0603 Numerical Simulation of Supercritical Carbon Dioxide through Supersonic Nozzle
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Our research group has proposed a numerical method for supercritical fluids; Supercritical-Fluid Simulator(SFS). In this paper, supercritical carbon dioxide flows impacting on a flat plate through supersonic nozzle are calculated using SFS and the flow features changing inlet pressure, inlet temperature and the distance to the flat plate are comparatively investigated. Especially, it is noted that the density in the nozzle is rapidly changed and is deeply dependent to the inlet boundary conditions.Keywords:
Supercritical Carbon Dioxide
Supercritical flow
Choked flow
Our research group has proposed a numerical method for supercritical fluids; Supercritical Fluid Simulator (SFS). In SFS, a numerical method based on the preconditioning method coupled with PROPATH is used. In this paper, we compute a supersonic free-jet assuming gas using SFS. Next, we compute a supersonic jet of supercritical CO_2 impacting on a flat plate with the drastic pressure decrease near the critical point. In both simulations, our results show good agreements with the experimental data. These results indicate the importance of numerical models considering accurate thermophysical properties for simulating supersonic flows of supercritical CO_2, such as RESS-process.
Supercritical flow
Choked flow
Supercritical Carbon Dioxide
Critical point (mathematics)
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Choked flow
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Summary The proper treatment of the pre-entry and post-exit streamtubes of supersonic aircraft and their “corresponding” windtunnel models was considered in some depth for supersonic fighter designs, and investigated in wave drag research, but as a result of the cancellations of the major supersonic fighter programmes the results were not published. This note sets out the salient conclusions. The development of the first supercritical air intake cowl is also outlined.
Choked flow
Supercritical flow
Wave drag
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Diagnostic data from large-scale, airframe-inlet model wind-tunnel tests have been analyzed to facilitate understanding of both axisymmetric and two-dimensional inlet performance in different installation configurations of highly maneuverable supersonic aircraft. Distortion pattern shifts have been used to identify duct swirl, apparently due to duct offset and loft. Examinations of total pressure surveys through the ducts of various inlet installations have been used to show the influence of flow separation at the inlet aperture and in the throat on performance degradation in various inlet configurations. Benefits and limitations of inlet shielding in supersonic maneuvering flight have been explored, showing performance advantages of half-axisymmetric inlets over two-dimensional inlets in the wing-shielded flowfields and more general performance advantages associated with fuselage shielding. Data comparisons have incorporated total pressure recovery, duct turbulence, and compressor face steady-state and dynamic flow distortion index showing, in particular, the importance of dynamic flow distortion measurement and sophisticated, high-speed analysis capability.
Airframe
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An introduction to supersonic gas flow is given, with emphasis on the features that distinguish supersonic from subsonic flow. Experimental methods for the study of supersonic flow are briefly considered and some simple flows are described.
Choked flow
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Choked flow
Separator (oil production)
Supersonic wind tunnel
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View Video Presentation: https://doi.org/10.2514/6.2021-1517.vid The energy transfer mechanisms for Mack's second mode and a supersonic mode based on spatial linear stability theory for a Mach 6 flat plate flow with $T_w=0.5 T_\infty$ is investigated. For the current conditions, the supersonic mode is unstable but obtains a relatively low amplification rate in comparison to the second mode. The energy analysis conducted in this paper shows that the total energy of the second mode is available throughout the boundary layer, however, for the supersonic mode, it is concentrated closer to the wall.~The combined effect of thermal production and production density dissipates most of the energy away from the critical layer for the supersonic mode.~As opposed to the second mode, a significant amount of energy is available in the free-stream in the case of supersonic mode. It is found that the energy is provided from the pressure strain transport term counteracting the shear-work. In the second part of the paper, direct numerical simulations were performed for the same flow conditions, and a decomposition of the disturbance flow field was performed. Some differences in the growth rates especially in the region where the supersonic mode appears was observed. Although the flow decomposition showed that the unstable mode F dominates the disturbance flow field, there appears to be a non-negligible contribution from the stable supersonic mode.
Choked flow
Mode (computer interface)
Dynamic Mode Decomposition
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Choked flow
Supercritical flow
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A procedure for calculating three-dimensional steady and nonsteady supersonic flows with the method of characteristics is developed and discussed. An approximate method is deduced from the characteristics method and shown to be of practical value at high supersonic speeds.
Choked flow
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