Blade Geometry Research Articles

Multifidelity Analysis of a Solo Propeller: Entropy Rise Using Vorticity Dynamics and Kinetic Energy Dissipation

Propellers for electric aviation are used in solo- and multirotor applications. Multifidelity analysis with reduced cycle time is crucial to explore several designs for energy minimization and range maximization. A low-fidelity design tool, py_BEM, is developed for design and analysis of a reverse-engineered solo 2-bladed propeller using blade-element momentum theory with physics enhancements including local Reynolds number effect, boundary-layer rotation, airfoil polar at large AoAs and stall delay. Spanwise properties from py_BEM are converted into 3D blade geometry using T-Blade3. S809 and NACA airfoil polar are utilized, obtained by XFOIL. Lift, drag, performance losses, wake analysis, comparison of 3D steady CFD with low fidelity tool, kinetic energy dissipation, entropy and exergy through irreversibility are analyzed. Spanwise thrust and torque comparison between low and high fidelity reveals the effect of blade rotation on the polar. Vorticity dynamics and boundary-vorticity flux methods describe the onset of flow separation and entropy rise. Various components of drag and loss are accounted. The entropy rise in the boundary layer and downstream propagation and mixing out with freestream are demonstrated qualitatively. Irreversibility is accounted downstream of the rotor using the second-law approach to understand the quality of available energy. The performance metrics are within 5% error for both fidelities.

Effectively using multifidelity optimization for wind turbine design

Abstract. Wind turbines are complex multidisciplinary systems that are challenging to design because of the tightly coupled interactions between different subsystems. Computational modeling attempts to resolve these couplings so we can efficiently explore new wind turbine systems early in the design process. Low-fidelity models are computationally efficient but make assumptions and simplifications that limit the accuracy of design studies, whereas high-fidelity models capture more of the actual physics but with increased computational cost. This paper details the use of multifidelity methods for optimizing wind turbine designs by using information from both low- and high-fidelity models to find an optimal solution at reduced cost. Specifically, a trust-region approach is used with a novel corrective function built from a nonlinear surrogate model. We find that for a diverse set of design problems – with examples given in rotor blade geometry design, wind turbine controller design, and wind power plant layout optimization – the multifidelity method finds the optimal design using 38 %–58 % of the computational cost of the high-fidelity-only optimization. The success of the multifidelity method in disparate applications suggests that it could be more broadly applied to other wind energy or otherwise generic applications.

Reverse Engineering Algorithm for Cutting of Ruled Geometries by Wire

Abrasive wire cutting (AWC) and wire electric discharge machining (WEDM) are efficient and economical processes for the fabrication of precision parts from bulk material. Operating costs and manufacturing lead times are low compared to more general methods such as 5-axis CNC milling, turning, or electro-discharge machining. In this paper, an algorithm based on differential geometry in Euclidean space is proposed for reverse engineering of ruled geometries. The algorithm can determine whether a given geometry is producible by wire cutting, and can also derive the associated wire trajectories. Implementation is demonstrated by producing complex turbine blade geometries on 4-axis wire cutting machines with an overall shape accuracy of 20–40 μm peak-to-valley.

Effect of tip speed ratio on the aerodynamic noise of a small wind turbine: An optimization study

A dual-objective optimization study was carried out to illuminate how the tip speed ratio of a small wind turbine affects the aerodynamic noise as well as the blade geometry. A 0.75 kW three-bladed small horizontal axis wind turbine was selected as the case study. Two important goals were considered in the study: maximization of the output power and the minimization of the aerodynamic noise. The former was calculated by the well-known blade-element momentum theory while a validated semi-empirical model was adopted for the computation of the latter. A combination of these goals defined the objective function and the weighted-sum approach was employed to find the optimal values for the design variables of the optimization including the distributions of the chord and the twist angle along the blade together with the tip speed ratio. The extracted power was calculated at the rated wind speed of 10 m/s while the noise was computed at lower wind speeds of 5 and 7.5 m/s. The genetic algorithm technique was adopted for the muti-objective optimization. The results revealed the importance of the blade tip region in producing the emitted aerodynamic noise. Specifically, an increase in the chord and twist values near the tip results in the reduction in the emitted noise. Results also show that a good compromise between the two goals is achievable such that a noticeable reduction in the emitted aerodynamic noise is attainable in exchange for a very small drop in the power coefficient. The optimization results also indicated that the noise could be adequately reduced at the smaller value of the tip speed ratio without a large reduction in output power which is due to the decrease in the rotational speed of the turbine.

