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A drag-type, vertical axis hydrokinetic turbine, partially embedded in a relatively shallow channel streambank, has been introduced to mitigate side wall erosion while producing energy [1,2]. The turbine is deployed at river mid-depth to minimize the interaction with erodible bed and biota, floating debris, ice and logs, and it operates at low tip speed ratio, which is relatively safe for fish. To quantify the turbine performance and wake characteristics and to improve its design, we conduct high fidelity large-eddy simulations (LES) in an open channel flow under different operating conditions and blade geometry. The complex turbine geometry, including the rotor and housing structure, are captured by the immersed boundary method, while the coupled level-set and volume-of-fluid method is used to compute the free surface. The resulting power coefficients at different tip speed ratios are compared against results obtained in a reduced scale prototype experiment, carried out at the St. Anthony Falls Laboratory, for validation. Quantifying the near wake flow structures generated by the turbine and their contribution to the side wall shear stresses, responsible for potential streambank erosion, has become a critical design component. Blade geometry is indeed improved through multiple iterations using the reduced shear stress at the stream bank and the increased power coefficient as a combined metric in our co-design strategy. We believe such a procedure is essential to pursue diffused renewable energy extraction with positive environmental impacts.

At present, the process of designing a GTE involves a large amount of computational modeling. With the help of computational modeling, it is possible to predict a behavior of an engine part during engine operations before conducting experimental studies. For example, the numerical dynamic behavior analysis of compressor blades and prediction of dynamic stress levels during fluctuations in free modes are urgent problems. A high level of dynamic stress in the compressor blades in resonant modes can break a blade and stop an engine. In this paper, we propose a simple vibration stress estimation method for the compressor blades based on the calculation of natural frequencies and vibration forms. The method is based on a comparative analysis and scaling of stresses by the value of the total potential or kinetic energy. This estimation method is valid for local changes in the blade geometry, which do not lead to changes in the natural frequencies and vibration forms of the blades, assuming that the geometry change does not change the level of the aerodynamic excitation of the blade or its damping. At the stage of development or revision of the blade, a large number of variants of the blade geometry needs to be analyzed in order to reduce dynamic stresses. The proposed vibration stress estimation method has shown its high efficiency in developing and refining the geometry of the compressor blade. The vibration stress estimation method was tested using the rotor blade of a high-pressure compressor. As a result of the experimental study of the rotor blade, a high level of vibration stresses exceeding the permissible level was found for natural frequencies and vibration forms. To reduce the vibration stresses, measures were proposed to modify the geometry of the blade. For the modified blade geometry, the vibration stress estimation was performed with a prediction of the vibration stress values based on the manifested vibration forms. In order to verify the estimated vibration stress change, an experimental study of the modified blade was conducted. The vibration stress estimation method for the compressor blades was successfully verified.

The increasing availability of data recording solutions in the field of machining in combination with major developments in Machine Learning and Artificial Intelligence enable new approaches towards optimization in the industrial environment. In the aviation industry, critical components must fulfil extremely high quality standards. This requires a stable and error-free manufacturing process, as well as an extensive geometrical compliance, what is until now verified by long-lasting coordinate measuring machine (CMM) inspection. This publication shows how machine data analysis can contribute to reduce CMM measurement effort and thus decrease component cycle time. For this purpose, production machine data from an aircraft engine Inconel compressor blisk blade 5-axis milling operation was recorded and analysed by subsequent application of machine learning algorithms to predict the geometric measurement characteristics.

Called by Green Ship of the Future to reduce the propeller noise pollution in the subsea environment and avoid the possibility of causing propeller–shaft–ship resonance, the low-frequency broadband noise (LFBN) of marine propellers was studied theoretically and experimentally. The spectral method is improved by considering the blade section thickness and anisotropy in the turbulence spectrum, both of which are found to be effective in improving the prediction accuracy when compared with the experimental results. A series of propellers with the same blade geometry but different blade number were tested in the large cavitation channel at the China Ship Scientific Research Centre. The peak values in all conditions were close to the first-order blade-passing frequency. The effects of blade number and the advance coefficient were investigated by testing the propellers operating under different conditions. The effects were also studied using both the spectral method and experiment, and the results were consistent. Furthermore, the quantitative dependence of the LFBN on the influencing parameters was investigated using the sensitivity analysis. The rotational speed and turbulence intensity were found to be the two main factors, with greater than 10% effects. In addition, the effects of thickness and anisotropy scaling factor were evaluated using the spectral method. The results of this study provide guidance for controlling the LFBN in propeller design and optimisation.

