Blade Position Research Articles

Intelligent Control of an Experimental Small-Scale Wind Turbine

Nowadays, wind turbines are one of the most popular devices for producing clean and renewable electric energy. The rotor blades catch the wind’s kinetic energy to produce rotational energy from the turbine and electric energy from the generator. In small-scale wind turbines, there are several methods to operate the blades to obtain the desired speed of rotation and power outputs. These methods include passive stall, active stall, and pitch control. Pitch control sets the angular position of the blades to face the wind to achieve a predefined relationship between turbine speed or power and wind velocity. Typically, conventional Proportional Integral (PI) controllers are used to set the angular position of the rotor blades or pitch angle. Nevertheless, the quality of speed or power regulation may vary substantially. This study introduces a rotor speed controller for a pitch-controlled small-scale wind turbine prototype based on fuzzy logic concepts. The basics of fuzzy systems required to implement this kind of controller are presented in detail to counteract the lack of such material in the technical literature. The knowledge base of the fuzzy speed controller is composed of Takagi–Sugeno–Kang (TSK) fuzzy inference rules that implement a dedicated PI controller for any desired interval of wind velocities. Each wind velocity interval is defined with a fuzzy set. Simulation experiments show that the TSK fuzzy PI speed controller can outperform the conventional PI controller in the speed and accuracy of response, stability, and robustness over the whole range of operation of the wind turbine prototype.

Twist and chord optimization using the linearization method on the taper blade of a micro-horizontal axis wind turbineTwist and chord optimization using the linearization method on the taper blade of a micro-horizontal axis wind turbine

The research aims to optimize the geometry of taper blade profiles for the Horizontal Axis Wind Turbine (HAWT) to improve aerodynamic performance and minimize fabrication complexity. The study used blade linearization as an optimization method for identifying a desirable twist (β) and chord (Cr). This approach enhances accuracy and boosts computational efficiency. It simplifies the optimization process by reducing complexity. In contrast, traditional nonlinear methods are slower and more resource-intensive due to complex aerodynamic interactions. The best β and Cr distributions were found by linearization with elements 1 and 10 of the blade length and positions 5%, 15%, 25%, 35%, 45%, 55%, 65%, 75%, 85, and 95% of the blade elements. The linearization results were used to determine the optimum performance of the HAWT design using simulation. The optimal blades for HAWT were fabricated and their performance evaluated under real wind conditions. The linearization of the 45% twist and chord of elements 1 and 10 provided the best blade shape. Optimized twist and chord yielded HAWT performance with the Cp of 45% to 47% at rotational speeds of 200–900 rpm and wind speeds of 2–10 m/s. Twist and chord optimization increased the Cp from 39.71% to 46.43% with a rotational speed of 550 rpm at a wind speed of 6 m/s, as well as the maximum mechanical power from 424.28 watts to 500.35 watts at a wind speed of 10 m/s. The result from real wind conditions showed that manufactured HWAT produced an average electrical power of 294.19 watts at a rotational speed of 590.66 rpm. These results demonstrate that the optimized design approach presents a close match and is still reasonable in comparison to practical conditions.

LiDAR-Based Unmanned Aerial Vehicle Offshore Wind Blade Inspection and Modeling

The deployment of offshore wind turbines (WTs) has emerged as a pivotal strategy in the transition to renewable energy, offering significant potential for clean electricity generation. However, these structures’ operation and maintenance (O&M) present unique challenges due to their remote locations and harsh marine environments. For these reasons, it is fundamental to promote the development of autonomous solutions to monitor the health condition of the construction parts, preventing structural damage and accidents. This paper explores the application of Unmanned Aerial Vehicles (UAVs) in the inspection and maintenance of offshore wind turbines, introducing a new strategy for autonomous wind turbine inspection and a simulation environment for testing and training autonomous inspection techniques under a more realistic offshore scenario. Instead of relying on visual information to detect the WT parts during the inspection, this method proposes a three-dimensional (3D) light detection and ranging (LiDAR) method that estimates the wind turbine pose (position, orientation, and blade configuration) and autonomously controls the UAV for a close inspection maneuver. The first tests were carried out mainly in a simulation framework, combining different WT poses, including different orientations, blade positions, and wind turbine movements, and finally, a mixed reality test, where a real vehicle performed a full inspection of a virtual wind turbine.

