The time response of an aspirating probe in gas sampling

Abstract

The flow near the tip of a choked-nozzle aspirating probe for gas density measurement is examined. Such probes are currently being used for studying how two dissimilar gases mix in unsteady, free-shear layers. The response of the probe to a step change in gas species is computed using asymptotic limit analysis. Such a change occurs when an interfacing vortex sheet separating the gas species passes over the probe. The limits used in the analysis correspond to small suction and large suction.