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"Circulation control"
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Lift augmentation of a circulation control airfoil in proximity to water waves
Wave is an important factor affecting the takeoff and landing of seaplanes. In order to study the effect of waves on the moving airfoil in proximity to the water surface, the influence of different wave parameters on the aerodynamic characteristics of the airfoil is investigated through numerical simulation by solving the Reynolds-averaged Navier-Stokes equations. Moreover, the lift-augmentation effect of constant blowing on the circulation control airfoil in proximity to water waves is investigated. The results show that the higher the wave height and the longer the wavelength, the larger the fluctuation amplitude of the lift coefficient of the airfoil. the lift-augmentation efficiency of the circulation control airfoil decreases significantly after the blowing momentum coefficient exceeds a certain value. When the airfoil is close to water waves, the increase of the blowing momentum coefficient not only augments the lift of the circulation control airfoil, but also aggravates the fluctuation of the lift force.
Journal Article
Unmanned aircraft systems traffic management : UTM
This book introduces unmanned aircraft systems traffic management (UTM) and how this new paradigm in traffic management integrates unmanned aircraft operations into national airspace systems. Exploring how UTM is expected to operate, including possible architectures for UTM implementations, and UTM services, including flight planning, strategic coordination, and conformance monitoring, Unmanned Aircraft Systems Traffic Management: UTM considers the boundaries of UTM and how it is expected to interlace with tactical coordination systems to maintain airspace safety. The book also presents the work of the global ecosystem of players advancing UTM, including relevant standards development organizations (SDOs), and considers UTM governance paradigms and challenges. FEATURES Describes UTM concept of operations (ConOps) and global variations in architectures Explores envisioned UTM services, including flight planning, strategic coordination, conformance monitoring, contingency management, constraints and geo-awareness, and remote identification Highlights cybersecurity standards development and awareness Covers approaches to the approval, management, and oversight of UTM components and ecosystem Considers the future of UTM and potential barriers to its success, international coordination, and regulatory reform This book is an essential, in-depth, annotated resource for developers, unmanned aircraft system operators, pilots, policy makers, researchers, and academics engaged in unmanned systems, transportation management, and the future of aviation.
Book
Aerodynamic characteristics of circulation control airfoils with Magnus rotating cylinder
In the aerodynamic performance optimization for aircraft, although both the Magnus effect and the Coanda effect have demonstrated significant potential increasing lift, reducing drag, and enabling flow control, the complex flow mechanisms arising from their coupled application remain insufficiently explored, which to some extent limits their engineering implementation. Major challenges in active flow control include structural vibrations and additional energy consumption induced by the Magnus effect, as well as uncertainties in flow separation and attachment behavior of the Coanda jet under varying conditions. To address these issues, the study proposes an innovative configuration that integrates a rotating trailing-edge cylinder with internal jet blowing to combine both effects within a single airfoil structure. Utilizing a unified numerical modeling approach, the research systematically investigates the influence of different jet momentum coefficients (C
µ
) and freestream Mach numbers (Ma) on the aerodynamic characteristics and coupled control performance of the airfoil. The results reveal that at moderate jet intensities (C
µ
= 0.075), an optimal lift-to-drag ratio can be achieved under limited energy consumption, while higher Ma values, despite reducing aerodynamic efficiency, significantly suppress aerodynamic load oscillations, contributing to improved flight stability. By establishing an evaluation framework focusing on both aerodynamic performance and energy consumption, this study identifies two factors influencing the effectiveness of coupled control, thereby filling a gap in the research on Magnus-Coanda coupled control performance and providing a theoretical foundation for the engineering application of active flow control systems under multi-condition cases.