Scraper Point Attitude Optimization in the Scraping Process of Aviation Composite Curved Surface

Aiming at the interference problem between the tool and the surface during the contact between the blade position and the composite material during the off-line programming scraping process of aviation composite parts, the contact effect of the blade during the scraping process of the composite surface is discussed, and a rotation projection attitude optimization strategy is proposed. Firstly, by constructing the mathematical model of the contact between the scraper and the surface, the geometric properties of the scraper and its contact on the surface are analyzed. Then, the non-uniform rational B-spline (NURBS) surface is used to reconstruct the surface, and the position information of the local area of the contact point is obtained to obtain the normal direction and curvature. In order to evaluate the contact effect of the scraper, an objective function is defined to minimize the contact error between the scraper linear trajectory and its projection on the surface, thereby quantifying the contact accuracy. By comparing the position and attitude of the scraper before and after optimization, the effectiveness of the proposed optimization method is verified. The optimized scraper posture significantly improves the contact accuracy with the composite surface, better adapts to the geometric characteristics of the complex surface, and ensures the efficiency and consistency of the scraping process. The research results provide a new perspective and method for the future development of automatic scraping process, and also provide an effective solution and technical means for other industries in the application scenario of curved scraping.

The Matching Mechanism and Flow Mechanisms of Supersonic Through-Flow Variable-Pitch Tandem Cascade

Abstract The geometric structure of the supersonic through-flow variable-pitch tandem fan poses challenges in ensuring optimal relative blade positions across various operating modes. This study employed numerical simulations to investigate the impact of axial overlap and percent pitch on the aerodynamic performance of fan in typical modes. Furthermore, it delved into the intricate interplay between the front and rear blades, offering detailed insights into the selection principles governing the relative blade positions in the supersonic through-flow variable-pitch tandem fan. The findings underscored the pivotal role of percent pitch based on chord direction in fan's aerodynamic performance. Specifically, supersonic and transonic modes exhibited superior performance when chord direction percent pitch was set at 10% and 100%, respectively. The key factor contributing to these lower losses was the influence of low-speed fluid from the wake of the front blade, which weakened the shock boundary layer interaction on the rear blade's surface. In the high-speed windmilling mode, within the confines of geometric constraints, higher percent pitch based on chord direction values corresponded to reduced losses. This outcome was primarily attributable to the gap-blocking effect, which diminished the shock boundary layer interaction on the rear blade's pressure side and improved the wake of the rear blade. However, in this mode, the loss demonstrated a positive correlation with the pressure ratio. Consequently, the selection of the relative blade position required a delicate balance between the competing demands of these two factors.

Influence of tungsten carbide spray treatment on anti-wear performance of Francis turbine runner blades surface

Based on the velocity similarity theory, a test system for sediment wear flow around Francis turbine runner blades was established. The sediment wear test was carried out on the surface of Francis turbine runner blades with severe sediment wear before and after tungsten carbide spraying. The wear rate prediction model was established, and the effect of tungsten carbide spraying on the wear resistance of runner blades was analyzed. The results show that the serious wear position of Francis turbine runner blade by sediment appears in the head and tail, and the greater the load, the more serious the wear; after tungsten carbide spraying treatment, the sediment wear of runner blades is reduced by more than 90%, and the wear life is greatly improved. The sprayed tungsten carbide coating treatment is effective in reducing the effects of sediment wear.

