NOx Emissions and Engine Performance Results for Studied Engine Concepts including final summary

In the cooperative EU project ATLLAS (Aerodynamic and Thermal Load Interactions with Lightweight Advanced Materials for High Speed Flight - EU 6 th framework) conceptual studies on supersonic transporters (SST) equipped with RAM-jets have been carried out. The main focus within the project was lightweight heat resistive materials, but also environmental aspects such as gas emissions and noise constituted part of the work. This report covers the emissions. The possibility of future RAM-jet SST's at high altitude cruise heights actualise matters of atmospheric changes due to exhaust gas emissions. The primary task regards NOx and whether it might threaten the ozone layer. With the aircraft concepts studied within ATLLAS - one Mach 6 and one Mach 3 concept - combustion products are emitted at considerably higher altitudes than for the aircraft fleet of today. This is at altitudes around 25 km's, i.e. in the lower stratosphere, compared to today's traffic which is found in the higher troposphere, around 10 km's above sea level. The report contains a literature study covering atmospheric NOx / ozone layer matters and low-NOx engine concepts as well as fundamental studies of cruise NOx levels for the conceptual ATLLAS aircraft. The results are related to possible future NOx limitations.