Speed Ratio Research Articles

Feature-wise scaling and shifting: Improving the generalization capability of neural networks through capturing independent information of features

From the perspective of input features, information can be divided into independent information and correlation information. Current neural networks mainly concentrate on the capturing of correlation information through connection weight parameters supplemented by bias parameters. This paper introduces feature-wise scaling and shifting (FwSS) into neural networks for capturing independent information of features, and proposes a new neural network FwSSNet. In the network, a pair of scale and shift parameters is added before each input of each network layer, and bias is removed. The parameters are initialized as 1 and 0, respectively, and trained at separate learning rates, to guarantee the fully capturing of independence and correlation information. The learning rates of FwSS parameters depend on input data and the training speed ratios of adjacent FwSS and connection sublayers, meanwhile those of weight parameters remain unchanged as plain networks. Further, FwSS unifies the scaling and shifting operations in batch normalization (BN), and FwSSNet with BN is established through introducing a preprocessing layer. FwSS parameters except those in the last layer of the network can be simply trained at the same learning rate as weight parameters. Experiments show that FwSS is generally helpful in improving the generalization capability of both fully connected neural networks and deep convolutional neural networks, and FWSSNets achieve higher accuracies on UCI repository and CIFAR-10.

Performance evaluation of a bidirectional horizontal axis tidal turbine with S-shaped blades by the sliced section method

Understanding the flow pressure distribution on the blade airfoil of the tidal turbine is of great significance for optimising the energy harvesting performance of the blades. In this paper, a bidirectional type horizontal tidal turbine (BHTT) with special S-shaped blades is proposed, which have a larger pitch diameter ratio provide excellent performance at low oncoming flow velocity by the theoretical, numerical and experimental methods. First, it is verified that the energy harvesting efficiency is basically the same in the case of bidirectional flow, and the S-shaped blade is divided into multiple slice sections, which could quantify the energy harvesting performance of each area of the blade. Then, using the method of mathematical statistics to divide more areas, the probability density shows a skewed distribution. The results show that the energy harvesting performance is less affected by flow velocity fluctuation, and the energy harvesting efficiency could reach 0.25-0.55 when the tip speed ratio is in the range of 0.2-0.5. Furthermore, the slice section method is adopted to make the influence of axial thrust intuitive and clear to study the turbine energy harvesting performance and improve the harvesting efficiency, which could provide a reference for the engineering design of tidal turbines.

Evaluation of the overset method applied to an active lift turbine

In the current context of energy transition, the development and improvement of energy recovery systems is essential. These system are numerous and some of them use turbines to convert flow kinetic energy into electricity. For a long time, vertical-axis turbines were considered less efficient than horizontal-axis ones. However, they are still better suited to urban areas. Thus, they are now being studied again and new turbine concepts are emerging that can works differently from today’s turbines. The entire dynamics of these new-generation turbines can be completely different from those of conventional turbines. The active lift turbine, for example, changes the trajectory of the blades (by varying the turbine radius) to convert the normal forces applying on them into torque. This particularity hinders the use of conventional rotation methods for turbines (Arbitrary Mesh Interface (AMI), Rotating Frame of Reference (RFR), …) in Computational Fluid Dynamics (CFD) and an innovative method such as overset could be an alternative. The purpose of this work is to evaluate the overset method for these new-generation turbines modelling. It enables the motion of a structure in its environment to be controlled at will. Various modelling parameters are being tested. The impact of the mesh size (mesh convergence), the turbulence modelling approach (RANS/LES) and the interpolation method between the background mesh and the overset mesh (Cell Volume Weight/Inverse distances) are evaluated and compared. The overset method is first validated on a conventional turbine (Darrieus turbine). The results obtained for the conventional turbine are close to those expected, with a relative error (numerical/experimental) between 3% and 8% depending of the Tip Speed Ratio (TSR) with an averaged error around 7%. Then overset method is extended to an active lift turbine to assess the potential of this new technology. The overset method proves its worth for this type of problem, which cannot be solved by conventional CFD methods of setting structures into motion. It provides control over blade motion without loss of information. Overall, this study demonstrates the interest and applicability of the overset method to the Active Lift Turbine or other kind of turbines that have a specific motion.

