Thermal Analysis of a Carbon Fiber Rope Barrier For Use in the Reusable Solid Rocket Motor Nozzle Joint-2
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HUNTSVILLE AL GEORGE C MARSHALL SPACE FLIGHT CENTER
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This study provides development and verification of analysis methods used to assess performance of a carbon fiber rope CFR thermal barrier system that is currently being qualified for use in Reusable Solid Rocket Motor RSRM nozzle joint-2. Modeled geometry for flow calculations considers the joint to be vented with the porous CFR barriers placed in the open assembly gap. Model development is based on a 1-D volume filling approach where flow resistances assembly gap and CFRs are defined by serially connected internal flow and the porous media Darcy relationships. Combustion gas flow rates are computed using the volume filling code by assuming a lumped distribution total joint fill volume on a per linear circumferential inch basis. Gas compressibility, friction and heat transfer are included in the modeling. Gas-to-wall heat transfer is simulated by concurrent solution of the compressible flow equations and a large thermal 2-D finite element FE conduction grid. The derived numerical technique loosely couples the FE conduction matrix with the compressible gas flow equations. Free constants that appear in the governing equations are calibrated by parametric model comparison to hot fire sub-scale test results. The calibrated model is then used to make full-scale motor predictions using RSRM aft dome environments. Model results indicate that CFR thermal barrier systems will provide a thermally benign and controlled pressurization environment for the RSRM nozzle joint-2 primary seal activation.
- Refractory Fibers