The Investigation of the Mixture Formation upon Fuel Injection into High-Temperature Gas Flows

Abstract

Combustion of a fuel in the combustion chambers of a gas-turbine engine and a gas-turbine plant is closely connected with the processes of mixing (Lefebvre, 1985). Investigations of these processes carried out by both experimental and computational methods have recently become especially crucial because of the necessity of solving ecological problems. One of the most pressing problems at present is account for the influence of droplets on an air flow. In some of the regimes of chamber operation this may lead to a substantial, almost twofold, change in the long range of a fuel spray and, consequently, to corresponding changes in the distributions of the concentrations of fuel phases. In this chapter physical models of the processes of interphase heat and mass transfer and computational techniques based on them are suggested. The present work is a continuation of research by Maiorova & Tretyakov, 2008. We set out to calculate the fields of air velocity and temperature as well as of the distribution of a liquid fuel in module combustion chambers with account for the processes of heating and evaporation of droplets in those regimes typical of combustion chambers in which there is a substantial interphase exchange. It is clear that when a cold fuel is supplied into a hot air flow, the droplets are heated and the air surrounding them is cooled. It is evident that at small flow rates of the fuel this cooling can be neglected. The aim of this work is to answer two questions: how much the air flow is cooled by fuel in the range of parameters typical of real combustion chambers, and how far the region of flow cooling extends. Moreover, the dependence of the flow characteristics on the means of fuel spraying (pressure atomizer, jetty or pneumatic) and also on the spraying air temperature is investigated.