Abstract

The propagation and stability of converging cylindrical shocks, produced in an annular shock tube, equipped with a three increment area contraction, was investigated for various cylindrical chamber widths and two annular shock Mach numbers of 1.26 and 1.44. The Method of Characteristics, integrated using the Hartree scheme, was employed to determine the shock Mach number and pressure-time variations in the cylindrical chamber. These numerical values were verified experimentally by employing a set of piezoelectric pressure transducers placed at five different locations. In narrow cylindrical chambers, a new test section was employed to determine boundary layer effect on the shock strength. For a cylindrical chamber width of 2.5 mm, experimental results were found in excellent agreement with the inviscid numerical solution. For smaller widths, an empirical equation of the shock Mach number variation was developed. Stability of the converging shocks was examined from the series of spark shadowgraphs taken near the geometric centre.