Supercritical Explosion Research Articles

A novel and sustainable approach to efficiently modify cotton material via a physical flash-explosion with sub- or SCF-CO2 as medium

A novel and eco-friendly approach to modify natural cotton fiber by flash-explosion with a sub- or supercritical fluid of carbon dioxide (sub- or SCF-CO2) for improving its structure and properties was constructed for the first time. The achieved results demonstrate that remarkable improvements in the coloration performance of cotton fiber by 71.1 % and the water retention by 1001.2 % against the control could be readily available by employing the flashily-explosion method at a recommended condition with 4-cycle explosion in sub- or SCF-CO2, and system temperature, fluid treatment duration and explosion number exhibited much more pronounced positive influences among all parameters. Additionally, minimal influences from the supercritical explosion on cotton fiber micronaire value, thermal property and tensile breaking strength were also observed. The scanning electron microscopy (SEM) and porosity investigations clearly show that plenty of micropores and/or strip fissures were formed on the fiber surfaces and their inner phases, and notably improved fiber surface area, pore volume and size were also obtained after a subsupercritical flash-explosion. Nuclear magnetic resonance hydrogen spectroscopy (1H NMR) and Fourier transform infrared spectroscopy (FT-IR) analysis disclose that numbers of hydrogen bonds between the fiber macrochains and/or from their intramolecular chains were broken by generating numerous free hydroxyl groups, which reasonably supported the improvements of the dye uptake behaviors and water retention properties, etc. The Energy-dispersive X-ray spectroscopy (EDS) analysis on the fiber cross-sections further confirms that a loosening of the inner aggregation structure of the cotton fiber was achieved after a flash explosion by significantly enhancing its coloration performance, etc. This innovative approach provides a promising idea and possibility as an alternative to chemical methods via mechanically and physically modifying fiber or other materials with sub- or SCF-CO2 fluid in an eco-friendly and sustainable manner.

Earth’s interior is working this way-answering the 10th problem proposed by “Science” journal

Materials all over the world are doing opening-closing movement. The thermal (heat energy) derived upward movement of material can be defined as opening, while the potential gravity of derived downward sinking movement be defined as closing. Opening-closing movement obtains the synchronized unity between vertical and horizontal opening-closing and the properties of interdependence, mutual opposition and transformation. So that, under the control and regulate of rotating movement it transforms all Earth material, tectonics and energy etc. from the state of disorder to be ordered, and finally built up the dynamically stable equilibrium system of opening-closing-rotating tectonics. Therefore, the unceas-ingly cyclic evolution of formation, destruction and renovation of the dynamically stable equilibrium system is the only basis and effective method for the research on the working of the Earth’s interior. For that, we have delineated 8 vertical-ly opening-closing tectonic cycles and the Earth crust spherical opening-closing tectonic cycle. And preliminary estab-lished the 4-dimensional working system of the Earth. The establishment of the dynamically stable equilibrium system is fulfilled in accordance with the 4 long term standing natural laws, such as, the gravity or mass balancing criteria, the min-imum internal energy principle in crystallization, geometric preferred orientation growth principle and principle of horizon-tal material homogeneity. Among them gravity balancing is the leading law. Nearly at about 4.0 Ga mantle lithosphere was formed as a lid covering the hot Earth and preliminarily built up the stable opening-closing-rotating tectonic system which made the Earth entering the evolution stage of dynamically stable equilibrium system. After that, each important geological event (lose balance) is not thing but poking a hole or tearing a fissure to destruct the balance of the Earth. The rotating movement and opening-closing movement will soon restore it to a new balance and thus formed an open-ing-closing cycle. Till now Earth has passed 5 megacycles. Plate tectonics studied the regularity of how did the litho-spheric mantle be poked and how did it be restored only for the youngest 4 cycles and then summing up as a theory. Therefore, it is restricted both in time and space and is unworthy to be titled as “global tectonics”. Earth is a living body, the working system in which including inner structure and its function is rather perfect, including: opening-closing movement, rotating movement and the lose balance movement to compose the movement system; Geo-fluids functioning as “blood”, Earth nucleus is the “ heart” for storing and supplying ”blood” and the mantle plumes connecting “bloods” comprised the “blood” system. Taking gravity balance as a criteria, the Earth’s dynamic equilibrium system is composed of: 4 gravity balance surfaces, 4 opening-closing transforming zones and the 2 mass balance lines on the surface of the sphere. Because the transformation of opening and closing has the function of spontaneous form-ing and self-adjusting, therefore, the interdependence, mutual opposition and transformation of opening and closing are the major dynamic mechanism and major motivation for the working system of the Earth’s interior. The essence of the change is the transformation of thermal energy to potential energy. The driving mechanism of the transformation is the destruction of opening-closing equilibrium by lose balance movement. The internal cause is the supercritical explosion induced by high temperature and pressure fluid and the external cause is mainly impact process.