Effects of Gurney Flaps on the Performance of a Horizontal Axis Ocean Current Turbine

Gurney flaps can enhance the hydrodynamic efficiency of airfoils, and they are currently used in several applications, including racing cars and wind turbines. However, there is a lack of studies in the literature on the application of Gurney flaps on the Horizontal Axis Ocean Current Turbine (HAOCT). The influence of Gurney flaps on the hydrodynamic efficiency of the HAOCT is evaluated through numerical analysis. The effect of the Gurney flaps on the turbine is evaluated after the validation of the utilized numerical method is completed using the wind tunnel experimental data of the two-dimensional NACA 63415 airfoil and the water tunnel experimental data of the NACA 638xx series rotor on the clean blade. By calculating the velocity and pressure fields of the 2D airfoil by CFD, it was possible to analyze the lift improvement with the addition of the Gurney flaps by evaluating the pressure difference between the pressure surface and the negative pressure surface, and the drag improvement was due to the Gurney flaps obstructing the chordal flow of the fluid in the wake. For the 2D NACA-63415 airfoil, the drag coefficient increases with the increase in the head angle, while the lift coefficient increases and then decreases. The flap height divided by the local chord length of the Gurney flaps is 0.01, and the lift-to-drag ratio is the highest when the head angle is 4°. For the NACA-638xx turbine, the addition of Gurney flaps significantly increases the axial thrust coefficient. At lower tip speed ratios, the effect of the Gurney flaps on the rotor’s power coefficient is limited, with the greatest increase in the power coefficient at a tip speed ratio of 6 and a decrease in the power coefficient increase as the tip speed ratio increases. Increasing the height of the Gurney flaps can increase the peak power coefficient, but the power performance decreases at high tip speed ratios. The Gurney flaps distributed at the root of the rotor have less effect on the power performance. A 0.4 local radius spread of the Gurney flaps increases the peak turbine power coefficient by only 0.34%, while full-length Gurney flaps can increase the peaked blade power coefficient by 10.68%, indicating that Gurney flaps can be used to design a new HAOCT.

Multi-objective optimization design of the wind-to-heat system blades based on the Particle Swarm Optimization algorithm

A novel wind turbine direct driving heat pump (WTDHP) system is proposed, in which the heat pump is employed to replace the wind turbine's generator. The impacts of the blades with different tip speed ratios on WTDHP system are analyzed in this study. The inverse design method, verified by importing the design shape into FAST for simulation and comparing the simulated tip speed ratio and axial induction factor, was employed to create blades with different tip speed ratios. The heating performances of different blade shape designs at various turbulence and wind speeds are understood. The conclusion is drawn that the blades with a low tip speed ratio (λ=6–8) are clearly superior for heating in the turbulence categories IEC A at wind speeds between 6 and 14 m/s. However, the dynamic responses of the system are weakened by low turbulence and wind speeds. Taking into account the cost and manufacturing process, the blades with a high tip speed ratio can be chosen. Furthermore, the multi-objective optimization of blades was carried out using the enhanced Particle Swarm Optimization (PSO) algorithm, considering heating capacity, flapping load and blade mass. Based on the Wilson method, initial blade of PSO optimization algorithm is generated. Obtaining the heating capacity, flapping load and blade mass in real time from the simulation, the objective functions is calculated to update the status of particle swarm. After optimization using the improved multi-objective algorithm under turbulent wind with an average wind speed of 7 m/s, the blade mass is reduced by 2.96%, the flapping moment is reduced by 3.17%, and the heating capacity is increased by 1.22%. The results show that the optimization effect is more obvious at higher wind speeds.

