Search Results (185)

Corner radius end mills (CREMs) are widely used in machining due to their unique tool geometry, which improves surface quality. Variations in cutting force during machining significantly impact machining quality. Therefore, precisely predicting cutting forces is critical for controlling machining chatter and enhancing accuracy. Traditional element force models have complex formulas and high computational demands when considering tool runout. This paper proposes a hybrid prediction model for CREMs that integrates the separate-edge-forecast method and the BP neural network. The integration approach incorporates runout effects into cutting force coefficients and addresses nonlinear effects from runout. The accuracy of the cutting force prediction model was validated through side milling on 7075 aluminum alloy. The results indicate that the maximum error between the predicted and measured forces is 9.43%, demonstrating that this model ensures high prediction accuracy while reducing computation cost. Full article

Pedestrian wind comfort is a critical factor in the design of sustainable and livable dense urban areas. This study systematically investigates the effects of surrounding building height and wind incidence angle on pedestrian-level wind conditions, analyzing a nine-building arrangement through validated Computational Fluid Dynamics (CFD) simulations. Scenarios included neighborhood heights varying from 0L to 6L and wind angles from 0° to 45°. The results reveal that wind angles aligned with urban canyons (0° case) induce a strong Venturi effect, creating hazardous conditions with Mean Velocity Ratio (MVR) peaks reaching 3.42. Conversely, an oblique 45° angle mitigates high speeds by promoting flow recirculation. While increasing neighborhood height generally intensifies channeling, the study also highlights that even an isolated building (0L case) can generate hazardous localized velocities due to flow separation around its corners. The Overall Mean Velocity Ratio (OMVR) analysis identifies that, among the studied cases, a 2L neighborhood height is the most tolerable configuration, striking a balance between sheltering and channeling effects. Ultimately, these findings highlight for urban planners the importance of analyzing diverse geometric configurations and wind scenarios, reinforcing the value of CFD as an essential tool for designing safer and more comfortable public spaces. Full article

The interaction between a shock wave and a boundary layer promotes corner separation and prevents performance enhancement in a supersonic compressor cascade. Different vortex generator (VG) designs are presented to control corner separation in a supersonic compressor cascade, including endwall VGs (EVG), suction surface VGs (SVG), and combined endwall and suction surface VGs (E-SVGs). It is demonstrated that EVG and coupled E-SVGs reduce losses in the supersonic compressor cascade. For an optimal EVG, the total loss is reduced by 24.6% and the endwall loss is reduced by 33.6%. The coupled E-SVG better controls corner separation and reduces endwall losses by 56.9%. The suppression mechanism is that vortices alter the direction of the separated flow, allowing it to overcome the chordwise pressure gradient. Moreover, the VGs change the shock structure near the endwall. For the EVG, clockwise vortices are effective in controlling corner separation due to their minor effect on the shock structure near the endwall. However, anticlockwise vortices are not suitable for controlling corner separation in the supersonic compressor because they increase the shock strength induced by the VG. The control mechanism of the coupled E-SVG on corner separation is also discussed. Full article

Corner separation at the junction of blade surfaces and end walls remains a significant challenge in compressor cascade performance. This study proposes a passive flow control strategy inspired by the geometric arrangement of biological fish scales to address this issue. A fish scale-like surface structure was applied to the suction side of a cascade blade to reduce viscous drag and modulate secondary flow behavior. Wind tunnel experiments and numerical simulations were conducted to evaluate its aerodynamic effects. The results show that the fish scale-inspired configuration induced climbing vortices that energized low-momentum fluid near the end wall, effectively suppressing both passage and corner vortices. This led to a reduction in spanwise flow penetration and a decrease in total pressure loss of up to 5.69%. The enhanced control of secondary flows also contributed to improved flow uniformity in the end-wall region. These findings highlight the potential of biologically inspired surface designs for corner vortex suppression and aerodynamic efficiency improvement in turbomachinery systems. Full article

