Generation Mechanism of Environmental Pollutants in the Frame Integrated Supersonic Nozzle Exhaust

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Whilst the interest for the faster than supersonic flight is ever increasing amongst those who feel natural to rely upon advanced technology, the world-wide concerns today involve the green house effect and thestratospheric ozone depletion phenomena, which vividly shows a lack of full confidence in our scientific and technological achievements. The environmental effect should be hereafter the first issue to be treated in exploring the developments of new technology.In the present study, the exhaust gas emission from the hydrogen fueled SCRam (Supersonic Combustion Ram) jet engine for HST (HyperSonic Transport) system has been examined. An emphasis is upon the thermo-fluid chemical process to produce pollutants (namely, NOx) at such propulsion system that inevitably operates in the stratospheric atmosphere and possesses a geometrically particular feature of full integration with the vehicle structure.The theoretical part presently treats computational improvements concerning the numerical stiffness due to the chemical reactions involving H-O-N species. The newly developed scheme is coupled with the Navier-Stokes equations of fluid motion to reveal the details of highly reactive SCRam jet external nozzle flows.The experimental part consists of NO gas injection into a space chamber in which the pressure and the Ozone concentration can be adjusted to simulate in the high altitude atmosphere. Flow visualization using schlieren and LIF optical method is employed to examine the injectant shock wave structure, the associated density gradient field and the NO number density distribution, wherefrom the depletion of Ozone due to NO injection is accessed.