Increase In Angle Research Articles

Transition of Liquid Drops on Microstructured Hygrophobic Surfaces from the Impaled Wenzel State to the "Fakir" Cassie-Baxter State.

Low adhesion of liquids on solid surfaces can be achieved with protrusions that minimize the contact area between the liquid and the solid. The wetting state where an air cushion forms under the drop is known as the Cassie-Baxter state. Surfaces where liquids form macroscopic contact angles above 150° are called superhydrophobic and superhygrophobic, if we refer to water or any liquid, respectively. The Cassie state is desirable for applications, but it is usually unstable compared to the Wenzel state, where the drop is in direct contact with the rough surface. The Cassie-to-Wenzel transition can be triggered by an increase in pressure and vibrations, but the inverse Wenzel-to-Cassie is much more difficult to observe. Here, we examine under what conditions the Wenzel-to-Cassie transition is triggered when the microscopic contact angle changes abruptly. For this, we applied a lubricant of low surface tension around drops that were in the Wenzel state on microstructured surfaces. The increase of the microscopic contact angle lifted the drop from the rough surface, when the pillar height and spacing are large and small, respectively. Numerical calculations for the drop-lubricant interface showed that the surface geometry requirements for the Wenzel-to-Cassie transition are stricter than the ones for the stability of the Cassie state. A surface geometry where the Cassie state is more stable than the Wenzel for a given Laplace pressure of the drop may not always allow the Wenzel-to-Cassie transition to take place. Therefore, the stability of the Cassie state is a necessary but insufficient condition for the inverse transition.

INVESTIGATION OF THE BENDING BEHAVIOR OF INC625/SUS316L LASER-CLADDING LAYERS APPLIED TO GGG40

Laser cladding is a multi-purpose thermal coating technology whose application area has increased rapidly in recent years. It can be used for the purposes of obtaining a thick (mm to cm) layer on surfaces by the interaction of different materials in powder form (especially metallic and metal-matrix composite) with the laser beam, thus repairing, restoring, improving and protecting the surface resistance of various industrial metallic parts. It is normally used to refurbishment, create and repair metallic components, hydraulic mills, gears, shafts, turbine blades, drilling tools, and other static or dynamically loaded mechanical parts. The benefits of laser cladding over alternative technologies include better metallurgy (bonding, hardness or lower porosity) as well as reduced part deformation and stress due to lower overall heat input. The melting of substrate material ensures a good metallurgical bond between the cladding layer and the substrate material. However, the melting of the substrate material causes dilution. Therefore, the melting of the substrate material should be controlled and kept to a minimum because high substrate melting causes an increase in the dilution, which may degrade the mechanical and corrosion properties of the clad layer. The laser beam over the substrate materials creates temperature gradients in the thickness direction that can lead to mechanical deformation (such as bending) and changes in the microstructural and interface properties. Depending on the substrate type and production history, as well as the laser-clad powder properties and process parameters (power, feed rate, clad speed etc.) used in the application, the deformation properties of the cladded part and its bending behavior can change. In this study, INC625 and SUS 316L+INC625 clad layers were applied on a GGG40 substrate with optimized parameters and then subjected to bending tests. Bending-test results were examined comparatively and their microstructural properties were examined. Cladding powder feedstock material properties, substrate type and its thermo-physical properties, clad process parameters and surface preparation conditions, number and thickness of layers are the most important factors affecting the bending behaviour in laser-cladding applications and require optimization studies. The INC625 clad layer on the SUS316L bond layer has reduced the diffusional effects, and the hardness distribution has a more homogeneous profile. In this way, an increase in bending angles was observed. The highest bending angle of 32° was measured with dublex-clad layered samples.

Effect of Different Skew Angle on Tensile Fracture Behavior of SiC Fiber Monofilament

Abstract In fiber reinforced composites (FRP), silicon carbide fiber is indispensable. Its mechanical properties determine the performance of ceramic matrix composites. Therefore, the tensile and fracture behavior of silicon carbide fiber monofilaments should be studied in depth. In order to make the test results of fiber properties more accurate, this paper takes SiC fiber monofilament as the research object, carries out tensile tests at different deflection angles, and carries out WEIBULL statistical analysis and comparison of the data. The microscopic morphology of the tensile fracture of each single fiber was observed by SEM, and the change rule of the mechanical properties and fracture behavior of the fiber with the deflection angle was summarized, and whether the slight deflection affected the test results was explored. The results showed that: (1) The mechanical properties of SiC fiber monofilament decreased gradually with the increase of deflection angle, and the extent of decline gradually increased. (2) With the increase of deflection angle, the proportion of stepped fracture gradually increases, and that of flat fracture gradually decreases.

