Characteristics of the Pulsatile Flow in a Self-excited Pulse Combustor Tailpipe

Abstract

This paper designs and describes a self-excited pulse combustion system. The experimental result shows that combustion oscillations can be produced with a steady supply of fuel and air without mechanical or aerodynamic valves. A large decoupling chamber with an exhaust pipe is connected at the end of the tailpipe of the pulse combustor. The temperatures and pressures along the tailpipe are measured. Pulsatile flow in the self-excited pulse combustor tailpipe is numerically simulated by FLUENT. A study case based on the experimental measurement data is simulated with compressible flow equations. Numerical simulation results which are close to the experimental measurement data show that the main characteristics are the increase in velocity amplitude and the decrease in mean velocity along the tailpipe, and the profiles of velocity at the tailpipe exit behave more like laminar pulsatile flows, whereas the profiles of velocity far away from the tailpipe exit behave like turbulence pulsatile flows. The profile of mean temperature along the tailpipe is affected only within a short distance from the tailpipe exit, where the amplitude of mass flow rate oscillation significantly increases. The pressure amplitude gradient is greater near the tailpipe exit than upstream. The pulsatile flow in the tailpipe of the self-excited pulse combustor behaves like an acoustic resonance in a Schmidt pulse combustor.