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Transient Side Load Analysis of Out-of-Round Film-Cooled Nozzle ExtensionsThere was interest in understanding the impact of out-of-round nozzle extension on the nozzle side load during transient startup operations. The out-of-round nozzle extension could be the result of asymmetric internal stresses, deformation induced by previous tests, and asymmetric loads induced by hardware attached to the nozzle. The objective of this study was therefore to computationally investigate the effect of out-of-round nozzle extension on the nozzle side loads during an engine startup transient. The rocket engine studied encompasses a regeneratively cooled chamber and nozzle, along with a film cooled nozzle extension. The computational methodology is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, and transient inlet boundary flow properties derived from an engine system simulation. Six three-dimensional cases were performed with the out-of-roundness achieved by three different degrees of ovalization, elongated on lateral y and z axes: one slightly out-of-round, one more out-of-round, and one significantly out-of-round. The results show that the separation line jump was the primary source of the peak side loads. Comparing to the peak side load of the perfectly round nozzle, the peak side loads increased for the slightly and more ovalized nozzle extensions, and either increased or decreased for the two significantly ovalized nozzle extensions. A theory based on the counteraction of the flow destabilizing effect of an exacerbated asymmetrical flow caused by a lower degree of ovalization, and the flow stabilizing effect of a more symmetrical flow, created also by ovalization, is presented to explain the observations obtained in this effort.
Document ID
20120015655
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Wang, Ten-See
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Lin, Jeff
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Ruf, Joe
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Guidos, Mike
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Date Acquired
August 26, 2013
Publication Date
July 30, 2012
Subject Category
Fluid Mechanics And Thermodynamics
Report/Patent Number
M12-1855
M11-1336
M12-1962
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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