Race 2 Space 2026 Critical Design Report: Difference between revisions
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In comparison with pintle injector, swirl injector promises higher combustion efficiency and more favourable manufacturing tolerances. At similar manufacturing complexity, swirl injectors outperform shear injectors in liquid-liquid operation. Mechanically, the pressure losses in swirl injector are primarily friction loss and orifice loss at its tangential inlets, which is less numerous and larger than a comparable impinging jet injector designs. This theoretically promises that swirl injectors convert pressure gradient energy to atomisation much more efficiently. Furthermore, swirl injector is a frontier capability we would like to develop more understanding of, especially in its atomisation and acoustic-coupling dynamic in hot fire operation. The demonstration of swirl injector mechanics is a primary objective of LD-A1. | In comparison with pintle injector, swirl injector promises higher combustion efficiency and more favourable manufacturing tolerances. At similar manufacturing complexity, swirl injectors outperform shear injectors in liquid-liquid operation. Mechanically, the pressure losses in swirl injector are primarily friction loss and orifice loss at its tangential inlets, which is less numerous and larger than a comparable impinging jet injector designs. This theoretically promises that swirl injectors convert pressure gradient energy to atomisation much more efficiently. Furthermore, swirl injector is a frontier capability we would like to develop more understanding of, especially in its atomisation and acoustic-coupling dynamic in hot fire operation. The demonstration of swirl injector mechanics is a primary objective of LD-A1. | ||
In design finalisation process, it was decided against the previous independent swirl elements design as it was found that the small scale of the individual element made it difficult to grab the work-piece during manufacturing process, and furthermore introduce many inter-propellant interfaces which creates additional complexity and remains extremely difficult to ensure consistent sealing for potentially negative overhead saving. The current design iteration hence simplifies the primary injector head down to only three-piece construction and completely deprecate a need for brazing. The general dimension of the injector is shown in Figure 3. | In design finalisation process, it was decided against the previous independent swirl elements design as it was found that the small scale of the individual element made it difficult to grab the work-piece during manufacturing process, and furthermore introduce many inter-propellant interfaces which creates additional complexity and remains extremely difficult to ensure consistent sealing for potentially negative overhead saving. The current design iteration hence simplifies the primary injector head down to only three-piece | ||
[[File:LD-A1 Injector head cut-away diagram.pdf|thumb|center|upright=2.0|Figure 2. - Injector head cut-away diagram]] | |||
construction and completely deprecate a need for brazing. The general dimension of the injector is shown in Figure 3. | |||
[[File:LD-A1 Injector dimension.pdf|thumb|right|Figure 3. - General dimension of coaxial injector element]] | [[File:LD-A1 Injector dimension.pdf|thumb|right|Figure 3. - General dimension of coaxial injector element]] | ||
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===A4.4 Interfaces=== | ===A4.4 Interfaces=== | ||
[[File:LD-A1_Injector_head_top_view.pdf|thumb|right|Figure 5. - Top view of injector head]] | |||
The injector head redesign has significantly simplify seals and interfaces required, with the flow path mostly segregated except at the injector nozzle tip itself. The design attempts to ensure fail-safe mode of failure, where the fuel and oxidiser do not mix even in case of broken seals, such that a safe shutdown can be attempted. | The injector head redesign has significantly simplify seals and interfaces required, with the flow path mostly segregated except at the injector nozzle tip itself. The design attempts to ensure fail-safe mode of failure, where the fuel and oxidiser do not mix even in case of broken seals, such that a safe shutdown can be attempted. | ||