Lean Angle Research Articles

Effects of Walking With a Cane on Frontal Plane Hip Joint Loading in Patients With Late-Stage Unilateral Hip Osteoarthritis

ObjectiveTo investigate the effects of walking with a cane on frontal plain bilateral hip joint loading in patients with late-stage unilateral hip osteoarthritis (OA). DesignNonrandomized experimental design. SettingUrban inpatient hospital. ParticipantsAdults (men, n=10; women, n=17) with osteoarthritis who were scheduled for total hip arthroplasty (N=27). InterventionGait with and without a T-cane was assessed using a 3-dimensional motion analysis system. Main Outcome MeasuresPeak hip adduction moment and hip adduction moment impulse, vertical ground reaction force, and ground reaction force impulse were assessed under 4 different conditions: OA side vs non-OA side with non-cane gait, OA side vs non-OA side with cane gait, non-cane vs cane gait on OA side, and non-cane vs cane gait on non-OA side. The lateral trunk lean angle in the stance phase on both sides was compared between with and without a cane. Pain during walking with and without a cane was also determined using a visual analog scale (0=no pain; 100=most painful). ResultsWalking with a cane reduced the peak hip adduction moment from an average of 0.76 to 0.57 Nm/kg (reduction approximately 25%) and the mean hip adduction moment impulse from 50.58 to 42.78 Nm/kg (reduction approximately 15%) on the affected side. Walking with a cane reduced the peak ground reaction force from an average of 10.15 to 9.20 N/kg but did not markedly affect the mean ground reaction force impulse on the affected side. The mean impulse of vertical ground force and hip adduction moment on the nonaffected side with a T-cane was larger than that without a cane (940.4 vs 899.2, 73.7 vs 68.8, respectively), albeit without statistical significance. The mean lateral trunk lean angle on the affected side was 5.85±3.95 degrees with a non-cane gait and 4.46±2.66 degrees with a T-cane gait, showing a significant difference. Furthermore, walking with a cane was associated with a significant decrease in the visual analog scale of pain from 42.1 to 26.4. ConclusionThese findings indicate that walking with a cane reduces the load and pain on the affected hip joint. The effect of the cane on the trunk lean was small, but it is worth noting that walking with a cane may increase the load on the healthy side.

Математическая модель модуля дистанционного мониторинга опор воздушной линии электропередачи по каналу измерения угла наклона опоры

In continuation of previously published results, we are currently building a mathematical model of a remote monitoring module for overhead power line poles by measuring a lean angle. For the purpose of this research, we found input and output variables for the said remote monitoring module and created a model of lean angle dynamics along and across a pole. The results of this research are already being tested by utility companies.

Interadministrator Reliability of a Modified Instrumented Push and Release Test of Reactive Balance.

Traditional assessments of reactive balance require sophisticated instrumentation to ensure objective, highly repeatable paradigms. This instrumentation is clinically impractical. The Push and Release test (P&R) is a well-validated clinical test that examines reactive balance, and the application of wearable inertial measurement units (IMU) enables sensitive and objective assessment of this clinically feasible test. The P&R relies on administrator experience and may be susceptible to interadministration reliability concerns. The purpose of this study was to evaluate the interadministrator reliability of objective outcomes from an instrumented, modified version of the P&R test. Crossover interadministrator design. Twenty healthy adults (20-35y) completed the P&R in 4 directions with 2 different administrators. Measures quantified using IMUs included step latency, step length, and time to stability. Lean angle (LA) at release was used as a measure of administration consistency. The intraclass correlation coefficient (ICC) estimate was used to assess interadministrator reliability in each direction. To determine consistency of LA within and across administrators, we calculated the SDs for each rater by direction and the interadministrator reliability of LA using ICC. Across individual directions, the ICC for agreement between raters ranged from .16 to .39 for step latency, from .52 to .62 for time to stability, and from .48 to .84 for step length. Summary metrics across all 4 directions produced higher ICC values. There was poor to moderate consistency in administration based on LA, but LA did not significantly affect any of the outcomes. The modified P&R yields moderate interadministrator reliability and high validity. Summary metrics over all 4 directions (the maximum step latency, the median time to stability, and the median step length) are likely more reliable than direction-specific scores. Variations in body size should also be considered when comparing populations.