Effects of tableting process parameters and powder lubrication levels on tablet surface temperature and moisture content

Punch sticking is a recurrent problem during the pharmaceutical tableting process. Powder moisture content plays a key role in the buildup of sticking; it evaporates due to increased tablet temperature, accumulates at the punch–tablet interface, and causes sticking through capillary force. This study investigated the effects of compaction pressure (CP), compaction speed (CS), and lubrication level (magnesium stearate (MgSt) ratio) on tablet surface temperature (TST) and tablet surface moisture content (TSMC). TST and TSMC were measured with an infrared thermal camera and near-infrared sensor, respectively. Microcrystalline cellulose was used as the tableting powder and MgSt as the lubricant. The low range of CS values (16–32 mm/s) considered in this study did not have significant effects on TST and TSMC. MgSt ratio had a significant positive effect on TST; this may be explained by the increase in powder blend effusivity with the addition of MgSt. However, MgSt ratio did not have a significant effect on TSMC. CP had a significant positive effect on both TST and TSMC. Increased CP induced higher heat generation through particle deformation and friction during the compaction phase, leading to increased TST. Furthermore, the water vapor diffusion rate through the powder bed might have increased due to the rise in thermal energy and led to further moisture accumulation at the tablet–punch interface, causing the significant positive effect of CP on TSMC. This result may explain the occurrence of sticking regardless of the CP applied during the tableting process.

Impact stress analysis on the pinch roll surface during hot rolled coiling and the improving methods

In order to reduce the occurrence of impact marks on the pinch roll surface, reduce the maximum impact stress, and prolong the service life of the pinch roll, the microstructure and mechanical properties of built-up welding layer by stellite delstain-442 welding wire were investigated firstly. Subsequently, impact stress simulation model between strip steel and pinch roll was established to reveal the effects of fore-end warping height, shape of strip, speed of strip, lead speed ratio and materials on the impact stress. The simulation results indicated that the fore-end warping height is the decisive factor on the impact stress. At fore-end warping height of 200 mm, the maximum impact stress between the strip steel fore-end and the pinch roll surface can reach 1300 MPa, obviously exceeding the yield limit of materials in use. Therefore, strictly controlling the fore-end warping height of the strip steel under 50 mm to reduce the maximum impact stress under 1000 MPa is the practicable way to reduce the occurrence of impact marks.

EFFICIENCY ANALYSIS OF ELECTROMECHANICAL CONVERSION SYSTEMS OF WIND TURBINES WITH AERODYNAMIC MULTIPLICATION

In this article, we have considered the state of development of high-power horizontal wind turbines. The most common wind turbines for operation with variable wind flow speed usually include a frequency converter to ensure the compatibility of generator with network. It leads to decrease in the efficiency of wind energy conversion system, while the use of direct connection of the generator to the axis of wind wheel leads to a significant increase in the weight and cost of the generator. The wind turbine with aerodynamic multiplication is an alternative to such systems. Its prototype with 750 kW power is manufactured and studied in Ukraine. This wind energy conversion system with the synchronous or induction generators offers the property to generate energy under optimal condition with invariable rotational speed of generator rotor within the wide range of variable speed of wind flow. In this case, it is not necessary to apply the frequency converter that contributes to increasing the efficiency and reducing the cost of wind turbine. As shown, the relative performances of mass, cost and efficiency of generators in proposed system comparatively to conventional one depend on the multiplication factor (i.e. ratio of the rotational speeds of wind turbine and generator). When the power of wind turbines is from 750 to 2500 kW, the multiplication factor is within the limits of 10.72 to 4.75. The theoretical and experimental study shows that the wind turbines with aerodynamic multiplication can be competitive as compared to conventional horizontal wind turbines. This article is aimed to comparative analysis of the quantitative and qualitative characteristics of the equipment used in high-power horizontal wind turbines with direct connection of generators to the axis of wind turbine and in wind turbines with aerodynamic multiplication. References 27, tables 1, figures 6.