The one-dimensional (1D) Sb(III)-based organic–inorganic hybrid perovskite (AImd)₂¹_∞[SbI₅] (AImd = 1-allylimidazolium) crystallizes in the orthorhombic, centrosymmetric space group Pnma. The structure consists of corner-sharing [SbI₆] octahedra forming 1D chains separated by allylimidazolium cations. Void analysis through Mercury CSD software confirmed a densely packed lattice with a calculated void volume of 1.1%. Integrated quantum theory of atoms in molecules (QTAIM) and non-covalent interactions index (NCI) analyses showed that C–H···I interactions between the cations and the ¹_∞[SbI₅]²⁻ network predominantly stabilize the supramolecular assembly followed by N–H···I hydrogen bonds. The calculated growth morphology (GM) model fits very well to the experimental morphology. UV–Vis diffuse reflectance spectroscopy allowed us to determine the optical band gap to 3.15 eV. Density functional theory (DFT) calculations employing the B3LYP, CAM-B3LYP, and PBE0 functionals were benchmarked against experimental data. CAM-B3LYP best reproduced Sb–I bond lengths, while PBE0 more accurately captured the HOMO–LUMO gap and the associated electronic descriptors. These results support the assignment of an inorganic-to-organic [Sb–I] → π* charge-transfer excitation, and clarify how structural dimensionality and cation identity shape the material’s optoelectronic properties. Full article

A highly loaded axial flow compressor often leads to significant flow separation, resulting in increased pressure loss and deterioration of the pressure increase ability. Improving flow separation within a compressor is crucial for enhancing aeroengine performance. This study proposes adding a fin structure to the jet cavity of the Coanda jet cascade to improve flow separation at the trailing edge and corner area. The fin structure is optimized using response surface technique and a multi-objective genetic algorithm based on numerical simulation, enabling more effective control of the simultaneous separation of the boundary corner and trailing edge of the layer. The response surface model developed in this study is accurately validated. The numerical results demonstrate a 2.13% reduction in the optimized blade total pressure loss coefficient and a 12.74% reduction in the endwall loss coefficient compared to those of the original unfinned construction under the same air injection conditions. The optimization procedure markedly improves flow separation in the compressor, leading to a considerable decrease in the volume of low-energy fluid on the blade’s suction surface, particularly in the corner area. The aerodynamic performance of the high-load cascade is enhanced. Full article

The manipulation of cells and bioparticles has garnered significant interest in the field of viscoelastic microfluidics, particularly regarding its capacity for single-stream focusing within a three-dimensional and simple microchannel structure. The inherent simplicity of this method enables the effective manipulation of particles, facilitating the separation and focusing of various cell types, including blood cells, circulating tumor cells (CTCs), and microalgae. However, the viscoelastic nature of the particles imposes limitations in the handling of submicron-sized particles, due to a significant decrease in the viscoelastic force acting on the particle. In this study, we propose a microfluidic device featuring a cruciform cross-sectional microchannel with 45 µm and 45 µm of its vertical and horizontal size, respectively. The cruciform microchannel, which has a 270° reflex angle on four corners, can increase the viscoelastic force on the particles, allowing the device to focus submicron-sized particles down to 180 nm in a single-stream manner. It is important to note that the single-stream formation was maintained, while the channel width at the outlet region was drastically increased, allowing for the enrichment of submicron-sized particles. For biological feasibility, the proposed device also demonstrates the single-stream focusing on biological particles such as bacteria. The presented microfluidic device would have great potential for the focusing and enrichment of nanoparticles including bacteria in a highly robust manner, expecting its use in the various fields such as diverse biological analysis and biomedical research. Full article

The Trombe Wall (TW) has gained recognition for its simplicity, efficiency, and zero operational costs, making it a key contributor to Sustainable Development Goals (SDGs) 7 and 11 by enhancing energy access and providing sustainable heating solutions. This passive solar technology is particularly beneficial in rural areas, offering cost-effective thermal comfort while minimizing environmental impact. This study evaluates the performance of three TW configurations attached to a room, designed with inclined glazing relative to the vertical air layer and stone layers at the bottom acting as thermal mass, commonly used in rural installations in Peru. Using 2D Computational Fluid Dynamics, the analysis compares an inclined heated wall with guided vanes featuring three or five blades to a configuration without vanes. Results show that the three-blade guided flow configuration achieves the highest temperature rise of 4 °C, with a reference temperature of 20 °C, under an absorber heat flux of 200–400 W/m², albeit with a slightly lower flow rate of 0.17–0.23 kg/s compared to the configuration without guided flow. The maximum thermal efficiency of 57.90% was observed for the three-blade configuration, which is 2.26% higher than the efficiency of the configuration without guided flow, under an absorber heat flux of 400 W/m². The obtained path-lines reveals that the three-blade configuration minimizes flow detachment, nearly eliminates recirculation near the bottom corner of the glazing, and reduces the separation bubble at the top corner of the massive wall near the outlet. These findings highlight the potential of guided vanes to enhance the performance of Trombe Walls in rural settings. Full article