One-step laser preparation of unidirectional liquid spontaneous transport structures

The Tilted Wedge Microcavity Array (TWMA) structure of the Nepenthes alata peristome allows for unidirectional fluid transport without any surface energy gradient. However, current methods of creating bionic Nepenthes alata peristome structures have significant improvement room in terms of structural shape, machining efficiency, and cost-effectiveness. To address these issues, in this paper, bionic Nepenthes alata peristome TWMA structures on 7075 aluminium alloy was built via a nanosecond laser with highly efficiency, low cost and flexible processing pattern. A unilateral tilted microcavity structure was fabricated by designing the laser processing path, and at the same time, the samples were tilted to change the angle at which the laser beam hit the working surface. This ensures that the microcavity is machined without destroying the microcavity structure underneath. The variation law of aluminum alloy ablation threshold under the influence of laser incidence angle was studied. The dimensional parameters of the TWMA structure were analysed in relation to laser incidence angle θ, laser processing power P, number of laser scans n, and laser scanning speed V. Additionally, liquid spreading tests were carried out on different surfaces of bionic structures, and the influence of surface wettability on the spreading results was investigated. The results indicate that the ablation threshold decreases initially and then increases with an increase in the laser incidence angle. This reflects the trend of the aluminium alloy absorption rate, which initially increases and then decreases with an increase in the incidence angle. For the prepared TWMA structure, the optimum speed of achieving the unidirectional spreading effect was found to be 2.41 mm s−1 with a surface contact angle (CA) of 35°. This study presents a low-cost and rapid preparation method for creating liquid unidirectional transport structures without any energy input.

Analyses of non-clean surface compressor blade cascades’ aerodynamic performance deterioration

Abstract The efficiency and dependability of the engine are directly impacted by the compressor’s performance, which is a crucial part of gas turbines. The blade cascade is significantly influenced by surface roughness in terms of flow characteristics and aerodynamic performance. In this study, the NACA65-410 airfoil is selected as the research object to investigate the variations in blade cascade performance and flow characteristics under different inflow and roughness conditions. The results show that the smooth surface blade cascade performs optimally when the Reynolds number increases from 120,000 to 200,000. As the angle of attack increases from -5° to 8°, the blade cascade performance deteriorates, and the degree of performance degradation increases with the increase in angle of attack. For the roughened blade cascade surface, the performance initially improves and then decreases as the equivalent sand grain density increases, and there exists a critical equivalent sand grain density that maximizes the blade cascade performance. When the Reynolds number is 120,000, the critical equivalent sand grain density is 225 μm, and when the Reynolds number is 160,000, the critical equivalent sand grain density is 111 μm. Based on the findings of this study, the degradation pattern of blade cascade performance can be predicted, and it can be utilized to enhance the overall performance of the compressor.

Research on the pitching hydrodynamic performance of pump-jet propelled submersible

Abstract Most of the current research in the world on the dynamical characteristics of pump-jet propelled submersibles has focused on the dynamic response of non-vector propulsion. However, the dynamics characteristics of water jet vector propulsion by external bypass excitation have been neglected. Therefore, this paper explores the variable vector deflection angle-controlled pitching motion in the vertical plane of the submersible and the isokinetic constant linear pitching motion water motion. ANSYS software is used to perform numerical calculations to investigate the changes of drag and Lifting force with velocity under different navigation states. Conclusion: In the process of surfacing, the change trend of Lifting force and drag is the same: when adjusting the navigation deflection angle, it increases rapidly, and then when floating in a constant straight line, it gradually decreases, and finally, the decrease rate tends to level off; when the elevation angle increases, the change amplitude of drag and Lifting force increases. During the dive, the drag force decreases and the Lifting force increases, gradually, the rate of decrease of drag force and the rate of increase of Lifting force become smaller; when the pitch angle increases, the Lifting force decreases rapidly and the decrease of drag force becomes larger.

Modification of Epoxy Coatings with Fluorocontaining Organosilicon Copolymers.

