Axisymmetric Inviscid Shock Tube Flow Simulation.
Abstract
An axisymmetric flow simulation was made for the highly transient flow in a variable cross-section area shock tube at pressure ratio of 16. The shock tube has a varying diameter driver section and a convergent divergent nozzle. A large and sudden area increase exists at the divergent section of the nozzle which leads to the driven section. Euler equations are solved using a time dependent implicit finite difference scheme. A validation computation was made for a constant area tube, at pressure ratio of 6.5 and the result was in good agreement with the corresponding experiment. These results were improved when the tube diaphragm effects were simulated and the divergent nozzle geometry was better modeled. However, four areas of necessary improvement were identified for achieving an accurate simulation: first, the proper modeling of the exact sudden area increase; second, better coordinates near the sudden large area increase third, inclusion of physical viscosity in the numerical simulation (i.e., use of Navier Stokes solver rather than an Euler's solver); fourth, mininization and examination of the role of the second order implicit numerical dissipation for a time accurate computation. The present procedure can only be used satisfactorily for shock tubes with continuous and mild area changes. Without these improvements, an inviscid, quasi-one-dimensional flow simulation can, and does, yield more accurate results in general, except for the peak overpressure which is usually underpredicted. For the present case of pressure ratio of 16 it was underpredicted by a factor of 30%.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1986
- Accession Number
- ADA178494
Entities
People
- Ameer G. Mikhail
- Charles J. Nietubicz
Organizations
- Ballistic Research Laboratory