Composite materials have become viable alternatives to traditional engineering materials for many different product categories. Liquid transfer moulding (LTM) processes, specifically resin transfer moulding (RTM), is a cost-effective manufacturing technique for creating high performance composite parts. These parts can be tailor-made to their specific application by optimizing the properties of the textile preform. Preforms which require little or no further assembly work and are close to the shape of the final part are critical to obtaining high quality parts while simultaneously reducing labour and costs associated with other composite manufacturing techniques. One type of fabric which is well suited for near-net- shape preforms is stitched non-crimp fabrics. These fabrics offer very high in-plane strength and stiffness while also having increased resistance to delamination. Manufacturing parts from these dry preforms typically involves long-scale fluid flow through both open channels and porous fibre bundles. This thesis documents and analyzes the flow of fluid through preforms manufactured from non-crimp fabrics featuring through-thickness stitches. The objective of this research is to determine the effect of this type of stitch on the RTM injection process. All of the tests used preforms with fibre volume fractions representative of primary and secondary structural parts. A series of trials was conducted using different fibre materials, flow rates, fibre volumes fractions, and degrees of fibre consolidation. All of the trials were conducted for cases similar to RTM. Consolidation of the fibres showed improvements to both the thoroughness of the filling and to the fibre volume fraction. Experimentally determined permeability data was shown to trend well with simple models and precision of the permeability data was comparable to values presented by other authors who studied fabrics which did not feature the through-thickness stitches.

As a hygroscopic salt, granular potash can easily absorb large quantities of water vapor from humid air during storage and transportation processes. Subsequent drying will result in potash particles sticking together to form clumps or cakes. In order to avoid or decrease caking, it is essential to know the local history of moisture content and moisture movement in a bed of potash. In this thesis, experimental measurements and numerical simulations are used to investigate moisture transport and redistribution by capillarity, gravity and diffusion effects within a potash bed. <p> The important properties required to model moisture transfer in granular porous potash (i.e. porosity, permeability, specific surface area and irreducible saturation) are investigated experimentally and theoretically. It is shown that for a mixture with a wide range of particle sizes the potash bed properties can be predicted knowing the properties for each narrow range of particle size in the mixture. <p> An experimental test facility was designed and constructed to test moisture transfer within a potash bed. The test procedures are presented along with an uncertainty analysis. The moisture content spatial distribution for different particle sizes under different initial conditions is investigated and data are presented. <p>A one-dimensional transient numerical model of moisture transport accounting for diffusion, capillarity and gravity effects within potash beds is developed. Two different moisture transport mechanisms are presented. In a wet region, where local moisture saturation level, S, is larger than an irreducible saturation, S0, liquid water exists as continuous liquid film on the particles; moisture is transferred by liquid film movement due to capillarity and gravity effects. In a dry region where S is less than S0, water vapor diffusion is the only mechanism of moisture transfer and water is adsorbed in layers on the surfaces. <p> From the experimental data and numerical simulation analysis, it is shown that the irreducible saturation, S0, is a strong function of particle size. It will decrease with a particle size increase. <p> The numerical model is validated by comparison with some typical experimental case studies. Agreement between the experimental data and simulation results is well within the experimental 95% uncertainty bounds. It is concluded from this research that the complex moisture transport process by diffusion, capillarity and gravity effects within a potash bed can be modeled and simulated. Experimental and simulation results indicate that direct water drainage will more readily occur for large particle sizes than for small particles for the same initial moisture content.

