GLTRS--Glenn
TITLE AND SUBTITLE:
A Simple Model of Pulsed Ejector Thrust Augmentation

AUTHOR(S):
Jack Wilson

REPORT DATE:
August 2003

FUNDING NUMBERS:
WBS-22-708-48-01
NAS3-00145

PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES):
QSS Group, Inc.
21000 Brookpark Road
Cleveland, Ohio 44135

PERFORMING ORGANIZATION REPORT NUMBER:
E-14107

SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
Washington, DC 20546-0001

REPORT TYPE AND DATES COVERED:
Final Contractor Report

SPONSORING/MONITORING AGENCY REPORT NUMBER:
NASA CR-2003-212541

SUPPLEMENTARY NOTES:
Project Manager, Richard L. Deloof, Aeronautics Directorate, NASA Glenn Research Center, organization code 2400, 216-433-6632.

ABSTRACT:
A simple model of thrust augmentation from a pulsed source is described. In the model it is assumed that the flow into the ejector is quasi-steady, and can be calculated using potential flow techniques. The velocity of the flow is related to the speed of the starting vortex ring formed by the jet. The vortex ring properties are obtained from the slug model, knowing the jet diameter, speed, and slug length. The model, when combined with experimental results, predicts an optimum ejector radius for thrust augmentation. Data on pulsed ejector performance for comparison with the model was obtained using a shrouded Hartmann-Sprenger tube as the pulsed jet source. A statistical experiment, in which ejector length, diameter, and nose radius were independent parameters, was performed at four different frequencies. These frequencies corresponded to four different slug length to diameter ratios, two below cut-off, and two above. Comparison of the model with the experimental data showed reasonable agreement. Maximum pulsed thrust augmentation is shown to occur for a pulsed source with slug length to diameter ratio equal to the cut-off value.

SUBJECT TERMS:
Ejectors; Thrust augmentation; Hartmann-Sprenger tubes

NUMBER OF PAGES:
31

PDF AVAILABLE FROM URL:
2003/CR-2003-212541.pdf ( 916 KB )
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