The gas-dynamic effects of a hemisphere-cylinder obstacle in a shock-tube driver

One form of gene and drug delivery can be achieved by accelerating micro-particles to a sufficient momentum to penetrate the outer layer of the skin, and target the tissue below. In hand-held clinical systems, the particles are accelerated in the transonic flow developed within a miniature shock-tube. These devices require a gas reservoir to be positioned coaxially inside the driver. This paper reports the examination of a nominally constant-area shock-tube containing a co-axial obstacle in the driver section ( Case 2). As a control, the flow-field in a prismatic shock-tube of the same cross-sectional area, with the same initial conditions is also studied ( Case 1). Static and Pitot pressures measured in each of the above cases are compared to one-dimensional theory and numerical computations. Significant deviations between Cases 1 & 2 are observed in the driver, but not in the driven section