Propulsive and Combustion Modeling of M=2 Aircraft Using Biofuels in Conceptual Design

The recent surge in environmental concerns and a revived interest in supersonic flight have spurred intensive scientific efforts aimed at realizing a new generation of sustainable supersonic aircraft. Simultaneously, the International Civil Aviation Organization (ICAO) Assembly Resolution Act A39-1 directs the Council to review its Annexes, ensuring they adequately address the challenges that the operation of supersonic aircraft may pose to the public. This thesis discusses a methodology and tools designed to anticipate, at the conceptual design stage, the emissions of a supersonic aircraft. The methodology is applied to analyze emissions for a supersonic aircraft with a flight speed of M=2, akin to the Concorde. The adoption of a modeling approach demonstrates the applicability of the methodology for estimating emissions resulting from the combustion of various types of fuels, particularly Alternative Aviation Fuels. The intention of this work is to use the Olympus 593 turbojet, reference test case for validation as well as to eventually assess the impact of biofuels on an already existing supersonic aircraft. The work starts with research on the aircraft and its propulsion system. In parallel, research was also carried out on the state of the art of aviation fuels and their characteristics, data useful later for estimating emissions. Through the analysis of the propulsive system, it is possible to obtain the performances for various operating conditions, thanks to a propulsive system design code written in Matlab environment and its subroutines, above all the extremely accurate gas model function, based on CEA model developed by NASA. Subsequently, through an in-depth design of the combustion chamber, in combination with the accurate gas model, it is possible to estimate emissions of NOx, UHC and CO for the considered engine and various types of fuel. The design of the combustor is necessary for the chosen method for the evaluation of emission indexes: the semi-empirical Lefebvre relations. In fact, Lefebvre have been expressed that NOx, CO and UHC formation is proportional to the product of three terms which are the mean residence time in the combustion zone, chemical reaction rates and mixing rates. Each of these terms is related to quantities in the combustion chamber such as Tpz, the temperature in the primary zone of the combustion chamber, Vc, the Combustion Volume, or Ve, the Evaporation Volume. The last in turn related to the flow rate in the primary zone and the effective evaporation constant λeff , defined as the ratio of square of the initial droplet diameter to the evaporation time.