One-dimensional acoustic analysis of spray combustion in liquid propellant rocket chambers

The operation of an experimental subscale liquid oxygen/gaseous hydrogen rocket chamber where the How is predominantly one-dimensional offers both experimental and analytical simplifications. By making unsteady pressure and velocity (by means of magnetic velocimetry) measurements at various locations within a motor wherein the flow is predominantly axial in direction, one is able to obtain the acoustic admittance as a function of axial location within the chamber. Comparing the measured pressure and velocity oscillations with a one-dimensional model of the chamber gas dynamics and droplet evaporation and combustion can shed light on which individual processes contribute to cryogenic engine combustion instability. To this end, a two-phase one-dimensional linearized model of the combustion chamber was developed. Results are shown for the steady-state variables with all chamber source terms and for the acoustic variables in the absence of fluctuating source terms.