Preparation of hydrophobic coatings is still a challenge for researchers in various fields of science. One of the easiest ways consists of the use of special modifiers. However, usually such modifiers are poorly compatible with organic polymeric matrixes, which leads to segregation of modifiers and deterioration of coating properties. In this work, we have synthesized a number of organosilicon copolymers and studied their compatibility with epoxy matrix and hydrophobic efficiency. It was shown that the increase of phenyl-containing units leads to increase of compatibility but decreases hydrophobic efficiency. Addition of small amounts of such modifiers into commercial epoxy paint material can lead to an increase of contact angle of the final coating from 63 to 87° without deterioration of other physico-mechanical properties. These results open new perspectives in preparation of organosilicon hydrophobic modifiers with directed properties for fields of application such as paints and coating materials.

Vortex-induced vibration characteristics of rigidly connected four-cylinder system and nonlinear energy sinks for vibration suppression

In order to study the vortex-induced vibration (VIV) characteristics of rigidly connected four-cylinder systems and the suppression of vortex-induced vibration by nonlinear energy sinks (NESs), a fluid–structure coupling dynamic simulation model of a two-degree-of-freedom rigidly connected four-cylinder system is established based on computational fluid dynamics, structural dynamics, and overset mesh technology. The accuracy of the numerical model established in this paper is verified by comparing with the experimental data of literatures. The results show that the dimensionless vertical amplitude of the four-cylinder system decreases with increase in the inflow angle, the reduced velocity advance of the maximum vertical amplitude moves forward and the frequency “lock-in” interval is shortened. Among them, the maximum amplitude at Ur=7 is 0.75 when the inflow angle is 0°, and the maximum amplitude is 0.54 at Ur=6.5 when the inflow angle is 45°. The corresponding frequency “lock-in” interval ranges from Ur=4.5–7 change to Ur=5–6.5. The NES can absorb the cylinder vibration energy, and when the NES parameter β=0.1,ξ=0.8,γ=0.8, the maximum vertical of the four-cylinder system with inflow angle of 0° can be reduced by 76%.

Investigation of far-wake models coupled with yaw-induction control for power optimization

Combined wake steering and induction control is a promising strategy for increasing collective wind farm power production over standard turbine control. However, computationally efficient models for predicting optimal control set points still need to be tested against high-fidelity simulations, particularly in regimes of high rotor thrust. In this study, large eddy simulations (LES) are used to investigate a two-turbine array using actuator disk modeling in conventionally neutral atmospheric conditions. The thrust coefficient and yaw-misalignment angle are independently prescribed to the upwind turbine in each simulation while downwind turbine operation is fixed. Analyzing the LES velocity fields shows that near-wake length decreases and wake recovery rate increases with increasing thrust. We model the wake behavior with a physics-based near-wake and induction model coupled with a Gaussian far-wake model. The near-wake model predicts the turbine thrust and power depending on the wake steering and induction control set point. The initial wake velocities predicted by the near-wake model are validated against LES data, and a calibrated far-wake model is used to estimate the power maximizing control set point and power gain. Both model-predicted and LES optimal set points exhibit increases in yaw angle and thrust coefficient for the leading turbine relative to standard control. The model-optimal set point predicts a power gain of 18.1% while the LES optimal set point results in a power gain of 20.7%. In contrast, using a tuned cosine model for the power-yaw relationship results in a set point with a lower magnitude of yaw, a thrust coefficient lower than in standard control, and predicts a power gain of 13.7%. Using the physics-based, model-predicted set points in LES results in a power within 1.5% of optimal, showing potential for joint yaw-induction control as a method for predictably increasing wind farm power output.

Study on the Damage and Failure Process of Prefabricated Hole-Fracture Combination Defects in Shale

The rock formations in oil and gas reservoirs are predominantly composed of laminated shale, which contains various defects such as pores and fractures. These defects have a significant impact on the stability of wellbore walls. As a result, this study utilized rock samples from a specific oil and gas reservoir and introduced pre-existing pore and fracture defects within them. Uniaxial compression tests were conducted on rock specimens with varying angles between the fractures and the bedding planes. The study involved measuring and analyzing the impact of pre-existing defect morphology on shale’s mechanical properties. Additionally, through the use of digital image correlation (DIC) technology, a comprehensive strain field map was obtained, depicting the initiation, propagation, and ultimate failure of surface cracks in shale under loading conditions. This allowed for both qualitative and quantitative analysis of the connection between shale’s damage and failure processes and the evolution of strain fields. Ultimately, this research provides a theoretical basis for wellbore stability and the development of shale oil and gas fields. Conclusions drawn from the study are as follows. With an increase in fracture angle, the rock’s elastic modulus gradually increases, and both compressive strength and strain exhibit a pattern of higher values on both ends and lower values in the middle. When the fracture angle is less than 30°, significant stress concentration occurs at the tip of the fracture. When the angle exceeds 60°, stress concentration around pores dominates. In the range of 30° to 60°, there is a combined stress concentration around both pores and fractures, significantly reducing rock stability. Crack propagation is influenced by bedding planes and exhibits varying degrees of ductility, ultimately resulting in a tension-shear mixed failure. When fractures are parallel to bedding planes (angle = 0°), defects are symmetrically distributed, and stress concentration at the fracture tip dominates, leading to crack initiation from the fracture tip and eventually forming an “H”-shaped tensile failure. When fractures are perpendicular to bedding planes (angle = 90°), stress concentration around pores is greater than at the fracture tip, causing cracks to initiate around pores and eventually collapsing on one side of the fracture.

