Aerodynamic shape optimization framework for engine installation in an unconventional airframe

未来20-30年，运输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从化石燃料转向无碳能源，如氢或电的努力同时进行。仅改变飞机外形对效率的提高所起的作用就很大，在采用融合翼机身（BWB）的情况下，通过减阻作用可达30%。然而，这种革命性的发展代表了一个重要的金融和技术风险，直到其相关的技术障碍被消除。这些障碍之一是，即使现代发动机也一代一代地改进，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处的流动质量的影响。当风扇叶片旋转通过连续的改变流动特性的袋时，袋与袋之间太多的空间梯度可能导致发动机的稳定性和结构完整性的问题。这个问题被非常规的配置所加剧，例如飞翼或BWB，特别是当发动机集成（埋）在机身中时。因此，提高这些非常规配置的成熟度以降低技术风险是重要的。如果在设计阶段的早期没有检查流动特性并使其充分稳定，那么就有很大的危险，飞机布局变得不切实际，上述的效率增益既不能得到保护，也不能实现。建议在概念水平之外，精心设计具有高度集成的推进系统的飞机构型，实现低阻力（高效率），并利用被动流动控制，以在具有苛刻空间要求的发动机处保持足够的流动均匀性。根据现有文献中的非常规构型的例子，建议审查、探索和确定其进气道（S形导管）和受发动机安装影响的其外表面部分的气动形状，以便使它们在任何飞行条件下都能令人满意地工作，从而消除与推进/机体一体化（派）有关的技术障碍。将考虑代表实际飞机工作包线的多个约束。通过构建自动形状优化的设计框架，将创建虚拟空气动力学实验室或试验台。例如，将量化机身和进气道气动外形的影响。安装在挂架短舱内的动力装置的效率将与嵌入机身内的动力装置的效率进行精确的比较。

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.