As a hygroscopic salt, granular potash can easily absorb large quantities of water vapor from humid air during storage and transportation processes. Subsequent drying will result in potash particles sticking together to form clumps or cakes. In order to avoid or decrease caking, it is essential to know the local history of moisture content and moisture movement in a bed of potash. In this thesis, experimental measurements and numerical simulations are used to investigate moisture transport and redistribution by capillarity, gravity and diffusion effects within a potash bed. <p> The important properties required to model moisture transfer in granular porous potash (i.e. porosity, permeability, specific surface area and irreducible saturation) are investigated experimentally and theoretically. It is shown that for a mixture with a wide range of particle sizes the potash bed properties can be predicted knowing the properties for each narrow range of particle size in the mixture. <p> An experimental test facility was designed and constructed to test moisture transfer within a potash bed. The test procedures are presented along with an uncertainty analysis. The moisture content spatial distribution for different particle sizes under different initial conditions is investigated and data are presented. <p>A one-dimensional transient numerical model of moisture transport accounting for diffusion, capillarity and gravity effects within potash beds is developed. Two different moisture transport mechanisms are presented. In a wet region, where local moisture saturation level, S, is larger than an irreducible saturation, S0, liquid water exists as continuous liquid film on the particles; moisture is transferred by liquid film movement due to capillarity and gravity effects. In a dry region where S is less than S0, water vapor diffusion is the only mechanism of moisture transfer and water is adsorbed in layers on the surfaces. <p> From the experimental data and numerical simulation analysis, it is shown that the irreducible saturation, S0, is a strong function of particle size. It will decrease with a particle size increase. <p> The numerical model is validated by comparison with some typical experimental case studies. Agreement between the experimental data and simulation results is well within the experimental 95% uncertainty bounds. It is concluded from this research that the complex moisture transport process by diffusion, capillarity and gravity effects within a potash bed can be modeled and simulated. Experimental and simulation results indicate that direct water drainage will more readily occur for large particle sizes than for small particles for the same initial moisture content.

This thesis covers two topics. The first subject involves tests run on a ultralite reflux tube supplied by Battelle Pacific Northwest Laboratories (PNL). The second topic involves tests to determine the relative wicking rates of several different fabrics. The ultralite reflux tube supplied by PNL was constructed of copper and Nextel 312. It had a 10 mil thick copper evaporator and a 10 mil thick copper condenser end cap. The bulk of the condenser was 2 mil thick copper covered by a one inch diameter Nextel 312 woven hose. A life test was run within the Heat Pipe Test Facility, a chamber used to simulate low earth orbit. The life test lasted for over 800 hours, during which time the reflux tube operated steadily with no drop in performance. At the end of the test the reflux tube was removed and observed. The only noticeable change was a slight discoloration of the Nextel 312 used to cover the condenser. This discoloration was consistent with previously observed phenomenon. The second topic, fabric wicking rate studies were done as a follow up study to the dry uptake tests previously conducted at Oregon State University. The purpose of the tests were to get a relative feel for the ability of different fabrics to wick water. This was achieved using a drop test in which the fabrics were laid out on a bridge connecting two containers. One of the containers was elevated above the other. The fabrics were allowed to wick water from the upper container to the lower container and the rate at which this was accomplished was measured. The fabrics were all able to move significant amounts of water. The stiffer fabrics seemed to perform better. The major transport mechanism was transport between fabric layers and the fabric and the bridge. / Graduation date: 1993

This thesis considers the effect of manufacturing conditions and polymer ratio on water permeability and morphology of free-films. A novel spray method for producing ethyl cellulose (EC) and hydroxypropyl cellulose (HPC) free-films was developed where several process parameters was controlled. The process was optimised by pre-spraying solvent until the system reached a steady-state temperature. This minimised the variation of outlet air temperature to &lt; 2.5 °C. Coating time was approximately 4 minutes excluding drying. Free-films were produced using 94 wt% solvent (95 %-ethanol) and 6 wt% polymer. The amount of HPC in the films was varied (wt% HPC defined as HPC/(HPC+EC)*100). Films with 30-40-50-57 wt% HPC were studied. Phase diagrams was constructed to study the phase transformation of polymer mixtures. Results show that all polymer mixtures with HPC content above 30 wt% were phase separated prior to film manufacturing. Temperature had an effect on the polymer phase transformation. In the phase diagram, the 2-phase area was larger for temperatures above 40 °C. The investigated manufacturing conditions were outlet air temperature (°C) and spray rate (g/min). Outlet air temperature was controlled by adjusting the inlet air temperature. The films were characterized by measuring water permeability (m2/s). Cross section structure of the films was analyzed with confocal laser scanning microscopy (CLSM). FITC-HPC was added for enhanced contrast between the domains. Higher outlet air temperature gave higher water permeability of the film whereas higher spray rate gave lower water permeability. The outlet air temperature had an impact on evaporation rate. The evaporation rate together with spray rate affected the solidification and hence the structure of the film. Images show that longer solidification time smeared the domains into larger domains. Lower water permeability was caused by less connectivity between the pores. In conclusion, experiments show that water permeability of EC/HPC free-films was highly dependent on the manufacturing conditions.

