Hydraulic machinery with high performance is of great significance for energy saving. Its design is a very challenging job for designers, and the inverse design method is a competitive way to do the ...job. The three-dimensional inverse design method and its applications to hydraulic machinery are herein reviewed. The flow is calculated based on potential flow theory, and the blade shape is calculated based on flow-tangency condition according to the calculated flow velocity. We also explain flow control theory by suppression of secondary flow and cavitation based on careful tailoring of the blade loading distribution and stacking condition in the inverse design of hydraulic machinery. Suggestions about the main challenge and future prospective of the inverse design method are given.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
A partially averaged Navier–Stokes method with a new expression of
f
k
based on the rotation-corrected energy spectrum is proposed. It is coupled with the shear-stress transport turbulence model to ...simulate two typical rotating flows: rotating channel flow and flow in a centrifugal pump impeller. The results of two traditional energy spectrum-based
f
k
expressions (ES1 and ES2) and DNS/experimental results are used for comparison. The results show that the
f
k
distribution predicted based on the rotation-corrected energy spectrum is more reasonable. In the region with enhanced turbulence, more turbulence scales exist, such as the pressure side in the rotating channel flow, where the
f
k
value is low and more turbulence scales are resolved. While in the region with suppressed turbulence, fewer turbulence scales exist, such as the suction side, where the
f
k
value is relatively high. The model with a new
f
k
expression can produce better results since it can give a more reasonable
f
k
distribution. At the same time, the new model is more efficient since it shows better calculation performance with the same mesh scale and low cost with comparable calculation performance.
The past one and a half decades have witnessed the tremendous progress of two-dimensional (2D) crystals, including graphene, transition-metal dichalcogenides, black phosphorus, MXenes, hexagonal ...boron nitride, etc., in a variety of fields. The key to their success is their unique structural, electrical, mechanical and optical properties. Herein, this paper gives a comprehensive summary on the recent advances in 2D materials for optoelectronic approaches with the emphasis on the morphology and structure, optical properties, synthesis methods, as well as detailed optoelectronic applications. Additionally, the challenges and perspectives in the current development of 2D materials are also summarized and indicated. Therefore, this review can provide a reference for further explorations and innovations of 2D material-based optoelectronics devices.
Self-powered photodetectors which operate without external power sources hold immense promise in future photodetection systems. To achieve high-performance selfpowered optoelectronic devices, ...efficient electron-hole pair separation is critical to generate high photocurrents. In this work, we successfully synthesized semiconducting graphene nanoribbons (GNRs) with a direct bandgap of 1.80 eV and employed them to construct a high-performance GNR/Al2O3/IGZO heterostructure photodetector. The built-in electric field in the heterojunctions enables this photodetector to exhibit remarkable performance, showing a responsivity of up to 68 mA/W, a detectivity of 8.34 ×1010 Jones, and rapid response times of 21/20 ms at zero bias. Furthermore, the photodetector features a wide spectral detection range of 405 to 1550 nm. These results highlight the promising potential of GNR/IGZO p-n heterojunction-based self-powered photodetectors in optoelectronic applications.
A three-dimensional inverse design of a low specific speed turbine is studied, and a set of design criteria for low specific speed turbine runner is proposed, including blade loading distributions ...and blade lean angles. The characteristics of the loading parameters for low specific speed turbine runner are summarized by analyzing the suction performance of different loading positions, loading slopes and blade lean angles based on the orthogonal experiment design and range analysis. It is found that the blade loading distribution at the band plays a more important role than it does at the crown and it should be fore loaded for both band and crown. The blade lean angle at the blade leading edge should be negative. Then, the blade is optimized through the inverse method by fixing blade lean angle, based on the response surface method. After seeking the optimal value of the response surface function, the optimal result of the design parameters is obtained, which is in conformity with the design criteria and verifies the rationality of the established design criteria for low specific speed turbine.
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To meet the growing demand in energy, great efforts have been devoted to improving the performances of energy–storages. Graphene, a remarkable two-dimensional (2D) material, holds immense potential ...for improving energy–storage performance owing to its exceptional properties, such as a large-specific surface area, remarkable thermal conductivity, excellent mechanical strength, and high-electronic mobility. This review provides a comprehensive summary of recent research advancements in the application of graphene for energy–storage. Initially, the fundamental properties of graphene are introduced. Subsequently, the latest developments in graphene-based energy–storage, encompassing lithium-ion batteries, sodium-ion batteries, supercapacitors, potassium-ion batteries and aluminum-ion batteries, are summarized. Finally, the challenges associated with graphene-based energy–storage applications are discussed, and the development prospects for this field are outlined.