Aiming to maximize the aerodynamic performance of the Distributed Electric Propulsion (DEP) aircraft, a hybrid design framework which focuses on the aerodynamic performance of the propeller/wing integration has been developed and validated numerically. Variable-fidelity modelling for propeller aerodynamics has been used to achieve computational efficiency with reasonable accuracy. By optimizing the aerodynamic loading distributions on the tractor propeller disk, the induced slipstream is redistributed into a form that is beneficial for the wing downstream, based on which the propeller blade geometry is generated through a rapid inversed design procedure. As compared with the Minimum Induced Loss (MIL) propeller at a specified thrust level, significant improvements of both the lift-to-drag ratio of the wing and the propeller/wing integrated aerodynamic efficiency is achieved, which shows great promise to deliver aerodynamic benefits for the wing within the propeller slipstream without any additional devices.

A sirocco fan (forward-curved centrifugal fan), including impeller blades and volute, is designed, and the empirical value ranges of several significant design parameters are discussed and summarized fromthe perspective of both aerodynamics and practical structure. Unsteady-flow numerical simulation and radiated sound-field calculation by indirect boundary element method are combined to evaluate its aerodynamic and acoustic performances. Both the discrete noise source from the rotating impeller and broadband noise source from the volute are considered. Obvious flow separation occurs in the flow passage of impeller blades due to large angle of attack, and the tongue region is the major noise source area due to the small impeller-tongue gap. Therefore, parametric studies for blade installation angle and impeller-tongue gap are performed. Analyses of flow- and sound-field indicate that appropriate reduction of blade geometry incidence angle weakens the flow separation, thereby improving both the aerodynamic and acoustic performances, and reasonable increase of the impeller-tongue gap has a remarkable noise reduction effect for the major noise source area near the volute tongue. The optimized sirocco fan meets the requirement of the industrial project, i.e., the far-field A-weighted sound power level lower than 64.0 dB(A), and achieves larger volume flow rate and total pressure rise. The results also imply that fast steady-flow numerical simulation result is indicative of the acoustic performance to some extent if the acoustic evaluation is urgent. Furthermore, optimization of the key structural parameters in the stage of design is preferable in practical engineering, instead of taking follow-up noise reduction measures.

This paper proposes a paradigm shift in the numerical simulation approach to predict rain erosion damage on wind turbine blades, given the blade geometry, its coating material, and the atmospheric conditions (wind and rain) expected at the installation site. Contrary to what has been done so far, numerical simulations (flow field and particle tracking) are used not to study a specific (wind and rain) operating condition but to build a large database of possible operating conditions of the blade section. A machine learning algorithm, trained on this database, defines a prediction module that gives the feature of the impact pattern over the 2‐D section, given the wind and rain flow. The advantage of this approach is that the prediction becomes much faster than using the standard simulations; thus, the study of a large set of variable operating conditions becomes possible. The module, coupled with an erosion model, is used to compute the erosion damage of the blade working on specific installation site. In this way, the variations of the flow conditions due to dynamic effects such as variable wind, wind turbulence, and turbine control can be also considered in the erosion computation. Here, we describe the method, the database creation, and the development of the prediction tool. Then, the method is applied to predict the erosion damage on a blade section of a reference wind turbine, after one year of operation in a rainy onshore site. Results are in good agreement with on field observations, showing the potential of the approach.