Cold plasma-assisted pretreatment for fabrication and characterization of rice starch-stearic acid complexes

The present study explored the modification of rice starch via dielectric barrier discharge cold plasma (DBD-CP) employing air and argon as the input gas, followed by complexation with stearic acid to yield modified rice starch-stearic acid complexes. The complexes were characterized by a V-type crystalline structure, exhibiting enhanced thermal stability and hydrophobicity compared to conventional rice starch-stearic acid complexes. Utilization of argon as the input gas markedly improved the modification effects on complexes over air, as evidenced by a further increase in the water contact angle to 78.99°, an ergosterol encapsulation rate of 50.91%, and an in vitro digestive release rate of 70.84% within the prepared Pickering emulsion. These findings indicate the significant potential of DBD-CP pretreatment with argon for enhancing the physicochemical properties of starch-fatty acid complexes, particularly in the formulation of Pickering emulsions with improved emulsifying capacities.

Study on acoustic emission and local deformation characteristics of feldspar vein-intrusive metagabbro at different angles of splitting

Feldspar vein-intrusive metagabbro is a special geological structure, and different stress angles have an important influence on the fracture mode and deformation characteristics of metagabbro. A Brazilian splitting test on feldspar vein-intrusive metagabbro was performed using three distinct stress angles (0°, 45°, and 90°), and acoustic emission signals and strain characteristics were monitored synchronously during the test. The results showed that the damage pattern of the feldspar vein-intrusive metagabbro was related to the feldspar mineral perforation damage on the main rupture surface. With the increase in stress angle, the percentage of high peak frequency increased gradually. The phenomenon of strain lagging stress appeared in the rock samples before the peak damage. The feldspar minerals played a controlling role in the expansion of microcracks in the feldspar vein-intrusive metagabbro. Significant differences in the local deformation coordination of rocks under different stress angles were observed. The deformation coordination of rock samples with a stress angle of 0° was much lower than that of other rock samples. This study is of great significance for the understanding of the deformation and damage laws of similar geological structures and also provides an important theoretical basis for the stability of deep chambers.

Analysis of Amplification Effect and Optimal Control of the Toggle-Style Negative Stiffness Viscous Damper

This paper proposes a new toggle-style negative stiffness viscous damper (TNVD), and evaluates the performance of the TNVD with the displacement amplification factor (fd) and the energy dissipation factor (fE). Firstly, the composition and characteristics of the TNVD are introduced. Subsequently, the displacement amplification factor is introduced to evaluate the displacement amplification ability of the TNVD, and it is decomposed into a geometric amplification factor and an effective displacement coefficient. Then, based on the geometric amplification factor and effective displacement coefficient, the correlation between the TNVD’s displacement amplification ability and inter-story deformation is studied, and an improved TNVD is proposed. By the comparison of the finite element calculation results, it is found that the improved TNVD can utilize the assumption of small structural deformation. After that, the impacts of plentiful aspects, such as the length of the lower connecting rod, the horizontal inclination angle of the lower connecting rod, the inter-story deformation limit, the cross-sectional area of the connecting rod, the damping coefficient, and the negative stiffness on the fd and fE of the improved TNVD, are expounded. The research results show that when the length of the TNVD’s lower connecting rod remains unchanged, the fd and fE present a trend of increasing first and then decreasing with the increase in the horizontal inclination angle of the lower connecting rod. When the inter-story deformation is fixed, there exists an optimal lower connecting rod’s length that satisfies a specific relationship to achieve the optimal geometric amplification factor of the TNVD. By adjusting the damping parameters of the TNVD, we can obtain a better effective displacement coefficient greater than 0.95 in the proposed target region. Meanwhile, the fd and fE increase with the decrease in the negative stiffness. An optimization strategy for the improved TNVD has been proposed to ensure that the TNVD has the characteristics of operational safety, ideal displacement amplification capability, and energy dissipation capability. Furthermore, a multi-objective control design method with an additional improved TNVD structure is proposed. The vibration reduction effect of the structure with the improved TNVD and the effectiveness of the optimization strategy are verified through examples.