Fractal Analysis of Failure Process and Damage Evolution of Jointed Sandstone Based on DIP Technique

The Lannigou gold mine deposit is mainly composed of calcium-bearing sandstone and siltstone, and there are a lot of microdefects such as joints and cracks in the sandstone. The mesostructure of jointed sandstone makes a difference to the fracture process and mechanical properties. The RFPA2D software and Digital Image Processing Technology (DIP) were used to create a real microscopic structural numerical model of jointed sandstone with varied dip angle prefabricated cracks. A digital image-based rock microscopic scale fracture box dimension algorithm was established with MATLAB software. It is used to analyze the fractal characteristics of the acoustic emission field of unique prefabricated fractured sandstone. This study demonstrates that the mechanical parameter of jointed sandstone with different prefabricated cracks have manifest anisotropy, which includes elastic modulus and compressive strength. When the leaning angle of the cracks increases, they all increase linearly. There are three modes of starting-crack under uniaxial compression: from the peak of the prefabricated crack; from the middle of the prefabricated crack; and from the joint. Damage degree and rupture model are quantitatively represented by the fractal dimension. The more fractal dimensions there are, the more serious the damage, and the more complicated the rupture mode becomes. This research offers a novel method for investigating the evolution of rock microscopic scale fractures. This has to have engineering practical value for in-depth studies of rock fracture, instability, and failure, as well as the mechanisms that cause rock engineering disasters.

Impact damage to the middle trough of a scraper conveyor based on the engineering discrete element method and orthogonal matrix analysis.

The middle trough serves as a key part of a scraper conveyor. During the working process, falling raw coal lands on the middle plate of the trough, causing impact damage. This study aims to find the optimal working condition combination to minimize impact damage to the middle trough based on the engineering discrete element method (EDEM) and orthogonal matrix analysis (OMA). In EDEM software, simulation data of the impact damage depth and normal cumulative contact energy of the middle trough corresponding to the four influencing factors of the transverse laying roll angle, front lean angle, raw coal particle size, and chain layout and spacing under different horizontal conditions are obtained. Matrices of the impact damage depth and normal cumulative contact energy are separately established. Based on the respective factor layer, level and evaluation index weight matrices, a global weight matrix is finally obtained. The optimal combination of working conditions is obtained, and the weight of each factor on impact damage to the middle trough is determined by the weight coefficient. The accuracy of the simulation results is then verified in experiments. Among the considered factors, the raw coal particle size achieves the highest impact damage coefficient. When the raw coal particle size is the smallest (0.5 times the basic particle size), the transverse roll angle and front lean angle of the middle trough are positive (5° and 10°, respectively), the chain adopts the double-center chain arrangement, and minimal impact damage to the middle trough occurs. OMA reduces the test times to determine the optimal working conditions of a scraper conveyor.

Influence of the blade leaning angle on the performance of a radial impulse turbine for OWC converters

Abstract Oscillating Water Column systems (OWC) have been in the spotlight in the last 20 years since these devices are considered one of the most promising devices among wave energy technology. These systems produce electricity by means a generator driven by a turbine, which takes advantage of the bidirectional flow created by the OWC itself. Among these turbines suitable for bidirectional flows, it is possible to find radial impulse turbines, which are the focus of this work. Traditionally, the radial impulse turbines have shown lower efficiencies than their competitors. However, the radial turbines present interesting mechanical features and, recently, some research show that the difference has been reduced. Following this thread, this work deals with another modification in the radial impulse turbine looking for a further improvement. By using a validated CFD model, it has been analysed the influence of the lean angle of the blade. Until now, all the turbines present in the literature are leaned zero degrees, leading to a strong interaction between the guide vanes and the blades. This work shows results of the same turbine, equipped with blades leaning from -5deg to 25deg, in order to determine the influence such a modification on the maximum total-to-static efficiency. Results have revealed a slight improvement in the maximum efficiency for positive leaning angles, whereas negative angles drive the turbine to worse performance.

