Validation experiment on the transition of three-dimensional boundary layers on wings with spanwise varying flow conditions

展向变流条件下机翼三维边界层转变验证实验

• 批准号: 162041067
• 负责人: Professor Dr.-Ing. Rolf Radespiel
• 金额: --
• 依托单位: Institut für Aerodynamik und Strömungstechnik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2010
• 资助国家: 德国
• 起止时间: 2009-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/162041067?language=en
• 关键词: Validation; experiment; transition; three; dimensional

Transition prediction is important for future laminar wing development for transport aircraft. Nowadays industrial design tools for stability analysis of the boundary layer use local data with the assumption of invariant flow conditions in spanwise direction. These assumptions are not generally valid on real wing configurations, and limit the accuracy of transition prediction. Until today there exist no experimental data to quantify the expected inaccuracy. The aim of the research project is to design and to conduct validation experiments on the transition on a swept wing with spanwise varying mean flow. The transition location is measured with infrared thermography over the whole area of the wing and is used to monitor crossflow vortices and their spanwise development. Possible dispersion effects in the area of wing sweep variations are investigated. Frequency spectra and the amplification of boundary layer instability modes are measured with hotfilm arrays.During the first project phase these measurements were performed in a medium size university wind tunnel, at Reynoldsnumbers of 2.75 million and with conventional levels of freestream turbulence. In the second phase the transition investigations will be particularly focussed at wing areas with spanwise varying crossflow instabilities. By performing these measurements in the larger DNW-NWB wind tunnel, significantly larger Reynoldsnumbers and lower freestream turbulence levels are obtained. This will add value to the resulting data base.

转变预测对于未来运输机层流机翼的开发非常重要。如今，用于边界层稳定性分析的工业设计工具使用本地数据，并假设翼展方向上的流动条件不变。这些假设通常不适用于真实的机翼配置，并且限制了过渡预测的准确性。直到今天，还没有实验数据来量化预期的不准确性。该研究项目的目的是设计并进行翼展变化平均流量的后掠翼过渡验证实验。过渡位置通过红外热成像技术在机翼的整个区域进行测量，并用于监测横流涡流及其翼展方向的发展。研究了机翼后掠角变化区域中可能的色散效应。频谱和边界层不稳定模式的放大通过热膜阵列进行测量。在项目的第一个阶段，这些测量是在中等规模的大学风洞中进行的，雷诺数为 275 万，自由流湍流的常规水平。在第二阶段，过渡研究将特别集中于具有翼展方向变化的横流不稳定性的机翼区域。通过在更大的 DNW-NWB 风洞中进行这些测量，可以获得明显更大的雷诺数和更低的自由流湍流水平。这将为生成的数据库增加价值。