Visualization of Shock Wave Propagation Behavior of the General-Purpose Batch Processing for Pressure Vessel by Numerical Simulation

Recently, National Institute of Technology, Okinawa College (ONCT) has been developing a new food processing method using underwater shock wave. The continuous-operation device was manufactured for the production of rice flour, the amount of milling flour per hour and the quality of the rice powder were evaluated. In the case of Yuzu (Citrus junos), an improved fragrance was obtained using this methods compared with other general processing method. The authors have also developed a batch-type crushing device (pressure vessel) for various food processing. However, the mechanism by which is processed using shock waves has not been clarified. Therefore, in this study, the propagation characteristics of a shock wave in the developed pressure vessel were evaluated by numerical simulation. The characteristics of processing is evaluated using shock wave and, the pressure resistance of the vessel was analyzed. In addition, food processing experiments using the developed device were performed. In which, in which “Yuzu” were crushed. Yuzu before-and-after crushing were compared, and the effect of shock wave were clarified.

EDS Containment Vessel Explosive Test and Analysis

This report documents the results of two of tests that were performed on an explosive containment vessel at Sandia National Laboratories in Albuquerque, New Mexico in July 2013 to provide some deeper understanding of the effects of charge geometry on the vessel response [1]. The vessel was fabricated under Code Case 2564 of the ASME Boiler and Pressure Vessel Code, which provides rules for the design of impulsively loaded vessels [2]. The explosive rating for the vessel, based on the Code Case, is nine (9) pounds TNT-equivalent. One explosive test consisted of a single, centrally located, 7.2 pound bare charge of Composition C-4 (equivalent to 9 pounds TNT). The other test used six each 1.2 pound charges of Composition C-4 (7.2 pounds total) distributed in two bays of three.

Experimental Determination of the Static Equivalent Pressures of Detonative Explosions of Stoichiometric CH4/O2/N2-Mixtures and CH4/O2-Mixtures in Long Pipes

In the recent past (PVP2013-97677, PVP2014-28197, PVP2015-45286) we had started to determine the static equivalent pressures pstat of the eight detonative pressure scenarios in long and short pipes for different detonable gas mixtures. The pstat-values are of vital importance for process design: by assigning static equivalent pressures to the highly dynamic detonative pressure peaks it is possible to apply the established pressure vessel guidelines, which can only cope with static loads, for the design of detonation pressure resistant pipes. One important finding was that the ratio R between pstat at the location where transition from deflagration to detonation occurs and pstat in the region of the stable detonation strongly depends on the reactivity of the gas mixture. In this paper we present experimental data showing the variation of R over the entire explosive range of Methane/O2/N2 mixtures. Qualitatively, the results should be representative for all other combustible/O2/N2-mixtures. Furthermore, recommendations for estimating pstat values of short pipe scenarios on basis of the long pipe scenarios are given.

Analytical and Numerical Solution for a Rigid Liquid-Column Moving in a Pipe With Fluctuating Reservoir-Head and Venting Entrapped-Gas

The motion of liquid filling a pipeline is impeded when the gas ahead of it cannot escape freely. Trapped gas will lead to a significant pressure build-up in front of the liquid column, which slows down the column and eventually bounces it back. This paper is an extension of previous work by the authors in the sense that the trapped gas can escape through a vent. Another addition is that the driving pressure is not kept constant but fluctuating. The obtained analytical and numerical solutions are utilized in parameter variation studies that give deeper insight in the system’s behavior.

