3 research outputs found
Upgrading the SR-30 Miniature Turbojet for Adaptable Exhaust
The California Polytechnic State University, San Luis Obispo (Cal Poly, SLO) Aerospace Department is requesting a variable nozzle adaptation for their SR-30 turbojet engine. The nozzle is intended for laboratory use in sophomore and junior level courses to supplement instruction on the effects that exhaust behavior has on the performance of propulsion technologies. Topics covered during a performance study of the SR-30 turbojet engine will include, but are not limited to: Brayton Cycle analysis, turbojet operation in ideal and non-ideal test conditions, instrumentation limitations, and basic nozzle operation. The SR-30 turbojet engine is similar in design and operation to engines used to power full-size jets, but is scaled down in size for practical use in educational laboratories. Current designs for variable area nozzles in the aeronautics industry are tailored for use on large jet engines, rather than small educational engines such as the SR-30 turbojet. Therefore, this senior project seeks to adapt existing technology designs to an appropriate scale, and manufacture a variable-area nozzle that will allow for controlled exhaust-flow restriction. The solution proposed in this document draws on existing fighter jet variable nozzles J85 and F119-PW-100 for inspiration in nozzle flap layout and uses common methods of robotic motion control, including linear electronic actuators and hydraulic actuators. Given the scale of the existing turbojet exhaust pipe, this senior project team, “TurboTRIO”, has determined that a circular nozzle would be difficult to actuate in an accurate, flexible, and durable manner. Similarly, design specifications such as thrust-vectoring capabilities and hydraulic control systems present themselves as unnecessarily complicated for the scope of this project. As such, these were likewise discarded. The proposed design is, consequently, a converging-diverging nozzle with a fixed-area converging duct and throat, and a variable-area diverging duct. The diverging duct will have a rectangular cross-section, and will be composed of two stationary flaps and two independently-actuated flaps controlled via mechanical linear actuation. This design will allow for educational demonstrations and performance analyses of a sonic converging nozzle, supersonic converging-diverging nozzle, and potentially engine thrust vectoring
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Quantifying Radiation Effects of Energetic Electron Precipitation From the Van Allen Radiation Belts Into the Earth’s Atmosphere
In this study, energetic particle precipitation from the Earth’s radiation belts was investigated as a source of radiation exposure for humans at airline altitudes. When a charged particle from the radiation belts (such as an electron) collides with the Earth’s upper atmosphere it can generate a cascade of collisions that propagate down through the atmosphere, ionizing atmospheric neutrals. Products of these collisions can deposit energy in the form of ionizing radiation, which can be of particular concern for humans when exposed to high doses over long periods of time. This study quantified the radiation dose that humans could be exposed to at varying altitudes in the Earth’s atmosphere due to Energetic Electron Precipitation (EEP). MEPED electron energy spectrum and flux data from the POES and MetOp satellite constellations were used as inputs for a Monte Carlo based radiation model, which computed the radiation dose rates at altitudes between 500 km and Earth’s surface. These predictions were compared with radiation doses measured at aviation altitudes by the ARMAS particle detectors, and with Iridium-Next REACH radiation measurements in LEO. Global maps of radiation dose were generated using both the REACH measurements and the MEPED forward-modeled predictions, and were used to characterize the spatial and temporal behavior of EEP events. Statistical analyses of the results are presented for data recorded during 2019 across all three data sources, and specific EEP events were identified and discussed. It was concluded that while energetic electron precipitation does reach aviation altitudes, it does not make up a large proportion of the radiation doses detected by ARMAS in this region of the atmosphere.</p