Scaling and Transition Effects on Hollow-Cylinder/Flare Shock/Boundary-Layer Interactions in Wind Tunnel Environments

A comprehensive investigation into the flow over a hollow-cylinder and ⩉ =15° flare has been conducted at Mach 5 with transitional Reynolds numbers. Experiments of two similar models have been conducted in LT5 at the University of Arizona and R2Ch at ONERA. Considerable differences in reattachment behavior were observed from infrared thermography measurements indicating that the reattachment in LT5 was approximately twice as far from the flare base as observed in R2Ch. Supporting simulations have been performed at the University of Arizona and the Technical University of Munich. Various effects are reviewed: Mach numbers and wall temperatures modulating boundary-layer development, 3D relief effects due to differences in normalized cylinder diameters, leading-edge bluntness effects, and the impact of freestream disturbances. Simulations show that modulation of freestream noise amplitude can scale the interaction size to match experiments. Experimental investigation of the respective noise environment between the two facilities showed that despite exhibiting similar noise magnitudes, they differed considerably in frequency content, suggesting that additional parameters are required when quantifying wind tunnel freestream noise conditions. These discrepancies are believed to lead to greater seeding of shear layer instabilities in R2Ch, resulting in faster transition, consistent with the experimentally observed smaller recirculation bubble.     «

A comprehensive investigation into the flow over a hollow-cylinder and ⩉ =15° flare has been conducted at Mach 5 with transitional Reynolds numbers. Experiments of two similar models have been conducted in LT5 at the University of Arizona and R2Ch at ONERA. Considerable differences in reattachment behavior were observed from infrared thermography measurements indicating that the reattachment in LT5 was approximately twice as far from the flare base as observed in R2Ch. Supporting simulations hav...     »

Acknowledgments The University of Arizona authors would like to thank the US Navy’s Office of Naval Research (ONR) and program manager Dr. Eric Marineau for providing funding for this work (N00014-20-1-2267 and N00014-23-1-2645). In addition, the authors would like to recognize the contribution of Sathyan Padmanabhan, Alejandro Roskelley Garcia, and Sam Bevier for their assistance when operating the test facility. The authors would also like to express their gratitude to Prof. Alex Craig for providing nozzle data from LT5. The ONERA authors would like to thank the R2Ch team as well as François Nicolas for the help they provided to gather the experimental data. This work was partially supported by the French Alternative Energies and Atomic Energy Commission (CEA) under the grant CEA 4600334751. The TUM authors gratefully acknowledge the Gauss Centre for Supercomputing e.V. (www.gauss-centre.eu) for funding this project by providing computing time on the GCS Supercomputer SuperMUC-NG at Leibniz Supercomputing Centre (www.lrz.de).     «

Acknowledgments The University of Arizona authors would like to thank the US Navy’s Office of Naval Research (ONR) and program manager Dr. Eric Marineau for providing funding for this work (N00014-20-1-2267 and N00014-23-1-2645). In addition, the authors would like to recognize the contribution of Sathyan Padmanabhan, Alejandro Roskelley Garcia, and Sam Bevier for their assistance when operating the test facility. The authors would also like to express their gratitude to Prof. Alex Craig for...     »