Kitzinger Euryale, Leclercq Tristan, Marquet Olivier, Piot Estelle, Sipp Denis
DAAA, ONERA, University of Paris-Saclay F-92190 Meudon - France.
ONERA/DMPE, University of Toulouse F-31055 Toulouse - France.
J Fluid Mech. 2023 Feb 23;957. doi: 10.1017/jfm.2023.38. eCollection 2023 Feb 25.
Linear stability analyses are performed to investigate the boundary layer instabilities developing in an incompressible flow around the whole leading-edge of swept ONERA-D and Joukowski airfoils of infinite span. The stability analyses conducted in our study are global in the chordwise direction and local in the spanwise direction. A neutral curve is drawn at a given leading-edge Reynolds number and several overlapping regions, called "lobes", are identified on a physical basis. A detailed study of the marginal modes reveals the presence of attachment-line and crossflow instabilities, as well as modes whose features do not fall within the standards of a specific type. Connected crossflow/Tollmien-Schlichting modes, that show a dominant spatial structure reminiscent of Tollmien-Schlichting waves but whose destabilization is linked to a crossflow mechanism, have been identified. The comparison of several neutral curves at different values reveals the greater stabilizing effect of the increase of on the crossflow instability compared to the attachment-line instability. The influence of the airfoil shape is also studied by comparing the neutral curves of the ONERA-D with the neutral curves of the Joukowski airfoil. These curves reveal similar characteristics with the presence of distinct lobes and their comparison at constant sweep angle shows that, under the conditions studied, the ONERA-D airfoil is more stable than the Joukowski airfoil, even for crossflow instabilities. The absolutely or convectively unstable nature of the flow in the spanwise direction is also tackled and our results suggest that the flow is only convectively unstable.
进行线性稳定性分析，以研究在无限展长的后掠ONERA - D翼型和儒科夫斯基翼型整个前缘周围不可压缩流中发展的边界层不稳定性。我们研究中进行的稳定性分析在弦向是全局的，在展向是局部的。在给定的前缘雷诺数下绘制中性曲线，并基于物理原理识别出几个重叠区域，称为“叶瓣”。对边缘模态的详细研究揭示了附着线和横流不稳定性的存在，以及一些其特征不属于特定类型标准的模态。已经识别出连接的横流/托利米恩 - 施利希廷模态，其显示出类似于托利米恩 - 施利希廷波的主导空间结构，但其失稳与横流机制有关。比较不同值下的几条中性曲线表明，与附着线不稳定性相比，增加对横流不稳定性具有更大的稳定作用。通过比较ONERA - D翼型的中性曲线和儒科夫斯基翼型的中性曲线，还研究了翼型形状的影响。这些曲线显示出相似的特征，存在明显的叶瓣，并且在恒定后掠角下进行比较表明，在所研究的条件下，即使对于横流不稳定性，ONERA - D翼型也比儒科夫斯基翼型更稳定。还研究了展向流动的绝对或对流不稳定性质，我们的结果表明流动仅是对流不稳定的。