The early stage of the thermal pulse explosions of aluminum nanowires under different energy deposition levels

Molecular dynamics simulations are performed to study the initial stage of the electrical explosions of Al nanowires in vacuum. The radial difference of wire expansion rate was observed in the early stages of the explosions. It is found that the wire radial expansion rate and the thermodynamic parameters interact with each other. We studied the time-varying thermodynamic parameters in the matched mode expansions, obtained the phase trajectories of wire material. Our results proved that the energy deposition levels dominate the explosion regime: when the energy ratio is less than 0.208, wire expansion will not develop into an explosion; phase explosion occurs under an underheated condition; supercritical explosion generally happens when the energy deposition is greater than the sublimation energy. We tracked the transformation trajectory of the deposited energy and found it is not preferentially transformed into the internal energy but simultaneously transformed into the explosion kinetic energy. As a result, even for the deposited energy reaching or exceeding the sublimation energy, material cannot be fully gasified. Finally, the deposition energy consumed by the internal energy has an upper limit: the sublimation energy.

Stability Analysis of A Thin Micropolar Fluid Flowing on A Rotating Circular Disk

ABSTRACTThe stability analysis of a thin micropolar fluid flowing on a rotating circular disk is investigated numerically. The target is restricted to some neighborhood of critical value in the linear stability analysis. First, a generalized nonlinear kinematic model is derived by the long wave perturbation method. The method of normal mode is applied to the linear stability. After the weakly nonlinear dynamics of a film flow is studied by using the method of multiple scales, the Ginzburg-Landau equation is determined to discuss the necessary condition in terms of the various states of subcritical stability, subcritical instability, supercritical stability, and supercritical explosion for the existence of such flow pattern. The modeling results indicate that the rotation number and the radius of circular disk play the significant roles in destabilizing the flow. Furthermore, the micropolar parameter K serves as the stabilizing factor in the thin film flow.

Weakly Nonlinear Stability Analysis of a Thin Magnetic Fluid during Spin Coating

This paper investigates the stability of a thin electrically conductive fluid under an applied uniform magnetic filed during spin coating. A generalized nonlinear kinematic model is derived by the long-wave perturbation method to represent the physical system. After linearizing the nonlinear evolution equation, the method of normal mode is applied to study the linear stability. Weakly nonlinear dynamics of film flow is studied by the multiple scales method. The Ginzburg-Landau equation is determined to discuss the necessary conditions of the various critical flow states, namely, subcritical stability, subcritical instability, supercritical stability, and supercritical explosion. The study reveals that the rotation number and the radius of the rotating circular disk generate similar destabilizing effects but the Hartmann number gives a stabilizing effect. Moreover, the optimum conditions can be found to alter stability of the film flow by controlling the applied magnetic field.

Weakly Nonlinear Stability Analysis of a Thin Liquid Film With Condensation Effects During Spin Coating

This paper investigates the stability of a thin liquid film with condensation effects during spin coating. A generalized nonlinear kinematic model is derived by the long-wave perturbation method to represent the physical system. The weakly nonlinear dynamics of a film flow are studied by the multiple scales method. The Ginzburg–Landau equation is determined to discuss the necessary conditions of the various states of the critical flow states, namely, subcritical stability, subcritical instability, supercritical stability, and supercritical explosion. The study reveals that decreasing the rotation number and the radius of the rotating circular disk generally stabilizes the flow.

Nonlinear stability analysis of thin condensate falling film inside a rotating vertical cylinder

This paper investigates the stability of thin condensate film flowing down on the inner surface of a rotating vertical cylinder by means of long wave perturbation method in a two-step procedure. In the first step, the normal mode method is used to characterize the linear behavior. In the second step, an elaborated nonlinear film flow model is solved by using the method of multiple scales to characterize flow behavior at various states of sub-critical stability, sub-critical instability, supercritical stability, and supercritical explosion. The procedure follows the previous research [C.I. Chen, C.K. Chen, Y.T. Yang, Int. J. Heat Mass Transfer 47 (2004) 1937–1951] which concerns with the thin condensate falling film on the outer surface of a rotating vertical cylinder. The modeling results indicate that by increasing the rotation speed, Ω, and the radius of cylinder, R, the condensate film becomes more stable, which is totally opposite to the previous study.

Nonlinear Stability Analysis of Thin Viscoelastic Film Flowing Down on the Inner Surface of a Rotating Vertical Cylinder

This paper investigates the stability of thin viscoelastic liquid film flowing down on the inner surface of a rotating vertical cylinder by means of the long wave perturbation. After proving the insufficiency of the linear model in characterization of certain flow behaviors, a generalized nonlinear kinematic model is then derived to represent the physical system. This model is solved through the following procedure. In the first step, the normal mode method is used to characterize the linear behaviors. The amplitude growth rates and the threshold conditions are characterized subsequently and summarized as the by-products of the linear solutions. In the second step, a nonlinear film flow model is solved by using the method of multiple scales to characterize flow behaviors at various states of sub-critical stability, sub-critical instability, supercritical stability, and supercritical explosion. The modeling results indicate that with the increase in the rotation speed Ω and the radius of cylinder R, the film flow system will be more stable.

