Response of Propellant Combustion to Unsteady Turbulent Flows.
Abstract
Turbularization of an acoustic boundary-layer (Stokes layer) on impermeable and permeable surfaces is analytically considered. The theoretical approach utilizes a second-order closure model of turbulence. For simple acoustic boundary-layers on impermeable surfaces, both the approximate solution and the numerical results for the critical acoustic Mach number required for turbulent transition are qualitatively confirmed by experiment. The calculations for acoustic boundary-layers with transpiration (injection) indicate a substantial reduction of the acoustic Mach number required for transition for small values of the normalized injection velocity. The results may provide a mechanism for flow-related combustion instability in practical systems, particularly solid propellant rockets, since turbularization of the near-surface combustion zone could result at relatively low acoustic Mach numbers. An analysis of the transitional and turbulent reactive acoustic boundary layer on a homogeneous solid-propellant surface is conducted to investigate potential mechanisms of combustion instability. A new technique is developed for the condensed-phase thermal layer, in which the propellant space is mapped onto the gas space and efficiently solved using the same adaptive numerical grid. Results are obtained at an acoustic pressure node in the absence of a mean axial flow. The results indicate that acoustically induced transition can occur at relatively low acoustic pressure amplitudes, propellant response to harmonic axial velocity fluctuations is rectified and results in a mean augmentation and that nominal propellant combustion parameters lead to increasing susceptibility to acoustic transition at elevated mean pressures.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1991
- Accession Number
- ADA239212
Entities
People
- Robert A. Beddini
- Ted A. Roberts
Organizations
- University of Illinois Urbana–Champaign