Analysis of combustion responses in liquid rocket engines

The combustion responses of the methanol and n-decane sprays reacting with air under the unstable waves are studied with a view to observing the oscillatory spray combustion, and investigating the effects of vaporization on the combustion instabilities. Navier-Stokes solutions for chemically reacting flows are used to calculate the flow variables, mass fractions and droplet histories, which in turn provide necessary data to detect the development of unstable waves. A preconditioned dual-time implicit algorithm is employed to simulate the low Mach flows with strong density variations inside the axisymmetric liquid propellant rocket combustor. Emphasized in the present study is the effect of vaporization-chemical interactions upon unstable waves. The results show that the droplets inside the flame strongly responds to the oscillating pressure, in return, flame is excited by amplifying fuel mass fluctuations. And pure vaporization without the interaction with flame, has much less contribution to amplify the unstable waves.