Experimental Study on the Propagation of a Pulsed Jet

Pratomo, Hariyo P. S. and Bremhort, Klaus (2012) Experimental Study on the Propagation of a Pulsed Jet. Procedia Engineering, 50 (1). pp. 174-187. ISSN 1877-7058

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Abstract

A preceding striking finding in an unsteady jet indicated that the jet departed from its linear trajectory after propagating some downstream locations from its nozzle exit region. In this paper, the propagation of an unsteady jet was experimentally studied. A hot-wire anemometer was used to sample the intermittent- turbulent flow. During the preliminary measurements, the jet was generated from a round nozzle with a varied pulsing frequency and constant mass flow rate. The present results show that the pulsed jet is axisymmetric. Unlike the earlier finding the jet follows a straight line trajectory to propagate further downstream. The flow field of the jet demonstrates the existence of two distinct regions, as found earlier, but it heavily relies on the level of pulsing frequency imposed on the jet. The steady jet part of the jet departs from a self-preserving steady jet having a greater value of aggregate turbulence intensity of around 35% of the mean centerline-axial velocity than that of a self-preserving steady jet. Along 50 diameters downstream, the pulsed jet spreading rate is found to be higher than that of a steady counterpart.

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