Validation of crack initiation model by means of cyclic full-scale blade test

Wind turbine rotor blades are subject to highly dynamic loads and designed for life cycles of at least 20 years, which means that materials are subjected to high-cycle fatigue. Fatigue is a design-driving loading for current and future blades. Bond lines of blades are exposed to a multi-axial stress-state due to the anisotropic thin-walled blade structure and curved, tapered, twisted, and airfoil-shaped blade geometry. To eliminate undesirable failure modes and thus increase the reliability of wind turbine rotor blades, standards and guidelines recommend that the multi-axial stress-states be taken into consideration for the limit state analysis. In addition, thermal residual stresses that develop during manufacture can have a significant impact on the fatigue life of the bond line. By means of a cyclic full-scale blade test of a commercial 81.6m long offshore blade, we validate a crack initiation model, which takes into account multi-axial thermal and mechanical stress-states, as well as the probabilistic stress-life, to predict the edge of crack initiation in the adhesive as well as the span-wise position. Both observations agreed well with the simulations. All residual normal stress components and cross-sectional plane shear stress made up the major part of the mean equivalent stress, while the mechanical stress amplitude components - longitudinal, peel, and cross-sectional plane shear stress - made up the major part of the equivalent stress amplitude.

3D printed rotor blades for a research wind turbine: Aerodynamic and structural design and testing

This study combines the design, the 3D printing and the testing of a small 3-bladed wind turbine rotor for research and teaching purposes. The objective is the additive manufacturing of a rotor with a radius of one meter, as an alternative to subtractive methods, such as computerized milling. The blade design is developed using freely available software packages. The aerodynamic considerations include the airfoil selection, the calculation of the blade geometry and the simulation of the ultimate load cases. The structural considerations are focussed on the printable materials, the infill structures and the retrofit of a load-carrying spar. The rotor blades are 3D printed with the BigRep One at the maker space of the TH Wildau. The structural integrity of the prototype blade is tested in terms of the ultimate root bending moments and the centrifugal forces at the HTW Berlin. The aerodynamic run-up tests are performed at the large wind tunnel of the TU Berlin measuring the power curves. The successful prototype paves the way for follow-up projects, such as open field tests and the 3D printing of larger rotor blades.

Structural and Thermal Analysis of F Class Gas Turbine Compressor Blade

In this study, the structural and thermal analysis of the final stage compressor rotor blades, which are currently used on-site, is performed by using the ANSYS program. For that reason, a 3D model of the existing compressor blade has been done. Later on, this model was transferred to the ANSYS program and analyzed. In the analysis, the parameters formed in the blade geometry were determined. By creating a design geometry with the selected parameters, the stress of the existing blade under operating conditions was examined. All external parameters in this study were taken from an F-class gas turbine operating under real field conditions. The stresses of the obtained values in different regions on the blade were examined. This study is also a reverse engineering study and the effects of real field conditions on the compressor blades have been analyzed.

Pengaruh Sudut Sudu Turbin Jenis Taper Terhadap Tip Speed Ratio (TSR) dan Power Coefficient (CP) pada Turbin Angin Horisontal Berbasis Q-Blade

The utilization of wind energy as a power plant still needs to be improved by looking at the turbine performance, which is not always the same in different regional conditions. This study aims to determine the effect of the blade angle of the turbine on the tip speed ratio (TSR) and power coefficient (CP) by using a Q-Blade simulation. Q-Blade software can predict the value of the power generated at the blade rotation by comparing the CP and TSR values. The type of airfoil NACA 4412, taper blade, blade's numbers (4), blade radius (0.3 m), wind speed ± 3.6 m/s were fixed variables in this study. The simulation generated a graph of the relationship between CP and TSR changed and a simulation image of the load distribution ensued in the blade geometry. The blade angle of 30 at the TSR number 5 produced the highest CP values, which was ±0.4. The low loading value in the axis/rotor region, at a variation of the blade angle of 30, balances the centrifugal force on the rotating fluid. The centrifugal force produces thrust on the turbine so that the blade rotates with a high CP value in that area.