The horizontal axis wind turbine (HAWT) design with low wind speed requires blade geometry selection. The analysis uses the potential flow panel method and the integral boundary layer formulation to analyze wind flow around the airfoil. The blade design with the blade element momentum (BEM) theory has an aerodynamic coefficient value along the blade. Power wind calculates to model the wind shear pressure at each blade. This research aims to determine the wind turbine rotor based on the performance, including the power coefficient, tip speed ratio, power, and rpm. The simulation uses an airfoil NACA 4412 which has optimal coefficient lift (Cl) = 1.92 at 190 pitch of angle, coefficient drag (Cd) = 0.0635 at 130 pitch angle and Cl / Cd = 155 at tilt angle = 40. Five models of 2.5 m diameter blades with different angles for each chord. The test results show that the change in the speed ratio affects the power coefficient so that the optimal power coefficient on NACA 4412 in experiment 5 is 0.56, and change in rotation per minute affects the output power so that the rotation per minute and the optimal power in experiment 4 with a value of 374 rpm and 553 W.

Parametric investigations of impeller blade geometry of a centrifugal compressor are carried out. The influence of the tip clearance on the compressor characteristics is studied in order to increase its efficiency. The effect of the size ratios of various impellers on the compressor efficiency is investigated, and their characteristics are compared.

The blades of a hydrokinetic turbine have a great impact on its performance due to they are the elements responsible for capturing the kinetic energy from water and transform it into rotational mechanical energy. In this work, numerical analyses on the performance of a multi-element blade section were developed. The lift and drag coefficients (CL and CD, respectively) of the hydrofoils with traditional and multi-element configurations were studied. For this purpose, 2D numerical analyses were conducted by using JavaFoil code. S805, S822, Eppler 420, Eppler 421, Eppler 422, Eppler 423, Eppler 857, Wortmann FX 74-CL5-140, Wortmann FX 74-CL5-140 MOD, Douglas/Liebeck LA203A, Selig S1210, Selig S1223 and UI-1720 profiles were tested. The results indicated that the Eppler 420 multi-element hydrofoil provided high efficiency to the turbine. This was attributed to its higher relationship between the maximum CL and CD (CLmax /CD), which was equal to 47.77, compared to that of the Selig S1223 profile (39.59) and other hydrofoils studied. Therefore, the final optimized blade section selected was an Eppler 420 multi-element hydrofoil with a flap chord length of 70% of that of the main profile. The hydrodynamic and structural designs of the optimized blade section were validated with detailed 3D numerical models, through ANSYs Fluent software. The fluid and structural domains were connected using one-way coupling. The influence of the blade geometry and the operational parameters on the stresses supported by the blades were found by analyzing the fluid-structure interaction. From the numerical analyses conducted, it was observed that the blades did not exhibit structural fails. In this regard, the multi-element hydrofoil might be used for the design of a horizontal-axis hydrokinetic turbine with a high efficiency.

A design and optimization procedure of simplified wind turbine rotors for small-scale applications is presented. The need for this research has arisen from the recent national initiative of the government of Sri Lanka titled ‘Battle for Wind Energy’ in promoting small scale grid connected wind plants for electricity customers under Net Metering scheme. The main objective of this research is to assist local developers to design optimum rotors for given electrical generators (as determined by customer requirements), suitable for wind characteristics at specific locations. Another objective is to enhance local manufacturing capabilities by providing a design option of a simplified rotor blade geometry. A study on the correlation between population density of electricity customers and wind energy potentials was carried out to categorize the demand centres based on wind energy potentials in proposing series of small-scale wind turbine designs. A unique and improved rotor design procedure is presented which attempts to match the point of maximum performance of a rotor (design tip speed ratio) with the design wind speed of a given location by considering generator performance. The new design procedure showed successful convergence on a unique blade diameter for each rotor configuration that allowed the design tip speed ratio to match the design wind speed. The performance evaluation of rotor designs showed that high solidity rotors work better on the low wind potential region while low solidity rotors dominate medium and high wind potential regions. The performance reductions of simplified rotor designs are not significant and therefore would be an effective way to enhance value addition through local manufacture. Problem statement • Lack of a rotor design procedure that considers generator performance. • Lack of a rotor design procedure for blades with an optimum simplified geometry. • Geographical mismatch between high resource sites and location of electricity consumers in Sri Lanka. • Lack of optimized small-scale wind turbine designs for sites with different wind potentials in Sri Lanka. • Limited opportunities for local manufacture in Sri Lanka. Major novel contributions • Identification of geographical locations most suitable for promoting small-scale wind turbines. • Creation of rotor design procedures for optimized and simplified blade geometries considering generator performance. • Creation of optimized and simplified wind turbine rotor designs for different wind potential regions in Sri Lanka.

