http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Analysis of Boundary-Layer Instabilities in Hypersonic, Three-Dimensional Flows
Spatial BiGlobal (SBG) theory was used to study boundary-layer transition on a hypersonic ﬁnned cone. A new solver, BLAST, has been developed to apply the equations in a nonorthogonal manner, which extends its applicability to realistic ﬂight vehicles. After veriﬁcation of the code with previous literature, it was applied to the ﬁnned cone at conditions corresponding to quiet wind-tunnel experiments. Boundary-layer instabilities in a horseshoe vortex emanating from the ﬁn-cone intersection are the focus of this study. Through this investigation, opportunities for improvement were identiﬁed regarding SBG and its interpretation. Speciﬁcally, the deﬁnition of the N factor was used to account for general-group velocity directions. The nonorthogonal equations were used to decouple the orientation of the stability grid from the direction of minimum basic-state change, which allows more control over the most important assumption inherent in spatial BiGlobal. This formulation also allowed computation of the ﬁrst SBG results to fully include a geometric feature like a full ﬁn in its domain, which is found to be necessary to achieve accurate solutions. The effects of other choices were examined as well, such as the inclusion of streamwise curvature, placement of the azimuthal boundaries, and choice of growth direction. Best practices are developed and discussed. SBG results are compared with experiments where possible, with particularly good agreement found for a laminar experimental condition at Mach 6 and Re′ = 5.9 × 10^6 m^-1. The correct frequencies are predicted as most-ampliﬁed in different regions of the vortex, with the hand-off from one dominant frequency to the other also correctly reproduced computationally. Features of these instabilities are identiﬁed, along with their characteristics and how they are affected by the basic state. The electronic version of this dissertation is accessible from https://hdl.handle.net/1969.1/198502
Doctor of Philosophy Texas A&M University 2022 https://hdl.handle.net/1969.1/198502