Experimental Study of 3D Concrete Printing Configurations Based on the Buildability Evaluation

Different formulations for 3D printable cementitious composites have been developed for extrusion-based printing. However, there is a lack of configuration guides for actual printing operations, which integrate one printable material and one printing system closely. Three testing methods for configuration determination were proposed and tested with three material proportions, with initial setting times of 2, 8, and 13 min, respectively. The building index (BI) measures the layer stacking stability based on the material, scale, and device. The height reduction test (HRT) quantifies the shortening in the height of the printed filaments. The leaning angle (LA) refers to the maximum slope of the stacked layers. In this study, results showed the critical values were (a) 0.167 for the height reduction ratio (HRR), (b) 40° for LA, and (c) 0~19.1, 0~61.1, and 0~99.4 for BI of the three mixtures. They were the meta parameters used to guide the CAD sketching, material development, and printing configurations, including the printing speed and layer height.

The significance of employee behaviours and soft management practices to avoid digital waste during a digital transformation

PurposeThe purpose of this study is to investigate the perceived effects between soft management practices, employee behaviours and the implementation of digital technologies in manufacturing plants, as well as how these relate to the emergence of digital waste.Design/methodology/approachThis paper uses case-based research. Data was collected in two large manufacturing companies based in Norway and Sweden through semi-structured interviews with two management representatives and four shop-floor employees. The data was used to evaluate 29 variables describing lean- and total quality management (TQM)-associated employee behaviours and soft management practices, in light of digital transformation.FindingsThe results suggest that several variables were positively influenced by the digital transformation process. These were top management leadership, middle management involvement, employee education, corporate social responsibility focus, innovation, knowledge sharing, work-family balance, psychological capital, job satisfaction and career commitment. Training employees, creativity, discretionary effort, turnover intention and proactivity appear to be negatively influenced by digital transformation The findings also indicate that several soft management practices and employee behaviours were not only influenced by manufacturing digitalization but also themselves influenced the process. The potential for digital waste creation was also detected in several variables, including reward and recognition and training employees.Practical implicationsManagers, practitioners and academics may learn about the importance of certain managerial practices and employees’ behavioural needs during the digital transformation process. The findings may help in prioritizing TQM and soft lean management practices and certain employee behaviours during the digital transformation and in creating awareness of digital waste.Originality/valueThis study builds on several existing studies discussing the impact of digital transformation on soft management practices and employee behaviours. It provides insights from a lean and TQM angle and offers a means of prioritizing certain practices and behaviours during a digital transformation. This study also highlights the significance of digital waste.

A Contra-Rotating Open Rotor Noise Reduction Methodology by Using Anhedral Blade Tip

Abstract In this article, a novel contra-rotating open rotor (CROR) noise reduction methodology based on the anhedral blade tip applied to the front blade is developed. Results indicate that anhedral blade tip can provide noise reduction over 60 deg. polar angle range in both upstream and downstream areas at takeoff condition. The noise reduction becomes more significant as the lean angle of anhedral blade tip increases, and the maximum noise reduction is over 4 dB. Further analysis shows that anhedral blade tip decreases the strength and size of blade tip vortex shed from the front blade and reduces its interaction with the rear rotor, which decreases the fluctuation of loading acting on the rear rotor and its loading noise. Furthermore, the anhedral blade tip does not have a significant effect on the aerodynamic performance of CROR at cruise.

