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Mass and radial deformation are of great importance for a high-pressure turbine disc (HPTD). However, computational cost of computer-aided engineering (CAE) is too high to optimise the mutually restricted objectives. A parameterisation-based method is proposed to speed the optimisation process of HPTD: ‘body-flange’-based parametric template is used to generate CAE samples; noise-based virtual samples are implemented to enlarge the training set, a cost-effective neural network is used as fitness function of non-dominated sorting genetic algorithm-II for optimisation whose initial population is the combination of different sample sets. Experiment results show that the proposed data-driven framework reduces the engineering difficulty of multi-objective optimisation, and it has high popularisation value for optimisation of other complex products. [ABSTRACT FROM PUBLISHER]

A preliminary analysis of turbine design, fit for pulsed flow, is proposed in this paper. It focuses on an academic 2D configuration using inviscid flows, since pressure loads due to wave propagation are several orders of magnitude higher than friction and viscous effects do not significantly impinge on the inviscid part, as previously shown by Hermet, 2021. As such, a large parametric study was carried out using the design of experiments methodology. A performance indicator adapted to unsteady environment is carefully defined before detailing the factors chosen for the design of experiments. Since the number of factors is substantial, a screening design to identify the factors influence on the output is first established. The non-influential factors are then omitted in a more quantitative study of the output law. The surface response calculation allows determining the factor level favouring the best output. Consequently, the main trends in the turbine design driven by a pulsed flow can be stated. [ABSTRACT FROM AUTHOR]

Today, the generated electrical energy using renewable energy is rapidly growing all over the world. The speed and direction of the wind are fundamental parameters affecting on power production of wind turbine that is constantly changing. One of the methods for controlling wind turbine power is changing the angle of the blades. In this paper, an adaptive control method has been used to control the wind turbine pitch angle. The proposed method is based on sliding mode control, whose coefficients have been calculated using the particle swarm optimization–support vector machine method. In order to evaluate the effectiveness of the proposed method, it has been compared with the Model Reference Adaptive Controller (MRAC) in the operating under disturbance. The results show that the proposed controller has a better performance than that of the MRAC in the presence of disturbance. Simulations show that the produced power at different wind velocities has reached its optimum value faster. [ABSTRACT FROM AUTHOR]

A bidirectional turbine used in an oscillating water column device extracts wave energy from oscillating airflow. To improve its power output, a concept of static extended trailing edge found in the wings of owl and merganser was adopted. The static extended trailing edge with 0–10% of chord length (C) was analyzed for different flow coefficients via Reynolds-averaged Navier–Stokes equation-based computational fluid dynamics (CFD) analysis. ANSYS-CFX 15.0 was used to simulate the flow. Grid convergence index was calculated to obtain optimum mesh, and numerical validation was done with experimental results. The static extended trailing edge with 5% C enhanced relative mean torque by 23.4% and, reduced relative mean efficiency by 5.4%, before stall condition. The modification increased pressure difference between the suction side and the pressure side and enhanced torque. The increased pressure drop reduced the efficiency. A further longer static extended trailing edge showed poorer stall characteristics. [ABSTRACT FROM AUTHOR]

The wind turbulence intensity observed on a site have an influence the wind turbine energy production and the lifetime of the blades. It is therefore primordial to master this parameter for the optimization of the production. So therefore, this study is interested on the modelling of the wind turbulence intensity at 10 m above the ground on the coast of Benin. Four years of wind data measured on the site of Cotonou Port Authority (PAC) from 2011 to 2014 and recorded with a temporal resolution of 10 min were used. From the transport equation of turbulent kinetic energy followed by a numerical simulation based on the Nelder-Mead algorithm developed under the Matlab software, we proposed five new models for estimating the wind turbulence intensity. The results of the different simulations reveal that four of proposed models and based on the roughness, the speed of friction and the length of Obukhov better fit the data, during the periods of January, April, June, July, August, September and December. The estimators of the Root Mean Square Error (RMSE) and the Mean Absolute Error (MAE) vary from (0.02; 0.01) in December to (0.09; 0.07) in August. As for the model which is a function of roughness and the wind shear coefficient (expressed only according to the wind speed), it gives better performance whatever the time of the year and the atmosphere stability conditions. The estimations errors are included between (0.02; 0.01) obtained in December and (0.08; 0.06) observed in March. A comparative study between the existing models in the literature and the best model proposed in this study showed that only this model gives the best adjustment with the data. It can therefore be used on the sites where turbulence is influenced by the roughness and the atmosphere stability. Finally, from this model a new wind turbine design class has been proposed for the site of Cotonou. It takes into account the actual levels of turbulence observed and thus allow to optimize the energy production. [ABSTRACT FROM AUTHOR]

