag reduction. Such revolutionary development however represents an important financial and technological risk, until its associated technology roadblocks are removed. One of these roadblocks is that even though modern engines also improve from generation to generation, their operability and high efficiency remain susceptible to the quality of the flow at the face of the engine or the fan. As the fan blades rotate through successive pockets of changing flow properties, too much spatial gradients from pocket to pocket can lead to issues of stability and structural integrity for the engines. This problem is exacerbated by unconventional configurations, such as the flying wing or the BWB, particularly when the engines are integrated (buried) in the airframe. It is thus important to elevate the maturity of these unconventional configurations to reduce the technological risk. If the flow behavior is not examined early in the design phase and sufficiently stabilized, there is the high risk that the aircraft configuration becomes impractical and that the efficiency gain above is neither protected nor realized. It is proposed to elaborate aircraft configurations with highly integrated propulsion systems beyond the conceptual level, achieving low drag (high efficiency) and taking advantage of passive flow control to maintain adequate flow uniformity at the engine(s) with demanding spatial requirements. With examples of unconventional configurations in the available literature, it is proposed to review, explore and determine aerodynamic shapes for their inlet (S-duct) and the portions of their external surfaces that are affected by the installation of the engine(s), such that these will operate satisfactorily at any flight conditions, thereby removing the technological roadblock associated with propulsion/airframe integration (PAI). Multiple constraints that are representative of the realistic aircraft operating envelope will be considered. A virtual aerodynamics laboratory or test bed will be created through the construction of a design framework for automatic shape optimization. For example, the impact of aero-shaping of the airframe and the inlet will be quantified. The efficiency of a powerplant installed in nacelles on pylon will be compared accurately with that embedded in the airframe.