Shapley Additive Explanations of Multigeometrical Variable Coupling Effect in Transonic Compressor

Abstract Optimization algorithms in the compressor detailed design stage generate big data of geometries and corresponding performances, but these data are often not exploited efficiently to unveil hidden compressor design guidance. In this work, the Shapley additive explanations (SHAP) method from game theory is proposed as an efficient methodology to extract design guidelines from databases. A database was generated when optimizing the blade features (sweep, lean, and end-bend) of Rotor 37. Based on this, a neural network is trained to predict compressor efficiency. The SHAP method is then applied to explain the neural network behavior, which provides information on the sensitivity of single geometrical variables and the coupling effect between multiple geometrical variables. Results show that the near-tip sweep and midspan lean angles are most influential on efficiency. Within the same group of variables, the adjacent variables tend to present strong positive coupling effects on efficiency. Among different groups, evident coupling effects are observed between sweep and lean and between lean and end-bend, but the coupling effect between sweep and end-bend is negligible. Flow mechanisms behind the coupling effects are discussed. For near-tip lean angles L3 and L4, the positive coupling effect is due to the change of the passage shock. For near-tip lean angle L4 and sweep angle S4, the change of detached shock leads to a negative coupling effect. The proposed data mining method based on the neural network and SHAP is promising and transferable to other turbomachinery optimization databases in the future.

Rod–Airfoil Interaction Noise at Different Rod Cross Sections and Airfoil Angles

Vortex–body interaction noise from a rod–airfoil model has been investigated experimentally in an aeroacoustic wind tunnel. The model configuration varies by changing either the rod cross section (circular, square, rhombic, and elliptical) or the install angle of the airfoil at three directions (attack angle , sweep angle , and lean angle ) independently. This paper aims to assess the effects of these parameters on the characteristics of vortex–body interaction noise. A near-field microphone array was applied to locate the noise sources on the rod–airfoil model, and a far-field microphone array determined the noise level and radiation directivity. The results suggest that, in the test range, both the elliptical rod cross section and the change of the airfoil install angles can visibly reduce vortex–body interaction noise compared to the baseline rod–airfoil containing the circular rod and the airfoil at zero angles. The interaction noise level decreases with the increase of the eccentricity of the elliptical rod. Of the angles, the most effective way is the change of the sweep angle , which can achieve a noise reduction of 8 dB when reaches 20 deg, but the attack angle has more influence in reducing the vortex shedding frequency. In addition, the noise source distribution of different frequencies also changes with the variation of rod–airfoil configurations. Flow visualization using particle image velocimetry was conducted to analyze the noise change mechanism. The findings from this study are beneficial for engineers in designing low-noise components in several aeronautical and industrial applications.

A data-driven framework for the safe integration of micro-mobility into the transport system: Comparing bicycles and e-scooters in field trials

Introduction: Recent advances in technology create new opportunities for micro-mobility solutions even as they pose new challenges to transport safety. For instance, in the last few years, e-scooters have become increasingly popular in several cities worldwide; however, in many cases, the municipalities were simply unprepared for the new competition for urban space between traditional road users and e-scooters, so that bans became a necessary, albeit drastic, solution. In many countries, traditional vehicles (such as bicycles) may not be intrinsically safer than e-scooters but are considered less of a safety threat, possibly because—for cyclists—social norms, traffic regulations, and access to infrastructure are established, reducing the number of negative stakeholders. Understanding e-scooter kinematics and e-scooterist behavior may help resolve conflicts among road users, by favoring a data-driven integration of these new e-vehicles into the transport system. In fact, regulations and solutions supported by data are more likely to be acceptable and effective for all stakeholders. As new personal-mobility solutions enter the market, e-scooters may just be the beginning of a micro-mobility revolution. Method: This paper introduces a framework (including planning, execution, analysis, and modeling) for a data-driven evaluation of micro-mobility vehicles. The framework leverages our experience assessing bicycle dynamics in real traffic to make objective and subjective comparisons across different micro-mobility solutions. In this paper, we use the framework to compare bicycles and e-scooters in field tests. Results: The preliminary results show that e-scooters may be more maneuverable and comfortable than bicycles, although the former require longer braking distances. Practical Applications: Data collected from e-scooters may, in the short term, facilitate policy making, geo-fencing solutions, and education; in the long run, the same data will promote the integration of e-scooters into a cooperative transport system in which connected automated vehicles share the urban space with micro-mobility vehicles. Finally, the framework and the models presented in this paper may serve as a reference for the future assessment of new micro-mobility vehicles and their users’ behavior (although advances in technology and novel micro-mobility solutions will inevitably require some adjustments).