Prediction of Progressive Erosion Characteristics of Centrifugal Pump Blades Based on Dynamic Boundaries

Abstract The conventional method of fixed boundaries for predicting erosion inadequately reflects the erosion characteristics of centrifugal pumps under realistic operating conditions. In this research, we employ the dynamic boundary method, considering the influence of changes in wall morphology due to erosion on the flow field. We utilize the Euler-Lagrange approach and the E/CRC erosion model, incorporating a dynamic boundary geometry reconstruction strategy, to predict the erosion characteristics of the IS80-50-315 single-stage single-suction centrifugal pump. Solid-liquid two-phase flow calculations are conducted on the pump to predict erosion characteristics under varied operating conditions. The results show that the dynamic boundary-based progressive erosion prediction method realistically forecasts the erosion characteristics of the overflow wall and captures the evolution of blade morphology with erosion time. Erosion intensity on the blade suction surface significantly surpasses that on the pressure surface, guided by particle distribution characteristics in the centrifugal pump flow channel. Particle diameter primarily influences the erosion position of centrifugal pump blades; smaller particles induce erosion in the middle region of the blade, while an increase in particle diameter shifts the severe erosion position towards the impeller outlet direction. At a consistent particle diameter, higher particle concentrations correspond to elevated erosion rates in the blade area. We establish a relationship between the blade mass loss rate and erosion time during 2500 hours of pump operation at the design condition, introducing the blade mass loss rate for convenient assessment and prediction of blade damage in the centrifugal pump.

Research on the container configuration for revolution-assisted horizontal vibration finishing of aero-engine blades

Vibration finishing has been widely used to improve aero-engine blades' surface quality and service performance. However, there are still problems after processing, such as uneven surfaces and large removal materials of the inlet and exhaust edge. The application of vibratory finishing is greatly limited. In order to realize the uniform processing of blades, a process scheme of revolution-assisted horizontal vibratory finishing was proposed. A reverse method of container configuration is proposed to change the force distribution at each blade position and realize the blade's machining uniformity. The results show that normal force is the main factor affecting the processing effect. When the blade is fixed in the container, the processing effect of the downward surface of the blade is related to the distance from the container bottom. The discrete signal of the normal force is transformed into a vector, and the difference coefficient CD is proposed. Based on the inverse method, it was found that increasing the distance between the blade's lower side and the container bottom and reducing the distance between the blade's upper side and the container bottom will reduce the normal force difference at different revolution stages. After the blade was processed with the reverse container, the surface roughness decreased from 0.85 ± 0.05 μm to 0.22 ± 0.02 μm, and the standard deviation of Ra decreases to 0.046. The average residual stress and its standard deviation are reduced to −332.51 MPa and 5.573. The research provides methods and ideas for designing container configuration and the uniformity of complex curved surface parts in mass finishing.

EXPERIMENTAL STUDIES OF THE PERFORMANCE EFFICIENCY OF A WIND TURBINE WITH COMBINED BLADES

This article studies the aerodynamic characteristics of a wind turbine at different streamline parameters. For this purpose, an experimental sample of the plant with combined power elements in rotating cylinders form with fixed blades was fabricated. The airflow velocity was varied, ranging from 3 to 12 m/s. The results of the experiment to study the variation of the angle α of the fixed blade position relative to the cylinder from the air flow velocity were analyzed. The changes in aerodynamic forces from the air flow velocity are graphically presented. It was found that at the optimal angle α = 0 ° of the fixed blade relative to the cylinder, the maximum values of aerodynamic forces were obtained. Graphs of the dependence of aerodynamic coefficients on the Reynolds number are also constructed, in which it is established that, at α= 0º, the minimum value of the lift coefficient is 0.012 N and the maximum value of the drag coefficient is 10.07 N at Re = 1∙105. The presented results show the effectiveness of the combined use of the and the fixed blade. The experimental results obtained on the aerodynamic parameters of a wind turbine can be used in the development of prototypes of installations designed for low wind speeds.

