Low frequency instability: A comparison of theory and experiment

✍ Scribed by M.W. Beckstead

• Publisher: Elsevier Science
• Year: 1968
• Tongue: English
• Weight: 606 KB
• Volume: 12
• Category: Article
• ISSN: 0010-2180
• DOI: 10.1016/0010-2180(68)90053-9

✦ Synopsis

The literature contains many theoretical analyses describing combustion instability of solid propellants. The majority of these have been applied Io acoustic instability and are therefore framed in a format compatible with the acoust,cs of a rocket chamber. Howuver. in the low frequency r6gim¢ these models should apply to non-acoustic instability as well as acoustic instability. In the present paper the results of two such models are compared and the response functions (which are ~h¢ eoa result of the analyses) were found to be ¢ssentiaUy the same function of frequency in both models. These results are tbr.n compared with non-acoustic data obtained with an L"burner. The data from the L ~' burner have been reduced to the formal: used in the models and then compared with the theoretical response function, h~ addition, non-acoustlc instability appears to b¢ critically dependent on the combustion and chamber time constants. In the models this relationship appear~ as the combustion phase lead relative to pressure. Therefore, the data have been compared with the predicted phase relationship as well as with the real part of the response function. From t' is curve.fining typa of eomparison, a value for the parameters in the models can be determined. With the parameters evaluated, the response functions of the combustion models can then be substituted directly into the result s of the non-acoustic analysis to give predictions for non-acoustic instability behavious, A comparison of the trends of theoretical calculations are qualitatively in agrecmeot with the actual data. However, slight discrepancies are pre~nt.