Transition on a Variable Bluntness 7-Degree Cone at High Reynolds Number

Mechanism for frustum transition over blunt cones at hypersonic speeds

“…The present analysis uses the half-angle cone with a nose-tip radius of that was used in the experiments by Jewell et al. (2018) conducted in the AFRL Mach-6 High Reynolds number facility. The AFRL Mach-6 facility operates at stagnation pressures from 700 to 2100 psi (4.83 to 14.5 MPa).…”

“…For sharp cone configurations, an amplification factor of was found to correlate with the onset of Mack-mode dominated transition in the same facility (Jewell & Kimmel 2017; Jewell et al. 2018). In the present case, the latter value of Mack-mode -factor would be achieved at by a planar Mack-mode disturbance at .…”

“…For these moderately blunt conditions, experiments by Stetson (1983) and Jewell et al. (2018) indicated that uncontrolled nose-tip roughness did not influence the transition onset location, suggesting that unsteady free-stream disturbances may play a role in initiating frustum transition over moderately large-bluntness cones. Computational analysis by Cook et al.…”

“…(2019 c ), which may lead to laminar–turbulent frustum transition on the 7-degree blunt cone that was tested in the AFRL Mach-6 high-Reynolds-number facility (Jewell et al. 2018). The methodologies used to investigate the nonlinear evolution of disturbances are summarized in § 2.…”

Nosetip bluntness effects on transition at hypersonic speeds: experimental and numerical analysis under NATO STO AVT-240

“…• half-angle variable-bluntness cone at zero angle of attack with similar nosetip bluntness values, which have also been shown to transition from laminar to turbulent flow without significant predicted amplification of first-or second-mode instability for smooth nosetips with radius larger than 1 mm and sufficient freestream Reynolds numbers. 66 A subset of the smooth cases, with R N = 5.08 mm and R N = 15.24 mm, have been repeated with 15 µm laser-machined roughness elements of approximately cubical shape located on the circle at 45 degrees from the apex of the spherical tip, which is near the sonic line for zero angle of attack. The array of roughness elements has been designed following the transient growth results of subsection III.C.…”