Investigations of cascaded micro-blowing for drag reduction in turbulent boundary layers

本建议是与俄罗斯科学院西伯利亚分院赫里斯蒂亚诺维奇理论和应用力学研究所进行的国际合作的一部分。这位俄罗斯合作伙伴将申请他在俄罗斯基础研究基金会的资金份额。本提案的目的是恢复微吹风的概念，以减少湍流表面摩擦阻力。这似乎是可行的，因为现代材料和新的生产方法允许制造微穿孔的光滑表面，不再对主流施加额外的粗糙度引起的阻力。使用俄罗斯合作伙伴最近的一次观测(到目前为止只获得了一个吹风面板)，在流向方向上串联这样的面板将导致给定减阻效果的吹气质量流量的显著降低，即到目前为止还没有研究过的显著的效率提高。将使用两种互补的技术来研究这个问题：使用俄罗斯最新的流动诊断设备的详细的实验室实验和对高性能计算机系统的直接数值模拟，该系统提供了不受德国可能不适当的湍流模型影响的有洞察力的数据。可以期待非常独特的结果，从而能够提取具有重要基础和实际意义的新的定性和定量信息。对于这一问题，将首次改进微吹边界层控制的预测和建模，并将获得用于湍流模型验证的数据。相关的考虑在许多方面都是开创性的，并解决了减少阻力的重要方面，以节省燃料，从而将环境污染降至最低。

The present proposal is part of an intended international cooperation with the Khristianovich Institute of Theoretical and Applied Mechanics of the Russian Academy of Science, Siberian Branch. The Russian partner will apply for his share of the funding at Russian Foundation of Basic Research.The purpose of the present proposal is to revive the concept of micro-blowing for turbulent skin friction drag reduction. This appears feasible because modern materials and new production methods allow manufacturing of micro-perforated smooth surfaces which do no longer exert additional roughness-induced drag on the main flow. Using a very recent observation of the Russian partner (obtained so far for a single blowing panel only) cascading of such panels in streamwise direction will lead to a considerable reduction of blowing mass-flow rates for a given drag reduction effect, i.e. a remarkable efficiency increase which has not been studied so far.The problem will be investigated using two complementary techniques: Detailed laboratory experiments with the latest flow-diagnostics devices in Russia and direct numerical simulations on a high-performance computer system that delivers insightful data that are not biased by a possibly inappropriate turbulence model in Germany. Very unique results can be expected allowing to extract new qualitative and quantitative information of great fundamental and practical importance. Prediction and modeling of boundary-layer control using micro-blowing will be improved and data for validation of turbulence models will be obtained, for the first time for this problem. The related considerations are pioneering in many aspects and address important aspects of drag reduction for fuel savings and hence minimizing pollution of the environment.