Maximum Pitch Research Articles

Experimental and numerical investigation of the thermal - hydraulic performance of flow inside helical coil elliptic tubes

Helical coil tubes are essential in a variety of engineering applications due to their improved heat transfer and compact shape. The current study presents an experimental and numerical investigation of geometrical optimization for helical coil elliptic tubes. Four distinct coil pitch values are examined with a constant perimeter for all geometries and three aspect ratio values (1, 0.75, 0.5) utilizing water as the working fluid across varying the volume flow rates. The helical coil has the same surface area as the tube for each coil. The numerical simulation is conducted using the ANSYS FLUENT CFD software (Version 19.2). The experimental and numerical results indicate that the increase in heat transfer due to an increase in mass flow rate is significantly greater than the improvement gained by changing the aspect ratios. Increasing the volume flow rate to 3 L/min significantly improves the average heat transfer coefficient, with a 66.6 % increase found at a maximum coil pitch of 0.08 m and an aspect ratio of 0.5. Furthermore, a helical coil with an aspect ratio of one (circular cross-section) exhibits the best compromise between pressure drop penalty and heat transfer enhancement, resulting in the greatest hydraulic thermal performance parameter.

Dynamics of JET runaway electron beams in D2-rich shattered pellet injection mitigation experiments

Abstract The publication provide further insights into the dynamics of JET runaway electron (RE) beams mitigated by D2-rich shattered pellet injection (SPI) (Reux et al 2022 Plasma Phys. Control. Fusion 64 034002). Multi-diagnostic analyses show that mechanisms causing continuous RE losses and energy transfer from hot electrons to cold background plasma can act before the SPI. After the SPI, measurements are compatible with a reduction of the maximum energy and pitch angle of the RE distribution while the population of supra-thermal electrons increases. The RE population growth is likely due to electron avalanche. Dark island-like pattern chains, characterised by an integer poloidal mode number and a certain minor radius, are identified in the JET RE beam synchrotron radiation videos. The synchrotron island dynamics is studied via a newly developed computer vision code (Sommariva and Silburn https://c4science.ch/source/pSpiPTV/). The radial motion of synchrotron island chains is found to be consistent with the most plausible time evolution of the radial current density profile compatible with both the RE synchrotron videos and the total RE current time trace. Similarly, correlations are identified between the temporal progression of the synchrotron islands poloidal rotation frequency and sudden MHD relaxation events. Loss-of-RE events probably caused by non-linear interactions between synchrotron islands are observed for the first time. Experimental evidences suggest that synchrotron islands are possibly related to the existence of magnetic islands which may lead to the development of new RE beam mitigation strategies.

Ditching characteristics of a seaplane under various wave conditions and effects of biomimetic floats

This paper presents a numerical investigation into the hydrodynamic loads and motions experienced by two seaplane models during ditching in calm water and regular waves. The original bare model is susceptible to jet flows and wave overwash at the nose, which can adversely impact the aircraft's ditching performance. To address these issues, we introduced two biomimetic floats symmetrically to the original model and assessed their influence on the ditching dynamics. A comparative analysis was conducted on the accelerations, impact loads, and the coupled heave and pitch motions of both the original and the redesigned model equipped with floats during ditching in both calm waters and regular waves. For the wave ditching scenario, a detailed investigation of the slamming phase was first carried out, involving impacts at the wave's zero-crossing, crest, and trough. The cases with a variety of wave heights, wave lengths, and wave headings were evaluated. A particular focus was placed on understanding how the biomimetic floats affect the seaplane's performance during ditching in both calm and wavy conditions. The analysis of maximum accelerations and pitch angles during wave ditching revealed that slamming at the wave trough presents the most significant hazards. Additionally, the phenomena of gliding and wave overwash were identified as substantial risks under wave conditions. The results suggested that the biomimetic floats can effectively mitigate the maximum horizontal acceleration and pitch angle of the original model, enhancing the safety of ditching operations in both calm water and waves.

