Diagnostics and Sensors for Turbine Engines

Abstract

There is a growing urgency for improved performance of combustion devices, for example higher efficiency and lower pollutant emissions. Because of high power requirements and strict size limitations, turbine engines for aircraft propulsion present a particularly difficult challenge. In order to increase specific thrust, improve efficiency and reduce engine size, recent efforts in turbine engine technology have been directed toward increased operating pressures (>30 atm). Maintenance of optimum conditions, e.g., turbine inlet temperature profiles, becomes more difficult as these engines are obliged to achieve optimal performance closer to materials limits and in off-design conditions. Active control of turbine engines offers great potential for such improvements. However, active control of turbine engine combustors requires sensors that are capable of monitoring high temperature and high pressure combustion gases. In such a hostile environment, optical techniques are a natural solution, as they offer the possibility of non-intrusive measurements. At the same time, measurement of combustion particulates, primarily soot, is of great interest. Soot plays a key role in radiative heat transfer in the combustor, and therefore, represents a significant source of combustor liner heating. Soot emissions from aircraft during takeoff are of interest since small particulates like soot have been determined to pose respiratory health risks. Finally, soot emitted from aircraft engines at higher altitudes may act as water condensation sites and therefore play an important role in global climate through changes in the earth’s albedo.