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Lateral jet interaction with a supersonic crossflowChristie, Robert 10 1900 (has links)
A lateral jet in a supersonic crossflow creates a highly complex three-dimensional flow
field which is not easily predicted. The aim of this research was to assess the use of a
RANS based CFD method to simulate a lateral jet in supersonic crossflow interaction by
comparing the performance of available RANS turbulence models.
Four turbulence models were trialled in increasingly complex configurations; a flat
plate, a body of revolution and a body of revolution at incidence. The results of this
numerical campaign were compared to existing experimental and numerical data.
Overall the Spalart-Allmaras turbulence model provided the best fit to experimental
data. The performance of the lateral jet as a reaction control system was assed by
calculating the force and moment amplification factors. The predicted flowfield
surrounding the interaction was analysed in detail and was shown to predict the
accepted shock and vortical structures. The lateral jet interaction flowfield over a body
of revolution was shown to be qualitatively the same as that over a flat plate.
An experimental facility was designed and manufactured allowing the study of the
lateral jet interaction in Cranfield University’s 2 ½” x 2 ½” supersonic windtunnel. The
interaction was studied with a freestream Mach number of 1.8, 2.4 & 3.1 and over a
range of pressure ratios (50≤PR≤200). Levels of unsteadiness in the interaction were
measured using high bandwidth pressure transducers. The level of unsteadiness was
quantified by calculating the OASPL of the pressure signal. OASPL was found to
increase with increasing levels of PR or MPR and to decrease with increases of Mach
number. The levels of unsteadiness found were low with the highest levels found
downstream of the jet.
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A Near Field Lagrangian Particle Modeling for the Multiphase Flow of Reaction Control System Thrusters in Space EnvironmentsZou, Janice 01 January 2024 (has links) (PDF)
In the current age of space exploration, the push to reach further to deep space presents a greater need for analysis and verification and validation of rocketry components in the space environment. Due to the nature of space, firings of rocket thrusters in space is a multi-regime problem. With the low density, pressure, and temperature of the environment, the resultant plume structure, seeded with unburnt fuel droplets, extends up to multiple orders of magnitude in distance as compared to a plume structure in the Earth’s atmosphere. The frozen droplets, or particles, create concerns including surface contamination and erosion, calling a cause for study and model development to understand particle behavior in this multi-regime environment. This work intends to develop a model to analyze and understand multiphase flow and particle behavior in this environment utilizing the lower fidelity, but more computationally efficient, RANS turbulence modeling. Particle properties are compared against a regime-defining parameter to understand the trends in behavior. Finally, the work closes out on a preliminary look into implementing fully reacting flow chemistry for the multiphase flow. These results and progress are promising in developing an efficient model that may be integrated into a hybrid model to better predict particle behavior and dispersion in this multi-regime environment.
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