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Influence of Reduced Mass Flow Rate and Chamber Backpressure on Swirl Injector Fluid MechanicsIndustry interest in variable-thrust liquid rocket engines places a demand on engine injector technology to operate over a wide range of liquid mass flow rates and chamber backpressures. One injection technology of current interest for variable thrust applications is an injector design with swirled fluids. Current swirl injector design methodologies do not take into account how swirl injector design parameters respond to elevated chamber backpressures at less than design mass flow rates. The current work was created to improve state-of-the-art swirl injector design methods in this area. The specific objective was to study the effects of elevated chamber backpressure and off-design mass flow rates on swirl injector fluid mechanics. Using a backpressure chamber with optical access, water was flowed through a swirl injector at various combinations of chamber backpressure and mass flow rates. The film thickness profile down the swirl injector nozzle section was measured through a transparent nozzle section of the injector. High speed video showed measurable increases in the film thickness profile with application of chamber backpressure and mass flow rates less than design. At prescribed combinations of chamber backpressure and injected mass flow rate, a discrete change in the film thickness profile was observed. Measured injector discharge coefficient values showed different trends with increasing chamber backpressure at low mass flow rates as opposed to near-design mass flow rates. Downstream spray angles showed classic changes in morphology as the mass flow rate was decreased below the design value. Increasing chamber backpressure decreased the spray angle at any injection mass flow rate. Experimental measurements and discussion of these results are reported in this paper.
Document ID
20090014735
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Kenny, R Jeremy
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Hulka, James R.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Date Acquired
August 24, 2013
Publication Date
December 8, 2008
Subject Category
Spacecraft Propulsion And Power
Report/Patent Number
MSFC-2179
Meeting Information
Meeting: 2008 JANNAF Interagency Propulsion Meeting
Location: Orlando, FL
Country: United States
Start Date: December 8, 2008
End Date: December 12, 2008
Sponsors: Department of the Air Force, NASA Headquarters, Department of the Army, Department of the Navy
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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