Dynamics of High Pressure Reacting Shear Flows
Technical Report,01 Jan 2014,26 Oct 2016
AFRL/RQRC EDWARDS AFB United States
Pagination or Media Count:
Hydrodynamic and combustion dynamics were investigated for reacting and non-reacting rocket injector flows. The experimental data was collected in a facility designed to directly visualize high pressure, acoustically driven flows. The facility was designed to establish traceability to extensive non-reacting data present in the literature, and to reproduce the challenging environment in liquid rocket engines, namely high supercritical pressures and cryogenic temperatures. The facility was upgraded to investigate both liquid hydrocarbons as well as hydrogen as fuels. Of special interest was how different rocket injector flow fields shear coaxial, swirl coaxial, impinging etc. coupled with acoustic perturbations. Acoustic-flame dynamics often rapidly amplify to reach the limit cycle of the thermo-acoustic instability cycle, passing through a series of intermediate states whose fundamentals are difficult to understand due to the rapidity with which the system passes through them. A unique open loop approach was taken to freeze these intermediate states for each injector by controlling both amplitude and frequency of the acoustic perturbations. Both sub and super-critical thermodynamic conditions were investigated to study the effect real gas effects have on atomization, mixing, and the combustion processes. High-speed diagnostics including pressure and image-based techniques were employed to investigate the dynamics. Optical diagnostics employed include back-lighting, shadowgraphy, and OH chemiluminescence. Decomposition techniques like proper orthogonal decomposition POD and dynamic mode decomposition DMD were used to identify dominant modes and frequencies from the high speed images taken for each flow field.
- Inorganic Chemistry
- Fluid Mechanics
- Combustion and Ignition