The behavior of bubbles migrating in porous media is a critical factor in several soil remediation operations such as in situ air sparging, supersaturated water injection, bioslurping, trench aeration and up-flow operation of moving bed sand filters as well as in the oil and gas industry. Groundwater aquifers are constantly polluted by human activity and a common threat to fresh water is the contamination by non-aqueous phase liquids (NAPL). In many NAPL removal technologies, gas bubbles carrying NAPL residuals move upwards through the water-saturated porous media and thus play an essential role in contaminant recovery. The mobilization of the residual oil blobs in oil reservoirs is another important application for rising bubbles in porous media. After an oil field is waterflooded, a significant fraction of oil, referred to as waterflood residual oil, remains trapped. A potential mechanism to recover this residual oil is the mobilization of oil by gas bubbles moving upwards in water-wet systems. The main focus of this work was to measure the velocity of bubbles of various lengths during their migration through a water-wet porous medium. Experiments were conducted in a saturated glass micromodel with different test liquids, air bubbles of varying lengths and different micromodel elevation angles. More than a hundred experimental runs were performed to measure the migration velocity of bubbles as a function of wetting fluid properties, bubble length, and micromodel inclination angle. The results showed a linear dependency of the average bubble velocity as a function of bubble length and the sine of inclination angle of the model. Comparisons were made using experimental data for air bubbles rising in kerosene, Soltrol 170 and dyed White Oil. The calculated permeability of the micromodel was obtained for different systems assuming the effective length for viscous dissipation is equal to the initial bubble length. It was found that the calculated permeability had an increasing trend with increasing bubble length. Laboratory visualization experiments were conducted for air bubbles in White Oil (viscosity of 12 cP) to visualize the periodic nature of the flow of rising bubbles in a pore network. The motion of the air bubbles in saturated micromodel was video-recorded by a digital camera, reviewed and analyzed using PowerDVD ™11 software. An image of a bubble migrating in the porous medium was obtained by capturing a still frame at a specific time and was analyzed to determine the bubble shape, the exact positions of the bubble front and bubble tail during motion and, thus, the dynamic length of the bubble. A deformation in the shape of the bubble tail end was observed for long bubbles. The dynamic bubble lengths were larger than the static bubble lengths and showed an increasing trend when increasing the angle of inclination. The dynamic bubble lengths were used to recalculate the bubble velocity and permeability. A linear correlation was found for the average bubble velocity as a function of dynamic bubble length. Numerical simulation was performed by modifying an existing MATLAB® simulation for the rise velocity of a gas bubble and the induced pressure field while it migrates though porous media. The results showed that the rise velocity of a gas bubble is affected by the grid size of the pore network in the direction perpendicular to the bubble migration. In reality, this effect is demonstrated by the presence of other bubbles near the rising bubble in porous media. The simulation results showed good agreement with experimental data for long bubbles with high velocities. More work is required to improve the accuracy of simulation results for relatively large bubbles.

A method used to calculate the fundamental properties that predict the overall wicking performance of a fabric was proposed and executed. The combination of a horizontal and downward wicking test provided detailed measurements of the pertinent properties to wicking performance: capillary pressure and permeability. This method was proposed due to flaws found in standard vertical wicking tests as well as erroneous assumptions made in other wicking tests. Assumptions that capillary pressure and permeability are characteristic constants of porous structures are incorrect and will produce misleading information about that substrate. It was experimentally proven that these properties were a function of the saturation level found within the voids of a fabric. To obtain relevant capillary pressure and permeability data for a given fabric, a range of saturation levels were tested and analyzed. It was shown that saturation levels decreased as the vertical distance traveled by moisture increased. This phenomenon occurs as a result of capillary pressure within the voids dropping below the functional range needed to support flow in those voids at increasing heights. As height is increased, capillary pressure needs to also increase; therefore, only smaller radii pores will fill. Once saturation levels are known at specific heights, capillary pressure and permeability calculations were made using Darcys law and the Lucas-Washburn equation. Although this phenomenon is well known in civil engineering, it has not been widely addressed in the textile sciences, especially in its implications for wicking tests.

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