Magnetogasdynamic Effects in the Flow Behind a Sphere

摘要

Maxworthy's experiments with the flight of a sphere through an incompressible electrically conducting fluid with an aligned magnetic field showed that transition in the trailing wake was moved to higher fluid mechanical Reynolds numbers. Theoretical and experimental work on suppression of vorticity in uniformly conducting incompressible fluids with imposed uniform transverse magnetic fields was ana lyzed to find a correlating parameter for C sub D, C sub f and transition to turbulence. Extension of the incompressible problem to the compressible one is based on the observed similarity of the transition processes in the hypersonic and incompressible wakes as suggested by Fay and Goldburg. Average values of the fluid properties in the base region were chosen as typical for the calculation of hypersonic wake transition Reynolds numbers, R and R sub H. Hypersonic experiments were performed. In the first set of runs made at 5 cm Hg pressure, a change in the luminous structure of the flow field occurred possibly suggestive of a change from turbulent to laminar wake flow. In the second set of experiments made at 5 cm and 2 cm Hg pressure, no MHD effect on the hypersonic turbulent flow field was evident. The paper concludes with a discussion of these results.