To overcome the lack of rural electricity in Indonesia vortex pico-hydro turbines are used as an option solution. This is due to the ability of the vortex turbine to work in low head conditions effectively. This study is conducted with comparison of curved and straight blade to obtain a more optimum turbine performance. Two methods are carried out in this study, analytical and computational method. Analytical methods are used to determine blade geometry and its performance while computational methods are used to analyse internal flow of turbine. As a result, the study concludes that hydraulic efficiency of vortex turbine in this study doesn’t affect much between straight and curved blades. The hydraulic efficiency for those blades is around 0.63. In addition, the study continued by analysing the optimum location of the blade in the basin. The results of the study show that the optimum ratio of depth and diameter of the blade is 0.33 with turbine efficiency is 0.84. Thus, the location of the blades is more important than the type of blades.

Computational fluid dynamic analysis was conducted with a new proposed Savonius hydrokinetic turbine with a parabolic blade shape specifically geared toward a small-scale power extraction. This parabolic blade geometry was developed by manipulating a couple of disparate kinds of blades in the recent past i.e. semicircular and arc shaped followed by a straight arc. The developed hydrokinetic turbine was tested numerically in a symmetric channel and its performance was evaluated concerning the power, thrust and torque coefficients. Simulations were also implemented with two other mentioned blades. The effects of Reynolds number at different tip speed ratios on the dynamic and static performance of all three models were discussed as well. The present investigation demonstrated a gain of 7.7% and 12% in maximum power coefficient with the new proposed Savonius hydrokinetic turbine by parabolic blade shape than that of the arc shaped followed by a straight arc and semicircular, respectively. Likewise, for this new proposed turbine, the maximum value of static torque coefficient improved by 4% and 25.8% than that of the arc shaped followed by a straight arc and semicircular, severally. For all three simulated blade profiles, the best performance was experienced at an optimum value of tip speed ratio 0.98 and Reynolds number 2 × 105. However, the new proposed turbine at all Reynolds numbers and tip speed ratios in the scope of this research showed a better performance than the other simulated models.

For a past few decades, metal matrix composite has a significant role in the various industrial and automobile applications. Production of metal matrix composite using stir casting technique is one of the most effective and economical technique. Achieving the uniform distribution of the reinforced particles was the major problem facing during the production of particle reinforced metal matrix composites and also achieving the effective fluid flow pattern was the greatest challenge to the research community. In this research, some of the major stir casting process parameters such as blade geometry, stirring speed and impeller position were optimized based on the vortex height of the fluid and settling time of the reinforced particles using visualization experiments and Grey relation analysis. Flow pattern of the fluid and the trace of the particles was analysed using a new technique called streak photography. Streak photography was one of the visualization experiments using glycerol water based model. Al8011/SiC metal matrix composites were manufactured based on the optimized stir casting process parameters. Finally, the fabricated composites were carried out for OM, SEM analysis and Brinell hardness testing for confirming the uniform distribution of the reinforced particles. Based on the confirmation results, 45ᴼ stirrer blade angle, impeller position 40 % from the base and 250 rpm stirring help to produce uniform distribution of the particles.

Utilization of hydro-power as a renewable energy source is now of prime importance in the world. Hydropower energy is available in abundance as a renewable source. For run-of river, low head reaction type Kaplan turbines mostly used. In this paper, a parametric study has been conducted on a complex geometry of Kaplan blade through static and dynamic computational analysis by varying the blade profile at different angles in the CAD model. Blade geometry surface and design were developed in Creo using the coordinate point system on the blade. Further blade profiles were analyzed to check and compare the output results. Results show that by changing the blade profile geometry, CAD models can be improved using the computational techniques. Consequences obtained were validated with the experimental/operational data and then four different blade profiles were developed. Research consequences showed improvement in the power output of the turbine.