Journal Article
Status and Prospect of Drilling Fluid Loss and Lost Circulation Control Technology in Fractured Formation
Lost circulation in fractured formation is the first major technical problem that restricts improvements in the quality and efficiency of oil and gas drilling engineering. Improving the success rate of one-time lost circulation control is an urgent demand to ensure “safe, efficient and economic” drilling in oilfields all over the world. In view of the current situation, where drilling fluid loss occurs and the plugging mechanism of fractured formation is not perfect, this paper systematically summarizes the drilling fluid loss mechanism and model of fractured formation. The mechanism and the main influencing factors to improve the formation’s pressure-bearing capacity, based on stress cage theory, fracture closure stress theory, fracture extension stress theory and chemical strengthening wellbore theory, are analyzed in detail. The properties and interaction mechanism of various types of lost circulation materials, such as bridging, high water loss, curable, liquid absorption and expansion and flexible gel, are introduced. The characteristics and distribution of drilling fluid loss in fractured formation are also clarified. Furthermore, it is proposed that lost circulation control technology for fractured formation should focus on the development of big data and intelligence, and adaptive and efficient intelligent lost circulation material should be continuously developed, which lays a theoretical foundation for improving the success rate of lost circulation control in fractured formation.
Journal Article
An IoT-based low-cost architecture for smart libraries using SDN
In the evolving landscape of smart libraries, this research pioneers an IoT-based low-cost architecture utilizing Software-Defined Networking (SDN). The increasing demand for more efficient and economical solutions in library management, particularly in the realm of RFID-based processes such as authentication, property circulation, and book loans, underscores the significance of this study. Leveraging the collaborative potential of IoT and SDN technologies, our proposed system introduces a fresh perspective to tackle these challenges and advance intelligent library management. In response to the evolving landscape of smart libraries, our research presents an Internet of Things (IoT)-based low-cost architecture utilizing SDN. The exploration of this architectural paradigm arises from a recognized gap in the existing literature, pointing towards the necessity for more efficient and cost-effective solutions in managing library processes. Our proposed algorithm integrates IoT and SDN technologies to intelligently oversee various library activities, specifically targeting RFID-based processes such as authentication, property circulation management, and book loan management. The system's architecture, encompasses components like the data center, SDN controllers, RFID tags, tag readers, and other network sensors. By leveraging the synergy between RFID and SDN, our innovative approach reduces the need for constant operator supervision in libraries. The scalability and software-oriented nature of the architecture cater to extensive library environments. Our study includes a two-phase investigation, combining practical implementation in a small-scale library with a simulation environment using MATLAB 2021. This research not only fills a crucial gap in current knowledge but also lays the foundation for future advancements in the integration of IoT and SDN technologies for intelligent library management.
Journal Article
Salt resistance property evaluation of lost circulation materials for wellbore strengthening in deep geological formations
Deep well drilling in high-salinity geological formations presents significant challenges, including recurrent loss of drilling fluids and repeated plugging failures. These issues necessitate a reevaluation of conventional lost circulation materials (LCMs) and their performance metrics. Here, we investigate the behavior of commonly used bridging LCMs under high-salinity conditions characteristic of the Kuqa foreland in China’s Tarim Basin. Our comprehensive experimental study reveals that high-salinity environments substantially impact the stability of LCM formed plugging zones. We demonstrate that after exposure to formation water with 200,000 mg/L salinity at 150 °C for 24 h, millimeter-sized calcium carbonate LCMs exhibit significant physical and mechanical changes. These include color darkening, 4.79% mass loss, and a 13.75% reduction in friction coefficient. The compressive strength degradation rates at D90 for pre- and post-high-salinity treatment were 17.58% and 5.48%, respectively. Walnut shell LCMs showed more pronounced alterations, with color change from dark brown to black, 32.51% mass loss, and a 28.57% decrease in friction coefficient. Their compressive strength degradation rates at D90 were 3.53% and 28.76% for pre- and post treatment, respectively. Synthetic polymer LCMs, while maintaining color stability, experienced a 9.51% mass loss and a 20.86% reduction in friction coefficient, with compressive strength degradation rates of 2.40% and 22.96% for pre- and post-treatment, respectively. Our findings indicate that the frictional performance and compressive strength of LCMs are compromised in deep, high-salinity geological formations. This deterioration leads to shearing instability and particle size degradation, ultimately resulting in plug failure. This study provides crucial insights for the selection of LCMs capable of maintaining long-term pressure stability in challenging deep, high-salinity formations, potentially revolutionizing drilling practices in such environments.