Primitive Model for the Random Excitation of a Tube Under Two-Phase Cross Flow

Flow-induced vibration of heat-exchangers tubes is particularly studied in the nuclear industry for safety and cost reasons. It implies to have, among others, relevant characterizations of the random buffeting forces the cross-flow applies to the tube bundle. Work is still needed in this domain, particularly for two-phase flow, to improve the available data as the ones for PWR steam generator, currently very envelope. In parallel to get new experimental data, using “real” or substitutional mixtures (e.g. air-water instead of steam-water for PWR), it is essential to understand the basic excitation mechanisms which induce the vibrations under two-phase flow, as e.g. the influence of flow regimes. In this general framework, what can be learnt from deliberately simple models may be a contributive help. As a first attempt on this issue, the paper deals with the elementary case of a single rigid tube under air-water cross flow. This case is part of experiments carried out at CEA-Saclay with bundles where both tube support reactions and flow characteristics are measured, with respectively piezo-electrical sensors and bi-optical probes (BOP). The information provided by the BOP (mean interface velocity, statistical distribution, etc.) feeds a primitive model of water “droplet” impulses on the tube, based on a lot of crude assumptions about impact velocity, momentum conservation, impulse shape, statistical independence, etc., and which uses analytical results of random processes constructed from the superposition of random pulses. The “equivalent” excitation force, obtained in terms of dimensional PSD, is compared to the one measured in the drag and lift direction with an acceptable agreement, at least in order of magnitude. Comments and lessons are drawn from this first attempt, and some paths are advanced to improve this kind of primitive models, especially for treating rigid square bundles under air-water cross flow.

Liquid Droplets in Contact With Cold Non-Equilibrium Atmospheric Pressure Plasmas

Recently, cold, non-equilibrium atmospheric pressure plasmas (CAPs) and their active chemistry have been extensively investigated to the benefit of a wide array of applications such as biomedical and industrial applications mainly in the area of materials processing and chemical synthesis, amongst many others. In general, these plasmas operate at standard conditions (i.e. 1 atm, 300K), are small (∼ cm) and rather simple to operate in comparison to other plasmas. Their complex chemistry gives rise to a wide array of both stable and transient reactive species: such as O3, H2O2, OH and NOx, next to charged species and (V)UV-radiation. This chemistry is the reason for their wide spread application and has already found many industrial applications from waste water treatment, stain free detergents and industrial scale production of oxidants. In recent years, bactericidal effects of CAPs gained increasing attention for applications such as dermatology, disinfection, dentistry and cancer treatment or stimulated blood coagulation. This paper aims to highlight recent research into new biological applications for complex mission scenarios involving humans in remote locations using CAPs for disinfection, bleaching or wound healing. Results using radiofrequency plasma jets for the inactivation of Pseudomonas aeruginosa are summarized, highlighting the importance of liquid plasma interactions. Work with such a CAP paved the way for a promising application in the field of biomedical applications presented here. It involves surface barrier discharges which can be used to treat larger surfaces compared to jets. Their physical construction, using floating or contained electrodes, offer a convenient way of controlling electrical current on a large scale, 3D treatment of both conducting and insulating surfaces with minimal heating. These devices may be tailored to specific skin treatments, allowing fast and effective treatment of larger skin surfaces while following the shape of the skin. This might reduce the need for bactericidal agents and would be a valuable application to assist humans in remote locations. These emerging technologies could be essential both for human health care under extreme conditions, as well as for research itself (sterilisation of tools and large areas, etc.). Especially in the absence of abundant resources (antibiotic agents, disinfectants and the like) alternative approaches to support humans in isolated locations have to be developed. Applications based on a good understanding of plasma chemistry would empower health care under extreme conditions to efficiently use and manage in situ resources. Their low mass, compact size, low power consumption and high reliability could make them essential use under extreme conditions.

Experimental Identification of Fluid-Elastic Coupling Forces on a Square Tube Bundle Subjected to Single-Phase Cross-Flow

