منابع مشابه
Secondary instability of crossflow vortices
Crossflow-dominated swept-wing boundary layers are known to undergo a highly nonlinear transition process. In low-disturbance environments, the primary instability of these flows consists mainly of stationary streamwise vortices that modify the mean velocity field and hence the stability characteristics of the boundary layer. The result is amplitude saturation of the dominant stationary mode an...
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Transition research under NASA’s Aeronautical Sciences Project seeks to develop a validated set of variable fidelity prediction tools with known strengths and limitations, so as to enable “sufficiently” accurate transition prediction and practical transition control for future vehicle concepts. This paper builds upon prior effort targeting the laminar breakdown mechanisms associated with statio...
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The flow in an enclosed rotating cylinder with a stationary lower end wall is investigated numerically. For fast rotation rates, the flow in the interior is primarily in the azimuthal direction, with an angular momentum distribution very close to that corresponding to solid-body rotation for about the inner-half radius. The differential rotation sets up a large-scale circulation that is primari...
متن کاملSecondary instability of superposed steady and unsteady crossflow vortices
Laminar-turbulent transition in a 3-D boundary layer under controlled simultaneous forcing of unstable steady and unsteady crossflow waves is investigated by means of direct numerical simulations. The flow configuration reproduces the accelerated 3-D flat-plate boundary layer of the ”Querstr ömungsprinzipexperiment”of the DLRG öttingen [1]. The superposition of high-amplitude steady and unstead...
متن کاملNumerical Simulations of hypersonic boundary-layer instability with localized roughness
The effect of localized roughness on a Ma=4.8 boundary-layer and its instability is investigated by means of unsteady direct numerical simulations. The occurrence of special flow features, such as shocks, boundary-layer separation zones, streamwise vortices and streamwise streaks behind a three-dimensional square-shaped roughness element are discussed. In order to investigate the convective ins...
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ژورنال
عنوان ژورنال: Journal of Spacecraft and Rockets
سال: 2019
ISSN: 0022-4650,1533-6794
DOI: 10.2514/1.a34289