Age-related changes in protective arm reaction kinematics, kinetics, and neuromuscular activation during evoked forward falls.

Fall related injuries in older adults are a major healthcare concern. During a fall, the hands and arms play an important role in minimizing trauma from ground impact. Although older adults are able to orient the hands and arms into a protective orientation after falling and prior to ground impact, an inability to avoid increased body impact occurs with age. Previous investigations have generally studied rapid arm movements in the pre-impact phase or absorbing energy in the post-impact phase. There are no known studies that have directly examined both the pre-impact and post-impact phase in sequence in a forward fall. The aim of this study was to identify age-related biomechanical and neuromuscular changes in evoked arm reactions in response to forward falls that may increase fall injury risk. Fourteen younger and 15 older adults participated. Falls were simulated while standing with torso and legs restrained via a moving pendulum system from 4 different initial lean angles. While there was not a significant age-related difference in the amount of energy absorbed post-impact (p=0.68), older adults exhibited an 11% smaller maximum vertical ground reaction force when normalized to body weight (p=0.031), and 8 degrees less elbow extension at impact (p=0.045). A significant interaction between age and initial lean angle (p=0.024), indicated that older adults required 54%, 54%, 41%, and 57% greater elbow angular displacement after impact at the low, medium, medium-high, and high initial lean angles compared to younger adults. These results suggested older adults may be at greater risk of increased body impact due to increased elbow flexion angular displacement after impact when the hands and arms are able to contact the ground first. Both groups exhibited robust modulation to the initial lean angle with no observed age-related differences in the initial onset timing or amplitude of muscle activation levels. There were no significant age-related differences in the EMG timing, amplitude or co-activation of muscle activation preceding impact or following impact indicating comparable neuromotor response patterns between older and younger adults. These results suggest that aging changes in muscular elements may be more implicated in the observed differences than changes in neuromuscular capacity. Future work is needed to test the efficacy of different modalities (e.g. instruction, strength, power, perturbation training, fall landing techniques) aimed at reducing fall injury risk.

Daily recommended effective and safer walking and running from integrative medicine

From Integrative Medicine point of view, people tend to exercise less, leading to decreased physical, nutritional and cognitive function. Authors have been involved in rehabilitation and workshop for various subjects with masters’ athletes. Previous walking methods have some problems, such as stretching the chest, large movement of arm swing, heel touchdown with extended knees and push backward with thumb-ball. In contrast, our recommended methods include walking with the concept of centered position, using the gravity center and reflection power by flat grounding, adjusting speed and striding with forward leaning angle and creating some effective image in the mind.

Influence of Blade Lean on Performance and Shock Wave/Tip Leakage Flow Interaction in a Transonic Compressor Rotor

