Publications

HIFiRE-1 boundary-layer transition: Ground test results and stability analysis

Juliano, Thomas J.; Kimmel, Roger L.; Willems, Sebastian; Gülhan, Ali; Wagnild, Ross M.

The HIFiRE-1 is a 7-degree half-angle circular cone with a 2.5-mm nose radius. A successful HIFiRE-1 flight experiment was carried out in March 2010. Due to an anomaly in the exoatmospheric pointing maneuver, the reentry angle of attack was higher than anticipated (5-15 degrees instead of near zero). A test campaign in the H2K hypersonic wind tunnel at DLR Cologne gathered high-frequency pressure fluctuation data and global heat flux via infrared (IR) thermography at the high angles of attack and Reynolds numbers encountered in the as-flown trajectory. This paper presents analysis of data collected at 0° angle of attack at freestream Reynolds numbers from 5.7 to 10.7.106 /m for 1.6-and 2.5-mm-radius nosetips. The transition onset and end locations derived from IR thermography coincide well with the earliest and largest amplification of pressure fluctuations identified by the fast-response surface-mounted pressure transducers. Stability analysis of the astested conditions was done with the Stability and Transition of Boundary Layers (STABL) software suite. An N-factor of 5.5 correlates well with transition location for the 1.6-mmradius nosetip. For the blunter nosetip, N ≈ 5.2 at transition. The peak pressure-fluctuation frequencies predicted by STABL agree within 8% of those measured.