Nonlinear stability analysis of thin Newtonian film flowing down on the inner surface of a rotating vertical cylinder

The paper presents both of the linear and nonlinear stability theories for characterization of Newtonian film flows down on the inner surface of a rotating in.nite vertical cylinder. After showing the insufficiency of the linear model in characterizing certain flow behaviors, a generalized nonlinear kinematic model is then derived to represent the physical system. The model is solved by the long wave perturbation method in a two-step procedure. In the first step, the normal mode method is used to characterize the linear behaviors. The amplitude growth rates and the threshold conditions are characterized subsequently and summarized as the by-products of the linear solutions. In the second step, an elaborated nonlinear film flow model is solved by using the method of multiple scales to characterize flow behaviors at various states of sub-critical stability, sub-critical instability, supercritical stability, and supercritical explosion. The modeling results indicate that by increasing the rotation speed, X, and the radius of cylinder, R, the film flow will make the flow system more stable.

Non-Linear Stability Analysis of a Thin Newtonian Film Flowing Down an Infinite Vertical Rotating Cylinder

Non-linear stability theories for the characterization of Newtonian film flow down an infinite vertical rotating cylinder is given. A generalized non-linear kinematic model is derived to represent the physical system and is solved by the long-wave perturbation method in a two-step procedure. In the first step, the normal mode method is used to characterize the linear behaviours. In the second step, an elaborated non-linear film flow model is solved by using the method of multiple scales to characterize flow behaviours at various states of subcritical stability, subcritical instability, supercritical stability, and supercritical explosion. The modelling results indicate that by increasing the rotation speed, ω, and decreasing the radius of cylinder, R, the film flow becomes less stable, generally.

Non-linear stability characterization of the thin micropolar liquid film flowing down the inner surface of a rotating vertical cylinder

Linear and non-linear stability analysis for characterization of micropolar film flowing down the inner surface of a rotating infinite vertical cylinder is given. A generalized non-linear kinematic model is derived to represent the physical system and is solved by the long wave perturbation method in the following procedure. First, the normal mode method is used to characterize the linear behaviors. Then, an elaborated non-linear film flow model is solved by using the method of multiple scales to characterize flow behaviors at various states of sub-critical stability, sub-critical instability, supercritical stability, and supercritical explosion. The modeling results indicate that by increasing the rotation speed, Ω, and the radius of cylinder, R, the film flow will generally stabilize the flow system.

Perturbation analysis to the nonlinear stability characterization of thin condensate falling film on the outer surface of a rotating vertical cylinder

The linear and nonlinear stability theories for characterization of condensate film flow down on the outer surface of a rotating infinite vertical cylinder is investigated analytically. A generalized nonlinear kinematic model is derived to represent the physical system and is solved by the long-wave perturbation method in a two-step procedure. In the first step, the normal mode method is used to characterize the linear behaviors. The amplitude growth rates and the threshold conditions are characterized subsequently and summarized as the by-products of the linear solutions. In the second step, an elaborated nonlinear film flow model is solved by using the method of multiple scales to characterize flow behaviors at various states of sub-critical stability, sub-critical instability, supercritical stability and supercritical explosion. The modeling results indicate that by increasing the rotation speed, Ω, and decreasing the radius of cylinder, R, the film flow becomes less stable, generally.

Weakly nonlinear stability analysis of thin viscoelastic film flowing down on the outer surface of a rotating vertical cylinder

The paper presents both of the linear and nonlinear stability theories for characterization of viscoelastic film flows down on the outer surface of a rotating infinite vertical cylinder. After showing the insufficiency of the linear model in characterizing certain flow behaviors, a generalized nonlinear kinematic model is then derived to represent the physical system. The model is solved by the long wave perturbation method in a two-step procedure. In the first step, the normal mode method is used to characterize the linear behaviors. The amplitude growth rates and the threshold conditions are characterized subsequently and summarized as the by-products of the linear solutions. In the second step, an elaborated nonlinear film flow model is solved by using the method of multiple scales to characterize flow behaviors at various states of sub-critical stability, sub-critical instability, supercritical stability, and supercritical explosion. The modeling results indicate that by increasing the rotation speed, Ω, and decreasing the radius of cylinder, R, the film flow will generally make the flow system less stable. In this study, the interaction of the rotation and the radius of cylinder are taken into account. Generally, Reynolds number is divided into three regions, which are Re<3, 3< Re<8 and 8< Re, for discussion corresponding to the pre-selected Rossby number ( Ro=0.1) and viscoelastic parameter ( k=0.05).

Homogeneous thermal explosion in a compressible atmosphere

The homogeneous change in temperature in a reactive atmosphere arising as a consequence of small-amplitude initial flow disturbances is studied using high-activation energy asymptotics. The disturbances consist of a velocity non-uniformity and a pressure gradient non-uniformity which vary linearly with respect to a suitably defined Lagrangian mass variable. The time-dependent flow divergence rates subsequently established by these disturbances, which correspond either to a local fluid expansion or compression, are shown to markedly influence the evolution of thermal energy within the fluid. For sufficiently large fluid expansion rates it is demonstrated that no supercritical thermal explosion, in which large temperature changes occur, is possible. The rate of removal of thermal energy in the form of kinetic energy is sufficient to overcome the increase in temperature brought about by chemical reaction. Finally, reaction zone solutions are developed in cases where a supercritical explosion exists.