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The time-resolved flow within an unsteady ejector

Heffer, JJH and Miller, RJ and Freeman, C (2008) The time-resolved flow within an unsteady ejector. 46th AIAA Aerospace Sciences Meeting and Exhibit.

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Abstract

The flow field within an unsteady ejector has been investigated using experimental and computational techniques. The experimental results show a peak thrust augmentation of 1.4; numerical simulation gives a value of 1.37. It is shown that the vortex ring dominates the flow field. At optimal thrust augmentation the vortex ring acts like a fluid piston accelerating the fluid inside the ejector. A model is proposed for the operation of unsteady ejectors, based on the vortex ring acting like a fluid piston. Control volume analysis is presented showing that mass entrainment is responsible for thrust augmentation. It is proposed that the spacing of successive vortex rings determines the mass entrainment and therefore thrust augmentation. The efficiency of unsteady ejectors was found to vary between 28% and 32% depending on the L/D ratio of the unsteady jet source. Copyright © 2008 by J H Heffer.

Item Type: Article
Subjects: UNSPECIFIED
Divisions: Div A > Turbomachinery
Depositing User: Cron Job
Date Deposited: 07 Mar 2014 12:05
Last Modified: 27 Nov 2014 19:20
DOI: