Study of an Uncooled Nozzle Throat for a Large Hypersonic Wind Tunnel

摘要

A study was made of the feasibility of an uncooled throat for a large hypersonic wind tunnel facility using currently available materials. Maximum fullscale stagnation conditions would be 2000psi, 4400R, 1500 lb/sec air flow, and throat diameter 10.5-inches. The basic throat concept was that of a ceramic insulation layer, composed of small pieces, that would form a protective liner within a metal structure. High resistance to thermal spalling was the material characteristic of greatest importance. Tests were made of several zirconia materials and two zirconium diboride compositions by exposing them to hot air flow in a sonic throat at maximum conditions of 800 psi and 3550R. Behavior of the zirconia materials ranged from minor cracking to complete fragmentation. The zirconium-diborides did not crack and were oxidation resistant at these conditions. In addition, the thermal stress distribution was studied for the individual blocks that would form the throat insulation. For this purpose the three-dimensional stress distribution was calculated for mechanically unrestrained blocks having one-dimensional temperature distributions. Effects of temperature distribution, block size and block shape were determined. The computer program is included with the report. It was concluded that currently available materials are not satisfactory for a throat that would be used with no cooling. (Author)