Predicting Erosion Damage in a Centrifugal Fan

Erosion damage can occur in fans and blowers during industrial processes, cooling, and mine ventilation. This study focuses on investigating erosion caused by particulate air flows in a centrifugal fan with forward-inclined blades. This type of fan is particularly vulnerable to erosion due to its radial flow component and flow recirculation. The flow field was solved separately, and the data transferred to the particle trajectory and erosion code. This in-house code implements the Lagrangian approach and the random walk algorithm, including statistical descriptions of particle sizes, release positions, and restitution factors. The study involved two types of dust particles, with a concentration between 100 and 500 μg/m3: The first type is the Saharan (North Africa) dust, which has a finer size between 0.1 and 100 microns. The second type is the Coarse Arizona Road Dust, also known as AC-coarse dust, which has a larger size ranging from 1 to 200 microns. The complex flow conditions within the impeller and scroll, as well as the concentration and size distribution of particles, are shown to affect the paths, impact conditions, and erosion patterns. The outer wall of the scroll is most heavily eroded due to high-impact velocities by particles exiting the impeller. Erosion is more pronounced on the pressure side of the full blades compared to the splitters and casing plate. The large non-uniformities of erosion patterns indicate a strong dependence with the blade position around the scroll. Therefore, the computed eroded mass is cumulated and averaged for all the surfaces of components. These results provide useful insights for monitoring erosion wear in centrifugal fans and selecting appropriate coatings to extend the lifespan.

Study on the design of short blade offset for the long and short blade runner of 1000 MW hydraulic turbine units

Abstract For such complex rotating machinery as hydraulic turbine, the hydraulic operation characteristics of the hydraulic turbine unit are significantly impacted by the short blade of the runner used as the splitter blade. To find the optimum position of the short blade, the study object is the 1000 MW hydraulic turbine, selects three circumferential offset positions of the short blade for numerical simulation calculation, obtains the runner flow pattern at different offsets, and explores the impact on the short blade offset on the vortex and pressure pulsation in the runner. The results show that the counterclockwise offset of the short blade will improve the flow pattern of the runner, reduce the scale of vortex in the runner and enhance the efficiency of the hydraulic turbine. The counterclockwise offset will increase the interference while decreasing the pressure pulsation in the vaneless region, at the runner’s inlet, and downstream of the short blade. When the offset δ=0.6, the peak-valley difference of pressure fluctuation in the vaneless zone is the smallest, accounting for only 1.38 % of the rated head. The main frequency of the vaneless zone gradually changes from 15fn to 30fn , and the main frequency of the runner inlet and the short blade downstream is 24fn . Due to the different weakening effects of short blades on the interference, low-frequency pulsation components of 4fn and 8fn appear.

A hierarchical adaptive selection neural network for dynamic impact localization of wind turbine blades

This paper focuses on the localization problem of dynamic impacts that can lead to significant damages on wind turbine blades (WTBs). Localization of dynamic impacts on WTBs is essential for wind turbines due to their vulnerability to dynamic impacts such as birds, stones, hails. The proposed deep learning methodology contributes to accurately locate the impacted blade and specific position using the measurements from a limited number of sensors. In particular, a novel hierarchical adaptive selection neural network is proposed, which integrates a classification subnetwork and a regression subnetwork. Specifically, an adaptive blade selection mechanism is designed to determine the impacted blade for classification while an adaptive window selection mechanism is developed to highlight the representative time period for regression. By deploying a limited number of sensors to acquire measured vibration data, the proposed method can accurately identify the collision locations of transient impacts loaded on WTBs. In both simulated and real-world experiments, the proposed method achieves the mean absolute error of 0.189 centimeter and 1.088 centimeter for impact localization. The experimental results demonstrate the superior performance of the proposed model in comparison with the existing methods for localizing impulsive loads on WTBs.

Vibration response analysis of boneless wiper-windshield system based on multi-body dynamics model

The vibration and noise generated by the boneless wiper-windshield system during its actual operation bother the occupants. Exploring the dynamic characteristics of the boneless wiper-windshield system is a prerequisite for understanding vibration and noise. In this paper, the dynamic characteristics of the boneless wiper-windshield system are investigated, and a rigid-flexible coupled multi-body dynamic model matching the real boneless wiper-windshield system is constructed. The friction characteristic of the dynamic model is studied through the wiper test bench experiment. The nonlinear dynamic response of the dynamic model is calculated with the Adams and results of the frictional vibration are well reproduced in real motions. The parallel analysis of the simulation calculation results and the real vehicle test results confirms the validity of the model. The results show that the vibration generation mechanism at the moments before and after the reversal can be explained by the instability of the wiper blades due to the negative friction characteristic. There are differences in the magnitude of the reversal impact force and the moment of reversal at each position of the wiper blade. The effect of the speed-gears on the system vibration is analyzed through the simulation results. The analysis method and simulation results in this article can provide reference for the research on vibration and noise control of boneless wiper systems.