A new methodology for the aerothermodynamic design of radial-inflow turbines used in organic Rankine cycles is presented. Initially, a fully detailed one-dimensional analysis was performed, where the real gas properties of R123 are calculated using the REFPROP© software. The developed model was validated against the most recent studies. Next, a 3D CFD analysis of the nozzle and the rotor was carried out using ANSYS-CFX® software. The 3D CFD method considered the influence of the rotor shroud curvature, which strongly influences the performance characteristics. The variations of this parameter allowed us to obtain uniform velocity contours, better blade loading and avoided the flow separation observed in the first attempt geometry. A comparison between the 1D mean-line and 3D CFD approach showed good agreement, validating the reliability of the two approaches. Also, an analysis of the 3D flowfield for different pressure ratios was performed to verify the quality of the method. The developed methodology has proven to be an appropriate tool for the radial-inflow ORC turbines design, which integrates uni- and three-dimensional models, for the prediction and improvement of the performance characteristics. The integration of these two approaches results in a novel procedure, since some phenomena associated with the three-dimensional characteristics of flow cannot be analyzed in detail in the one-dimensional analysis and are only possible to detect by a complete 3D CFD study. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to develop structural design of a wind turbine foundation and tower. The structural modeling was performed in program Tower 7. All structural elements are calculated according to the applicable regulations of Eurocode and National Annexes. The structure consists of a steel tower calculated in segments and a reinforced concrete foundation made in a monolithic design. The wind turbine tower is a steel tubular tower, while the foundation is made of reinforced concrete in a circular shape. [ABSTRACT FROM AUTHOR]

This paper presents a method for multi-objective optimization design of wind turbines at the system level through a coupled blade-tower model, aiming at finding the coupling effects between blade and tower and improving the wind turbines' performances. The formulation and implementation that enable the aerodynamic and structural integrated design of the blade and tower simultaneously are detailed. The maximum annual energy production (AEP) and the minimum wind turbine mass are taken as two conflicted objectives. Main aerodynamic and structural parameters of the blade and tower are employed as design variables. Various design requirements including stress, strain, deflection, vibration and buckling limits are considered as constraints. The blade element momentum (BEM) theory combined with the finite element method (FEM) are applied to evaluate the aerodynamic performances and structural behaviors of the turbine. Moreover, the non-dominated sorting genetic algorithm (NSGA) II is used to achieve the best trade-off solutions between the objectives. To show the efficiency and reliability of the method, a commercial 1.5 MW wind turbine is used as a case study. Satisfactory results that can both increase the AEP and decrease the mass are obtained, which are superior to the results achieved by optimizing the blade and tower separately. • Wind turbine is optimized at the system level through a coupled blade-tower model. • Two conflicted objective functions are selected to achieve the best trade-off solutions. • The effects between the blade and tower are found under a specific wind condition. • Optimal results both increasing the AEP and decreasing the turbine mass are obtained. [ABSTRACT FROM AUTHOR]

