Abstract: An infrared visualized air turbulence method in which helium is mixed with a heavier-than-air tracer gas such as nitrous oxide in order to cause the density of the tracer gas to be approximately equal to the density of the ambient air stream under study. To enable more accurate measurement of the velocity of the air stream, tracer gas is injected into the stream in a direction extending substantially perpendicular to the direction of flow if the stream. In one of the methods of the invention, an infrared camera and a warm background are placed on one side of an air stream and reflective surfaces are located at opposite sides of the air stream in order to enable infrared visualization of air flow in situations where it is not possible to locate the camera and the warm background on opposite sides of the air stream.

Abstract: A laminar air flow is directed through a space and becomes turbulent upon encountering objects in the space. In order to enable the turbulence in the air flow to be visualized, laminar streams of a tracer gas are introduced into the laminar air flow in the same direction and approximately at the same velocity as the laminar air flow. The tracer gas is a gas such as nitrous oxide having a vibrational absorption frequency in the infrared range. A warm background is positioned at one side of the tracer gas streams and a filter-equipped infrared camera is positioned at the opposite side of the streams and is directed toward the warm background. The camera detects the flow pattern of the tracer gas and produces a permanent photographic image of such pattern.