Evaluating the Ergonomic Performance of a Novel Periodontal Curette with Adaptive Handle Design

(1) Background: Periodontal instrumentation with dental curettes is associated with discomfort, fatigue, and musculoskeletal diseases. The goal of this study was to compare comfort, fatigue, and muscle work using three different curettes. (2) Methods: Eight hygienists each scaled three typodonts using the three different curettes. Curette A was a prototype with a novel adaptive design, Curette B had a conventional stainless-steel design, and Curette C featured a conventional silicon-covered handle. Time-based work in four muscles, comfort, fatigue, tactile feedback, grip and blade position, and pinch and grasp strength were recorded. Statistical analysis was performed using a General Linear Model (GLIM) and Tukey’s post hoc test. The level of significance was set at p < 0.05. (3) Results: Comfort, correct grasp, fingertip placement, and blade-to-tooth adaptation were significantly better with Curette A (p < 0.05). While pinch and grasp strength were significantly reduced post-instrumentation for Curettes B and C (p < 0.05), they remained unchanged for Curette A. Curette A required significantly less total muscle work and work in individual muscles, resulting in significantly less post-instrumentation fatigue than for Curettes B and C, but similar levels of tactile feedback (p < 0.05). (4) Conclusions: The ergonomic performance of a prototype adaptive periodontal curette was significantly better than that of two conventional instruments with rigid handle designs.

Numerical study of the influence of quadrotor blade parameters on aerodynamic noise generation

The aim of this paper is to study the effect of variation of the parameters of a small-sized quadrotor blade on the level of aerodynamic noise and its frequency spectrum. There is a certain discrepancy between the calculated and experimental data available today. The reason for this is that the study of quadrotor rotor noise is carried out using various theoretical models that do not consider certain factors of sound generation or additional artificial sound sources, which result in an overestimated noise level. Therefore, there is a need for an accurate model, the calculation of which more closely matches the experimental data. In the paper below, an aerodynamic noise model is proposed to study the noise of a quadrocopter blade, which considers the non-stationarity and three-dimensionality of the sound generation and propagation process. The research methods are based on the numerical calculation of the characteristics of the near and far sound fields in the potential approximation: pressure coefficient, sound pressure level, and spectrum of the generated sound. The main parameters that were varied during numerical calculations were the rotor speed of the quadrotor, angle of attack, torsion angle, and blade position in the plane of rotation. The NASA parabolic profile was used as the test profile. Results and conclusions. The results of numerical calculations in the near field revealed three areas of sound generation above the blade surface. The first region, which is more unstable, is caused by blade torsion. The other two sound generation areas are smoothly distributed along the blade’s swing, and the pressure change level in each of them doubles. The level of generated aerodynamic noise is largely dependent on the blade speed and the distance from the blade at which the noise is calculated. The angle of attack and blade pitch have a smaller effect on the generated noise level, and in the far field, they have almost no effect on the maximum noise level. The dependence of noise on the distance to the blade, as well as the blade parameters, which were chosen similar to those studied by other authors, showed a fairly good agreement with the calculations of these authors and with experimental studies. Because of aerodynamic calculations and noise generation around the quadrotor blade using ANSYS software, it was found that sound vibrations occur during the flow around the blade tip, with a level of 120 dB in the immediate vicinity of the blade surface. Calculations using a 3D model of the propeller confirmed that the volume reached 80 dB at the nearest reference point, which closely matches the data from the calculation based on the potential model and the experimental data.

