Design and development of a 12 x 12 shock tube

The simple one-dimensional theory for the inviscid flow in a constant area shock tube is reviewed and data on wave velocities and flow durations, derived on the basis of this theory, is presented in graphical form. Consideration is given to the deviations from these predicted results, which will arise as a consequence of, the real gas effects, the viscous nature of the channel gas and the non-ideal diaphragm performance. The design of the shock tube is described in detail and illustrated. Novel features included are, the hydraulic clamp and the rubber suspension. Likewise the instrumentation is described, with particular emphasis on the design and use of thin film heat transfer gauges. A theoretical assessment of the real diaphragm opening is made, with particular reference to large thin steel discs, as used in the 12" x 12" Shock Tube. Wave diagrams, following the non-instantaneous diaphragm opening, are plotted for two particular cases and comparison is made with shock trajectories measured over the first six feet of the tube length. Theoretical consideration is given to the variation in state parameters, with time, after the passage of the shock wave past a fixed station. The criterion for shock formation is discussed and White's definition ratified, in the absence of petal rebound. The effect of non-ideal diaphragm performance on flow durations, which should be obtained at a fixed station, is noted. Measurements of, diaphragm opening time, shock trajectories and flow duration are plotted. Measured flow durations are compared with work of a similar nature in a smaller tube and an improvement noted. A method of assessing flow uniformity is discussed and a rudimentary evaluation of its sensitivity made