Marine current power has been utilized in recent years as one of the most foreseeable renewable energy sources. In this study, the optimal design of hydrofoil is carried out for hydrokinetic turbines to improve their hydrodynamic performance in Golden Gate Strait with the low-speed current. In order to design optimal hydrofoils for different sections of a blade, Particle Swarm Optimization (PSO) and XFoil are coupled. For hydrofoil's shape parameterization, the B-spline curve is used. The coordinate's values of the control points are designated to act as optimization parameters. Five hydrofoils from root to tip are designed for a turbine at low current speed with three blades. Hydrofoils are optimized from hub to tip in distances 0.4, 1.2, 2.4, 3.4, and 4.4 m. Optimum chord length and twist angle distribution along the blade are obtained using Harp_Opt, which is based on Blade Element Momentum theory. Finally, the power coefficient, rotational speed, cavitation criteria, and power are calculated for an optimized turbine and compared to the first turbine and Betz criterion. It is assured that cavitation will not occur at the tip of the blade which the linear velocity is maximum. The summation of cavitation number and minimum pressure coefficient (σ + Cp Min) is estimated to be 1.8. The power coefficient is computed using Harp_opt for both initial turbines with hydrofoil NACA 4415 and turbine with optimized cross sections from hub to tip. The power coefficient is improved 26% for speeds of 0.5–2 m/s and 50% for speeds of 2–3 m/s. An optimal marine current turbine which is useable for relatively lower currents is designed in this study by applying and combining different tools for different stages of research. • Optimal design of hydrofoil for hydrokinetic turbines in Golden Gate Strait. • Applying the Particle Swarm Optimization method coupled with XFoil. • B-spline curve foe parameterization of the hydrofoil shape. • Using Harp_Opt to obtain the optimum chord length and twist angle distribution along the blade. • Power improvement of 26% for speeds 0.5–2 m/s and 50% for speeds 2–3 m/s. [ABSTRACT FROM AUTHOR]

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. • A novel idea to design wind turbine blade design from a windfarm perspective. • Over 5% increase in energy capture achieved with farm-optimized turbine designs. • Farm-optimized turbine geometries are very different from conventional designs. • Increase in energy capture is associated with increase in blade loads. • Proposed framework readily extensible to other solvers and farm layouts. [ABSTRACT FROM AUTHOR]

The novel solar-wind integrated system has been firstly used for hydrogen production in literature with validating theoretical, simulated and experimental studies. This integrated system consists of two main parts; solar-assisted wind turbine and alkaline electrolysis cell. In the first part of this system, the semi-flexible PV panels are smoothly integrated on the vertical axis wind turbine blade. This is a unique design in literature, unlike the hybrid systems that include wind turbines and solar PV panels in published literature. The production and testing of the hybrid integrated system in a single structure were performed both in laboratory conditions and also the system was set up the roof of ATU (Adana Alparslan Turkes Science and Technology University) in Adana. The second part includes hydrogen production via alkaline electrolysis system. The cathodes consist of nickel-coated copper (Cu/Ni) and nickel-vanadium binary coated copper (Cu/NiV), that was produced via electrodeposition technique by self-supporting. The performance of electrodes was compared in 1 M KOH solution via I–V behavior, electrochemical impedance spectroscopy, and long term cathodic polarization analysis. Results showed that polarization resistance was decreased almost 4 times by NiV when comparing the Ni. The surface inhomogeneity values were 0.91 and 0.81 for Cu/Ni and Cu/NiV respectively. The hydrogen gas evolved at the cathodes was also measured and higher volumes were detected for NiV binary coating. Image 1 • The novel solar-wind integrated system was set up. • The semi-flexible PV panels were smoothly integrated on the vertical axis wind turbine blade. • Alkaline electrolysis was achieved for hydrogen production by harvested energy. • Different cathodes were compared with hydrogen evolution performance. [ABSTRACT FROM AUTHOR]