Hybrid sand cat‐galactic swarm optimization‐based adaptive maximum power point tracking and blade pitch controller for wind energy conversion system

SummaryAs wind energy is sustainable, pollution‐free, easily available, and free of cost, it has become an efficient source of renewable energy for electricity generation. But, the problem with wind energy is that it varies with time, seasons, and location. This makes the Wind Energy Conversion System (WECS) unstable as it frequently needs to match the load demands. The balance in power generation by wind energy is essential since it has to be connected to various grids. So, this unbalanced energy production can affect the stability of the associated power grids as well. It also results in expensive regulatory measures, storage options, and load shedding. So, the stable operation of the WECS is highly essential to adapt it as a trustable source of electricity production. The stable operation of the WECS requires a robust and advanced system for control. Better control of the wind power extracting model is achieved by controlling the Maximum Power Point Tracking (MPPT) and blade pitch. So, an Adaptive MPPT and Blade Pitch Controller (BPC) for the WECS have been developed in this article, with the support of a hybrid optimization algorithm. In order to enhance the working principles of this controller, two effective algorithms such as Sand Cat Swarm Optimization (SCSO) and Galactic Swarm Optimization (GSO) are integrated and named Hybrid Sand Cat Galactic Swarm Optimization (HSC‐GSO). With the help of the recommended HSC‐GSO, the functionality of the controller is enhanced and also at the same time this algorithm helps to optimize the three gains in the Proportional Integral Differential (PID) controller of both MPPT and BPC, respectively. Moreover, with the support of the proposed HSC‐GSO the damping oscillations in the WECS output power and voltage are minimized. In the end, the numerical analysis is conducted for the presented system by comparing it with the traditional techniques. From the overall result analysis, the stability of the recommended adaptive WECS is 97, which is higher than the conventional algorithms such as DHOA, SCSO, GSO, and DA. Thus, it has been proved that the proposed HSC‐GSO algorithm for the parameters optimization in the PID controller of MPPT and the PID controller of BPC attains high robustness, increased steady‐state stability, and efficient transient response than the traditional techniques.

Vortex-shedding modes of a pair of side-by-side thin pitching plates

We have conducted three-dimensional (3D) direct numerical simulations to analyze vortex-shedding modes past vertically arranged, side-by-side 3D pitching plates, considering cases where the plates are in the same, opposite, and different phases. The simulations are performed at a Reynolds number Re=1000, with a dimensionless pitching frequency St=1, and a maximum pitching angle θmax=15°. The vortex-shedding modes reveal horseshoe vortices transforming into distorted hairpin-like structures in the far wake for in-phase plates. Opposite phase plates exhibit helical distortion and core bifurcation, while different phase angles produce meridionally twisted, entangled hairpins. We observe a reverse von Kármán vortex street for in- and different-phase plates, while the opposite shows a reverse Kármán vortex street for the upper plate and a Kármán vortex street for the lower plate. The streakline visualizations reveal wake compression and spoke-like structures symmetrically emanating from the shear layer extremities around the plates' central region. We find leapfrog-like cross-stream vortex interaction when the plates are in phase. The line-time diagram reveals alternating patches of low-intensity cells, switching between negative and positive, alongside continuous bands of both positive and negative cells. Both plates produce similar thrust for the parameters examined in this study.

Terrestrial locomotion stability of undulating fin amphibious robots: Separated elastic fin rays and asynchronous control

To address the problem of poor postural stability in an undulating fin robot during terrestrial locomotion, this study proposes a novel design featuring separate elastic fin rays with an asynchronous control scheme for bilateral fin surfaces. In this scheme, the robotic fin ray structure and surface driving mode are innovatively designed to mitigate the pitch-angle instability caused by adverse factors, such as integral rigid fin rays and synchronized fin surfaces. Expanding on the ground dynamics model of the robot, this study examined the variation in the pitch angle of the robot body. In this study, an innovative design with separated elastic fin rays was proposed and their feasibility was validated through finite element simulations. In addition, a virtual simulation prototype of the robot was developed to verify the robot body stability under asynchronous fin surface control. The simulation results show that separate elastic fin rays and asynchronous control can effectively improve the postural stability of robots in terrestrial locomotion. In this study, a robot prototype was tested experimentally in various terrestrial environments. The experimental results indicate that equipping the robot with separated elastic fin rays and employing asynchronous motion control significantly enhances the motion postural stability across typical terrain conditions. The maximum pitch angle range can be reduced by 42.7–52.4%, providing new insights for the design of amphibious robots with undulating fins.

