Numerical Simulation of Diaphragm Rupture
Abstract
The results from computer simulations of the gasdynamic processes that occur during and after the rupture of diaphragms within shock tubes and expansion tubes are presented. A twodimensional and axisymmetric finitevolume code that solves the unsteady Euler equations for inviscid compressible flow, was used to perform the simulations. The flow domains were represented as unstructured meshes of triangular cells and solutionadaptive remeshing was used to focus computational effort in regions where the flowfield gradients were high. The ability of the code to produce accurate solutions to the Euler equations was verified by examining the following test cases: supersonic vortex flow between two arcs, an ideal shock tube, and supersonic flow over a cone. The ideal shock tube problem was studied in detail, in particular the shock speed. The computed shock speed was accurate when the initial pressure ratio was low. When the initial pressure ratio was high the flow was difficult to resolve because of the large density ratio at the contact surface where significant numerical diffusion occurred. However, solutionadaptive remeshing was used to control the error and reasonable estimates for the shock speed were obtained. The code was used to perform multidimensional simulations of the gradual opening of a primary diaphragm within a shock tube. The development of the flow, in particular the contact surface was examined and found to be strongly dependent on the initial pressure ratio across the diaphragm. For high initial pressure ratios across the diaphragm, previous experiments have shown that the measured shock speed can exceed the shock speed predicted by onedimensional models. The shock speeds computed via the present multidimensional simulation were higher than those estimated by previous onedimensional models and were closer to the experimental measurements. This indicates that multidimensional flow effects were partly responsible for the relatively high shock speeds measured in the experiments.
 Publication:

NASA STI/Recon Technical Report N
 Pub Date:
 December 1997
 Bibcode:
 1997STIN...0301114P
 Keywords:

 Computerized Simulation;
 Gas Dynamics;
 Diaphragms (Mechanics);
 Shock Waves;
 Rupturing;
 Computational Grids;
 Numerical Analysis;
 Unsteady Flow;
 Euler Equations Of Motion;
 Finite Volume Method;
 Supersonic Flow;
 Pressure Ratio;
 Error Analysis;
 Vortices;
 Differential Equations;
 Flow Distribution;
 Shock Tubes;
 Two Dimensional Flow;
 Structural Mechanics