Effect of Yaw Angle on Large Scale Three-blade Horizontal Axis Wind Turbines

Offshore Horizontal Axis Wind Turbines (HAWT) are used globally as a source of clean and renewable energy. Turbine efficiency can be improved by optimizing the geometry of the turbine blades. Turbines are generally designed in a way that its orientation is adjustable to ensure the wind direction is aligned with the axis of the turbine shaft. The deflection angle from this position is defined as yaw angle of the turbine. Understanding the effects of the yaw angle on the wind turbine performance is important for the turbine safety and performance analysis. In this study, performance of a yawed HAWT is studied by computational fluid dynamics. The wind flow around the turbine is simulated by solving the Reynolds-Averaged Navier-Stokes equations using software ANSYS Fluent. The principal aim of this study is to quantify the yaw angle on the efficiency of the turbine and to check the accuracy of existing empirical formula. A three-bladed 100-m diameter prototype HAWT was analysed through comprehensive Computational Fluid Dynamics (CFD) simulations. The turbine efficiency reaches its maximum value of 33.9% at 0° yaw angle and decreases with the increase of yaw angle. It was proved that the cosine law can estimate the turbine efficiency with a yaw angle with an error less 10% when the yaw angle is between –30° and 30°. The relative error of the cosine law increase at larger yaw angles because of the power is reduced significantly.

Mathematical Modeling of Transient Processes in the Susceptible Motion Transmission in a Ship Propulsion System Containing a Shaft Synchronous Generator

Within the scope of the presented work, a mathematical model of a prototype of a complex motion transmission on a ship was developed. The abovementioned motion transmission includes long elastic elements with distributed mechanical parameters. The system, containing the motion transmission under consideration, is driven by an engine via epicyclic gearing. The torque is transmitted via a long drive shaft to a propeller working with a variable blade geometry. The rotor of a synchronous generator is mounted on the ship’s long drive shaft. This shaft generator produces electricity that is fed to the ship’s electrical network. With the use of the developed mathematical model, electromechanical transients occurring during the transmission of mechanical power are analyzed. This paper analyzes the motion transmission with the use of computer simulation and presents the results of research.

Impact of video laryngoscope shape on first-attempt success during non-supine emergency department intubations

IntroductionLaryngoscope blade shape may differentially facilitate first-attempt success in patients intubated in non-supine positions in the emergency department (ED). Therefore, we analyzed first-attempt success in ramped and upright positions stratified by hyperangulated or standard geometry video laryngoscopes (VL). MethodsWe performed a secondary analysis of the National Emergency Airway Registry (NEAR) on ED intubations from January 1, 2016 to December 31, 2018. Our primary outcome was first-attempt success, and secondary outcomes included first-attempt success without adverse events and glottic view. We included all VL intubation attempts in the ramped and upright positions on medical patients >17-years-old. We calculated adjusted odds ratios (aOR) using a multivariable logistic regression mixed-effects model with site as a random effect and blade type, obesity / morbid obesity, training level (i.e., post-graduate year), operator-perceived difficult airway, and presence of an objective difficult airway finding as fixed effects. ResultsOur analysis included 266 attempts with hyperangulated blades and 370 attempts with standard geometry blades in the ramped cohort, and 116 attempts with hyperangulated attempts and 55 attempts with standard geometry blades in the upright cohort. In the ramped cohort, 244 (91.7%) of hyperangulated first attempts were successful, and 341 (92.2%) of standard geometry first attempts were successful (aOR 1.02 [95% confidence interval 0.56, 1.84]). In the upright cohort, 107 (92.2%) of hyperangulated first attempts were successful, and 50 (90.9%) of standard geometry first attempts were successful (aOR 1.04 [0.28, 3.86]). There was no difference across the secondary outcomes, including first-attempt success without adverse events. ConclusionHyperangulated and standard geometry VL had similar first-attempt success in ramped and upright position intubations in the ED.

Enhancement Attempts for a Three-Bladed Savonius Turbine Performance

In this work, the performance of a new wind turbine design derived from a conventional Savonius turbine is investigated by numerical simulations. The new design consists of three blades without passage between them (closed center). All unsteady computations (which mean computational fluid dynamics as well in the next sections) presented in the current work depend on a commercial software ANSYS Fluent 19. In particular, the blade geometry, the influence of a deflecting plate, and the influence of mobile parts on the returning plate have been investigated in detail. Since first results were partly disappointing for the turbine with a deflector but very interesting for the turbine with an opening blade, these same properties have also been investigated for the classical Savonius turbine. By comparison between both, an optimal solution can emerge from this first study for these designs. The results indicated that the opening blade design improved the performance by 25.9% at λ = 0.7; however, the deflecting plate reduces the performance along the operating range.

