Methods and instrumentation for the investigation of nonstationary processes in liquid-propellant rocket engines

At the nonstationary regimes of the liquid rocket engine operation essential fraction of the pulse duration relate to the transitional (preflame and postflame) processes which accompany the engine switching-on and switching-off. Some diagnostics methods and instrumentation have been developed for investigation of the processes in the combustion chambers, nozzles and jets of the spacecraft engines under nonstationary conditions. On the basis of experimentally obtained spatial, spectral and time characteristics of jet self-radiation in the visible and infrared spectral areas, the nonequilibrium degree of flow in the nozzle, the parameters distribution over a cross section, sizes and concentration of the carbon particles have been evaluated. Sizes, concentration and phase status of the propellant particles were determined by scattering characteristics of the laser light passing through the medium under test. A film thermometry was used for investigation of the engine thermal status at pulse modes of operation and for determination of heat fluxes on the surface of the chamber elements.