As parallel computing becomes increasingly important in many real-world applications, a batch sequential experimental design (BSED), which adds a batch of computer experiments per iteration and runs these simulations in parallel, is gaining popularity in surrogate modeling. This article proposes sequential online dispatch in design of experiments (SODDE) for single- and multiple-response surrogate modeling when multiple processors work in parallel but not independently. The proposed method includes several unique features: 1) it works with any popular acquisition function to select a single new sample point at each iteration; 2) it minimizes the idle time of all processors; 3) it rapidly updates the surrogate model; and 4) it dynamically reconstructs the surrogate model when a simulation process aborts, minimizing the impact incurred by the abortion. The effectiveness of SODDE is evaluated in one mathematical example and one industrial problem. The latter problem considers blade design of horizontal axis wind turbines (HAWTs). The cost of finding blade geometry that results in the desired aerodynamic behavior of HAWTs is estimated for BSED and SODDE. Relative to BSED, SODDE reduces the costs by up to approximately 31%. Note to Practitioners —Computer simulation models are often used to represent the behavior of complex engineered systems, such as automobiles, aircraft, and wind turbines. Although running computer simulations allows analyzing the performance of these systems, the simulations can still be computationally costly (e.g., hours of runtime for numerically solving a large number of differential equations in one simulation), which makes the performance analysis task challenging. It is important to design an innovative simulation process that replaces the original expensive simulation models by cheap-to-build surrogate models, and at the same time, minimize the computational costs for building the surrogate models. The new method developed in this article allows experimental designers to run batch sequential iterations and run these iterations in parallel. This, in engineering practice, will help meet the need for long and complex experimental designs scenarios in a parallel computing environment, where the computer “up time” (or runtime) needs to be maximized to save time and ultimately, money. Cost analysis results from an industrial problem involving the inverse design of wind turbine blades suggest that the proposed method reduces the computational costs by up to approximately 31% over an existing method.

El estudio realizado corresponde al tipo de investigación tecnológica, ya que mediante la aplicación de las metodologías de diseño mecánico, se buscó mejorar el rendimiento de una trituradora de botellas tipo PET; el nivel de investigación es experimental, debido a que considerando el tipo de geometría de la cuchilla de corte, se buscó determinar aquel que proporciona mayor rendimiento de trituración. El objetivo de esta investigación fue diseñar un prototipo de trituradora cuya geometría de cuchilla de corte permita mejorar el rendimiento de trituración de botellas tipo PET. Considerando la metodología de diseño VDI 2221, se elaboró la lista de exigencias para el diseño de un prototipo de una máquina trituradora de plásticos PET y la matriz morfológica correspondiente y se obtuvo resultados cualitativos que indican que el rendimiento de trituración está en función de la geometría de la cuchilla de corte de la trituradora de botellas tipo PET. Así mismo, se utilizó el cálculo de diseño mecánico para seleccionar los componentes del prototipo de trituradora, el resultado cuantitativo de este estudio realizado requirió de las mediciones de rendimiento de trituración según el tipo de geometría las cuchillas de corte, luego mediante el análisis de la varianza (ANOVA) de un factor, se determinó que para un nivel de confianza del 95 % el tipo de geometría C (cuchilla con 3 uñas) proporciona mayor rendimiento de trituración con un valor promedio de 21.72 kg/h.

Shrouding of HAWT in a flanged diffuser is among techniques of wind power augmentation especially in urban areas. In this paper, a small scale of Flanged Diffuser Augmented Wind Turbine (FDAWT) was presented with flanges angle (?f) of 0°. The rotor fit for FDAWT was designed based on a modified blade element momentum theory, which adopts on developing the preliminary rotor blade geometry in terms of pitch angle. The modification of the blade pitch angle was based on the maximum wind speeds in the empty flanged diffuser at rotor position along the blade sections. The models of rotor and diffuser were fabricated and experimented in the wind tunnel. The experimental tests were conducted to calculate the power at a different wind velocity ranged 5 - 9 m/s. The performance tests were in terms of power coefficient, CP and torque coefficient, CQ as a function of the tip speed ratio as well as maximum power as a function of the wind velocity. The results show the rate of increase in the maximum power producing for the FDAWT with the modified rotor up to 291% more than what it is for the preliminary bare HAWT, while this increase was only 257% for FDAWT with the preliminary rotor.