Experimental and numerical investigation of micro-scale effusion and transpiration air cooling on cascaded turbine blades

Micro cooling utilizing the micro-sized cooling hole or a porous structure on the surface is a promising technology in cooling applications of gas turbine blades. Although there have been numerous parametric studies on basic geometries to enhance the performance of micro cooling, little has been done for experimental study on blade geometry. This study comprehensively investigated micro cooling performance by applying effusion and transpiration cooling to C3X blades arranged in a cascade. The overall cooling effectiveness distribution on the blade surface was estimated by using infrared thermometry. In addition, the velocity and thermal boundary layer formation by cooling air were qualitatively investigated by a flow visualization using the smoke-laser sheet technique and numerical simulation using the shear stress transport k-ω turbulence model. Micro cooling performs effectively because of the convective heat transfer through the microstructure of the blade wall but also the reduction of heat transfer from the hot mainstream due to the formation of a uniform coolant layer on the blade surface. Especially at the mass flow ratio of 5.3% used for typical gas turbine cooling, effusion cooling and transpiration cooling achieve the overall cooling effectiveness of 0.4 and 0.6, respectively.

Aerodynamic Optimization of the Sizing and Blade Designs of Hovering Corotating Coaxial Rotors

Corotating coaxial rotors are seeing renewed interest in distributed electric propulsion systems and electric vertical take-off and landing (eVTOL) aircraft. The recent literature reports many interesting investigations, using prescribed rotor blades, into the flow phenomena as well as aerodynamic and aeroacoustic benefits of corotating rotors. However, the subject of the design of blade geometries, optimized to a design goal, for corotating rotors is currently lacking in the literature. This paper is written from such a design perspective, by extending a previous generalized approach to the aerodynamic optimization of counterrotating rotors to corotating rotors. The previous requirement for upper and lower counterrotating rotor torques to be equal can now be lifted in the case of corotating rotors, enabling improved versatility in the optimization of corotating blade designs. The optimization is demonstrated on an application example to address the conflicting conditions that index angles (high) for aeroacoustic benefits of reduced noise are at odds with those (low) for aerodynamic efficiency. The approach demonstrated in this paper is to set the index angle for reduced noise and then recover back the aerodynamic efficiency by using the newly developed aerodynamic optimization technique.

Optimal adjustment of mine fan geometry and operation

Mine fans consume significant electrical power, so it is important to ensure high efficiency of their operation. The aim of this study is to develop a method to determine the most economically efficient method to adjust axial fan geometry and operation at the maximum average efficiency in all operating modes. The method includes a developed mathematical model of the single-stage axial fan duty and a genetic algorithm for optimizing the fan parameters. The initial data for the mathematical model were the geometry of the fan blades of the average radius and the parameters of the fan operating mode. The result of the calculation was the fan efficiency in a preset operating mode. Two adjustment scenarios are modeled: fans with variable pitch blades and fans with variable rotation speed. The fan efficiency was determined by calculating the total pressure loss at the unit stage at the middle radius with regard to the loss at the blade tips. Since the mathematical model contains a large number of independent parameters, and there exists the possibility of local extrema, the optimization is performed using the genetic algorithm. The mathematical model of the fan with variable pitch blades was tested using experimental data. The error of the mathematical model in continuous modes at high efficiency (>75%) never exceeds 1.5%. As a case-study, the optimal fan parameters are determined for two preset operating modes and for two adjustment scenarios of fans with variable pitch blades and with variable rotation speed. On the basis of the obtained geometric parameters at the average radius of blades, using the constant circulation law, the fan designs were developed and then investigated by numerical simulation in CFX program. It is shown that if the air flow rate in operating modes differs significantly and the pressure is not, it is advisable to use fans with variable pitch blades.