Design and Driving Performance Study of Soft Actuators for Hand Rehabilitation Training.

To address the application requirements of soft actuators in rehabilitation training gloves, and in combination with ergonomic requirements, we designed a segmented soft actuator with bending and elongation modules. This actuator can achieve independent or coupled movements of the finger joints. A finite element model of the joint actuator was established to compare the driving performance of actuators with different structural forms. Numerical calculations were used to analyze the effects of structural size parameters on the bending characteristics and end output force of the actuator. The design was then refined based on these analyses. The joint actuator designed in this study demonstrated a 71% increase in bending angle compared to the standard fast pneumatic network structure. Key factors affecting the driving performance include the thickness of the constraint layer, the inner wall thickness of the chamber, chamber height, chamber width, chamber spacing, chamber length, and the number of chambers. After improvements, the bending angle of the joint actuator increased by 60.6%, and the output force increased by 145.9%, indicating significant improvement. This study designed and improved a soft actuator for hand rehabilitation training, achieving independent and coupled joint movements. The bending angle, bending shape, and joint driving force of the soft actuator meet the requirements for finger rehabilitation training.

Aerodynamic and Structural Assessment of Floating Wind Turbine Rotor Under Varying Tilt Angle

Predicting the aerodynamic performance of floating offshore wind turbines (FOWTs) proves challenging due to platform motion induced by waves. The effect of wind and waves results in a six-degree-of-freedom motion of the platform, directly influencing turbine performance. Understanding the impact of specific degrees of freedom (DOF) motions on aerodynamics and structural response is crucial for effective wind turbine design. This research examines the impact of rotor tilt on both aerodynamic performance and structural response. The investigation employs computational fluid dynamics (CFD) analysis and mapping aerodynamic loads onto the finite element (FE) mesh for structural analysis. The study employs a comprehensive 3D simulation, utilizing the moving reference frame (MRF) method for the NREL 5 MW reference wind turbine CFD simulations. It explores different rotor tilt angles (5°, 10°, 15°, and 20°) encountered by offshore structures during their operation and examines their impact on aerodynamic performance. Predicted aerodynamic loads were mapped onto the blade FE mesh using the radial basis function (RBF) interpolation technique and solved using the open-source FE solver CalculiX. The analysis shows that the turbine performance is relatively unaffected up to a tilt angle of 10°. However, further increase in rotor tilt angle adversely impacts turbine performance, leading to notable reductions in thrust and power output. The fluid-structure coupled analysis provided insights into the deformations and stresses experienced by the turbine blade, indicating a notable increase in flap-wise displacement for larger tilt angles, while edge-wise displacement is not as significantly affected. The maximum stress location on the blade generally correlates well with actual observations.

Research on the operation and quality control of small rock hole shotcrete robot

A small rock shotcrete robot is applied in the deep tunnel dynamic disaster physical simulation system in order to simulate the final operation process of the tunnel project. The robot’s spraying operation and control include many kind of factors. In this paper, the main parameters affecting the spraying operation are analyzed by establishing the spraying model and coating growth model. For matching reasonably the spraying parameters, the matching equation of spraying quality and spraying gun parameter model and spraying feed speed has been derived. Based on the matching equation, the spraying gun structure and robot control system are designed, and the spraying distance and spraying gun movement velocity including horizontal and vertical driving have been controlled better. On the basis of theoretical analysis, a small rock hole shotcrete robot prototype has been developed and the spraying experiments have been finished. The experimental results showed that the model and equation established can guided the spraying quality control. With the increase of the injection elevation angle, the length of the long and short axes of the elliptic coating becomes larger, and the average thickness of the coating center is between 2.23 and 2.34 mm, which meets the design index of the injection robot. The rock hole shotcrete robot meet the design requirements.

