The role of clustered particles in the formation of a secondary flow (“wake”) occuring at the gas expiring into a rarefied medium in condensation modes is established. The “wake” boundaries were found by comparing the spectral and photometric measurements. Possible mechanisms for initiating luminescence in "wake" are considered. The role of energy exchange of clusters with background gas in the afterglow of the "wake" has been found out. The wavelengths and corresponding transitions in the neutral (Ar-I) and once ionized (Ar-II) argon atoms, which determine the anomalous glow, were discovered. The lifetimes in the excited state of particles in the central part and on the periphery of the clustered flow are detected. The effect of condensation on the background gas penetration into the primary traditional supersonic jet and into the “wake” zone is found.
The role of condensation on the shape and size of a supersonic argon stream flowing from a nozzle into a rarefied space is considered. It is shown that with the growth of cluster sizes, both the primary "traditional" supersonic jet and the external cluster flow formed when heavy clusters penetrate through the lateral compressed layers of the primary flow into the surrounding background gas increases. The type of correction factor in the well-known empirical formula proposed by Ashkenas and Sherman is found, taking into account which this formula can be used in conditions of clustered flows. The reasons for the impact of clusters on the gas dynamics of supersonic flow, conditions and limitations of such an effect are discussed.
Приведены результаты моделирования процессов, происходящих в сверхзвуковых потоках разреженных газов при истечении из сопел космических аппаратов и их движении в разреженной атмосфере произвольно заданного состава. Результаты иллюстрированы примерами измерений на компактном лабораторном газодинамическом стенде с помощью современных диагностических методов.
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