The tangential velocity profile and momentum transfer within a microgravity, vortex separator

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Title: The tangential velocity profile and momentum transfer within a microgravity, vortex separator
Author: Ellis, Michael Clay
Abstract: Liquid and gas do not separate naturally in microgravity , presenting a problem for twophase space systems . Increased integration of multiphase systems requires a separation method adaptable to a variety of systems . Researchers at Texas A &M University (TAMU ) have developed a microgravity vortex separator (MVS ) capable of handling both a wide range of inlet conditions and changes in these conditions . To optimize the MVS design , the effects of nozzle area , separator geometry , and inlet flow rate must be understood . Computational fluid dynamics (CFD ) , in the form of Adapco ?s Star -CD , is used , along with laboratory testing , to accomplish this goal . Furthermore , as analysis aids for the laboratory data and CFD results , relationships for radial pressure , bubble transit time , and momentum transfer were developed . Ground testing data showed a linear relationship between rotational speed and inlet flow rate . The CFD results compared well with the ground data and indicated that the majority of the rotational flow travels at nearly the same rotational speed . Examination of the tangential velocity profile also showed that a reduction of nozzle outlet area resulted in increased tangential velocities . Using dimensional analysis , a relationship between separator radius , inlet momentum rate , fluid properties , and rotational speed was found . Applying this relationship to the ground data and CFD results showed a strong correlation between the two dimensionless groups . Linear regression provided an equation linking rotational speed to the separator parameters . This equation was tested against the ground data and shown to predict average rotational speed well for all separator models . These results were used to calculate the radial and axial transit times of gas bubbles within the separation volume . Radial transit time was found to decrease more rapidly than axial transit time as gas volume increased , indicating axial and radial transit times are closest in value for the all liquid case and increasing gas core diameter improves the operational characteristics of the separator . From a design standpoint , the all liquid case provides a minimum flow rate for successful phase separation . Maximum flow rate depends on the pressure resources of the system .
URI: http : / /hdl .handle .net /1969 .1 /ETD -TAMU -1167
Date: 2009-05-15


The tangential velocity profile and momentum transfer within a microgravity, vortex separator. Available electronically from http : / /hdl .handle .net /1969 .1 /ETD -TAMU -1167 .

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