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Some injector element detail effects on screech in hydrogen-oxygen rocketsAn experimental investigation was conducted to learn more about how the specific details of a concentric tube injection element affect the screech characteristics of a hydrogen-oxygen rocket engine. The four variables investigated were (1) impingement angle, (2) oxidizer tube blunt base thickness, (3) oxidizer tube recess and extension, and (4) oxidizer tube-annulus concentricity. Tests were made using a 27.34-cm (10.77-in.) diameter heat sink combustor at nominally 300-psia chamber pressure. All of the test variables were investigated using a 157 element circular pattern injector. Additional oxidizer tube recess tests were made with a 421 element hexagonal pattern injector. Tests were conducted over the oxidant-fuel ratio range of 4 to 6. Stability evaluation for each configuration was made using the hydrogen temperature rating technique. Several element configurations were also cold flow tested using nitrogen and water as simulants. The element detail changes resulted in changes in hydrogen injector pressure drop even though the physical injection area was constant for all similar tests in both hot firing and cold flow tests. These changes in injector pressure drop produced changes in combustion stability. The data were correlated with a modified version of a previously reported injection area ratio correlation. By interpreting changes in injector pressure drop as changes in injector hydrogen flow resistance, the data were compared with a hydrogen flow response stability model and were found to be in agreement.
Document ID
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Hannum, N. P.
(NASA Lewis Research Center Cleveland, OH, United States)
Russell, L. M.
(NASA Lewis Research Center Cleveland, OH, United States)
Vincent, D. W.
(NASA Lewis Research Center Cleveland, OH, United States)
Conrad, E. W.
(NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
September 3, 2013
Publication Date
February 1, 1974
Subject Category
Propulsion Systems
Report/Patent Number
Accession Number
Funding Number(s)
Distribution Limits
Work of the US Gov. Public Use Permitted.
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