Aerodynamic and Structural Design Procedures Supported by Fabrication and Flight Testing of a Small Unmanned Helicopter

In this work, typical design, production, and testing procedures for a small unmanned helicopter are explained and performed. In doing so, preliminary sizing of the helicopter and three main disciplines are conducted: aerodynamic analytical and numerical simulations, power calculations, and structure analysis assessment. First, a thorough survey is implemented to obtain the trends for the maximum take-off weight versus some design constraints such as rotor diameter, motor power, payload, and empty weight. Performance calculation results are obtained to figure out all aspects that correspond to the specified mission. The designed rotor geometry along with the aerodynamic characteristics and flight performance variables is then validated using the blade element theory and numerical simulations. Second, based on the power curves obtained for different flight regimes, an electric brushless motor is selected. The numerical simulations (Computational Fluid Dynamics) analysis is used to enhance the selection which implies that the motor power should be greater than 5.4 kW to overcome the drag forces. The motor power selection corresponds to a maximum rotor pitch angle of 15∘ and a maximum rotor speed of 1450 RPM. Then, the aerodynamic loads are used as an input for the structural analysis using one-way coupling of fluid–structure interaction (FSI) and consequently designing the internal structure of the blade. Eventually, the internal structure manufactured using carbon fiber-reinforced polymer (CFRP) by applying a combined technique between wet layup and compression molding. The blade is statically tested compared with numerical finite element model results. The fuselage structure along with hub and tail units is manufactured and assembled with the existing on-shelf components to examine the helicopter lift capability with different payloads up to 9 kg. The results show that the detailed design process is significant for manufacturing such blades and the helicopter is capable of lifting off the ground with various payloads depending on the rotor pitch angles (8∘, 12∘, and 15∘) at a constant rotor speed of 1450 RPM.

Aerodynamic Performance of a Hovering Cycloidal Rotor: A CFD Study with Experimental Validation

A three‐dimensional (3D) unsteady Reynolds averaged Navier‐Stokes (URANS) computational fluid dynamics (CFD) toolkit for cycloidal rotors was developed and used to perform a parametric study. It included blade aspect ratio, side disks, pitch mechanism, blade camber, and shaft size. The influence of the pitch rod length showed the importance of the lift distribution between the upstream and downstream parts of the rotor cylinder. The application of blade camber significantly affected thrust and power, while having a limited effect on efficiency. A similar effect was obtained by varying the pitch rod lengths. The presence of a central axis in the rotor had a negligible effect on efficiency. The most significant impact on efficiency came from the side disks, which behaved similarly to winglets on fixed‐wing aircraft. However, changing the aspect ratio of the blades showed a similar response to that of aircraft wings, but with a smaller effect, making it conceivable to fly a square-bladed cyclorotor without side disks. To verify the CFD model, a cycloidal rotor was also built using 3D printed parts and carbon fiber tubing. It was then operated on a test rig where thrust and power were measured for speeds ranging from 408 to 2528 RPM. On the test bench, the blades were pitched with a uniform asymmetric mechanism. The maximum nose‐up pitch angle in upstream of the rotor axis was 34.8°. Due to its rotation around the rotor and its pitching in the opposite direction, the maximum nose‐up pitch angle of the downstream blade was 38.6°. The obtained rotor thrust and power curves and the flow visualization around the rotor confirmed the validity of the CFD toolkit.

Syntactic-Prosodic Interface in Information Structure: The Interplay between Syntactic Markedness and Prosodic Prominence of Focus

There is a vast body of research that attempts to get a window into the information structure-prosody interface. These accounts take a simplistic view and examine the prosody of information structure divorced from syntax. The current study postulates that the prosodic encoding of information structure is constrained by some syntactic factors. The basic hypothesis of the study is that syntactic markedness, as an independent syntactic variable, contributes to the eventual prosodic encoding of focus, particularly its prosodic prominence. Given that marked focus constituents basically manipulate syntax in such a way as to stand out syntagmatically, the study hypothesizes that syntactically unmarked focus constituents are predicted to be more prosodically prominent than marked constituents and, as a corollary, are predicted to be realized with higher maximum pitch, higher scaling of the H tonal target of the focus accent compared to the H of the preceding and following accents, and lower scaling of the L tonal target. To test these hypotheses, the study provides a prosodic investigation of two data sets that feature marked focus constructions and unmarked ones. The results of the study show that syntactic markedness is a highly significant predictor for focus prosody

Effects of the gap ratio on the flow field structures and the aerodynamic performance of an airfoil with ridge ice

Under SLD icing conditions, the ridge ice may appear on the surface of aircraft, which led to the significant aerodynamic deterioration and affected aircraft flight safety. The present study experimentally investigated the effects of the gap ratio on the flow field structures and aerodynamic performance of an airfoil with ridge ice. Detailed measurements were performed in a low-speed reflux wind tunnel by utilizing the Particle Image Velocimetry (PIV) technique and a high-sensitivity six-component balance. The results showed that the maximum lift coefficient, stall angle, and maximum pitch moment coefficient of the airfoil increased as the gap ratio enlarged. At AOA = 10 deg, the separation bubble length decreased by 77 % when the gap ratio changed from 0 to 0.1. Meanwhile, the separation bubble length decreased by 68 % when the gap ratio changed from 0.1 to 0.3. Besides, as the increase of the gap ratio, the average vorticity, turbulent kinetic energy, and Reynolds shear stress in the selected region above the airfoil decreased, while the average velocity increased. In addition, the gap ratio did not have an apparent effect on the transition onset positions and the maximum spanwise vorticity in the flow field.

