Purpose

The purpose of this paper is to propose a new approach of using additively manufactured parametric models in the wind tunnel test-based aerodynamic shape optimization (ASO) framework and to present its applicability test results obtained from a realistic aircraft design problem.

Design/methodology/approach

For aircraft shape optimization, the following three methodologies were used. First, as a validation study, the possibility of using rapid prototyping (RP) model in the wind tunnel test was verified. Second, through the wind tunnel test-based ASO, the application and feasibility of the real fighter aircraft shape optimization were verified. A generic fighter configuration is parameterized to generate various test models using additive manufacturing. Wind tunnel tests are conducted to measure their stability criteria in high angle of attack (AOA). Finally, a computational fluid dynamics (CFD) study was performed and analysis procedures, costs and results compared to the wind tunnel test were compared and reviewed.

Findings

RP technology can significantly reduce the time and cost of generating parametric wind tunnel models and can open up new possibilities for wind tunnel tests to be used in the rigorous aerodynamic design loop. There was a slight difference between the results of the RP model and the metallic model because of rigidity and surface roughness. However, the tendency of the aerodynamic characteristics was very similarly predictable. Although there are limitations to obtaining precise aerodynamic data, it is a suitable method to be applied to comparative studies on various shapes with large geo-metric changes in the early phase of design. The CFD analysis indicates that the wind tunnel-based ASO using the RP model shows the efficiency corresponding to the CFD shape optimization.

Research limitations/implications

The RP parametric models may have various assembly error sources and rigidity problems. The proposed methodology may not be suitable for collecting the accurate aerodynamic database of a final design; rather, the methodology is more suitable to screen out many configurations having fairly large shape variation in the early stage of the design process.

Practical implications

The wind tunnel test-based ASO can replace or supplement CFD-based ASO. In areas where CFD accuracy is low, such as high AOA flight characteristics, RP model wind tunnel-based ASO can be a research method that can secure both efficiency and accuracy advantages, providing ten times more effective in terms of cost and time. The wind tunnel test is used to obtain aerodynamic data at the final stage of shape design. It can be extended to a comparative study of several shapes in the early design phase. This procedure can be applied for both industrial level and educational aircraft design activities.

Originality/value

This study is the application to be applied as a parametric study on the whole aircraft, rather than using the RP model applying a simple partial control surface or configuration change of a part of the wing. The possibility of using the RP model was confirmed by comparing and verifying each other in a medium-sized wind tunnel using a relatively large RP model and a metallic model. It was verified that it can be applied in the shape design process, not the shape verification in the traditional design procedure, and a comparison with the CFD method was also performed. With further development and validation efforts, the new design framework may become an industrial standard for future aircraft development.

中文翻译：

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使用增材制造的参数模型进行基于风洞试验的空气动力学形状优化

目的

本文的目的是提出一种在基于风洞测试的空气动力学形状优化（ASO）框架中使用增材制造的参数模型的新方法，并提出从实际飞机设计问题中获得的适用性测试结果。

设计/方法/方法

为了优化飞机形状，使用了以下三种方法。首先，作为验证研究，验证了在风洞测试中使用快速原型（RP）模型的可能性。其次，通过基于风洞试验的ASO，验证了实际战斗机形状优化的应用和可行性。对通用战斗机配置进行参数化，以使用增材制造生成各种测试模型。进行风洞测试以在高攻角（AOA）中测量其稳定性标准。最后，进行了计算流体动力学（CFD）研究，并对与风洞试验相比的分析程序，成本和结果进行了比较和审查。

发现

RP技术可以显着减少生成参数化风洞模型的时间和成本，并且可以为在严格的空气动力学设计环路中使用风洞测试开辟新的可能性。由于刚性和表面粗糙度，RP模型和金属模型的结果之间存在细微差异。然而，空气动力学特征的趋势非常相似地可预测。尽管获取精确的空气动力学数据存在局限性，但它是一种适合的方法，可用于在设计初期对具有较大几何尺寸变化的各种形状进行比较研究。CFD分析表明，使用RP模型的基于风洞的ASO表现出与CFD形状优化相对应的效率。

研究局限/意义

RP参数模型可能具有各种装配误差源和刚性问题。所提出的方法可能不适合收集最终设计的准确空气动力学数据库；相反，该方法更适合在设计过程的早期阶段筛选出形状变化较大的许多配置。

实际影响

基于风洞测试的ASO可以替代或补充基于CFD的ASO。在CFD精度较低的区域，例如较高的AOA飞行特性，基于RP模型的基于风洞的ASO可以成为一种既可以确保效率又可以保证准确性优势的研究方法，从而在成本和时间方面提高十倍。风洞测试用于在形状设计的最后阶段获得空气动力学数据。它可以扩展到早期设计阶段对几种形状的比较研究。此程序可用于工业级和教育飞机设计活动。

创意/价值

该研究是作为整个飞机的参数研究而应用的应用程序，而不是使用通过简单的局部控制面或机翼部分配置改变而使用的RP模型。通过使用相对较大的RP模型和金属模型在中型风洞中进行比较和验证，可以确定使用RP模型的可能性。验证了它可以应用于形状设计过程，而不是传统设计过程中的形状验证，并且还与CFD方法进行了比较。随着进一步的开发和验证工作，新的设计框架可能成为未来飞机开发的工业标准。