Graphite Heating Element Operating Temperature Measurements in the NSWCHypervelocity Wind Tunnel 9

摘要

This report documents real-time temperature measurements of a graphite heatingelement operating in the Naval Surface Warfare Center, Dahlgren Division (NSWCDD) Hypervelocity Wind Tunnel No. 9 facility. Tunnel 9 uses a large graphite element to heat nitrogen gas to 3100 deg F prior to releasing this gas to the test section, where it achieves hypersonic speeds to Mach 16.5. The present effort focused on obtaining the operating temperature of an uncoated heating element with a view to determine if an oxidation-resistant, silicon-carbide coated, graphite element, of the same size now used in the facility, might be used to batch-heat air in the heating vessel. The reported results appear promising in that the measured peak surface temperature of the element could be held to below 4000 deg F during a standard heating cycle. The measured temperatures, which were well below the predicted service limits given in this report for the silicon-carbide coating system, suggest that a silicon-carbide coated element concept warrants further study.