Journal Article
Preparation and Performance Evaluation of Graphene Oxide-Based Self-Healing Gel for Lost Circulation Control
Lost circulation is a major challenge in oil and gas drilling operations, severely restricting drilling efficiency and compromising operational safety. Conventional bridging and plugging materials rely on precise particle-to-fracture size matching, resulting in low success rates. Self-healing gels penetrate loss zones as discrete particles that progressively swell, accumulate, and self-repair in integrated gel masses to effectively seal fracture networks. Self-healing gels effectively overcome the shortcomings of traditional bridging agents including poor adaptability to fractures, uncontrollable gel formation of conventional downhole crosslinking gels, and the low strength of conventional pre-crosslinked gels. This work employs stearyl methacrylate (SMA) as a hydrophobic monomer, acrylamide (AM) and acrylic acid (AA) as hydrophilic monomers, and graphene oxide (GO) as an inorganic dopant to develop a GO-based self-healing organic–inorganic hybrid plugging material (SG gel). The results demonstrate that the incorporation of GO significantly enhances the material’s mechanical and rheological properties, with the SG-1.5 gel exhibiting a rheological strength of 3750 Pa and a tensile fracture stress of 27.1 kPa. GO enhances the crosslinking density of the gel network through physical crosslinking interactions, thereby improving thermal stability and reducing the swelling ratio of the gel. Under conditions of 120 °C and 6 MPa, SG-1.5 gel demonstrated a fluid loss volume of only 34.6 mL in 60–80-mesh sand bed tests. This gel achieves self-healing within fractures through dynamic hydrophobic associations and GO-enabled physical crosslinking interactions, forming a compact plugging layer. It provides an efficient solution for lost circulation control in drilling fluids.
Journal Article
Palaeolatitudinal distribution of lithologic indicators of climate in a palaeogeographic framework
Whether the latitudinal distribution of climate-sensitive lithologies is stable through greenhouse and icehouse regimes remains unclear. Previous studies suggest that the palaeolatitudinal distribution of palaeoclimate indicators, including coals, evaporites, reefs and carbonates, has remained broadly similar since the Permian period, leading to the conclusion that atmospheric and oceanic circulation control their distribution rather than the latitudinal temperature gradient. Here we revisit a global-scale compilation of lithologic indicators of climate, including coals, evaporites and glacial deposits, back to the Devonian period. We test the sensitivity of their latitudinal distributions to the uneven distribution of continental areas through time and to global tectonic models, correct the latitudinal distributions of lithologies for sampling- and continental area-bias, and use statistical methods to fit these distributions with probability density functions and estimate their high-density latitudinal ranges with 50% and 95% confidence intervals. The results suggest that the palaeolatitudinal distributions of lithologies have changed through deep geological time, notably a pronounced poleward shift in the distribution of coals at the beginning of the Permian. The distribution of evaporites indicates a clearly bimodal distribution over the past ~400 Ma, except for Early Devonian, Early Carboniferous, the earliest Permian and Middle and Late Jurassic times. We discuss how the patterns indicated by these lithologies change through time in response to plate motion, orography, evolution and greenhouse/icehouse conditions. This study highlights that combining tectonic reconstructions with a comprehensive lithologic database and novel data analysis approaches provide insights into the nature and causes of shifting climatic zones through deep time.
Journal Article
Estimation of blade loads for a variable pitch vertical axis wind turbine from particle image velocimetry
This paper presents the flow fields and aerodynamic loading of a two bladed H‐type vertical axis wind turbine with active variable pitch for load and circulation control. Particle Image Velocimetry is used to capture flow fields at six azimuthal positions of the blades during operation, three upwind and three downwind. Flow phenomena such as dynamic stall and tower shadow are captured in the flow fields. The phase‐averaged velocity fields and their time and spatial derivatives are used to calculate the normal and tangential loading at each position for each pitching configuration using the Noca formulation of the flux equations. The results show the effect of load shifting from the upwind to downwind region of the actuator using pitch and the effects of dynamic stall on the blades. The results also provide an unique database for model validation.
Journal Article