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Fuel injection by means of solid cryogenic pellets is expected to provide a sound and efficient tool. Hence, the installation of a pellet launching system will be a necessity. Yet, pellets are considered as a serviceable actuator for integrated supplementary functions as, e.g., fast and efficient delivery of seeding gas, or in case needed, the pacing of edge-localized modes. Consequently, a control scheme has to be developed that is capable of mastering the simultaneous actuations covering different tasks. Our scheme relies on pellet launching by a centrifuge accelerator, providing the option for precisely predictable pellet injection sequences. In order to develop a suitable actuator control scheme, as a first step the central part was brought into service at ASDEX Upgrade. It proved operational for feedback particle flux control of a single pellet source. In a subsequent step, it is now upgraded to enable multitasked control of the JT-60SA multipellet source currently under construction. In its finally designated configuration, this control scheme provides a potential solution for a reactor-grade system.

The surface dynamics of the rotating thermal convection are examined in finely resolved laboratory flows. Deep rotating convection creates geostrophic turbulent flow at the surface, the regime of c...

International audience; The discrete element (roughness) method developed a few decades ago is revisited using the double averaging technique applied to the Navier-Stokes equation. A k − ω based DANS turbulence model is thus derived to be able to account for roughness effects. Several closure relations are proposed to model all terms induced by the use of the double averaging. The momentum and energy equations are considered in their simplified forms adapted to a 1D channel code in accordance with the DNS results used for the validation. To reconcile the discrete element (roughness) method with the double averaged Navier-Stokes equations the notion of representative elementary roughness is introduced. A large validation dataset coming from various DNS configurations is then used to assess the predictions of the proposed DANS model. Yet not fully complete, especially regarding the dispersive terms due to a lack of data, the performed validation already proves the overall excellent behavior of the DANS model and demonstrates the relevance of the present methodology based on the representative elementary roughness.

Rewetting a hot dry surface is the establishment of wet contact between the hot surface and a liquid at a lower temperature. Rewetting occurs after destabilizing a vapor film that exists between th...

International audience; Industrial chimneys, launch vehicles and stacks are examples of large diameter circular cross section structures that can be prone to cross-wind vortex-induced vibration (VIV). VIV has been extensively studied for both fundamental and applied issues, but few documented studies concern high Reynolds number regimes (> 5 × 105) in atmospheric turbulent wind. This paper introduces a field test on a slender light and low damped chimney designed to experience “super-critical” VIV at moderate wind velocity. The chimney was recently erected in a wind monitored field, near the Atlantic coast of France. The purpose of this paper is to present the first vibration results obtained during a sequential 13-day period in September 2020. A statistical analysis has been performed on the amplitude and dominant frequency responses and results are reported in term of probability distribution as a function of wind speed and direction. VIV events of low (30% of diameter) have been highlighted in a range of wind velocity 25% lower than expected, along with significant influence of the wind direction – low turbulence easterly wind giving vortex-induced vibrations with the highest amplitude.

In water atomization, a molten metal stream is fragmented by high-pressure water sprays by means of momentum transfer. In this work, a flat fan water spray is considered as a two-phase flow: water ...

Under the Boussinesq approximation for buoyancy driven flows, density variations are restricted to the gravity term. In contrast, the Gay-Lussac (GL) approach is developed based on considering dens...

This study was aimed at examining the influence of the system rotation as an external action on the development of vortical structures and combustion. Specifically, three-dimensional direct numeric...

Variable volume Helmholtz resonator systems offer an advantage for trim adjustment active control in liquid rocket engines due to the low bandwidth requirement on the actuator. In the present work,...

In this paper, we analyze metro cascading failure induced by load fluctuation and present a robust station capacity assignment method. A cascading failure model is proposed by considering system in...

Explosion often has a chain reaction in the accident field. The aerosol is injected into the high-temperature and high-pressure area produced in the first explosion and a superimposed explosion may...

An adaptable algorithm is proposed in this study, which can predict the complete load-shortening curve of a stiffened panel subjected to uniaxial longitudinal compression. The algorithm provides an extension to existing empirical formulae initially derived for predicting the ultimate compressive strength of stiffened panels. Based on observations from a series of nonlinear finite element analyses, the compressive load-shortening behaviour of stiffened panels is idealised with a linear pre-collapse response, an arc-shaped nonlinear ultimate collapse region and an asymptotic post-collapse decay. The algorithm allows direct modification of the elastic stiffness, ultimate strain, ultimate strength and post-collapse characteristics of the load shortening curve. This enables the load shortening curve to incorporate characteristics specific to the type of stiffened panel under analysis. The capability of the algorithm is demonstrated through an application with the simplified progressive collapse method to calculate the ultimate ship hull strength of four merchant ships and one naval vessel.

Spark ignition by low-energetic electrical discharges in combustible fuel/air mixtures is a significant safety risk in various industries. In the present paper, OH-LIF measurements and numerical si...