Safety Analysis of Initial Separation Phase for AUV Deployment of Mission Payloads

This study verifies the effects of deployment parameters on the safe separation of Autonomous Underwater Vehicles (AUVs) and mission payloads. The initial separation phase is meticulously modeled based on computational fluid dynamics (CFD) simulations employing the cubic constitutive Shear Stress Transport (SST) k-ω turbulence model and overset grid technologies. This phase is characterized by a 6-degree-of-freedom (6-DOF) framework incorporating Dynamic Fluid-Body Interaction (DFBI), supported by empirical validation. The SST k-ω turbulence model demonstrates superior performance in managing flows characterized by adverse pressure gradients and separation. DFBI entails computationally modeling fluid–solid interactions during motion or deformation. The utilization of overset grids presents several advantages, including enhanced computational efficiency by concentrating computational resources solely on regions of interest, simplified handling of intricate geometries and moving bodies, and adaptability in adjusting grids to accommodate changing simulation conditions. This research analyzes mission payloads’ trajectories and attitude adjustments after release from AUVs under various cruising speeds and initial release dynamics, such as descent and angular velocities. Additionally, this study evaluates the effects of varying ocean currents at different depths on separation safety. Results indicate that the interaction between AUVs and mission payloads during separation increases under higher navigational speeds, reducing the separation speed and degrading the stability. As the initial drop velocities increase, fast transition through the AUV’s immediate flow field promotes separation. The core of this process is the initial pitch angle management upon deployment. Optimizing initial pitching angular velocity prolongs the time for mission payloads to reach their maximum pitch angle, thus decreasing horizontal displacement and improving separation safety. Deploying AUVs at greater depths alleviates the influence of ocean currents, thereby reducing disturbances during payload separation.

Droplet dynamics affecting the shape of patterns formed spontaneously by transforming UV-curable emulsions

Forming large pitch and depth patterns spontaneously based on a bottom–up approach is a challenging task but with great industrial value. It is possible to spontaneously form an uneven (concave–convex) patterns with submillimeter-to-millimeter-scale pitches and depths by the direct pattern exposure of a UV-curable oil-in-water (O/W) emulsion liquid film. UV irradiation generates a latent pattern of a cured particle aggregation in the liquid film, and an uneven structure is spontaneously formed during the subsequent drying process. This process does not require any printing and embossing plates or development process. In this report, we presented an example of unevenness formation with a maximum pattern depth of approximately 0.4 mm and a maximum pitch width of 5 mm. The patterns formed by this method have raised edges in the exposed areas and fogging in unexposed areas. The pattern shapes become conspicuous under overexposure conditions, but the formation mechanism has not yet been understood in detail and needs to be investigated. In this study, we focused on the exposure process and clarified the mechanism of pattern formation by analyzing the dynamics of emulsion droplets in the medium by an in situ microscopy observation method. As a result, we found that the fogging was mainly caused by light leakage from the exposed area, and the raised pattern edges were caused by droplets transported from the unexposed area to the exposed area. Furthermore, the convection caused by the heat generated from polymerization is a determining factor affecting all these phenomena. By controlling the pattern shape related to convection utilizing direct projection exposure, we showed an example of eliminating raised pattern edges with a height difference of approximately 0.1 mm. By devising and selecting exposure methods, we can expand the range of design applications such as interior decorative patterns.

Enhancing the Performance of an Oscillating Wing Energy Harvester Using a Leading-Edge Flap

In this study, we investigated the power generation capability of an oscillating wing energy harvester featuring an actively controlled flap positioned at the wing’s leading edge. The findings revealed that attaching a leading-edge flap reduces fluid flow separation below the wing’s lower surface at the leading edge, resulting in smoother flow and increased velocity near the hinge region. The leading-edge flap increases the pressure difference across the wing’s surface, thereby enhancing the overall performance. In addition, the introduction of the leading-edge flap effectively elongates the wing’s effective projected length in the heaving direction, leading to increased thrust. We examined flap lengths ranging from 10% to 50% of the chord length, with the maximum pitch angles of the wing and flap varying from 75° to 105° and 30° to 55°, respectively. The optimal power generation was achieved using a flap length of 40% of the chord length, combined with maximum wing and flap pitch angles of 95° and 45°, respectively. These conditions yielded a 29.9% overall power output increase and a 20.2% efficiency improvement compared to the case without the leading-edge flap.

