NOL Hyperballistics Tunnel No. 4 Results 1: Air Liquefaction
Abstract
Since the presence of condensed air in a hypersonic wind tunnel can make the operation of the tunnel difficult, and since liquefaction can occur when the temperature and pressure in the test section are below the condensation values, an investigation was carried out on the liquefaction of air in a hypersonic wind tunnel. The tunnel used was built to operate at Mach numbers up to 11. The liquefaction was investigated under conditions in which the temperature and pressure of the supply air could be varied. It was found that air, unlike water vapor, does not supersaturate and heating of the supply air is required for satisfactory operation of a hypersonic wind tunnel. Experimental measurements show that a portion of the air condenses at or shortly after it reaches the predicted conditions for equilibrium-saturation in the nozzle. Since the presence of liquefaction may affect standard methods of measuring the Mach number of the flow in the tunnel, the response of these standard methods to liquefaction was examined. It was found that pitot-tube determinations of Mach number are relatively insensitive to air liquefaction whereas determinations using static pressures and shock-wave angles that are produced by slender bodies vary with the amount of air condensation. By maintaining a high temperature in the supply air the various standard methods for measuring the Mach number were found to give consistent Mach number data.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 04, 1951
- Accession Number
- AD0895214
Entities
People
- E. Stollenwerk
- G. Lundquist
- P. Wegener
- S. Reed
Organizations
- Naval Ordnance Laboratory