Enhancement efficiency of Michell-Banki turbine using NACA 6512 modified blade profile via CFD

The small hydroelectric power plants (SHPP) are implemented in non-interconnected zones (NIZ) of developing countries. In which, the provision of electrical energy from the national interconnected system is not economically feasible. Therefore, in the literature, hydroelectric generation technologies have been implemented taking advantage of the energy available in the rivers. One of these technologies is the Michell-Banki type cross-flow turbines (MBT), which, despite having lower efficiencies than turbines such as Pelton and Francis, maintain their efficiency although fluctuations in site conditions. For this reason, different studies have been made to increase the efficiency of the MBT by making geometric modifications to both the nozzle and the rotor.
 The purpose of this study is to determine numerically the effect of the geometry of the blades that form the runner on the efficiency of Michell-Banki Turbine (MBT). For this, two (2) geometries were studied corresponding to a circular sector of a standard tubular profile and an airfoil NACA 6512 modified in curvature profile and chord length, according to the profile of the standard tubular blade. For this study, transient simulations for multiphase water-air flow were implemented using a k-ε turbulence model in the Ansys 2020R1® CFX software. The two (2) turbine models were configured to the same hydraulic conditions of head and volumetric flow corresponding to 0.5 m and 16.27 L/s, respectively. Variations in rotational speed were configured between 100 and 200 RPM with 20 RPM steps. It was found that using the modified 6512 hydrodynamic profile, at 140 RPM increased efficiency by 6 %, compared to the conventional tubular type blade geometry

Optimization of blade geometry by neural network in natural convection and entropy generation of nanofluids within an oblique square cavity with the effects of volumetric radiation with LB method

Optimization of blade geometry by neural network in natural convection and entropy generation of nanofluids within an oblique square cavity with the effects of volumetric radiation with LB method

A Conceptual Alternative Machine Learning-Based Method for Mesh Sensitivities Calculation in a Turbomachinery Blades Optimisation Framework

In gradient-based aerodynamic optimisation, the functional gradient required by the optimiser can be obtained as a product of adjoint-based functional sensitivities to volume grid nodes and the volume mesh sensitivities to the design parameters. For turbomachinery applications, it is desirable to use the actual blade design variables as degrees of freedom for the optimisation process, but this can lead to tedious programming tasks. As an alternative, a Machine Learning (ML) model is created to mimic and differentiate the blade geometry and the mesh generation processes. The typical ML forward pass is followed by a back differentiation operation enabling the computation of the volume mesh derivatives with respect to design parameters. The model is tested by comparing the ML-predicted and reference grid, and the modelled sensitivities are verified through algorithmic differentiation. The modelled mesh sensitivities are successfully employed for adjoint-based reverse engineering and design optimisation problems on a turbine blade.

Effect of spiral blade geometry on 3D-printed concrete rheological properties and extrudability using discrete element modeling

Sizes and shapes of spiral blades have a great influence on 3D printable concrete construction. This study is presented to answer two research questions: How does spiral blade geometry affect rheological properties of 3D printing mixtures? What are effects of the rheological properties of 3D printing mixture on final extrudability? The discrete element model formed by particles bonded with liquid bridges is used to analyze the influence of 3D printer blade size, shape, and rotation speed on the extrudability of cement-based materials. It is demonstrated that effects of spiral blade geometry on rheological properties and resulting extrudability of 3D printing mixtures are considerable. The research results could be good references about geometry of spiral blades for 3D concrete printing industry. However, the microscopic time-varying constitutive model of particle bonding has not been generated in this paper. It might be one of the future research directions.

Проектирование стенд-макета для исследования внутрикорпусных движителей подводных объектов

Object and purpose of research. This research was intended to design and manufacture a dummy test rig for self-propulsion testing of various in-hull propulsors. This test rig will be used to test waterjet designs for underwater objects. Materials and methods. Analytical assessments on geometry of propeller and stator blades, numerical simulation of operational condition for two-row blade system operating in the water duct as per in-house KSRC techniques. Main results. Interaction of internal waterjets with the hull of underwater object has never been studied before. To estimate this interaction, it was decided to perform self-propulsion tests with a suitable hull model. This work included design and manufacturing of a dummy test rig representing a hull of underwater object and enabling hydrodynamic measurements for an in-hull waterjet. Another result of this work was design and manufacturing of a four-row in-hull propulsion unit. Conclusion. The dummy test rig manufactured in this work could be further used to optimize in-hull waterjets of various configurations. Apart from the configuration described in this paper, it could also be feasible to design, manufacture and apply a combined rim-driven propulsion motor in the initial part of the water duct.