Blade lean has been extensively used in axial compressor stators to control flow separations, but its influence mechanism on transonic compressor rotors remains to be revealed. The aim of this study is to numerically explore the influence of blade lean on the performance and shock wave/tip leakage flow interaction in a transonic compressor rotor. The effects of leaned pattern (positively lean and negatively lean), leaned angle and leaned height were studied. Results showed that, compared with baseline configuration, the efficiency and total pressure ratio of the entire constant rotating speed line of positively leaned rotor were both decreased. The absolute value of peak efficiency was reduced by as much as 4.34% at 20° lean angle, whereas the maximum reduction of peak total pressure ratio was 0.1 at 20° lean angle. The tip leakage flow streamlines of baseline transonic rotor can be divided into two parts, i.e., the primary vortex and secondary vortex which arises after the shock. Due to shock/tip leakage vortex interaction, the primary vortex enlarged and low-momentum region showed up after the shock; under near stall (NS) condition, tip leakage vortex breakdown occurred after interacting with shock. As positively leaned angle increased, the shock and the shock/tip leakage vortex interaction point moved upstream. In addition, the phenomenon of tip leakage vortex breakdown was enhanced. For negatively leaned rotors, as negatively leaned angle increased, the peak efficiency and total pressure ratio showed a tendency of first increasing and then decreasing. At 5° leaned angle, the peak efficiency was increased by 0.8% at most, and the maximum increment of total pressure ratio was 0.05 at 5° leaned angle. Besides, the loading of blade tip reduced and the loading moved toward trailing edge, resulting in the downstream movements of primary vortex, shock front and shock/tip leakage vortex interaction location. The results may help to improve the near tip flow field of transonic compressor rotor with leaned blade technology.

Asymptotic Trajectory Tracking of Autonomous Bicycles via Backstepping and Optimal Control

This letter studies the trajectory tracking problem for an autonomous bicycle that is a non-minimum phase, strongly nonlinear system. As compared with most existing methods dealing only with approximate trajectory tracking, this letter proposes a constructive design to achieve asymptotic trajectory tracking. More specifically, under the assumption that the desired trajectory is generated by a virtual bicycle, a novel asymptotic trajectory tracking controller design scheme is presented. Firstly, the nonlinear dynamics of the autonomous bicycle is established. Secondly, it is decomposed into two interconnected subsystems: a tracking subsystem and a balancing subsystem. For the tracking subsystem, the popular backstepping approach is applied to determine the propulsive force of the bicycle. For the balancing subsystem, optimal control is applied to determine the steering angular velocity of the handlebar in order to balance the bicycle and align the bicycle with the desired yaw angle. Thirdly, to tackle the strong coupling between the tracking and the balancing systems, the small-gain technique is applied for the first time to prove the asymptotic stability of the closed-loop bicycle system. Finally, the efficacy of the proposed exact trajectory tracking control methodology is validated by numerical simulations.

Test-retest reliability of the FALL FIT system for assessing and training protective arm reactions in response to a forward fall

The use of the hands and arms is an important protective mechanism in avoiding fall-related injury. The aim of this study was to evaluate the test-retest reliability of fall dynamics and evokd protective arm response kinematics and kinetics in forward falls simulated using the FALL simulator For Injury prevention Training and assessment system (FALL FIT). Fall FIT allows experimental control of the fall height and acceleration of the body during a forward fall. Two falls were simulated starting from 4 initial lean angles in Experiment 1 and with 4 different fall accelerations in Experiment 2. Fourteen younger adults (25.1±3.5 years) and 13 older adults (71.3±3.7 years) participated in Experiment 1 and 13 younger adults (31.8±5.7 years) participated in Experiment 2. Intraclass correlation coefficients (ICC) were used to the evaluate absolute agreement of single measures at each condition and averages across conditions. Average measures of fall dynamics and evoked kinematics and kinetics exhibited excellent reliability (ICC(A,4)>0.86). The reliability of single measures (ICC(A,1) > 0.59) was good to excellent, although 18% of single measures had a reliability (ICC(A,1)) between 0.00 and 0.57. The FALL FIT was shown to have good to excellent reliability for most measures. FALL FIT can produce a wide range of fall dynamics through modulation of initial lean angle and body acceleration. Additionally, the range of fall velocities and evoked kinematics and kinetics are consistent with previous fall research.•The FALL FIT can be used to gain further insight into the control of protective arm reactions and may provide a therapeutic tool to assess and train protective arm reactions.