Thermal cracking permeability enhancement (TCPE) is a method to improve the coalbed methane (CBM) extraction efficiency and yield in low-permeability CBM reservoirs, but this method can change the ...

Considering the importance of correctly understanding the dynamics of microstructure materials for their applications in related technologies, by eliminating the shortcomings and some overlooked physical concepts in the existing asymmetric elastic theories, we have presented an asymmetric elastodynamic model based on a U(1) gauge theory with quantum electrodynamics (QED) structure. Accordingly, we have shown that there is a correspondence between an elastic theory, which can explain the behavior of elastic waves within an asymmetric elastic medium, and QED. More specific, we have indicated that the corresponding elastic wave equations are somehow analogous to QED ones. In this regard, by adding vibrational degrees of freedom and introducing a gauge property of the waves of displacement for the waves of rotation, we have generalized and modified the related Cosserat theory (CT) for an elastic environment. Thus on macro scales, the elastic waves can possess the QED treatment. This analogy provides a new paradigm of fermions and bosons. Also, from experimental point of view, we have shown that the behavior of elastic waves in a granular medium is equivalent to behavior of light in dispersive media, which can be explained using QED. Hence, contrary to the Cosserat and discrete models, this amended CT has qualitatively been indicated to be consistent with the corresponding empirical observations., 14 pages,1 figure; revised version, added refs

To study the influence of flame-spreading behaviour in the ignition process of different charging structures in high-density charge chambers, a visualisation device was designed, and the ignition p...

The spray combustion of LOX/GCH4 in the pintle injector is simulated to study the combustion characteristics at a subcritical condition by considering the effects of pintle opening distance and pin...

In order to better explore the spontaneous combustion characteristics of lignite, a low-temperature heating experimental device was used to study the changes in the physical and chemical structure ...

Many gas explosion accidents show that gas explosion can easily cause a large number of casualties and huge property losses in coal mines. Therefore, the sliding device is established to study its ...

Effective dimension reduction is a key factor in facilitating large-scale simulation of high-dimensional dynamical systems. The behaviour of low-dimensional surrogate models often relies on accurat...

The objective of this paper is to propose a new intermittency transport equation that is naturally capable of capturing the effects of free-stream turbulence and pressure gradient on bypass and nat...

A complex plasma medium (containing Cairns nonthermal electron, adiabatically warm inertial ion, and stationary positively charged dust (PCD) species (making a plasma system very complex) is consid...

In this paper, a large-eddy simulation study of turbulent free surface flow over a natural rough bed is presented. A three-dimensional multiphase flow model is employed to study the roughness effects on the turbulence properties and free surface dynamics. The governing equations have been discretized using the finite volume method, with the Cartesian cut-cell method being implemented to deal with the precise scanned gravel bed topography and the deformable free surface being captured by a volume of fluid method. The predicted mean flow velocities and turbulence statistics have been compared with experimental data. A close agreement has been obtained between the two sets of results, providing confirmation that this complementary approach to experimental investigations gives further insight into the turbulent free surface flow dynamics over rough beds. It is found that small waves are generated on the free surface due to the roughness effect for the relative low submergence case.

Automotive airbag gas generants have been studied extensively to meet design and safety requirements. Additives have historically been used to increase their burning rates, but the effects of addit...

Side-wall quenching (SWQ) is one of the generic configurations for flame-wall interaction and has been widely investigated through simulations using detailed and reduced chemical kinetics. In all p...

Deflagration-to-detonation transition (DDT) in gas (oxygen)–liquid n-heptane film and gas (oxygen)–liquid n-decane film systems is registered experimentally using a fused or exploding wire as a wea...

The first Floating Production Storage and Offloading platforms (FPSOs), many still operating in Campos Basin, were converted from single-hull oil tankers. Therefore, collision leading to the FPSO s...

In recent years, reinforced thermoplastic composite pipe (RTP) is widely sought after because of its high strength and corrosion resistance. The development of a connector that is easy to install a...

In the context of the development of HALO3D (High Altitude Low Orbit 3D), an edge-based Finite Element Method multidisciplinary solver for hypersonic flows, this paper presents the simulation of fl...

Very low Earth orbits (VLEOs) have an altitude of 100–450 km and have become a popular topic in space technology owing to their high application potential. However, spacecraft experience stronger a...

We present a systematic approach to extract the characteristic vortex region that contains the essential features of a complex flow field. The process involves the analysis of the complex eigenvalu...

A numerical experiment is conducted to examine the ignition of a near-flammability-limit low-Lewis-number mixture and the evolution processes of the resulting premixed flames in a circular thermall...

A better understanding of semiconductor bridge (SCB) discharge behavior under different firing conditions was crucial to revealing the mechanism of the SCB ignition technique. In this paper, the te...

Experimental investigations were made on the stabilization and dynamics of non-premixed methane-air flame in a series of radial microchannels with a diameter of 60 mm and widths of 2.0, 2.5 and 3.0...

