Industrial applications of shock waves

Abstract

Shock waves have been traditionally considered to be an integral part of flow field features in the area of high-speed aerodynamics. Physically the propagation of shock waves in any media is invariably associated with instantaneous increase in pressure and temperature behind the shockwave. The capability of shock waves to generate non-linear pressure and temperature spikes in the medium of propagation finds very interesting applications in variety of areas such as medicine, biological sciences, material processing, manufacturing, and microelectronic industries. This paper reviews four new industrial applications of shock waves that have been developed in the Shock Waves Laboratory (SWL), Department of Aerospace Engineering, IISc, Bangalore. They are shock wave assisted (a) cell transformation, (b) preservative injection into Bamboos, (c) sandal oil extraction, and (d) removal of micron size dust from silicon wafer surfaces. The shock waves generated in an underwater shock wave generator are exploited in successfully injecting the desired deoxyribonucleic acid into Escherichia coli and Agrobacterium cells. The vertical shock wave reactor is applicable in successfully injecting the water-soluble chemical preservative (copper—chrome—arsenic) to samples of bamboo. The exposure of sandalwood samples to shock wave loading in the horizontal diaphragmless shock tube resulted in the drastic reduction (40 per cent) of time required for oil extraction. Further, a new shock wave assisted technique for micron-size dust removal from silicon wafer surfaces has been developed in collaboration with the Interdisciplinary Shock Wave Research Center, Tohoku University, Sendai, Japan. The strong vortex field generated behind the Mach reflection of a shock wave has been used to remove micron size dust particles from the surface of silicon wafers. The salient features of these new industrial applications of shock waves are described in this paper along with some important results.