A thermal power plant for the East African Rift countries is under study for combined energy and freshwater generation using geothermal water, available at above 500 kPa pressure and temperature exceeding 150°C. This article presents the computational fluid dynamics (CFD) model and analysis of the two-phase turbine used for power generation in this total flow thermal plant. Flash boiling was implemented using a two-fluid multiphase model with the thermal phase-change criteria for heat, mass, and momentum transfer in the CFD solver ANSYS CFX. Initially, flashing flow in a converging-diverging nozzle was validated. This stationary nozzle model was then extended to a curved rotating nozzle reaction turbine and the results of flow and power were evaluated against available test data at 400 kPa feed water pressure under subcooled condition of 117°C and a very low backpressure of 6 kPa. Flow through this turbine was predicted within 8% deviation. An overestimate in thermodynamic power by 30-50% was predicted at speeds below 4000 rpm, while at the design speed of 4623 rpm the deviation was less than 5%. Rotor torque and hence power estimate was found to be dependent on the bubble size, bubble number density, and heat transfer parameters prescribed in the CFD model. The vapour dryness fraction at turbine exit was close to an isentropic expansion vapour quality. The isentropic efficiency was 7.5-17% for the analysed speed range. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Drainage & Irrigation Machinery Engineering / Paiguan Jixie Gongcheng Xuebao is the property of Editorial Department of Drainage & Irrigation Machinery Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An investigation on the unsteady hydrodynamic behaviour of a new scale model tidal turbine at the University of Auckland has been conducted, using FAST software from National Renewable Energy Laboratory. The turbine blades are designed to achieve the optimal angle of attack based on maximizing lift-to-drag ratio, and then the distribution of chord lengths and pitch angles is determined. In this way, a highly efficient but a lightly loaded tidal turbine model design utilizing the S814 profile, is achieved. Oscillatory motions of flows with single frequency over a range of current numbers and reduced frequencies have been considered. The investigation shows that the unsteadiness of the hydrodynamics on the blades is governed by the dynamic inflow phenomenon. The mean angle of attack along the blade is maintained at or very near the initial optimal value. The effects of the oscillatory frequency and velocity amplitude on the unsteady hydrodynamic loading are explored. A quasi-steady analysis is used to clarify the hydrodynamic response of the model as a lightly loaded rotor. A mathematical model is added to the investigation to analyse the role of the forcing components relative to oscillatory velocity and acceleration on the phase of the unsteady loading. • The steady out-of-plane loading was approximately 8.7 times higher than the in-plane loading. • Dynamic inflow phenomenon instead of dynamic stall determines the unsteady hydrodynamic loading. • The quasi-steady behaviour of hydrodynamic loading is highlighted and explained. • A mathematic model is applied to explain changes in phase of unsteady hydrodynamic loading. [ABSTRACT FROM AUTHOR]

Blade tip clearance is one of the important parameters affecting the performance, safety and stability of a gas turbine engine. However, it is difficult to measure the tip clearance in real time and accurately during the development and test process of an engine. In order to promote the development of tip clearance–measuring technology and the optimal design of the gas turbine engine, some typical measuring methods of tip clearance and a novel measuring method based on AC discharge are introduced. In this article, the significance for measuring tip clearance of an engine is illustrated first. Then, operating principles, characteristics and developments of those typical measurement approaches are introduced. After that, these methods are analyzed, and the particular characteristic of each measuring approach is summarized. [ABSTRACT FROM AUTHOR]

Improved hydrodynamic design of a Horizontal Axis Tidal Turbine (HATT) blade is key to increasing the efficiency and annual power production of the turbine. One of the crucial stages in hydrodynamic design is the selection of the 2D cross-section (hydrofoil) of the blade. Selecting the hydrofoils for a blade design that results in superior turbine characteristics for a given flow condition is tedious. In this study instead of choosing hydrofoils for a given flow condition, a base hydrofoil geometry is optimized to obtain a new hydrofoil that has superior characteristics for the given flow conditions. Hydrofoils were optimized for the flow conditions prevalent in South East Asia. Optimization was performed until the desired objectives were met while satisfying a set of constraints. Maximizing lift-to-drag ratio and lift coefficient of the hydrofoil was set as objectives (non-conflicting) while avoiding cavitation during turbine operation was one of the constraints. OpenMDAO and NSGAII were used to set up and solve the multi-objective optimization problem respectively to generate four optimized hydrofoils. Harp_opt was used to design a 1 m rotor HATT blade using the optimized hydrofoils which exhibited better performance than another 1 m rotor HATT blade designed with NREL hydrofoils as 2D sections. • Optimized hydrofoils were generated for tidal turbines using NSGAII. • Low Reynolds number flow in tropical conditions of SE Asia is considered. • Maximizing lift-to-drag ratio improved power production of the turbine. • Hydrofoils were optimized to avoid cavitation during turbine operation. [ABSTRACT FROM AUTHOR]