The dynamical effects of roughness geometry on the response of a half-height turbulent channel flow to an impulse acceleration are investigated using direct numerical simulations. Two rough surface...

EU-DEMO will be the next step in Europe after ITER on the path toward a fusion power plant. The matter injection systems have to provide the requested material in order to establish, maintain, and terminate the burning plasma. Their main function is to fuel the plasma, but other tasks are addressed as well like delivering matter for generating sufficient core radiation and divertor buffering. In the preconceptual design phase performed from 2014 to 2020, the matter injection systems, in particular pellet injection and gas injection, have been assessed. This work describes the main findings and state of the art of the matter injection systems at the transition from the preconceptual design phase to the conceptual design phase.

For complex flow systems like the one of the wind turbine wakes, which include a range of interacting turbulent scales, there is the potential to reduce the high dimensionality of the problem to lo...

Demanding marine operations increase the complexity of manoeuvring. A highly accurate ship model promotes predicting ship motions and advancing control safety. It is crucial to identify the unknown hydrodynamic coefficients under environmental disturbance to establish accurate mathematical models. In this paper, the identification procedure for a 3 degree of freedom hydrodynamic model under disturbance is completed based on the support vector machine with multiple manoeuvres datasets. The algorithm is validated on the clean ship model and the results present good fitness with the reference. Experiments in different sea states are conducted to investigate the effects of the turbulence on the identification performance. Generalisation results show that the models identified in the gentle and moderate environments have less than 10% deviations and are considered allowable. The higher perturbations, the lower fidelity the identified model has. Models identified under disturbance could provide different levels of reliable support for the operation decision system. © 2021 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License (http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited, and is not altered, transformed, or built upon in any way

A novel formulation of the sodium lignin sulfonate (SLS) [bio based branched chain lignin polymer modified with the sulfonic acid] and the pomegranate rind extract (PRE), a wastage plant biomolecul...

Extreme storm-safe drilling riser, a solution to overcome high time cost of riser emergency retrieval under the situation of the imminent typhoon arrival, is to modify the existing drilling riser t...

The present paper introduces the development and verification of two ship performance models which have been implemented in a voyage planning tool designed for Arctic operations of commercial vessels. An ice resistance estimation algorithm for ice-floe conditions is proposed and implemented in the ship performance models. The fuel consumption predicted using both of the models are compared against full-scale measurements collected on a cargo ship on the Northern Sea Route. Two further case studies representing different Arctic transit periods are also investigated. This work found that both models predict ship fuel consumption with good and satisfactory accuracy and identified directions for future efforts. Overall, the demonstrations prove that an Arctic voyage planning tool, combined with ship performance estimates taking into account the effect of ice and other environmental parameters, can facilitate safe and sustainable Arctic shipping.

Subsea oil production facilities may face extreme or accidental events in association with site-specific conditions. In this paper, qualitative and quantitative assessment for the subsea manifold s...

In the present study, the effect of Hf and Ti substitution of Zr in the ZrCo alloy, used for hydrogen isotope storage, has been investigated in order to ascertain the improvement of the anti-dispro...

In an underwater compressed air energy storage system, fracture of the flexible riser often occurs. To solve this problem, we proposed a static analysis method for a flexible riser based on Cossera...

International audience; In this paper, a closed-form analytical solution procedure is proposed to solve the coupled fluid-structure interaction (FSI) equations that involve the first-order Doubly Asymptotic Approximation (DAA1) formulation. An efficient method comprised of the nonstandard finite difference (NSFD) scheme is applied. First of all, analytical equations are developed to analyze the response of a rigid mass-spring oscillator in an air-backed condition when it is subjected to a plane shock exponential wave coming from a far-field underwater explosion. After validating the results with LS-DYNA/USA (DAA1), these equations are extended to determine the response of a two-dimensional, simply-supported rectangular plate, and then tested on the isotropic and orthotropic plates within a small deflection regime. Parametric studies are also performed by varying the load decay times, peak pressures, as well as the aspect ratios of the plate. Finally, the advantages and limitations of the proposed formulae are exposed along with suggestions for the future work.

The article addresses the implications of adopting (a) non-kinetic theory-based correlations for the estimation of thermodynamic and transport properties and (b) over-simplifying assumptions, as re...

Micro-porous propellants enhanced with chopped carbon fibers (CCFs) were studied to investigate the effects of CCFs on the mechanical properties, thermal behavior, and combustion performance. The r...

The main objective of this paper is to investigate the bearing capacity behaviour of cracked plates considering low-cycle fatigue (LCF) propagation under cyclic loads. The accumulative plastic dama...

This paper presents a one-step method that significantly simplifies the biomass carbonization preparation with Fe0 as active catalyst. The catalyst activity was compared to that of the catalyst pre...

Gob buried pipe is a common technological means for gas extraction. This method can effectively address the transfinite gas problems on the working face. However, it may induce spontaneous coal com...