The efficiency and accuracy of numerical simulation on power unit is the key to study the relevant aerodynamic layout with multiple rotating power units. However, the numerical simulation of the power unit using real geometry all faces the problem of low solution efficiency. Taking the rotor hovering state as an example, the real blade was firstly simplified and replaced by a thin mesh disk to establish the effective momentum source method. Then, using fan-shaped mesh region that changes with time to replace real blade and simulate the rotation, the unsteady momentum source method which could get the revolution of tip vortex was proposed. The results show that the momentum source method with the input of accurate blade force distribution can simulate rotor wake better, and the influence that blade geometry acts on wake mainly reflects in the blade force distribution. In addition, the unsteady momentum source method can simulate the revolution of tip vortex, and its consumptions of computing resources and calculation time are only about 1/8 of the unsteady numerical simulation based on the real geometry.

This investigative work was carry out through a factorial planning, using Design of Experiment (DoE) in order to evaluate the impact performance properties of Kevlar® woven structure impregnated with Non-Newtonian Fluids (NNF). Pull out and drop tower tests were performed. The pull out test showed that Kevlar® strength values with NNF composition 3 were better (10.55 N) when compared to others (1 and 2). The drop tower test showed that woven samples with highest concentration of NNF nanoparticles (3OR) exhibited the best behavior with respect to the penetration depth for P1 (19.5%) and S1 (48.0%) knife blade geometries. Thus, evidencing best residual energy dissipation when compared to the others. Results also showed that the composition (1, 2 and 3) of NNF as well as the orientation of the woven layers can be used to improve impact performance properties. Therefore, the impact protection performance depends on the friction between the yarns (pull out), the knife blade geometry and mainly the composition of the NNF which, in turn, is directly related to the nanoparticle and agent content of silane coupling present in the composition of the Non-Newtonian Fluid. Finally, this study also demonstrates that the use of statistical analysis promoted the improvement for obtaining and effectiveness of the behavior of lightweight impact protection textile structures.

An inverse design approach is proposed to compute wind turbine blade geometries which maximize the aggregate power output from a wind farm. An iterative inverse algorithm is used to solve the optimization problem. The algorithm seeks to minimize the target function, f = − C P , av , where C P , av is the average normalized mechanical power of all the turbines in the wind farm. An upper bound on the blade planform area, representative of the blade weight, is imposed to demonstrate how to incorporate constraints in the design process. The power coefficients ( C P ) of the turbines in the farm are computed by solving the Reynolds Averaged Navier Stokes equations with the turbine rotors modeled as momentum sources using the actuator disk model. The inverse design is carried out using the trust-region-reflective method, which is a nonlinear least squares regression solver. The computation cost is reduced by computing the Jacobian once every few iterations and approximating it using Broyden's method in between. The proposed design approach is first demonstrated to maximize the isolated performance of single- and dual-rotor wind turbines and subsequently used to design the blades for a 3-turbine array and a ten-turbine array in which the downstream turbines operate directly in the wake of the upstream turbines. For a turbine-turbine spacing of four rotor diameters, the farm-optimized blade designs increase the farm power output by over five percent and the optimized blade geometries are found to be considerably different from the blade geometry optimized for isolated turbine operation. As the turbine-turbine spacing is increased to eight rotor diameters, the difference between the blade geometry optimized for farm operation versus that for isolated operation, is reduced.

The shape of a wind turbine blade plays a critical role in the efficiency and robustness of energy production. In particular, the Wavy Leading Edge is a morphology that can be implemented in the blades to improve the operating range in unsteady conditions. The best performance is achieved by fine-tuning the blade geometry to the specific context. An aerodynamic exploration of these kinds of morphologies implies generating and evaluating design iterations. Accordingly, this work presents the development of the generative tool Albatros $$\hbox {Create}^{\textregistered }$$. Through interactive visualization, infographics, and centralized parameterization, its goal is to support the geometrical definition of the aerodynamic surfaces of horizontal-axis turbines with or without a wavy leading edge. New airfoil profiles can be created, and 3D models of the rotors designed can be automatically generated. The software was implemented in the design of two rotors which were then recreated in a benchmarking analysis with four other softwares. None of the four managed to generate the smooth surfaces in fully-editable models that were achieved with Albatros Create. This work aims at empowering the research community with a user-friendly tool for exploring rotor designs through virtual prototypes. This can help to integrate further the design, modeling, and optimization stages, addressing a wider audience and facilitating the implementation of Wavy Leading Edge morphologies.

