Propulsion System Flow Stability Program (Dynamic). Part IX. Combustion Instability Model Program Description and Parametric Study Results

Part IX describes a theoretical investigation of combustion instability in aircraft engine augmentors. Included is a general description of the analytical model and its digital computer solution. The model determines the frequencies, amplitudes, and spatial distributions of self-excited pressure oscillations in an afterburner or duct burner. The results of a parametric investigation of combustion instability in two turbojet afterburners are also reported. Good agreement between computed and observed trends has confirmed the conceptual validity of the analytical model. The parametric study also confirmed the utility of the computer programs in evaluating design modifications for suppressing or eliminating combustion instability. The computer programs are recommended for use now in engine design projects, but more advanced treatment of some of the input quantities, in conjunction with experimental data, will doubtlessly refine the accuracy of the solution. (Author) Prepared in cooperation with Northern Research and Engineering Corp., Cambridge, Mass., Rept. no. NREC-1133B-1-Vol-1 and Pratt and Whitney Aircraft, Hartford, Conn. See also Part 8, AD-866 499 and Part 10, AD-866 556.