Slushes are two-phase solid-liquid single-species cryogenic fluids that exhibit an increased density and a greater heat capacity in respect to normal boiling point fluids. This promising features are of big interest for applications that exploit the slush as a thermal fluid, like super magnets refrigeration or air conditioning, and for aerospace systems that use slush fluids as fuel or oxidizer. Several pro- grams in the frame of the research on Slush Hydrogen (SLH2) as a new-generation fuel for aerospace propulsion system have been started in the past and still continue to be performed in the present (National Aeronautics and Space Administration (NASA)’s National Space Plane (NASP), European Space Agency (ESA)’s Future European Space Transportation Investigations Programme (FESTIP) and Japan Aerospace eXploration Agency (JAXA) program for researh on SLH2 are the most famous examples). In this work a numerical simulation based on a finite-volumes discretization using the software libra- ry OpenFOAM is carried on on solid-liquid multiphase flows (slurry) and slush flows inside a typical pipe geometry, very common in propulsion pipelines. A benchmark with previous experiments and simulations is also performed to assess the degree of accuracy of the code in predicting pressure drops and solid phase fraction dispersion. The effects of particle size, inlet velocity and concentration is also investigated.
Gli "slush" sono correnti bifase solido-liquido composte da una singola specie in entrambi gli stati di aggregazione che esibiscono una densità più alta e una maggiore capacità termica rispetto al solo liquido puro. Queste promettenti caratteristiche sono di grande interesse in applicazioni che utilizzano gli slush come fluidi termici di lavoro, come per esempio nella refrigerazione dei super magneti, condizionamento e per sistemi aerospaziali dove gli slush andrebbero utilizzati come combustibile e/o ossidante. Diversi programmi nell'ambito della ricerca sull'idrogeno slush (SLH2) sono stati inaugurati nel passato e continuano ad essere sviluppati nel presente (National Aeronautics and Space Administration (NASA)'s National Space Plane (NASP), European Space Agency's (ESA) Future European Space Transportation Investigations Programme (FESTIP) e Japan Aerospace eXploration Agency (JAXA) program for research on SLH2 sono i pià famosi esempi). In questa tesi è presentata una simulazione numerica basata su una modellazione a volumi finiti (FVM) usando una la libreria opensource OpenFOAM di corrent bifase solido-liquido (cosiddetti "slurry flows") e correnti slush all'interno di una tipica geometria tubolare, molto comune nelle linee propulsive. Viene affrontata la validazione dei risultati su dati sperimentali provenienti da letteratura in modo da stimare il grado di accuratezza del codice nel predire le cadute di pressione e le distribuzioni di particolato solido. Vengono inoltre presentati gli effetti della dimensione delle particelle, della velocità di immissione e della concentrazione sulle caratteristiche della corrente.
Numerical simulation of two-phase solid-liquid slush flows for propulsion systems
DI BATTISTA, RUBEN
2015/2016
Abstract
Slushes are two-phase solid-liquid single-species cryogenic fluids that exhibit an increased density and a greater heat capacity in respect to normal boiling point fluids. This promising features are of big interest for applications that exploit the slush as a thermal fluid, like super magnets refrigeration or air conditioning, and for aerospace systems that use slush fluids as fuel or oxidizer. Several pro- grams in the frame of the research on Slush Hydrogen (SLH2) as a new-generation fuel for aerospace propulsion system have been started in the past and still continue to be performed in the present (National Aeronautics and Space Administration (NASA)’s National Space Plane (NASP), European Space Agency (ESA)’s Future European Space Transportation Investigations Programme (FESTIP) and Japan Aerospace eXploration Agency (JAXA) program for researh on SLH2 are the most famous examples). In this work a numerical simulation based on a finite-volumes discretization using the software libra- ry OpenFOAM is carried on on solid-liquid multiphase flows (slurry) and slush flows inside a typical pipe geometry, very common in propulsion pipelines. A benchmark with previous experiments and simulations is also performed to assess the degree of accuracy of the code in predicting pressure drops and solid phase fraction dispersion. The effects of particle size, inlet velocity and concentration is also investigated.File | Dimensione | Formato | |
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https://hdl.handle.net/10589/124962