Numerical investigation of the use of flexible blades for vertical axis wind turbines

This study proposes a novel vertical axis wind turbine (VAWT) design with flexible blades aiming to improve their energy extraction capability. The blade deformation is achieved using Ansys Fluent dynamic mesh and user-defined functions to control the position of the blades nodes at specific azimuthal angles. An optimization study is carried out using computational Fluid Dynamics (CFD) simulations and Design of Experiments (DOE) to get the optimal design parameters of the flexible blade at different Tip Speed Ratios (TSRs). In addition, a comparison between the DOE results of both 2D and 3D CFD simulations is achieved to assess the use of 2D simulations for optimization purposes. Also, a detailed numerical study of the aerodynamic performance of the turbine based on this new design is done to compare the rigid and flexible blade models' power coefficient and flow fields around the blades. Results of 2D and 3D CFD simulations show that the flexible blades are able to improve the power coefficient of the turbine by up to 66% and 32% respectively at low tip speed ratios diminishing gradually with increasing tip speed ratios. It is also noticeable that similar pattern in power coefficient results was obtained from the 2D and 3D simulations of both turbine models. This, in turn, demonstrates the efficacy of 2D simulations in accurately determining optimized design parameters while significantly reducing computational costs compared to 3D simulations.

Detonation in van der Waals Gas

Solving problems of detonation control is associated with obtaining detailed information about the gas dynamics accompanying the detonation process. This paper focuses on the dynamics of real gas flow through a plane detonation wave. The influence of real gas parameters on the Chapman–Jouguet detonation process has been studied. The process is described using the Rankine–Hugoniot system of equations. To model the thermodynamic properties of a real gas, the van der Waals equation of state is used. Equations are obtained to determine the ratio of speeds and pressures during the passage of a wave. The influence of van der Waals parameters on changes in the parameters of the detonation process was elucidated. An increase in parameter A slows down the increase in pressure in the detonation wave, and an increase in parameter B enhances it. Differences in the speed of combustion products for ideal and real gases are shown. For an ideal gas, combustion products flow from the detonation front at a critical (sonic) speed. For a van der Waals gas, the speed of combustion products may be greater than the critical one. Moreover, both factors, additional pressure (A) and additional volume (B), lead to acceleration of combustion products. Effects of heat release on the process parameters were elucidated.

Wind Speed Spectrum of a Moving Vehicle under Turbulent Crosswinds

Wind loads have become one of the key influencing factors for the running safety of vehicles and comfort of passengers. The investigation of the wind speed spectrum characteristics of a moving vehicle under turbulent crosswinds is of great importance. Expressions of the wind speed spectrum of a moving vehicle were obtained from the von Kármán spectrum, based on Taylor’s frozen flow hypothesis. The influencing factors, including the ratio of the vehicle speed to the wind speed and wind yaw angles, were analyzed. The change rules of the wind speed spectrum peak and its corresponding frequency were also studied. The results show that the wind speed spectrum peak values of the moving vehicle were larger than those of the static vehicle. The wind speed spectrum peak values corresponding to the moving vehicle were first increased and then decreased, as the wind yaw angles increased. Some of the frequencies corresponding to the longitudinal wind speed spectrum values of the moving vehicle were smaller than those of the static vehicle. Therefore, the energy had been transferred to the lower frequency. For the moving vehicle, the frequency values corresponding to the longitudinal wind speed spectrum peak were first increased and then decreased, as the ratio of the vehicle speed to the wind speed and the wind yaw angle increased.

