Onset of detonation through a cold flow analysis using metallic diaphragms – an experimental approach

Abstract

Modern era is looking for high speed transportation systems across globe with due comfort. Innovative design in both aerodynamic and propulsion studies have been made for achieving supersonic to hypersonic speeds ranging a claim of 1km/s under stratosphere limit. The complexity in designing such vehicles in a high-altitude test facility is borne due to the fact that simulation of such conditions as low density, no shock conditions, high rate of dissipation and shock flow comes from unavailability of sufficient technology to pressurize gases to the optimal testing conditions. The prominent ways of constructing a shock tube either involve a blow down type or a vacuum suction type. Here a blow down type shock tube require a built-up pressure comparable to the velocity at the test section. Fibre diaphragms blow out at less critical pressure and are unsuitable for high speed flows. Metal foil are incepted as a concept of diaphragms for this particular problem. Aluminium foils are stacked across a mounting flange on a settling chamber to determine the maximum pressure at which blow down occurs. The results are tabulated for an incremental pressure schema of 1 bar to 10 bar with which it was found that the wave pressure development occurs during each batch of aluminium and recorded to be between 3.5 bar and 9 bar the successive velocities at the exit was found to be increasing with increase of blast pressure.