Extension of the Steady Flow Duration of a Ludwieg Tube Using a Reservoir-orifice Method : Part11, Case of Orifices with Variable Opening Area

A reservoir-orifice with variable opening area has been developed for extending the useful steady flow duration of a Ludwieg tube. The orifice which separates the reservoir from the supply tube is made such that its opening area increases properly from a certain initial to a final value during the running. The unsteady expansion waves generated by the opening of a valve or a diaphragm propagate upstream in the supply tube and interact with this orifice. The interaction process is investigated, and the conditions when the reflected waves become compression, Mach or expansion waves are clarified. When the orifice reflects only Mach waves, i.e., complete elimination of the reflected waves can be achieved, the extended running time by the present method is much longer than that of the conventional Ludwieg tubes.