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Published December 2008 | Published
Journal Article Open

Experiments on the mechanism of inducing transition between regular and Mach reflection

Abstract

A study of the mechanism by which disturbances can cause tripping between steady-flow regular and Mach reflection in the dual-solution domain is presented. Computational results indicate that the disturbance shock created as a result of the impact of dense particles on one of the shock-generating wedges can cause transition from regular to Mach reflection. The disturbance shock may also be generated by direct energy deposition on the wedge. Estimates of the lower bound of the required energy for transition to occur are presented and compared to values obtained computationally. Experiments were performed at Mach 4.0 in a Ludwieg tube that has a test duration of 100 ms. Proper starting of the flow necessitated operation with an upstream diaphragm and modifications in the dump tank. The reflection state was changed by rapid rotation of one of the shock-generating wedges. The flow in the facility is sufficiently quiet to permit entering the dual-solution domain to approximately its midpoint before spontaneous transition to the Mach reflection occurs. The short test time prompted a study of the effect of wedge rotation speed on the transition from regular to Mach reflection. Transition due to deposition of energy on one of the wedges was also examined by using a pulsed laser focused on one of the two wedges. Measurements of the minimum energy to bring about transition and of the rapid growth of the Mach stem to its steady-state are compared to numerical and theoretical predictions.

Additional Information

© 2008 American Institute of Physics. Received 15 July 2008; accepted 7 November 2008; published 18 December 2008. This work was funded by the Air Force Office of Scientific Research under the supervision of Dr. John Schmisseur. A portion of Christopher Mouton's studies were funded by the National Defense Science and Engineering Grant. Special thanks to Bahram Valiferdowsi for his extensive help in the design, manufacture, and repair of the Ludwieg tube facility. Thanks also to James Quirk for his help on the computational aspects of this work, and to Nicolas Ponchaut for his review of this work. The nozzle contour was designed by John Korte of NASA Langley Research Center.

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August 22, 2023
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