Unstable flow characteristics in vaneless region with emphasis on the rotor-stator interaction for a pump turbine at pump mode using large runner blade lean

In this study, the unstable flow characteristics in vaneless region of the pump-turbine with different runner blade lean has been numerically investigated by using a modified SST k-ω partially averaged Navier-Stokes model. Results on the characteristic curves show good agreements between the experiment and simulation, and indicate that with the increase of blade lean angle (θ of 0°, 2°, 4°, 6°, 10° and 15°), the positive slope on characteristic curve is gradually alleviated. It is noted that the runner with large blade lean (θ of 15°) can suppress the peak value region of boundary vorticity flux at blade trailing edge from the crown side to mid-span section, and the unstable flow near the mid-span in runner blade-to-blade passage as well as in vaneless region. It is confirmed that the runner with large blade lean spatially and temporally changes the flow near the blade trailing edge and in vaneless region, and is beneficial to improve the flow stability. Finally, the proper orthogonal decomposition analysis reveals that the runner model with large blade lean effectively alleviates the dominant flow oscillation with the low frequency of 0.088fn (or 0.044fn), corresponding to the unstable flow evolution in vaneless region.

Novel high-fidelity tyre model for motorcycles to be characterised by quasi-static manoeuvres – rationale and numerical validation

Although diverse tyre model formulations exist in the literature, they are suited for characterisation using a dedicated test bench, preventing parameters' estimation in driving conditions. This study defined a novel motorcycle tyre model, characterisable through driving manoeuvres using simple instrumentation consisting in an inertial measurement unit, steering position sensor and wheel speed sensors. Acquired signals were used to estimate instantaneous tyre forces, moments, slip angle and other properties, which were employed to calculate tyre model's parameters. Tyre model development and validation were performed in a simulation environment: we used a Magic Formula tyre-equipped motorcycle model to perform a set of manoeuvres, which were employed to characterise the proposed tyre model. Lastly, a set of quasi-static manoeuvres was conducted using the same motorcycle model equipped with the two tyre models, and results were compared. Comparison results showed a close reproduction of real tyre forces, moments and slips by the proposed tyre model for quasi-static manoeuvres, accurately reproducing motorcycle dynamics. Therefore, steering torque was correctly predicted for different lateral acceleration values. These results show that the proposed tyre model can be characterised, for both longitudinal and lateral dynamics, using this limited set of manoeuvres and simple instrumentation; the correctly predicted steering torque could allow the use of this tyre model for handling description.

Influence of Various Stator Parameters on the Open-Water Performance of Pump-Jet Propulsion

In order to improve the hydrodynamic performance of pump-jet propulsion (PJP) when matching stator with the rotor, the RANS method with SST k-ω turbulence model is employed to study the influence of six kinds of stator parameters, which are classified into three groups, i.e., stator solidity, stator angles and rotor–stator spacing (S). Results show that the stator solidity involves the blade number (Ns) and chord length (L), has an obvious acceleration effect at and after stator, and produces a higher thrust and torque with a slight efficiency change. Further comparing Ns and L results, we find greater distinctions between the two cases when stator solidity is greatly adjusted. Three stator angles, i.e., stagger angle (α), lean angle (γ), and sweep angle (β), are studied. The α has the biggest effect on the thrust, torque, and efficiency; meanwhile, it shifts the advance number that corresponds to maximum efficiency. The effect of γ is similar to α, but its influence is far less than α. However, there is little difference between various β cases except for off-design conditions, where the efficiency drops dramatically as β increases. The S has a slight effect on PJP performance. Even though S decreases 34% relative to the original PJP, the rotor thrust and torque increase by less than 1%. In addition, we compare torque balance locations under various parameters, and each component force is analyzed in detail to explain the reason for performance variation. The present work is conducive to future optimization in PJP design.