With an interest in developing and studying the stability of laminar undisturbed basic-state solutions, this work is focused on accurately modeling the laminar flowfield of the boundary layer transition (BOLT) geometry under nominal and off-nominal conditions (i.e., nonzero angles of pitch and yaw). The BOLT flowfield is studied using the DPLR flow solver with MUSCL Steger–Warming fluxes using a set of five grids at different resolutions and identical grid topologies. A total of three different sets of conditions are studied: two flight conditions and one wind-tunnel-scale (33%) condition. (1) For the two sets of nominal flight operating conditions, it is found that the flow structures in the centerline region of BOLT are similar to those found in prior studies including in shape, location, and extent both vertically and spanwise, but a detailed comparison of velocity contours shows that further quantitative convergence studies are warranted. The centerline region, however, extends to at most 4 cm in semi-span at the aft end of the geometry (20% of the semi-span). Away from the centerline and where wind-tunnel-scale results have observed regions of possibly transitional behavior, the laminar flowfield converges with high accuracy. (2) For nominal wind-tunnel operating conditions, all grid resolutions simulated show good agreement in most regions as compared with prior results, with any differences falling within the scatter of existing experimental and DNS results. Aside from this focus, boundary-layer stability is examined outboard of the centerline region at nonzero pitch and yaw for a flight case, and second mode and stationary crossflow instabilities are considered. Second-mode instability is found to be locally significant at certain pitch and yaw angles particularly downstream of the swept leading edges. In addition, stationary crossflow is found to become highly amplified in significant wedges extending to the aft end of the BOLT geometry, with N-factors consistent with those found for HIFiRE-5b associated with transitional flow. The reasons for amplification of these different instabilities are also investigated from a physics-based perspective.

出于开发和研究层流未受干扰基本状态解的稳定性的兴趣，这项工作的重点是准确模拟标称和非标称条件（即非零倾角）下边界层过渡 (BOLT) 几何形状的层流流场和偏航）。使用带有 MUSCL Steger-Warming 通量的 DPLR 流求解器，使用一组具有不同分辨率和相同网格拓扑的五个网格来研究 BOLT 流场。总共研究了三组不同的条件：两种飞行条件和一种风洞尺度 (33%) 条件。(1) 对于两组标称飞行工况，发现 BOLT 中心线区域的流动结构与先前研究中发现的相似，包括垂直和展向的形状、位置和范围，但速度等值线的详细比较表明，进一步的定量收敛研究是有必要的。然而，中心线区域在几何体的后端（半跨的 20%）延伸至半跨中最多 4 厘米。远离中心线和风洞尺度结果观察到可能过渡行为的区域，层流流场以高精度收敛。(2) 对于标称风洞运行条件，模拟的所有网格分辨率与之前的结果相比在大多数地区都表现出良好的一致性，任何差异都属于现有实验和 DNS 结果的分散范围内。除了这个重点，边界层稳定性在非零俯仰和偏航飞行案例的中心线区域外​​侧进行了检查，并考虑了第二模式和固定横流不稳定性。发现第二模式不稳定性在某些俯仰角和偏航角下局部显着，特别是在后掠前缘的下游。此外，发现在延伸到 BOLT 几何形状后端的重要楔形中，固定横流会被高度放大，N因子与 HIFiRE-5b 与过渡流相关的发现一致。还从基于物理学的角度研究了这些不同不稳定性放大的原因。