Engineering topics

Benjamin, M. A.

Publications and source records attributed to Benjamin, M. A..

3 records

NASA NTRS1993

Initial development of the two-dimensional ejector shear layer - Experimental results

An experimental investigation designed to study the development of shear layers in a two-dimensional single-nozzle ejector has been completed. In this study, combinations of air/air, argon/air, helium/air, and air/helium were used as the supersonic primary and subsonic secondary, respectively. Mixing of the gases occurred in a constant-area tube 39.1 mm high by 25.4 mm wide, where the inlet static pressure was maintained at 35 kPa. The cases studied resulted in convective Mach numbers between 0.058 and 1.64, density ratios between 0.102 and 3.49, and velocity ratios between 0.065 and 0.811. The resulting data shows the differences in the shear-layer development for the various combinations of independent variables utilized in the investigation. The normalized growth-rates in the near-field were found to be similar to two-dimensional mixing layers. These results have enhanced the ability to analyze and design ejector systems as well as providing a better understanding of the physics.

Benjamin, M. A.↗

NASA NTRS1993

Comparison of the initial development of shear layers in two-dimensional and axisymmetric ejector configurations

A two-phase experimental investigation designed to study the development of shear layers in axisymmetric and two-dimensional single-nozzle ejectors has been completed. In this study, combinations of similar and dissimilar gases were used as the supersonic primary and subsonic secondary. Test cases included combinations of air/air, argon/air and helium/air as the supersonic primary and subsonic secondary, respectively. Similar flow conditions were studied for each ejector configuration. Mixing of the gases occurred in a constant-area tube, where the inlet pressure was maintained at 34.5 kPa. The cases studied resulted in convective Mach numbers that range between 0.06 and 1.9. The data gathered shows differences between the initial shear-layer development for the two ejector geometries, and also between the different test cases studied for each ejector configuration. The measured growth rates for the axisymmetric ejector are more than twice those measured for the two-dimensional ejector. However, in both cases the results show that compressibility has a reducing effect on the growth rate. Further, in the region immediately after the inlet to the mixing tube, compressibility seems to affect the ejector shear layers in a manner similar to that of two-stream two-dimensional mixing layers.

Dufflocq, M.↗

NASA NTRS1992

Initial development of the axisymmetric ejector shear layer

An experimental investigation designed to study the development of shear layers in an axisymmetric single-nozzle ejector has been completed. In this study, combinations of air/air, argon/air and helium/air were used as the supersonic primary and subsonic secondary, respectively. Mixing of the gases occurred in a constant-area tube, where the inlet pressure was maintained at 5 psia. The cases studied resulted in convective Mach numbers between 0.3 and 1.9. The resulting data shows dramatic differences in the shear-layer development for the various combinations of independent variables utilized in the investigation. Further, in the region immediately after the inlet to the mixing tube, the axisymmetric shear layers seem to behave in a manner similar to that of two-dimensional mixing layers. The results have enhanced the ability to analyze and design ejector systems as well as providing a better understanding of the physics.

Dufflocq, M.↗