Graphite Heating Element Thermal and Structural Performance in the NSWC (Naval Surface Warfare Center) Hypervelocity Wind Tunnel 9 - A Finite Element Analysis.

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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.

Author(s):
Metzger, Michael A.
Author Organization(s):
NAVAL SURFACE WARFARE CENTER SILVER SPRING MD
Descriptive Note:
Final rept.
Supplementary Note:
Original contains color plates: All DTIC and NTIS reproductions will be in black and white.
Pagination:
0077

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DOCUMENT & CONTEXTUAL SUMMARY

Distribution:
Approved For Public Release, Document Partially Illegible
Distribution Statement:
Approved For Public Release; Distribution Is Unlimited. Document Partially Illegible.

RECORD

Collection: TR
Identifying Numbers
Report Number(s):
NSWC-TR-88-146
Monitor Series:
NSWC
 Subject Terms
Joint Capability Areas:
JCA_5_Command and Control; JCA_5.3_Planning; JCA_6.4.1_Secure Information Exchange; JCA_3.2_Engagement; JCA_3_Force Application; JCA_3.2.1_Kinetic Means; JCA_6.4_Information Assurance; JCA_6_Net Centric; JCA_1_Force Support; JCA_1.3_Human Capital Management; JCA_1.3.2_Personnel Management
Communities of Interest:
Ground and Sea Platforms
Descriptor(s):
*THERMOMECHANICS, *HEATING ELEMENTS, STRESSES, HEAT TRANSFER, COMPUTER PROGRAMS, ANGLES, TENSILE STRENGTH, LIFE EXPECTANCY(SERVICE LIFE), PERFORMANCE(ENGINEERING), RESISTANCE, FINITE ELEMENT ANALYSIS, CRACKS, THEORY, FAILURE, CURRENT DENSITY, GRAPHITE, STRAIN(MECHANICS), TUNNELS, FRACTURE(MECHANICS), NITROGEN, GASES, BRITTLENESS, THERMAL EXPANSION, CONFIGURATIONS, HEATING, OPERATION, FATIGUE(MECHANICS), ELECTRIC CURRENT, HEAT FLUX, FAILURE(MECHANICS), WIND TUNNELS, THERMAL STRESSES, HYPERSONIC WIND TUNNELS, REFRACTORY MATERIALS, CONDENSATION, HYPERSONIC FLOW, HEATERS
Field(s)/Group(s):
Air Conditioning, Heating, Lighting and Ventilating
Report Date:
1988 Jun 01