Detonation is the supersonic mode of combustion that occurs in munitions (military explosives and high explosives). These munitions result in blast waves that are hazardous to human life and structures. As a result, there is a high desire to mitigate these blast waves. One such method is to surround the explosive with mitigants (liquid, granular, and cellular porous material). For the safe storing and use of munitions, it is crucial to study the explosive dispersal of mitigant, the ensuing blast wave attenuation, and specifically, the mechanisms underlying this interaction. Current research involving mitigant blast wave attenuation is conducted in many configurations. The study aims to evaluate one configuration, shock tubes with particle suspension. Blast waves are simulated in the form of detonations initiated by DDT (deflagration-to-detonation) with mitigants in the form of dispersed particles. These dispersed particles included aluminum oxide, Al2O3, and aluminum, Al. The flame-flow interactions are experimentally studied using Particle Image Velocimetry (PIV) and pressure transducers. The effect of particle suspension on blast waves is revealed, portraying a decrease in mitigation performance.

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Two existing evaporation two-phase heat transfer models are validated using 526 experimental data points for pure refrigerants and refrigerant mixtures. The Kido et al. (1995) model fails to predict pure refrigerant data sets except their R22 experimental data set. The Cavallini et al. (1999) model successfully predicts the available R22 data sets; however, the model over-predicts the R12 and the R134a data sets. In addition, the Cavallini et al. (1999) mixture model fails to predict the available 155 refrigerant mixture data points. The proposed modified model, based on the Cavallini et al. (1999) model, successfully predicts the experimental data for pure refrigerant and for refrigerant mixtures.

The objective of this research is to simulate a pushorming operation for the manufacturing of copper tube elbows using the finite element method. This model may be useful in the design of tooling. The influences of lubricant type, the tube blank material, and a minute surface defect are considered in the model. Tensile tests of annealed copper specimens are conducted to derive stress-strain data, defining the material behavior of the copper tube blank. In addition, friction tests are performed to obtain static and dynamic friction coefficients for a wet and dry lubricant types, which are used in the forming process. The finite element study of the forming operation has proven to require a considerable amount of time for modeling and processing. The verification examples and the pushorming models demonstrate the ability of the finite element program to include: contact with friction, the actuating of hydraulically controlled components, buckling, and nonlinearity.

The last few decades have seen a significant development of complex heat transfer enhancement geometries such as a helicallyinned tube. The arising problem is that as the fins become more complex, so does the prediction of their performance. In addition to discussing existing prediction tools, this dissertation demonstrates the successful use of artificial neural networks as a correlating method for experimentally- measured heat transfer and friction data of helicallyinned tubes.

We are now witnessing changing environmental conditions and these changes will likely continue into the coming decades due to projected increases in temperatures on the earth surface. Recent model projections suggest that the global mean surface air temperatures will increase by 1.4 to 5.8 °C by 2100. The consequences of these high temperatures include reductions in crop yields. Soybean is one of the major crops grown in the US, where high temperatures (>35 °C) during reproductive growth decreased yield. Two experiments were conducted to determine the effects of temperature on soybean pollen germination properties and identify responses to temperature among genotypes. Pollen collected from 44 genotypes grown outdoors in large pots was subjected to in vitro temperature treatments that varied from 15 to 50 °C at 5 °C increments in Experiment I. The mean cardinal temperatures (Tbase, Topt, and Tmax), averaged over 44 genotypes, were 13.2, 30.2 and 47.2 °C for pollen germination and 12.1, 36.1 and 47.0 °C for pollen tube growth. The relationship between Tbase and Topt for pollen germination was high indicating that genotypes with high Tbase also had higher Topt. The relationship was weak between Tbase and Tmax. The Topt for pollen tube growth was 5.8 ¢XC higher than the Topt for pollen germination. The study also showed significant genotypic variability for physiological parameters studied, but no significant correlations between the observed physiological parameters with any of the pollen germination or pollen tube growth parameters were studied. This indicated that physiological parameters, measured under ambient conditions may not be useful to identify reproductive tolerance to high temperatures in soybean. Total response index (TSRI), the sum of individual responses of all pollen parameters differentiated genotypes and their tolerance to high temperature. A heat-tolerant genotype (DG 5630RR) identified using TSRI technique, when grown at optimum and high temperature conditions in experiment II, were actually less sensitive to high temperatures compared to heat-sensitive and heat-intermediate sensitive genotypes indicating that pollen can be used as screening tool for heat tolerance. The identified high-temperature tolerant genotypes, based on pollen germination parameters, might be useful in current and future soybean breeding programs.

This work can be viewed in three separate sections, each of which build off of the prior. The first part of this study examined the flow in a 1/16th scale calandria test section based on a typical CANDU moderator layout. The experiments utilized forced flow supplied to the vessel and electrical heated rods to mimic the heat flow from calandria tubes. The size of the vessel, flow rates, and power levels were used to scale the experiments such that the provided representative temperature fields. The temperature field inside the vessel was measured and shown to compare well with CFD predictions over a wide range of inlet conditions and power levels. Additionally, this work addressed the scaling distortions in the experiment which occurred due to physical limitations when performing experiments at 1/16 scale (e.g., a smaller number of heater rods with a larger diameter were used in the experiment because at 1/16-scale direct fabrication of 390 fuel channel simulators is not feasible). The work proposed the H factor addition to the Ar. This additional scaling criteria was shown to better maintain the flow regimes expected CANDU moderators by taking into account distortions introduced by surface heating instead of volumetric heating in addition to the reduction in total number of tubes. While this work involved forced convective flows at the inlet of the vessel, in some regions of the calandria buoyancy induced forces were sufficiently high such that these phenomena altered the direction and magnitude of the flows as compared to purely forced convective behavior. Hence further work, discussed below, was initiated to better understand and measure these local phenomena where buoyancy forces are of similar magnitude as those of forced convection. Such local conditions we have terms mixed convection regime for the purposes of this thesis. The second part of this work further examined the mixed convection between a subset of the CANDU calandria tubes, namely how does a lower tube effect the mixed convection heat transfer of the upper tube in an inline arrangement. To isolate and measure the phenomena with sufficient detail, a small number of tubes was studied and advanced diagnostics such as Particle Image Velocimetry (PIV) and Laser Induced Fluorescence (LIF) were employed. This study combined fluid velocity, temperature and wall temperature measurements with CFD simulations to develop a mechanistic model and understanding of the effect of natural convection plumes from lower elevations on the natural circulation phenomena on an upper cylinder. Superposition of the natural convection phenomena combined with pseudo forced convection effects from the lower elevation cylinder’s plume was used to model the mixed convection phenomena. This model was shown to perform well, with nearly all data being predicted to with +-20% for experiments performed in this work, and experiments in literature. A major finding from the preceding discussion is the importance of the lower elevation plume velocity on the local phenomena on the upper cylinder. The third section further expanded upon the prior two by replacing the lower cylinder with a diffuser nozzle which could provide a forced convective component with accurately defined velocities. Such measurements allow for accurate definition of the local Ri number and allowed full access for instrumentation to observe the velocity fields. The major contribution of this work was a flow regime map that defined the phenomena around a heated cylinder under mixed convection conditions. Additionally, the establishment of a database of fluid temperature and velocity measurements for a wide range of Ri was also developed and used to further validate CFD predictions. / Thesis / Doctor of Philosophy (PhD)

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