Numerical Investigations of NOx-Formation in Scramjet Combustors using Wall and Strut Injectors

摘要

In the development of new propulsion systems, the ecological impact always has to be considered. On the long run this will also be the case for scramjets, if used for passenger transportation. In the present paper the NOx-formation of scramjet combustors is investigated. The impact of NOx-emissions of aircrafts on the ozone layer is highlighted and the chemical processes of NOx in the troposphere and stratosphere are explained briefly. A short survey of the formation of NOx under the specific conditions of a scramjet combus-tor is given. In order to analyse the NOx-emissions of a scramjet engine a model scramjet combustor with hydrogen injection is investigated numerically. Thereby the fuel is injected by a lobed strut, or by a wall injector. For the sake of comparability the geometry and boundary conditions are chosen identical. This allows an assessment of the different injection strategies. In a detailed study variation of the flight Mach number, equivalence ratio, of the air inlet contraction ratio and inlet losses is performed. Thus for a model scramjet combustor the influence of different operating conditions on pollutant formation is investigated.