From 1940 to the present, Turkish seismic standards for masonry building have gradually evolved, culminating in the performance-based TBEC (2018). Unregulated tenant expansions and informal construction, especially in rural areas, continue to be a significant cause of seismic risk despite developments in ring beam design, mortar categorization, and capacity-based criteria. This paper critically examines the structural flaws caused by such expansions in partly built unreinforced masonry homes, focusing in particular on areas of moderate-to-high seismicity. The research shows that occupant changes often ignore necessary seismic protections by means of post-earthquake field observations, comparative code analysis, and recorded failure patterns. Among them are wall slenderness ratios, ring beam continuity, and masonry unit and mortar quality checks. Common ensuing failures include corner disintegration, roof–wall separation, and diagonal shear cracking. Relying on qualitative analysis of reoccurring damage mechanisms seen during field investigations, the results come from post-disaster evaluations of 2568 masonry dwellings after the 2023 Kahramanmaraş earthquakes. This paper emphasizes a continual gap between seismic rules and informal building practice and contends that without official acknowledgment of owner-built changes, code efficacy stays constrained. These results are also of worldwide importance for earthquake-prone areas struggling to control informal or self-built buildings. Full article

This paper reviews the evolution of flow control methods for bladed linear cascades, focusing on passive techniques like riblets, grooves, vortex generators (VGs), and blade slots, which have proven effective in reducing drag, suppressing flow separation, and enhancing stability. The review outlines key historical developments that have improved flow efficiency and reduced losses in cascades. Bio-inspired designs, including riblets and grooves, help stabilize the boundary layer, reduce loss coefficients, and improve flow turning, which is vital for controlling drag and secondary flow effects. Vortex generators, fences, and slotted wingtips enhance stall margins and suppress corner separation, improving performance under off-design conditions. These methods are optimized based on aerodynamic parameters such as Reynolds number and boundary layer characteristics, offering substantial efficiency gains in high-performance compressors. Advancements in computational tools, like high-fidelity simulations and optimization techniques, have provided deeper insights into complex flow phenomena, including turbulence and vortex dynamics. Despite these advancements, challenges remain in fully optimizing these methods for diverse operating conditions and ensuring their practical application. This review highlights promising strategies for improving flow control efficiency and robustness, contributing to the design of next-generation turbomachinery. Full article

Suction is an important control method in the shock wave and boundary layer interaction (SWBLI). Aimed at the problem of separation bubbles induced at the expansion corners, this study investigates the influence of suction on both the dimensions of bubble and the structure of the flow field at varying positions and back pressures under Ma = 2.73. As the upstream suction hole moves to the shoulder point, the size of the separation bubble decreases slightly. The decrease in back pressure leads to an increase in flow deflection angle α_h. The low-kinetic-energy fluid in the boundary layer is removed and the thickness of the boundary layer decreases. Suction downstream of the shoulder point leads to an obvious change in separation bubble size. When the bleed position is upstream of the actual location of incident shock (D_down = 2δ), the separation zone is located at the trailing edge of the hole, and the convergence of the separation shock wave (SS) and the barrier shock wave (BSW) leads to a large increase in the pressure plateau. At the downstream of the incident shock (D_down = 5δ), the separation zone is situated at the leading edge of the hole, resulting in a substantial reduction in the size of the separation bubble. The flow reaches 88.5% of the theoretical expansion value at the shoulder point and directly turns into the bleeding area at the leeward side of the separation bubble. The deflection angle α_h reaches the maximum of 46°, and the sonic flow coefficient Q_sonic increases significantly. At the theoretical incident shock position (D_down = 7δ), the separation zone is far from the suction hole position; the two are almost decoupled. The size of the bubble increases rapidly and the reattachment shock wave (RS) appears. Full article

