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No abstract

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and This report results from a contract tasking University of BARI as follows: The kinetics of nozzle expansion flow is a topic of large interest due to its linking with technological applications. Usually one can treat the problem by using two approaches. The first one is to use complicated 2D fluid dynamics codes with poor kinetics, the second one is to use 1D nozzle codes emphasizing the role of chemical kinetics in affecting the whole fluid-chemical problem. The second approach has been used by our group to characterize simple gases such as H2, N2, O2 and their mixtures. The peculiarity of our approach is to describe each vibrational level of the molecule as a new species thus avoiding the concept of vibrational temperature. This approach could be in principle extended to polyatomic molecules even though in this case the state tot state kinetics becomes a very difficult problem. These concepts will be developed in the present proposal which deals with the characterization of the kinetics of NH3 through nozzles of different geometries. Our proposal consists of different steps including: 1) development of a realistic kinetics for ammonia decomposition, 2) development of a realistic macroscopic model for vibrational deactivation of polyatomic molecules, 3) evaluation of the dependence of rates on vibrational temperature, 4) insertion of points 1-3 in the nozzle equations and 5) examination of results for different nozzle geometries.

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and This report results from a contract tasking University of BARI as follows: The kinetics of nozzle expansion flow is a topic of large interest due to its linking with technological applications. Usually one can treat the problem by using two approaches. The first one is to use complicated 2D fluid dynamics codes with poor kinetics, the second one is to use 1D nozzle codes emphasizing the role of chemical kinetics in affecting the whole fluid-chemical problem. The second approach has been used by our group to characterize simple gases such as H2, N2, O2 and their mixtures. The peculiarity of our approach is to describe each vibrational level of the molecule as a new species thus avoiding the concept of vibrational temperature. This approach could be in principle extended to polyatomic molecules even though in this case the state tot state kinetics becomes a very difficult problem. These concepts will be developed in the present proposal which deals with the characterization of the kinetics of NH3 through nozzles of different geometries. Our proposal consists of different steps including: 1) development of a realistic kinetics for ammonia decomposition, 2) development of a realistic macroscopic model for vibrational deactivation of polyatomic molecules, 3) evaluation of the dependence of rates on vibrational temperature, 4) insertion of points 1-3 in the nozzle equations and 5) examination of results for different nozzle geometries.

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and This report results from a contract tasking University of BARI as follows: The kinetics of nozzle expansion flow is a topic of large interest due to its linking with technological applications. Usually one can treat the problem by using two approaches. The first one is to use complicated 2D fluid dynamics codes with poor kinetics, the second one is to use 1D nozzle codes emphasizing the role of chemical kinetics in affecting the whole fluid-chemical problem. The second approach has been used by our group to characterize simple gases such as H2, N2, O2 and their mixtures. The peculiarity of our approach is to describe each vibrational level of the molecule as a new species thus avoiding the concept of vibrational temperature. This approach could be in principle extended to polyatomic molecules even though in this case the state tot state kinetics becomes a very difficult problem. These concepts will be developed in the present proposal which deals with the characterization of the kinetics of NH3 through nozzles of different geometries. Our proposal consists of different steps including: 1) development of a realistic kinetics for ammonia decomposition, 2) development of a realistic macroscopic model for vibrational deactivation of polyatomic molecules, 3) evaluation of the dependence of rates on vibrational temperature, 4) insertion of points 1-3 in the nozzle equations and 5) examination of results for different nozzle geometries.