Numerical Study on the Automatic Ballast Control of a Floating Dock

Abstract The ballast control of a floating dock mainly relies on manual operations, which can be time-consuming and requires skilled workers. This study proposes an automatic ballast control system for floating docks, which improves operational efficiency and safety during the vessel docking process. A numerical model is developed to simulate the dynamic process of the floating dock's operations, which includes a six degrees-of-freedom (6DOF) model, a hydrostatic force model, a hydrodynamic force model, and a hydraulic model. The hydrostatic force model is developed using the Archimedes law and a strip theory along the longitudinal direction. The hydrodynamic model is made based on the effects of added mass and dynamic damping. The hydraulic model is proposed to deal with the hydraulic calculation of the ballast water system. The present automatic ballast control is designed based on a modified proportional controller (P-controller) to control the valve opening angles when the pitch or roll angles are larger than the corresponding threshold values. Without using controllers, the roll angles of the dock can reach 8.9 deg and 13 deg during the ballasting and de-ballasting operations, respectively. The present modified P-controller with optimized control parameters can stabilize the dock during the de-ballasting operation and keep the maximum pitch and roll angles no larger than 0.016 deg and 0.0783 deg, respectively. During the ballasting operation with the same control parameters, the roll and pitch are below 0.0604 deg and 0.0145 deg, respectively. The present automatic control will be further implemented in the vessel docking cases and can significantly improve the stability of the dock.

Dynamic response of a floating dock under corrosion-induced accidents

Dynamic responses of a floating dock under corrosion-induced accidents are studied using a numerical method. The numerical model is proposed to calculate the dynamic responses of the floating dock during operations. It includes a six-degree-of-freedom (6-DOF) model, a hydrostatic force model, a hydrodynamic force model, and a hydraulic model. The effects of the corrosion-induced holes on the stability of the floating dock are investigated and the results show that the maximum pitch and roll angles are 0.18° and 0.69° respectively when there is one hole located at one tank. The maximum pitch and roll angles become 0.42° and 2.04° respectively when there are two holes located at different tanks. The results indicate that situations involving more than one corroded hole result in large roll and pitch angles, which ultimately increase the risk of the vessel capsizing. This analysis not only emphasizes potential hazards but also presents an opportunity for the maritime sector to enhance safety, operational efficiency, and environmental responsibility.

Flight test of flying wing aircraft controlled by dual synthetic jets at Ma0.2

To explore the application potential of zero-mass-flux dual synthetic jets in flight control of flying wing aircraft (FWA), dual synthetic jet actuators (DSJAs) are integrated into a FWA and flight tests without deflections of rudders are firstly carried out to verify the viability of DSJAs to manipulate three-axis attitudes at a cruising speed of 70 m/s. Two active flow control methods of circulation control and reverse jet control performed by DSJAs are utilized to execute the three-axis control. Novel flight control effectors based on DSJAs are designed and achieve the integration with the FWA. Flight tests show that three-axis flight control is realized by DSJAs distributed in different locations. The maximum roll, pitch and yaw angular velocities are 10.12°/s, 6.17°/s and 8.38°/s respectively. The work initially verifies rudderless flight control ability of DSJAs at a cruising speed of 70 m/s and the control ability will be improved by the further optimization of DSJAs.

Prediction of Voice Outcomes After Hemithyroidectomy Using Skin Electrode Intraoperative Neuromonitoring

