Graphite Heating Element Thermal and Structural Performance in the NSWC (Naval Surface Warfare Center) Hypervelocity Wind Tunnel 9 - A Finite Element Analysis.
Abstract
A general finite element based method for investigating the electrical, thermal, and thermostructural performance of electrically powered heating devices is presented. The method is used to investigate the performance of a graphite heater configuration used in the NSWC Hypervelocity Wind Tunnel Facility (No.9) for heating nitrogen gas to temperatures up to 3100F prior to a tunnel run ro prevent condensation of the gas during tunnel operation. The graphite heaters presently have a limited and erratic service life a newly installed heater may fail after only 1 or as many as 100 or more tunnel run cycles. Electrical, thermal, and thermostructural performance data are presented for two graphite heater configurations. The thermostructural model is shown to correctly predict brittle fracture at fillet locations in the heater body where, in fact, most fractures are known to occur. Two methods for reducing fillet stresses are proposed which, if implemented, could substantially increase the useful service life of the graphite heaters. Keywords: Brittle failure; Refractory material; Fatigue mechanics; Strain mechanics; Thermal stresses; Joule heating; PATRAN computer program; Current density; Resistivity; Thermal expansion; Strain-to-failure; Heating elements; Failure theory; Hypersonic flows; Electric current; Cracks; Probability; Heat transfer; Voltage; Heat flux; Service life; Finite element analysis; Thermostructural; Stresses; Resistance heating; ABAQUS computer program; Conductivity; Tensile strength.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1988
- Accession Number
- ADA211936
Entities
People
- Michael A. Metzger
Organizations
- Naval Surface Warfare Center