Hydrodynamicsof three-phase bubbling pools, composed of batch mixtures of water and paper fiber with air throughput, were experimentally studied. Air flow through quiescent liquids or slurries was studied with a vertical transparent test column, Three similar test series were performed using pure water, and water pulp mixtures with 1% and 2% consistency (fiber weight percent). Void fraction profiles were obtained using the gamma-ray denSitometry technique. The observed flow patterns in the pulp suspensions were significantly different than pure water, and those reported in the literature for non-fibrous three-phase coltmms. Gas channeling was observed at all gas superficial velocities and pulp consistencies, leading to poor mixing and shorter gas residence times. Three-dimensional fiocs resulting in tortuous, three-dimensional bubble paths could be observed in the 2% consistency tests.A vertical cocurrent flow system was also studied in which air and pulp suspensions or water could flow simultaneously. Gamma densitometry was applied to measure gas holdup profiles through the test section. Many of the aforementioned features were observed in the cocurrent flow column. Of particular importance is the 'increase in gas holdup that can occur as pulp superficial velocity is increased, due to a decrease in bubble aggregation.Bubbles that are hindered by the pulp network structure can be carried away by the bulk flow before other bubbles coltide and aggregate with the impeded bubbles. As a result, there are fewer large bubbles that break through the network structure and escape with a small dwell time.

Hydrodynamics of three-phase bubbling pools, composed of batch mixtures of water and paper fiber with air throughput, were experimentally studied. Air flow through quiescent liquids or slurries was studied with a vertical transparent test column, Three similar test series were performed using pure water, and water pulp mixtures with 1% and 2% consistency (fiber weight percent). Void fraction profiles were obtained using the gamma-ray denSitometry technique. The observed flow patterns in the pulp suspensions were significantly different than pure water, and those reported in the literature for non-fibrous three-phase coltmms. Gas channeling was observed at all gas superficial velocities and pulp consistencies, leading to poor mixing and shorter gas residence times. Three-dimensional fiocs resulting in tortuous, three-dimensional bubble paths could be observed in the 2% consistency tests. A vertical cocurrent flow system was also studied in which air and pulp suspensions or water could flow simultaneously. Gamma densitometry was applied to measure gas holdup profiles through the test section. Many of the aforementioned features were observed in the cocurrent flow column. Of particular importance is the 'increase in gas holdup that can occur as pulp superficial velocity is increased, due to a decrease in bubble aggregation. Bubbles that are hindered by the pulp network structure can be carried away by the bulk flow before other bubbles coltide and aggregate with the impeded bubbles. As a result, there are fewer large bubbles that break through the network structure and escape with a small dwell time.

Recent advances in paper drying research have identified a phase-change process that offers significant improvements in drying rates and sheet solids contents. A fundamental study focusing on the hypothesized boiling process within the sheet required the development of an apparatus to perform boiling experiments in a bed of ceramic fibers. The apparatus is composed of a boiling cell, a heat supply system, a digital data acquisition system, and associated process control systems for control of heater surface temperature and cell pressure. Boiling curves measured with this system indicate that heat transfer is governed largely by the physical characteristics of the fiber bed. This paper presents a detailed explanation of the boiling apparatus.

A laser-Doppler velocimeter (LDV) was used in a cold-flow study of a simulated entrained-flow coal gasifier. The study was designed to provide fundamental information about the flows in such a gasifier and to provide data for the validation of a turbulence submodel used in modeling combustion processes. Measurements in 20 swirling and nonswirling flow cases were made with several levels of replication. This study emphasized the effects of inlet conditions on flow properties within the simulated reactor.Unsteady flow phenomena with time scales on the order of seconds to minutes were sometimes observed. The unsteadiness was apparently associated with relaminarization-type flow transitions.Comparisons were made with model predictions from PCGC-2, a model for combustion processes based on the k -c turbulence model. Several areas of weakness in the model results were observed, but the unusual flow regimes measured in this study may be beyond the abilities of practical computer models.

If it is not possible to use vision when navigating through one's surroundings, moving safely and effectively becomes much harder. In such cases, non-speech audio cues can serve as navigation beacons, as well as denote features in the environment relevant to the user. This paper outlines and summarizes the development and evaluation of a System for Wearable Audio Navigation (SWAN), including an overview of completed, ongoing, and future research relating to the sounds used, the human-system interaction, output hardware, divided attention, and task effects.