Analysis of moisture condensation in engine inlet ducts

An analytical model of moisture condensation in engine inlet ducts is presented. At moderate subsonic Mach numbers found in engine inlets, the process must rely solely upon heterogeneous condensation and the presence of particulate matter in the air stream. A parametric study indicates that ambient relative humidity and particle concentration are the most significant parameters affecting the process. Results for both equilibrium and non-equilibrium conditions are presented. Graphs show the conditions under which condensation will occur, the maximum temperature rise of the gas phase, and the maximum size of the water droplets. The critical (minimum) particle size which will act as a condensation nucleus is determined, and the effect of the particle size distribution is examined. The effect of parameters upon non-equilibrium gas-phase temperature, droplet temperature, and droplet growth are shown. Results for two-dimensional flow in a typical inlet duct indicate regions of condensation followed by regions of droplet evaporation can be produced by combined geometric and dynamic effects.