Design, kinematic and fluid-structure interaction analysis of a morphing wing

The application of morphing wing enables vehicles to show better aerodynamic performance in various flight conditions. This article proposes a modular bilateral triangular pyramid (BTP) unit-based morphing wing skeleton (MWS) mechanism that may achieve continuous variable span-wise bend, span-wise twist, and sweep. A lockable morphing (LM) unit with the BTP unit is designed. Based on the Denavit–Hartenberg coordinate method and motion influence coefficient method, the kinematics of MWS mechanism is conducted. The theoretical models of the kinematic characteristics of the MWS mechanism during the three morphing patterns are obtained. The kinematic simulation models of three morphing configurations of the MWS mechanism are performed. The driving speed ratio of the linear actuator of span-wise bend and twist is analyzed during the twisting phase, and the analysis shows that there be a speed ratio minimizes the coupling bend angle. By comparing the results between the theoretical and simulation models, the accuracies of kinematic theoretical models under different morphing configurations are verified. At last, this article conducted a two-way fluid-structure interaction (FSI) analysis of morphing wing to obtain the influence of aerodynamic load on the flexible skin and skeleton mechanism, as well as the influence of structural deformation on the aerodynamic characteristics. Results show that the initial and swept states have the greatest impact on the out of plane bearing capacity of the flexible skin. In addition, the out-of-plane bulging deformation located at the trailing edge of the flexible skin is beneficial for improving aerodynamic performance, while the protrusion located at the leading edge increases air resistance. These findings provide important theoretical basis for the application of the MWS mechanism.

Simulation based QoS aware dynamic caching scheme for heterogeneous content requests in vehicular edge computing

The Internet of Vehicles (IoV) has witnessed a substantial surge in its expansion during recent years, with the integration of edge servers emerging as an increasingly prevalent practice to cater to content requests that demand a superior quality of service. Nonetheless, conventional cache policies often prove inadequate for IoV applications, primarily due to their incapacity to effectively handle a diverse array of content requests, the high-speed mobility of vehicles, and the inherent instability of network connections. Within the scope of this study, we commence by bifurcating various content requests into two distinct categories: latency-sensitive content request and bandwidth-sensitive content request. Subsequently, we establish a model to evaluate the service quality under the joint consideration of different types of content requests, the mobility of vehicles and storage capacity of edge nodes. Furthermore, we transform the quality-of-service (QoS) penalty function into a system reward function. This adaption enables us to propose an innovative edge cache scheme founded upon the Deep Deterministic Policy Gradient (DDPG) algorithm of Reinforcement Learning (RL) method, which empowers dynamic adjustments in response to the evolving IoV environment. To validate the effectiveness of our proposed approach, we harness the Simulation of Urban Mobility (SUMO) traffic simulation software and construct a traffic road scenario based on a specific part segment of Nanjing Beltway. A wide-ranging set of contrast experiments was performed to ensure the improved performance of the DDPG based deep reinforcement learning method. Simulation experimental results show that the proposed algorithm converges quickly and outperforms existing algorithms in terms of service quality-hit ratio for latency-sensitive content and transmission speed for bandwidth-sensitive content.

Numerical investigation into performance of Savonius wind turbine equipped with inner blades: Overlap ratio effect

This research focuses on the effect of overlap ratio on the performance of Savonius rotor in the presence of inner blades in such a way that inner blade tip is parallel to the main blade tip and root. Findings reveal that at low overlap ratios, using inner blade that the inner blade tip is parallel to the main blade root leads to a higher power and torque coefficients than the other inner blade configuration and also conventional rotor. This research indicates that for the overlapped rotor and for the two inner blade configurations, the higher power and torque coefficients could be obtained at high and low tip speed ratios, respectively. Results show that for both inner blade configurations, the overlapped rotors overcome the negative torque generated by the non-overlapped one. It is also shown that at high overlap ratio, using inner blade has no advantage over the conventional rotor.