With the advancement of science and technology, wind power generation has been widely adopted globally. However, ice accretion severely limits the operational efficiency and structural safety of wind turbines in cold regions, while existing research primarily focuses on the impact of supercooled droplets on blade icing, the influence of ice crystals in cold environments on the blade icing process has been largely overlooked. This study systematically simulated the accretion of ice crystals and supercooled droplets under clear ice conditions. It evaluated the effects of various ice crystal parameters on the icing process using Fensap-Ice, which is an advanced icing simulation tool. The results indicate that ice accretion, driven by the combined action of ice crystals and supercooled droplets, weakened ice corners, making the ice shape smoother and fuller. When the angle of attack of the ice-covered airfoil exceeded 15°, a separating vortex formed on the suction side of the blade, leading to a reduction in the lift coefficient. The findings of this study highlight the critical role of ice crystals in the icing process and provide a scientific foundation for understanding the icing mechanism under complex meteorological conditions. Full article

The construction sector generates more than one-third of global waste. Although there is a consensus on the need to reduce it, empirical research evaluating current systems to develop circular solutions remains limited. Using a full-scale model, this article evaluates the disassemblability of the corner joint between two prefabricated lightweight timber-framed walls, a system widely adopted in residential construction in North America. The analysis deconstructed the disassembly actions, identified their level of difficulty, and classified the recovered materials into three categories: reusable, recyclable, and waste. The results reveal that the lack of design criteria for disassembly significantly limits the system’s circularity, as it prioritizes assembly speed and energy performance. The predominant use of nails as fasteners complicates the separation of layers, damages materials, and restricts their reuse. This highlights the urgent need to redesign construction solutions that enable efficient disassembly, promote component recovery, and extend their time in circulation. This study establishes a foundation for the evolution of lightweight timber-framed panel design toward systems more aligned with circularity principles. Full article

Tandem blades have been recognized for their potential to enhance the loading capacity of compressors. However, tandem stators currently do not exhibit advantages due to insufficient understanding of the complex end-wall flow mechanisms. To address this, an extensive study was conducted on tandem stators using experimental and numerical methods. The analysis focused on loss development, three-dimensional flow structures, and interaction mechanisms between front and rear blades. The results indicated the following: (1) The rear blade’s influence on the front blade has contrasting effects in mid-span and end-wall regions. The stagnation action of the rear blade increases front blade load, leading to greater corner separation losses. (2) Mid-span flow losses account for over 60% of total losses near stalls, primarily due to increased mixing losses from the migration of front blade corner separations towards the mid-span region in the rear blade channel. (3) At higher mass flow rates, corner separations occur in the rear blade, driven by significant circumferential pressure differences at the front section of the rear blade, causing end-wall fluid migration towards suction surfaces. (4) Corner stalls predominantly occur in the front blade, with associated losses exceeding those in conventional blades. Full article

Freedom of design and the cost-effective production of structural parts have led to much research interest in Wire Arc Additive Manufacturing (WAAM). Nevertheless, WAAM is subject to design constraints and fundamentally differs from other additive manufacturing processes. Consequently, design guidelines and supporting design evaluation tools adapted to WAAM are needed. One geometric approach to design evaluation is the use of a three-dimensional medial axis transformation (3D-MAT) to derive local geometry indicators. Previous works define the thickness and radius indicators. In this work, the angle between opposing faces and a mass gradient indicator are added. To apply the literature design rules regarding wall thickness, clearance, bead angle, and edge radius to specific geometry regions, features are classified by the indicators. Following a literature suggestion, wall and corner regions are differentiated by the angle indicator. An angle of ${65}^{°}$ is identified as an effective separation limit. Additionally, the analogy of Heuvers’ spheres to the MAT helps estimate a limit of ${\displaystyle \frac{k_H-1}{k_H+1}}$ for the mass gradient ($k_H$: Heuvers’ factor). Finally, tests on example parts demonstrate the method’s effectiveness in verifying compliance to the specified rules. With a numerical complexity of $\mathcal{O}\left(n^2\right)$, this method is more efficient than finite element analyses, providing early feedback in the design process. Full article