Background and Objectives This study focused on predicting voice outcomes following hemithyroidectomy using skin electrode intraoperative neuromonitoring (IONM).Subjects and Method The study involved 82 patients who underwent hemithyroidectomy. During the surgery, the researchers recorded skin IONM values for the vagus nerve and recurrent laryngeal nerve. Voice quality evaluations were conducted before the surgery and at various intervals after the surgery (one week, one month, three months, six months, and one year) using the multidimensional voice program (MDVP), voice handicap index (VHI), and the grade, roughness, breathiness, asthenia, strain (GRBAS) scale. The study aimed to correlate perioperative skin IONM values with subjective and objective voice outcomes.Results The VHI scores increased up to three months post-surgery, with statistically significant changes observed at one week post-surgery. The GRBAS scale scores also increased significantly at one month post-surgery. Similar trends were observed in the MDVP data, including a decrease in the maximum pitch between one week and three months post-surgery. Additionally, the study found that lower delta-V values (difference between the preoperative and postoperative signal amplitude of vagus nerve stimulation) were associated with higher F0 values at one week and three months post-surgery, while jitter and noise-to-harmonic ratio were higher in the group with higher delta-V values at three months post-surgery.Conclusion Greater differences between the preoperative and postoperative signal amplitude of vagus nerve stimulation during surgery were linked to worse postoperative voice outcomes. Voice parameters worsened for up to 3 months after hemithyroidectomy but showed signs of recovery afterwards. These findings offer insights into predicting and managing voice outcomes after hemithyroidectomy.

Evolution of wake structure with aspect ratio behind a thin pitching panel

The evolution of wake structures behind thin pitching panels at Reynolds number 1000 is studied numerically for a wide range of aspect ratios (0.54≤AR≤16). At the maximum pitching angle (θmax) of 5° and 15°, simulations are performed for pitching frequency St=0.5,1. The higher pitching angle and frequency promote thrust generation for all the AR. Although the propulsive power grows with AR in the thrust cases, the propulsion efficiency remains insensitive to the AR. Higher AR imparts stabilizing effect on the flow in the drag regime, though it triggers instabilities with asymmetric vortex pairing in the thrust cases. Wake topology for the drag cases reveals the emergence of horseshoe vortices and bridgelets-type vortex structures within the range of AR studied. The wake consists of entangled vortices undergoing subsequent reconnections in the thrust cases. A smaller θmax and St induces organized 3D structures for AR≤4, although the end instabilities diffuse for increasing AR, resulting in a 2D wake signature at larger AR. The spanwise circulation data show the dominant influence of primary instability in rendering a high horizontal velocity-compressed separated region in the drag regime.

Research on the Performance Characteristics and Unsteady Flow Mechanism of a Centrifugal Pump under Pitch Motion

Pitch motion is the key factor affecting the performance characteristics of centrifugal pumps on board ships and exacerbates hydraulic excitation to induce the unsteady vibration of pump units. A hydraulic test platform with swing motion is established to explore the effects of pitch motion on a pump’s performance characteristics. An obvious hump zone exists in the head characteristic curve in the low-flow-rate condition due to the pitch motion. The pump head in the shut-off condition has a significant decrease due to the pitch motion, compared to the static state. The head decrease gradually increases as the maximum pitch angle increases or the pitch period shortens. Specifically, the head in the rated flow condition decreases by 6.3 % to reach a minimum at the maximum pitch angle of 20 degrees in a period of 5 s. Based on a multiple-reference coordinate system, a large eddy simulation with a shear-modified eddy viscosity model is employed to simulate inner flow characteristics under the influence of pitch motion. A distinct vortex flow appears near the blade suction surface and becomes increasingly turbulent as the pitch period shortens. The pitch motion intensifies the unsteady stretching and deformation of vortices. The periodic variations in fluid-induced pressure over time present parabolic features, and the amplitude in the frequency domain reaches its maximum value within a pitch period of 5 s.

Understanding Shoulder and Elbow Injuries in the Windmill Softball Pitcher.

Although pitching-related injuries in the overhead athlete have been studied extensively, injuries associated with windmill pitching are not as clearly elucidated. Windmill pitching produces high forces and torques in the upper extremity, and studies have shown it creates similar shoulder and elbow joint loads to those reported in baseball pitchers. Studies have shown that the windmill pitching motion generates high levels of biceps activation with an eccentric load, placing the biceps at increased risk for overuse injuries. Although the American Orthopaedic Society for Sports Medicine published prevention guidelines including recommendations for maximum pitch counts in softball, these recommendations have not been adopted by most United States softball governing bodies. The repetitive windmill motion in conjunction with high pitch count demands in competitive softball creates notable challenges for the sports medicine physician. As with overhead throwing athletes, identifying and preventing overuse is crucial in preventing injuries in the windmill pitcher, and prevention and rehabilitation should focus on optimizing mechanics and kinematics, core, hip, and lower body strength, and recognition of muscle fatigue. With more than two million fastpitch softball participants in the United States, it is essential to better understand the etiology, evaluation, and prevention of injuries in the windmill pitching athlete.