Finite element analysis and experiment of cutting rape shoot stalks based on Ansys

The cutting device is a key component of the rape shoot stalks harvester, and currently there is little research on the cutting device for edible rape shoots. Based on the material characteristics of edible rape shoot stalks, this paper conducts mechanical and finite element analysis on the cutting device to ensure low-resistance and high-efficiency cutting operations. Slip cutting angle of the cutter is set at 20° to ensure that the stalk is clamped during cutting, and the cutting speed ratio of the cutter is determined to be 0.8 to avoid missed cuts and overcuts. The cutting angle of inclination is upward to assist the post-cutting rape shoot stalks to tilt backward. The maximum cutting stress and cutting energy consumption of the blade are used as evaluation indicators for the experiment. Through single-factor simulation experiments, it is found that the cutting speed and cutting angle of inclination have a significant impact on the low-resistance and high-efficiency cutting of the device. Through multi-factor simulation experiments, the optimal working parameter combination of the device is determined to be a cutting speed of 0.3 m/s and a cutting angle of inclination of 7.13°. At this working parameter, the device can achieve low-resistance and high-efficiency cutting, and it has been verified that the cutting device can cut the stalk in one go with a smooth cut without tearing. This paper provides a theoretical basis for the design and parameter determination of the cutting device for vegetable rape shoot stalks harvesters.

Unsteady Reynolds-Averaged Navier–Stokes Simulations of a Ducted Wind Turbine

Abstract An unsteady Reynolds-averaged Navier–Stokes model on body-fitted meshes in a commercial package (SimericsMP+) with a mismatched grid interface is used to study fluid dynamics around a ducted wind turbine. The model is validated by studying turbulent flow past a marine propeller. The nondimensional thrust and torque coefficients are compared against experimental data and results from a large eddy simulation model. Both coefficients are found to be within 3% of experimental results. Following this validation, the impact of different tip speed ratios on the ducted wind turbine's fluid dynamics is assessed. The optimal tip speed ratio is found to be the design value of 3.93 with a maximum power coefficient of 0.465 based on the duct exit area. The corresponding thrust coefficient is found to be 1.02 based on the rotor area. Lower tip speed ratios experience larger flow separation on the duct interior. Higher tip speed ratios decrease the size of the low-velocity region behind the hub. The ducted wind turbine's performance at design conditions is compared to an open rotor. The ducted wind turbine increases the power coefficient by 96% over the open rotor. The impact of hub size on the ducted wind turbine is also studied by simulating a smaller hub with 77% diameter. At the design tip speed ratio, the smaller hub has a power coefficient of 0.417. The maximum power coefficient is found to be 0.446 at a higher tip speed ratio of 4.5.

Simulation Method for Rubber Compounding under Isothermal Partial Filling Conditions

Rubber mixing is an important link in the production of rubber products. Computational fluid dynamics (CFD) simulation is often used to explore the effect of rubber mixing parameters on rubber mixing effect. Previous CFD-based rubber mixing simulation studies did not consider the impact of using 2D or 3D numerical calculation models on the numerical simulation results. In order to investigate the differences between 2D and 3D numerical computational models in rubber compounding CFD simulation problems, in this paper, we compare and analyze the results obtained from 2D and 3D computational models under different rotational speed conditions to investigate the differences between the models in the numerical simulation of rubber compounding. Three different experimental speeds of the rubber mixer—39, 44, and 49 r/min—were set during the study using 2D and 3D asynchronous rotor models with a speed ratio of 1.15, respectively. The rubber was processed using the Bird–Carreau model. The phase interface between rubber and air was calculated using the volume of fluid (VOF) method. The numerical simulation results of different models show that the rotational speed set to 49 r/min shows the best dispersion distribution effect; the mixing effect and speed change rule obtained by the 2D model are consistent with the results obtained by the 3D model. The performance of the results of the two models is consistent when exploring the numerical simulation of rubber compounding.