23rd International Conference on Material Forming, ESAFORM 2020, Cottbus, Germany, 4 May 2020 - 6 May 2020; Procedia manufacturing 47, 1050-1057 (2020). doi:10.1016/j.promfg.2020.04.114 special issue: "23rd International Conference on Material Forming / edited by Markus Bambach", Published by Elsevier, Amsterdam [u.a.]

Many airfoils could be used to form a wind turbine blade. Different airfoil would result in an altered blade planform and its performance characteristics. Airfoil identification that should be included in the design then becomes an important task. Utilizing Blade Element Momentum Theory computation procedures, eleven types of airfoils were applied in blade geometries of rotors of 2.4 m in diameters. The changes in the distribution of chord lengths, twists, solidity ratio, and Reynolds numbers of the blades were compared as geometry parameters. The designed and off designed powers and thrusts were calculated, and the characteristics of the performance of the rotor were represented by the coefficient of power and coefficient of thrust.The calculated geometries showed that distinct airfoils resulted in different segments sizes of the blades and different performance characteristics of the rotors. The use of an airfoil that has a high lift coefficient and a high glide ratio in the design of a blade will produce a narrow blade and a small solidity ratio. The design will also have a high power coefficient at the tip speed ratio design. However, the blade power coefficient may be sensitive to changes in rotational speed.

Variable inlet guide vanes (VIGV) are the main control element to adjust the flow rate of industrial centrifugal compressors by customized pre-swirl in the inlet plane of the impeller. The efficient working range of VIGVs is however restricted due to open flow separation occurring at critical stagger angles. In order to overcome the narrow limitations of current blade geometries and to enhance the operating range of the compressor, split blades consisting of a separate front and tail blade segment proved to be particularly promising in previous linear-cascade measurements. Each blade segment is thereby individually staggered. This enables a gradual flow deflection along the chord length. Secondary flow losses, however, were not considered in the previous investigations with linear-cascades. To highlight the potential of the split blade concept under more application-oriented conditions including all relevant flow effects, highly resolved field measurements were conducted in the wake of annular VIGVs. Four different blade configurations, a customary reference case and three variations of the split blade with full, partial and missing sealing in the gap between the segments, were assessed using five-hole probe measurements. By investigating a wide range of stagger angles, the coverage of the full low-loss working range of the VIGV could be ensured. Especially, the fully sealed split blade configuration proved its capacity to extend the efficient operational range significantly.

In this research work, the investigation and optimization of small horizontal axis wind turbine blade at low wind speed is pursued. In this paper, an optimized design method based on BEM Theory is explained blade radius of 0.2 m rotors investigated with and without winglet blade geometry of 10 Low Reynolds number airfoils. An Xfoil and CFD software were used to devise a novel airfoil (MAF) suitable for use at low Reynolds number. A Matlab program was developed to use BEM theory and optimize blade geometry. The experimental blades were developed using the 3D printing additive manufacturing technique. The airfoils E210, NACA2412, S1223, SG6043, E216, NACA4415, SD7080, SD7033, S1210 and MAF were tested at the wind speed of 2-6 m/s. The airfoils and optimum blade geometry were investigated with the aid of the Xfoil software at Reynolds number of 100,000. The initial investigation range included tip speed ratios from 3 to 10, solidity from 0.0431 – 0.1181, and angle of attacks from 2o to 20o. Later on these parameters were varied in MATLAB and Xfoil software for optimization and investigation of the power coefficient, lift coefficient, drag coefficient and lift to drag ratio. The cut-in wind speed of the rotors was 2 m/s with the winglet-equipped blades and without winglets. It was found that the E210, SG6043, E216 NACA4415 and MAF airfoil displayed better performance than the NACA 2412, S1223, SD7080, S1210 & SD7003 for the geometry optimized for the operating conditions and manufacturing method described.