The aerodynamic performance of horizontal-axis wind turbines is strongly dependent on many parameters, among which the airfoil type and the blade geometry (mainly defined by the chord and the twist distributions) are considered the most critical ones. In this article, an approach giving the appropriate airfoil for a small wind turbine design was conducted by performing an aerodynamic improvement of the blade's airfoil. First, a preliminary design of the rotor blades of a small wind turbine (11 kW) was conducted using the small wind turbine rotor design code. This preliminary approach was done for different airfoils, and it resulted in a maximum power coefficient of 0.40. Then, the aerodynamic efficiency of the wind turbine was improved by modifying the geometry of the airfoils. This technique targets the optimization of the lift-to-drag ratio (Cl/Cd) of the airfoil within a range of angles of attack. Also, a non-uniform rational B-spline approximation of the airfoil was adopted in order to reduce the number of the design variables of the optimization. This methodology determined the best airfoil for the design of a small wind turbine, and it gave an improved power coefficient of 0.42. [ABSTRACT FROM AUTHOR]

This article presents selected results from the development process of a small, prototype multi-bladed wind turbine designed to replace the American western-style, wind-driven water pumps still encountered in the Maltese rural landscape. The main focus of this article is on the rotor design, fabrication and system assembly, as well as on the results of the first open field tests. While the new design proves that the new machine is capable of aesthetically representing the windmills of old, preliminary findings indicate that it is also capable of meeting its predicted performance characteristics in a satisfactory manner, albeit subject to the installation site's specific wind climatology. [ABSTRACT FROM AUTHOR]

In this work, a 370-W small wind turbine was developed which is equipped to a controllable nuzzle-diffuser duct. The developed duct is consisting of a fixed ring and a two-piece diffuser which can rotate on each other and so the diffuser wall opening will have altered from 0 to 180°. This mechanism is developed to control speed-up ratio and drag forces acting on the turbine structure in high ranges of wind speeds. The rotor is designed using BEM algorithm and the duct geometry is reached by CFD works considering the atheistic aspect of view. As the turbine is designed for a comprehensive research project, so it contains several a subsystems like an electromagnetic brake, external electric starter motor, electromagnetic flywheel, variable nacelle, etc. The designed mechanism fabricated using several machining processes as turning, milling, boring, drilling, welding and rolling works. The turbine performance implemented in a low-speed wind tunnel. Experimental results show a comprehensive raise in power generation and rotor speed by shrouded wind turbines. In the 180-degree diffuser wall opening, the augmentation ratio in average is 39.75% while the ratio is 28.5% for a complete diffuser augmented wind turbine. The rotor speed-up ratio for them is 53 and 74% respectively. • The fully closed duct augments the turbine power by 37% compared with the bare one. • The fully closed duct raises the rotor speed by 61% comparing to the bare one. • The half-closed duct augments the turbine power by 37% comparing to the bare one. • The half-closed duct raises the rotor speed by 80% compared with the bare one. • The controlled duct augments the power and rotor speed by 50 and 61% respectively. [ABSTRACT FROM AUTHOR]

Multiobjective optimisation and integrated aerodynamic-structural design of wind turbine blades are emerging approaches, both requiring significant number of high fidelity analyses. Designer-in-the-loop blade modelling and pre/post-processing using specialised software is the bottleneck of high fidelity analysis and therefore a major obstacle in performing a robust optimisation, where thousands of high fidelity analyses are required to find the optimum solution. Removing this bottleneck is the driver for the development of WTBM, an automated wind turbine blade modeller. WTBM takes parameters defining the blade and its operating condition as inputs and generates pre-processor, solver and post-processor APDL files required by ANSYS for high fidelity analysis. The inputs can be generated automatically within an optimisation process, hence so can be the APDL files, allowing a fully automated optimisation in which any of the parameters which are required to define the size, topology, structure and material of a blade to be treated as a design variable. The solver parameters will be also updated automatically as necessary. The performance of WTBM-ANSYS in conducting hundreds of automated high fidelity analyses within an optimisation process is shown through multiobjective structural design and multiobjective integrated design case studies. Image 1076 • WTBM is an automated wind turbine blade modeller allowing iterative high fidelity structural analyses. • WTBM generates solver, pre and post processor APDL files for ANSYS. • WTBM-ANSYS is used for multiobjective optimisation and integrated design of blades. [ABSTRACT FROM AUTHOR]

