EXPERIMENTAL AND NUMERICAL-STUDIES OF EVAPORATING WAVY FUEL FILMS IN TURBULENT AIR-FLOW

In extending earlier studies the present paper is concerned with the two phase flow inside prefilming airblast atomizers of gas turbine combustors at elevated temperatures. A numerical procedure is presented, which describes the internal flow of the nozzle, with the turbulent air flow and the shear driven evaporating wavy liquid film. The flow conditions of the film and gas at the atomizing edge as well as the pressure drop inside the nozzle are predicted. The theoretical results are compared with detailed measurements of the wavy liquid film and of the gas phase. For the experiments, the test section and the optical measuring techniques for evaporating wavy liquid films presented in a recent paper were employed. Using time-averaged values for the thickness, the velocity and the roughness of the film and assuming laminar film flow, the code leads to accurate predictions of the interaction of the liquid film with the gas phase. A variation of the dominating parameters such as the gas velocity, gas temperature, liquid flow rate, and pressure illustrates the accuracy of the numerical predictions with respect to the gas flow as well as to the film flow. The pressure drop as well as the film temperature, film thickness and velocity are accurately predicted under all conditions. Although the present study is focused on prefilming airblast atomization, the benefits of the calculational procedure are not limited to atomization processes. Quite similar flow conditions are found in intake pipes of internal combustion engines and in film vaporization employing combustors.