Characterization of dust is crucial for current and future Mars space missions, since the dust has a significant impact on the climate of the planet, is constantly present in its atmosphere, and may damage scientific payloads and degrade the performances of the instruments and devices operating on the planet. In this view, the MicroMED was designed and manufactured to characterize the Martian dust. This optical particle counter has been selected as part of the ExoMars 2022 payload to assess the size distribution and concentration of mineral airborne grains. Within the framework of this research project, this thesis work describes extensive testing of the fluidic system of the instrument, a key design point to be evaluated for the scientific return of the instrument and its calibration. The testing activity has foreseen the calibration of the pressure sensors, commercial MEMS used for the evaluation of the pressure drop in the optical head of the instrument during the particle analysis. A mockup of the vacuum pump designed for MicroMED has been characterized as well. The pump is employed to perform the intake of the dust particles, and testing has been performed in simulated conditions of the Martian atmospheric pressure. Moreover, the pressure drop caused by the fluidic resistance of the MicroMED has been evaluated at different environmental pressures and working conditions of the pump. The latter parameter has been also compared with a CFD model of the optical head, developed using commercial simulation software, and, employing the empirical results, the fluidic resistance index has been estimated. The agreement between the obtained experimental and numerical results has proved the robustness of the performed research activity and related findings.
La caratterizzazione della polvere è fondamentale per le attuali e future missioni spaziali su Marte. Poiché la polvere è costantemente presente nella sua atmosfera, ha un impatto significativo sul clima del pianeta, e può danneggiare i carichi utili scientifici e degradare le prestazioni degli strumenti e dei dispositivi che operano su di esso. In quest'ottica, il MicroMED è stato progettato e realizzato per caratterizzare la polvere marziana. Questo contatore ottico di particelle farà parte del payload selezionato per la missione ExoMars 2022 per valutare la distribuzione delle dimensioni e la concentrazione dei grani minerali presenti nell'aria. Nell'ambito di questo progetto di ricerca, questo lavoro di tesi descrive un test approfondito del sistema fluidico dello strumento, un punto aspetto per valutare il ritorno scientifico dello strumento e la sua calibrazione. L'attività di test ha previsto la calibrazione dei sensori di pressione, MEMS commerciali utilizzati per la valutazione della caduta di pressione nella testa ottica dello strumento durante l'analisi delle particelle. È stato caratterizzato anche un mockup della pompa da vuoto progettata per MicroMED. La pompa è impiegata per eseguire l'aspirazione delle particelle di polvere, e i test sono stati eseguiti in condizioni simulate della pressione atmosferica marziana. Inoltre, la caduta di pressione causata dalla resistenza fluidica del MicroMED è stata valutata a diverse pressioni ambientali ed operative lavoro della pompa. Quest'ultimo parametro è stato anche confrontato con un modello CFD della testa ottica dello strumento, sviluppato utilizzando un software di simulazione commerciale, e, utilizzando i risultati empirici, è stato stimato l'indice di resistenza fluidica. L'accordo tra i risultati sperimentali e numerici ottenuti ha dimostrato la solidità dell'attività di ricerca svolta e dei relativi risultati.
Testing and modelling of the MicroMED dust analyzer fluidic system
Vieira Vaz Junior, Elimar
2020/2021
Abstract
Characterization of dust is crucial for current and future Mars space missions, since the dust has a significant impact on the climate of the planet, is constantly present in its atmosphere, and may damage scientific payloads and degrade the performances of the instruments and devices operating on the planet. In this view, the MicroMED was designed and manufactured to characterize the Martian dust. This optical particle counter has been selected as part of the ExoMars 2022 payload to assess the size distribution and concentration of mineral airborne grains. Within the framework of this research project, this thesis work describes extensive testing of the fluidic system of the instrument, a key design point to be evaluated for the scientific return of the instrument and its calibration. The testing activity has foreseen the calibration of the pressure sensors, commercial MEMS used for the evaluation of the pressure drop in the optical head of the instrument during the particle analysis. A mockup of the vacuum pump designed for MicroMED has been characterized as well. The pump is employed to perform the intake of the dust particles, and testing has been performed in simulated conditions of the Martian atmospheric pressure. Moreover, the pressure drop caused by the fluidic resistance of the MicroMED has been evaluated at different environmental pressures and working conditions of the pump. The latter parameter has been also compared with a CFD model of the optical head, developed using commercial simulation software, and, employing the empirical results, the fluidic resistance index has been estimated. The agreement between the obtained experimental and numerical results has proved the robustness of the performed research activity and related findings.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/179583