Design and Analysis of Mechanisms of 7-, 8- and 9-Speed Automatic Transmissions for Vehicle Powertrains

As the core device of engine-driven vehicle powertrains, the automatic transmission (AT) can obtain different output torques and speeds. Designing new mechanisms is the foundation for developing innovative ATs. This paper proposes an innovative design method for 7-speed, 8-speed and 9-speed AT mechanisms based on fractionated planetary gear trains (PGTs) and investigates the performance analysis of the AT mechanisms. Firstly, the detection of symmetric vertices in the PGT graph is studied, and a method for the topologic synthesis of 11-link 2-degree-of-freedom (DOF) fractionated PGTs is proposed. Secondly, the innovative design of 7-speed, 8-speed and 9-speed AT mechanisms is explored, leading to the discovery of two novel 7-speed AT mechanisms, three novel 8-speed AT mechanisms and four novel 9-speed AT mechanisms. Finally, the performance analyses of kinematics, torque, power flow and transmission efficiency of the AT mechanisms are conducted, and AMESim (Simcenter Amesim 2020.1) software is utilized to simulate speed ratios and transmission efficiencies of the AT mechanisms. The analysis and simulation results demonstrate that the nine novel AT mechanisms obtained in this study exhibit excellent overall performances. The speed ratios of each AT mechanism are reasonable, the step ratio is between 1.1 and 1.8, and the transmission efficiency exceeds 0.95. There is no cyclic power, or the cyclic power values are within an acceptable limit.

Numerical analysis of airfoils used in an omni-directional-guide vane structure of vertical axis wind turbine for high-rise buildings

This document introduces a novel concept involving an Omni-Directional Guided Vane (ODGV) encompassing a vertical axis wind turbine (VAWT) with the goal of improving its overall performance. Extensive three-dimensional computational analysis of the airfoils used in this novel ODGV structure is conducted to investigate the impact of various geometric parameters. Diverse geometric configurations of the ODGV are explored to analyze wind flow behavior across the turbine utilizing a well-validated computational fluid dynamics (CFD) model. The numerical investigations employ the Reynolds Averaged Navier–Stokes (RANS) modeling approach with the k-epsilon turbulence model. The steady state governing equations are solved using the validated CFD solver STAR CCM+. The study considers three distinct inlet velocities: 3, 6, and 9[Formula: see text]m/s, with the aim of improving flow behavior and velocity through the ODGV. Four different modifications of the ODGV are examined, and the accuracy of the CFD model is affirmed through comparison with NACA airfoil data. Integration of the ODGV results in an enhanced self-starting behavior of the VAWT, leading to a reduction in the cut-in speed. Validation results demonstrate a strong agreement with the data obtained from CFD simulations. These results suggest that most shape ratios, except for 0.3 and 0.4 at Tip Speed Ratio (TSR) of 1.3 and 3, contribute to enhancing power and torque coefficients. Furthermore, the findings indicate that with a Sharpe ratio of 0.56, both torque and power coefficients could be improved by up to 48% and 58%, respectively.

Flattening aluminum plates with tuning asymmetric rolling parameters

The asymmetric rolling (ASR) process can introduce shear strains inside the plate, resulting in the improvements of microstructures and mechanical properties. Its industrial application for rolling the (mid-)thick plates is impeded by the uncontrollable bending behavior. In this study, the influences of rolling parameters on the bending behavior of the rolled AA 7050 aluminum alloy plates were investigated. It is found that the plate will bend towards the slower roll with larger speed ratios and initial plate thickness as well as lower thickness reduction. A flat plate can be obtained by choosing appropriate rolling parameters. The equivalent plastic strain rate distribution is considered to be critical to the plate bending, the downward bending (towards faster roll) would be associated with an obvious increase of the equivalent plastic strain rate at the top surface of the plate near the end of the deformation zone. Multi-pass asymmetric rolling routes considering bending optimization were proposed and verified through rolling trials. As the speed ratio increased from 1.1 to 1.2, the through-thickness plastic strain became more homogeneous and the total rolling pass numbers decreased by 33 % (from 9 passes to 6 passes).