Kenneth J. Plotkin
Wyle Labs., 2001 Jefferson Davis Hwy., Ste. 701, Arlington, VA 22202
Two well-accepted effects of turbulence on sonic boom shock waves are the presence of random perturbations behind the shock waves, and random thickening of ths shocks themselves. Crow [J. Fluid Mech. 37, 529--563 (1969)] proposed a first-scattering model for the perturbations. This theory has been well accepted. Plotkin and George [J. Fluid Mech. 54, 449--467 (1972)] proposed a second-scattering/energy-balance theory for shock thickening. Pierce [J. Acoust. Soc. Am. 49, 906--924 (1971)] proposed a shock folding theory for thickening, and has recently [AIAA Paper 95-105] proposed a dispersion model. These thickening models present different perspectives, but are consistent with each other. Small-scale experiments by several workers have failed to fully replicate shock thickening, with consequent assertions that either thickening does not occur, or that it does occur but that the various theories are incorrect. It has been found that those experiments do not fully replicate the flight-test conditions, and that formulas from the theories have been applied without testing whether the necessary conditions have been met. A variation of the Plotkin/George theory is presented, which more closely relates that theory to Crow's perturbation model.