Numerical and Experimental Determination of the Optimal Length of Cylindrical Mixing Chamber of Supersonic Gas Ejector

The article presents the results of numerical calculations and experimental investigations of supersonic gas ejectors with cylindrical mixing chambers of different lengths. The calculations were performed using Ansys Fluent 12.0 software package. Satisfactory agreement between the calculated and the experimental values of the optimal relative length of the cylindrical mixing chamber is shown. The optimal relative length is in the range of 12–15 calibers. When the mixing chamber relative length is more than 7-8 calibers, the calculating error of the basic parameters of the supersonic gas ejector does not exceed 11%, while for smaller relative lengths it reaches 35%. The results of numerical simulation of the flow show that during critical operation stages a supersonic non-uniform gas jet is formed in the cylindrical mixing chamber. The jet is decelerated through a complex system of shock waves, the length of which may be several calibers depending on the ejector working conditions.

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