Shaken and Stirred: A Comparative Study of Earthquake‐Triggered Soft‐Sediment Deformation Structures in Lake Sediments

AbstractSubaqueous paleoseismic studies used soft sediment deformation structures (SSDS) to discern the shaking strength of past earthquakes, as the deformation degree of SSDS related to Kelvin Helmholtz Instability evolves from disturbed lamination and folds to intraclast breccia with higher peak ground accelerations (PGA). We lack comparative studies of different sediment types with SSDS related to earthquakes from different seismogenic sources to comprehend how these factors modulate earthquake‐induced deformation. Here, we compile sediment records with seven earthquake‐triggered SSDS from 10 lakes with organic‐, carbonate‐, siliciclastic‐, and diatom‐rich sediment from three subduction zones and one collisional setting. We target basin sequences with slope angles <0.65° to reduce the influence of gravitational downslope stress. We find that even minimal increases in slope angle, maximal 1°, lead to higher deformation degrees and, for some earthquakes, SSDS are only present at >0.65°. Fine‐grained clastics enhance sediment susceptibility to deformation, whereas abundant diatoms reduce it, demonstrating the influence of composition. Deformation correlates best with PGA and the vicinity of the earthquakes, suggesting that high frequency shaking promotes deformation. In addition, deformation only occurs above a minimum magnitude dependent on sediment composition, and higher deformation degrees in our studied basin sedimentary sequences only above Mw 4.9 for all sediment types, suggesting that sufficient duration of shaking—magnitude correlates with duration—is essential for SSDS development. We advise taking multiple cores on gentle slopes to study SSDS—additional to basin cores—to resolve small magnitude local earthquakes and relative differences in frequency content of past events.

Honeycomb structure design of automotive crash box

The crash box can protect the safety of passengers when a car collides. Due to its excellent mechanical properties, honeycomb structure can be applied to automotive crash boxes. Two kinds of crash boxes made of regular hexagonal honeycomb structure and re-entrant hexagonal honeycomb are designed. The research results indicate that, compared to the crash box made of hexagonal honeycombs, the crash boxes made of re-entrant hexagonal honeycombs have superior energy absorption ability. Furthermore, the influence of different structural parameters on the energy absorption performance (EAP) of the crash box made of re-entrant hexagonal honeycombs is analyzed. It is found that the total energy absorption and peak force increase with the increase of thickness and concave angle. The research in this article provides certain reference significance for the design of honeycomb structure crash boxes.

Engineering optics and thermodynamics design of parabolic trough solar collector

Abstract The development and design of parabolic trough solar thermal collectors (PTC) need to comprehensively consider the influence of optic, thermodynamic, layout, and other factors. The optics and thermodynamic analysis of PTC with different configurations was carried out, and the influence of layout on heat collection was studied. In the case of determined PTC aperture size, the distribution trend of solar irradiation flux density of different HCE diameters is the same, and the peak value of solar irradiation flux density is higher when the concentration ratio is larger. For the PTC with the same concentration ratio, with the incidence angle increase, the intercept rate and optical efficiency of the PTC decrease, the thermal energy loss rate increases, and the thermal efficiency decreases. Under the same incidence angle, with the increase of concentration ratio, the PTC’s intercept rate and optical efficiency decrease gradually, and the average efficiency of the PTC increases first and then decreases. In the process of PTC design and selection, considering the concentration ratio, latitude, and cost factors, the aperture size of 8.2 m and the HCE of the inner diameter of 90 mm can be used as the recommended configuration scheme for subsequent HCE development.

Numerical study on the influence of the bucket offset angle on the flow field of Pelton turbines with six-nozzles

Abstract Pelton turbines are emerging as a primary means for exploiting ultra-high water head resources. The hydraulic performance of a Pelton turbine is determined by the design of its runner/bucket. Among the critical parameters that affect the hydraulic performance of multi-nozzle Pelton turbines is the bucket offset angle (α). To investigate the influence of bucket offset angle on the flow field of Pelton turbines with six nozzles, this study conducted unsteady numerical simulations of gas-liquid two-phase flow for various bucket offset angles, employing the VOF multiphase model combined with the SST k-ω turbulence model. The results reveal that as the bucket offset angle increases, the axial width of the water sheet formed by the current jet progressively widens, with a tendency to catch up with the water film formed by the previous jet during the torque rising stage. Moreover, the increased bucket offset angle causes the water sheet to distribute more closely to the bucket cutout, raising the risk of leakage from the cutout. Notably, at α= 10°, some of the water sheet has already flowed out of the cutout and collided with the subsequent jet.