KLIPPEL FEIL SYNDROME AND ASSOCIATED ANOMALIES

Introduction: Klippel-Feil syndrome (KFS) is a rare genetic disorder characterized by abnormal the development of the cervical spine, which leads to the fusion of two or more cervical vertebrae. Incidence is 1:40 000 - 42 000. Inheritance is usually autosomal dominant. The gene mutation is most often found on the long arm of chromosome 8q22.1.The syndrome was first described by French physicians, Maurice Klippel and André Feil in 1912 with the classic clinical triad of manifestations consisting of a low posterior hairline, short neck, and limited neck range of motion. There may be skin folds on the neck - Pterygium colli, and the shoulder blades are high - Sprengel Deformity. Scoliosis is often present. Accompanying, hidden anomalies may be more important than neck deformity. A clinical finding with an objective examination is sufficient to suspect this syndrome. And then additional diagnostic methods are applied. Surgical intervention is carried out in the event of instability on the spine with the aim of eliminating it, as well as correcting scoliosis. Therapy of accompanying anomalies - kidney, neurological disorders, hearing disorders. Physical therapy is also recommended, which gives modest results. The life span of people with Klippel-Feil syndrome is shortened due to frequent anomalies of the internal organs. Case report: The paper presents a girl aged 10 years and 10/12 months. Pronounced hypertelorism. On the upper lip, a scar after cleft lip and palate surgery, left. Teeth carious, irregularly arranged. Neck short with pterygium. Low hairline. Pronounced scoliosis. High position of the shoulder blades. Abdominal ultrasound shows agenesis of the right kidney. IVP - the right kidney is not shown, the left kidney is compensatory enlarged. A diagnosis of Klippel Feil syndrome was made in a tertiary institution. Parents refuse further tests and treatment. Conclusion: In every child with Klippel-Feil syndrome, further examination and detection of accompanying, hidden anomalies that may be more important than the neck deformity is necessary.

Effects of Turbulence‐Induced Blade Position on Flow and Combustion in a Wankel Rotary Engine

Aiming at the problem of low turbulent velocity and incomplete combustion in the combustion process of the Wankel rotary engine (WRE), and setting turbulence‐induced blade (TIB) in the combustion chamber recess is an effective means to enhance the turbulent motion and promote combustion. Carifying the optimal arrangement position of TIB can get better combustion performance. Therefore, a computational fluid dynamics (CFD) simulation model of a WRE with TIB was established in this paper. Based on the differential pressure perturbation mechanism, the influence of the arrangement position of the TIB on the flow field and combustion performance were analyzed. The results showed that when the ratio of blade arrangement distance is less than 0.66, the pressure difference between the leading and trailing of the blade is small. At this time, the in‐cylinder flow is mainly disturbed by the forced disturbance of the TIB, the increase of the turbulent velocity is not obvious, and the diffusion velocity of the flame to the rotor direction is small. When the ratio of blade arrangement distance is greater than 0.66, the pressure difference between the leading and trailing of the blade is large. At this time, the In‐cylinder flow is affected by the pressure difference flow in addition to the forced disturbance of the TIB. The turbulent velocity is effectively enhanced, and the flame velocity is fast to the rotor direction. When the ratio of blade arrangement distance is 0.66, it shows the best combustion performance, and the indicated work is the largest. Compared to the scheme without TIB, the indicated work is increased by 16%.