Two-dimensional (2D) materials have sparked intense interest among the scientific community owing to their extraordinary mechanical, optical, electronic, and thermal properties. In particular, the ...outstanding electronic and optical properties of 2D materials make them show great application potential in high-performance photodetectors (PDs), which can be applied in many fields such as high-frequency communication, novel biomedical imaging, national security, and so on. Here, the recent research progress of PDs based on 2D materials including graphene, transition metal carbides, transition-metal dichalcogenides, black phosphorus, and hexagonal boron nitride is comprehensively and systematically reviewed. First, the primary detection mechanism of 2D material-based PDs is introduced. Second, the structure and optical properties of 2D materials, as well as their applications in PDs, are heavily discussed. Finally, the opportunities and challenges of 2D material-based PDs are summarized and prospected. This review will provide a reference for the further application of 2D crystal-based PDs.
In this study, the numerical simulation of the NACA66(modified) hydrofoil is carried out by using the cavitation flow solution method considering compressibility. The cavities shedding behaviors and ...pressure fluctuation characteristics are discussed. The simulation results reproduce the cavities shedding process, which is in good agreement with the experimental results. The results show that cavities are affected by the re-entrant jet and shock wave successively. The large-scale cavities shedding caused by re-entrant jet provides the premise for the generation of shock waves. The phenomenon of detached cavities collapses induces the formation of shock waves. The pressure distribution of the monitoring points shows that the shock wave propagates upstream from the trailing edge of the hydrofoil, which is the main reason for the rapid shedding and collapse of the residual cavities. The shock wave propagation speed shows that there is an acceleration in shock wave propagation process. The increase of driving pressure caused by the residual cavity collapses is the main reason for accelerated propagation of shock wave.
•The shock wave phenomenon is captured effectively by the compressible method.•The large-scale shedding of the cavity caused by the re-entrant jet leads to the generation of shock waves.•The collapse of residual cavity is the main reason for the acceleration of shock wave propagation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Pipeline turbines are designed to supply power for smart sensors installed in water pipelines. They are installed in the water supply pipe network directly and should meet the performance ...requirements for starting up at low flow rates and having low pressure loss at high flow rates. To this end, we designed two types of vertical axis pipeline turbines with lift-type runner and drag-type runner respectively, and conducted both experimental test and numerical simulations on the hydraulic performance of both the turbines. The results show that both the lift-type and drag-type turbines can meet the performance requirements. Under the same incoming flow conditions, the critical startup flow rate, the tip speed ratio, and the power coefficient of the lift-type turbine is larger. And the startup process of the lift-type turbine is unstable. While the drag-type turbine shows the opposite performances in these respects. In the range of incoming flow velocity studied, the pressure loss of both the turbines increases with the incoming flow velocity, however, the maximum pressure loss is controlled in an acceptable range, which will not affect the normal water supply.
•Lift-type and drag-type hydro turbine with vertical axis for power generation from water pipelines are designed.•Lift-type turbine has poorer startup performance but better power performance than drag-type turbine.•The reason of the startup performance of both the turbines are analyzed.•Both the turbines have reasonably low pressure loss.•Similar power coefficient and pressure loss characteristics are found with the same type wind turbine.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The gel polymer electrolyte (GPE) in flexible zinc–air batteries (ZABs) requires exceptional water retention, ion conductivity, and stretchability. However, some GPEs used in ZABs face issues, such ...as electrolyte evaporation and poor cycle life. Here, we develop a sodium polyacrylate-based GPE for rechargeable ZABs by incorporating graphene oxide nanoribbons (GONRs) and cellulose nanofibers (CNF). This fosters hydrogen bonds that create ionic conductive channels, enhancing the ionic conductivity and ZAB performance. The GPE demonstrates excellent water retention, stretchability, and ion conductivity of 268.2 mS cm–1. It stretches up to 20.4 times its length, making it a promising candidate for energy storage due to its adjustable shape, mechanical strength, and GONR flexibility. Rechargeable sandwich-type ZABs with this GPE exhibit over 323 h cycle life at 2 mA cm–2 and a discharge power density of 90.7 mW cm–2. Cable-type all-solid-state ZABs achieve an energy density of 87.8 mW cm–2 with high flexibility, highlighting the potential for wearable energy applications.
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