Impact of dielectric separation on transition point and accessible flow enthalpy of inductive plasmas

In order to develop inductive electric propulsion systems towards flight-ready status, an investigation into the influence of the dielectric separation between plasma and inductive coil has been conducted. This was completed by varying the wall thickness of the thruster discharge tube. The investigation assessed discharges of argon and an argon-nitrogen mixture. Additionally, results of a similar investigation utilising air have been included for comparison. The sum of these investigations showed two contrasting trends. The argon condition exhibited a preference for thicker walls, with transitions to the higher inductive regime occurring at lower input powers with increasing wall thickness. Results for Ar:N2 and air showed the opposite, with system thermal power increasing with decreasing wall thicknesses. This behaviour has been proposed to include contributions of both the mechanical dielectric separation caused by the choice of chamber wall thickness, and the gasdynamic dielectric separation owing to the discharge thermal boundary laye

Transient electromagnetic behaviour in inductive oxygen and argon–oxygen plasmas

In order to develop inductive electric propulsion as a flexible, throttleable technology for future space operations, a greater understanding of discharge transitions within the inductive plasma generator discharge chamber is required. This paper presents a non-intrusive method to determine the conditions under which transitions between the capacitive, low inductive, and high inductive regimes occur with greater accuracy, as well as determining the proportion of a single discharge cycle the plasma spends in either capacitive or inductive regime. Such a method allows a more robust method of classification of inductive discharges than previously available and can be applied to numerous gases. This approach presents an advantage over previous methods which relied on strongly radiating or thermally reactive gases to exhibit certain behaviour (due to the restriction of classical diagnostics on such high power sources) before a transition could be confirmed. This paper presents results from the proposed method applied to a pure oxygen plasma as well as two combinations of argon and oxygen (at 1:1 and 3:2 Ar:O2 volumetric ratios) in order to assess the tunability of electromagnetic regime transitions through modifications of gas composition rather than mechanical alterations. Transitions to the higher inductive mode were observed for much lower input powers for the argon–oxygen blends, as was expected, allowing final discharge conditions to occupy the inductive regime for 94% and 85% of a single discharge cycle for the 3:2 and 1:1 Ar:O2 mixtures, respectively. Pure oxygen achieved a maximum inductive proportion of 71% by comparison

Modification of the Eddy Dissipation Concept for turbulence/chemistry interaction in the context of MILD combustion

info:eu-repo/semantics/nonPublishe

Experimental and numerical study of transcritical oxygen-hydrogen rocket flame response to transverse acoustic excitation

The response of a transcritical oxygen-hydrogen flame to transverse acoustic velocity was investigated using a combination of experimental analyses and numerical modelling. The experiment was conducted on a rectangular rocket combustor with shear coaxial injectors and continuously forced transverse acoustic field. Simultaneous high-speed shadowgraph and filtered OH* radiation images were collected and reduced using dynamic mode decomposition in order to characterise the flame response to the acoustic disturbance. CFD modelling of a representative single injector under forcing conditions was carried out to gain insights into the three-dimensional features of the reacting flow field. Invisible in the 2D projection, the model reveals that the excited LOX jet develops into a flattened and widened structure normal to the imposed acoustic velocity. The comparison of co-located structures allowed features in the imaging to be attributed to the deformation and transverse displacement of lower density oxygen surrounding the denser liquid oxygen core by the transverse acoustic velocity