Reference Score of C7 Angle among College Students of North India

Introduction: The sagittal shoulder C7 angle is specialised to analyse shoulder posture in the sagittal plane. the curvature of the cervical spine can influence the location and movement of the shoulder girdle like, a higher C7 angle leads to greater cervical lordosis, whereas a lower C7 angle leads to forward head posture and changes in shoulder blade position, affecting shoulder function and biomechanics. Aim: To establish normative score of C7 angle among college-going students of North India. Materials and Methods: A total 57 college-going male students with any musculo-skeletal condition in neck and head are included in this study to establish the normative score of C7 angle. The C7 angle was calculated in two phases. Firstly, the authors here took photographs of neck and head of participants in sagittal plane and angle was calculated by Kinovea software which were reliable methods. Results: Normative was establish for the participants which came to be abmormal. The p-value obtained was less than 0.05. Hence Subhi Kumari, BPT Student, Department of Physiotherapy, Maharishi Markandeshwar Institute of Physiotherapy and Rehabilitation, Maharishi Markandeshwar (Deemed to be University), Mullana, Ambala, Haryana, India. Joydip Saha, Assistant Professor, Department of Physiotherapy, Maharishi Markandeshwar Institute of Physiotherapy and Rehabilitation, Maharishi Markandeshwar (Deemed to be University), Mullana, Ambala, Haryana, India. Reference Score of C7 Angle among College Students of North India Abstract ID-UG 11 the normative value is represented in terms of median and IQR. The p-value <0.05 indicates a non-normal distribution. The researchers most likely performed a normality test on the C7 angle measurements collected from the individuals. A p-value <0.05 indicates that the data deviates from a normal distribution. To put it simply, the C7 angle scores were not distributed uniformly, as a conventional bell curve would be. Traditionally, the average (mean) serves as the normative value. However, extreme values in non-normal distributions have a significant influence on the mean. Because the C7 angle scores were not normally distributed, taking the mean as the normative value could be deceptive. It may be skewed to greater or lower values based on the data. Conclusion: The analysis was successful and normative score for C7 angle was 55.03 as well as results will help to determine normal value of C7 angle among college-going students.

Mitigation of In-Plane Vibrations in Large-Scale Wind Turbine Blades with a Track Tuned Mass Damper

To mitigate in-plane vibrations of wind turbine blades, a track tuned mass damper (TMD) is proposed and its performance for mitigating blade in-plane vibration is investigated considering various influence factors. Firstly, the organization and operational principles of the damping control device are explained. Then, the equations of motion of the individual TMD-equipped blade are then deduced from Euler–Lagrange. Secondly, blade’s wind loading is calculated by blade element momentum theory considering the blade rotation effect through the rotating sample spectrum. Thirdly, the dynamical response of the blade based on the MATLAB/SIMULINK tool is calculated. The peak maximum displacement and standard deviation of the blade tip are chosen as the estimation indicators to assess the TMD’s effectiveness of the device considering actually various argument including mass ratio μ , damping ratio ξ , and installation position x 0 / L . Based on the assumption that the mass block in the vibration reduction control device has no contact with the inside surface of the blade web in operation, the optimal relative values of mass ratio, damping ratio, and installation position of a single blade are determined as 0.03, 15%, and 0.55, respectively. As a result, the reduction of the peak value and the standard deviation can reach 52.78% and 53.75%, respectively. Therefore, with the optimal parameters, the designed vibration control device effectively not only reduces the blade tip displacement but also avoids the damage due to in-plane vibrations.

A numerical study on the blade–vortex interaction of a two-dimensional Darrieus–Savonius combined vertical axis wind turbine

To investigate power losses of a Darrieus–Savonius combined vertical axis wind turbine (hybrid VAWT) associated with the interaction between blades and wake, it is crucial to understand the flow phenomena around the turbine. This study presents a two-dimensional numerical analysis of vortex dynamics for a hybrid VAWT. The integration of a Savonius rotor in the hybrid VAWT improves self-starting capability but introduces vortices that cause transient load fluctuations on the Darrieus blades. This study attempts to characterize the flow features around the hybrid VAWT and correlate them with the Darrieus blade force variation in one revolution. Results demonstrate the capability of numerical modeling in handling a wide range of operational conditions: the relevant position of Savonius and Darrieus blades (attachment angle γ=0°−90°) and Savonius' tip speed ratio λS (0.2–0.8, varied Savonius' rotational speed). The torque increase in the Darrieus blade in hybrid VAWT (compared to a single Darrieus rotor) due to the appearance of the vortex shedding from the advanced Savonius blade is independent of the attachment angle and tip speed ratio. Apart from start-up and power performances of the hybrid VAWT, the most rapid force fluctuation is identified when the Darrieus blade interacts with Savonius' wake at γ=0° and λS=0.8, which is considered undesirable. Furthermore, attachment angles of 60° and 90° exhibit better power coefficients compared to those of 0° and 30° for the hybrid VAWT. This study contributes to a comprehensive understanding of flow dynamics in hybrid VAWTs, revealing the correlation between torque variation and vortex development.