Numerical investigation of fuel droplets burning in a wave rotor combustor

To numerically investigate the impacts of n-heptane droplets size on a wave rotor combustor operation, unsteady two-phase reacting compressible flow simulations is performed using an in-house code. The results confirm that using fine liquid fuel droplets smaller than about 6 μm, at considered temperature range, instead of gaseous fuel, will not have a noticeable effect on pressure gain of the considered combustor. As the size of liquid fuel droplets increases, changes in the distribution of the fuel mass fraction in the gas phase, which is related to droplets evaporation delay, increases. The results show that for the present gas-fueled wave rotor combustor design, the pressure gain and mass flow rate get oscillatory at a droplet size of 17 μm. To use larger droplets, the port timings and rotation speed must be modified in such a way that for droplets size of 30 μm, rotation speed must be reduced by about 34% compared to a gas-fueled combustor. In addition, using a gas fuel in a liquid-fueled wave rotor combustor exhibits oscillatory behavior.