The importance of fluid-elastic coupling forces in tube bundle vibrations is well documented and can hardly be over-emphasized, in view of their damaging potential. Even when adequate tube supports are provided to suppress fluid-elastic instabilities, the flow-coupling forces still affect the dynamical tube responses and remain a significant issue, in particular concerning the vibro-impact motions of tubes assembled using clearance supports. Therefore, the need remains for more advanced models of fluid-elastic coupling, as well as for experimental flow-coupling coefficients to feed and validate such models. In this work, we report an extensive series of experiments performed at CEA-Saclay leading to the identification of stiffness and damping fluid-elastic coefficients, for a 3×5 square tube bundle (D = 30 mm, P/D = 1.5) subjected to single-phase transverse flow. The bundle is rigid, except for the central tube which is mounted on a flexible suspension (two parallel steel blades) allowing for translation motions of the tube in the lift direction. The system is thus single-degree of freedom, allowing fluid-elastic instability to arise through a negative damping mechanism. The flow-coupling stiffness and damping coefficients, Kf(Vr) and Cf(Vr), are experimentally identified as functions of the reduced velocity Vr. Identification is achieved on the basis of changes in tube vibration frequency and reduced damping as a function of flow velocity, assuming a constant fluid added mass. In the present experiments, coefficient identification is performed well beyond the instability boundary, by using active control, thereafter allowing exploration of a significant range of flow velocity. The modal frequency and the modal mass of the system are respectively modified by changing the tube suspension stiffness, and/or by adding a mass to the system. We can thus assert how the fluid-elastic coefficients change, for this configuration, with these two system parameters, all other parameters being kept constant. The results obtained from the configurations tested suggest that formulations for coefficient reduction may be improved, in order to better collapse the identified data.

Experimental Investigation of Resonant Coupling Between Turbulent Flow Past a Rectangular Cavity and a Standing Gravity Wave

Coupling between self-excited oscillations of turbulent flow of water in an open channel along the opening of a rectangular cavity and the standing gravity wave in the cavity was investigated experimentally for a range of inflow velocities and characteristic depths of the water. The objective of the current investigation is to examine the effect of water depth on the onset of fully coupled oscillations of the shear flow past the cavity. Video recording of the oscillating free-surface inside the resonator cavity in conjunction with free-surface elevation measurements using a capacitive wave gauge provided representation of the resonant wave modes of the cavity as well as the degree of the flow-wave coupling in terms of the amplitude and the quality factor of the associated spectral peak. Moreover, application of digital particle image velocimetry (PIV) provided insight into the evolution of the vortical structures that formed across the cavity opening. Coherent oscillations were attainable for a wide range of water depths. Variation of the water depth affected the degree of coupling between the shear layer oscillations and the gravity wave as well as the three-dimensionality of the flow structure.

Towards Detailed Material Deformation Patterns in the Hypervelocity Impacts of Laminated Plates With Smoothed Particle Hydrodynamics

Hypervelocity impacts onto the outer structure of spacecraft induce shock waves, which in case of multimaterial structures interact with the material interfaces. This interaction is expected to produce different deformation patterns for laminates compared to the patterns appearing for materials with homogeneous density. In order to exhibit these different features and to show that the Smoothed Particle Hydrodynamics computational method is capable of describing them, a numerical hypervelocity impact experiment is performed for three plates. The first one is a laminate, with discontinuous density and material parameters, the second is a simple homogenized version of the laminate and the last is a monolithic metal plate.

Characteristics of Turbulence and Drag Forces on Foreign Objects in Tube Arrays

Steam generator tube wear due to foreign objects (FOs) is a significant industry problem. Removal of foreign objects comes with challenges related to accessibility and the environment inside the steam generator. It is therefore of interest to estimate the rate of wear due to foreign objects lodged within the SG; particularly in the tube-sheet region. To estimate wear, the fluid forces acting on the FO are a key input. Much remains unknown regarding the characteristics of fluid forces acting on small objects located within tube arrays. In the work reported here, an exploratory study of fluid forces acting on complex geometry objects was done. Force measurements were conducted in a wind-tunnel on a range of objects to investigate the effect of object geometry on the drag coefficient and the parameters which may be used to develop drag coefficient correlations. Turbulence forces acting on FOs in a tube array were found to be intimately related to turbulence forces acting on the tubes themselves. A direct relation between the corresponding force PSDs, via turbulence force correlations, is reported. This is a potentially useful result with regard to the nature of fluid forces acting on foreign objects in general.