In this article is present the procedure for the design of all components of a pico-hydro system, is designed a pico hydraulic propeller turbine according to the specific condition of water potential to an estimated site of operation based on a theoretical and technical analysis. For this purpose, the main characteristics of the runner are determined for medium of statistics correlations of different designs of turbine around the world, and defining restrictions for the design such as turbine head, nominal rate flow and power required, from the data mentioned above, the value of all the variables related to the behavior of the fluid in its passage through the impeller is established and from the value of said variables and the geometry established for the impeller, the geometry is determined and the specifications of the other components of the pico-hydro system such as the spiral chamber, the suction tube, the generator and the distributor, for which two types were studied, which are a distributor of axial input of the fluid and another radial input of the fluid with respect to the axis of rotation of the turbine. For the verification of the design and expected results, a modern engineering tool is used, such as computational fluid dynamics (CFD), especially the component (CFX) to predict the flow and performance that the designed system can produce. Finally, a technical-economic analysis is carried out to study the feasibility of implementing this type of systems in a rural area. The design of the present pico-hydro system and the contribution of computational fluid dynamics CFD, can be a viable alternative to meet the demands of electricity in a rural area that does not have this service by the supply networks responsible for this function. [ABSTRACT FROM AUTHOR]

The aerodynamic performance of three different configurations of vertical axis wind turbines (VAWT), namely: (a) conventional Darrieus troposkein VAWT (based on turbines designed by Sandia National Laboratories), (b) novel 50% STS‐VAWT (50% shifted‐troposkein‐shaped STS‐VAWT), and (c) novel 100% STS‐VAWT were investigated numerically. An in‐house code, which combined the blade element theory (BET) and the vortex filament method (VFM), was used. The main purpose of this work was to develop an aerodynamic code to predict the performance of conventional VAWT as well as assess the novel 50% and 100% STS‐VAWT configurations. Simulation results (power coefficients) were verified and then validated against experimental data available from the literature (2‐, 5‐, and 17‐m conventional troposkein VAWT measured by Sandia National Laboratories). Additional numerical results showed that the 50% STS‐VAWT outperformed both the conventional VAWT and the 100% STS‐VAWT by up to 14% (peak power), within the range of rotation and turbine sizes that were investigated in the present work. [ABSTRACT FROM AUTHOR]

The work presented in this paper used rigorous 3D flow-field analysis combined with multi-objective constrained shape design optimization for the design of complete blade + bladelet configurations for a three-blade horizontal-axis wind turbine. The fluid flow analysis in this work was performed using Openfoam software. The 3D, steady, incompressible, turbulent flow Reynolds-Averaged Navier-Stokes equations were solved in the rotating frame of reference for each combination of wind turbine blade and bladelet geometry. The free stream uniform wind speed in all cases was assumed to be 9 m s-1. The three simultaneous design optimization objectives were as follows: (a) maximize the coefficient of power, (b) minimize the coefficient of thrust force, and (c) minimize twisting moment around the blade axis. The bladelet geometry was fully defined by using a small number of parameters. The optimization was carried out by creating a multidimensional response surface for each of the simultaneous objectives. The response surfaces were based on radial basis functions, where the support points were designs analyzed using the high-fidelity computational fluid dynamics (CFD) analysis of the full blade + bladelet geometry. The response surfaces were then coupled to an optimization algorithm in modefrontier software. The predicted values of the objective functions for the optimum designs were then again validated using Openfoam high-fidelity analysis code. Results for a Pareto-optimized bladelet on a given blade indicate that more than 4% increase in the coefficient of power at minimal thrust force penalty is possible at off-design conditions compared to the same wind turbine rotor blade without a bladelet. [ABSTRACT FROM AUTHOR]

Injury and mortality of fish during downstream passage through hydropower turbines is among the leading direct impacts of hydropower. Understanding the relationships among various strike variables and injury and mortality rates are necessary for improvements in turbine design. We subjected three species of fish to simulated blade strike in laboratory studies with different blade thicknesses, impact velocities, and body orientations to develop relationships between these variables and probability of injury and mortality. Midbody strikes resulted in higher mortality than head strikes, and tail strikes produced the least mortality. Lateral strikes caused more mortality than dorsal and ventral strikes, and higher strike velocities and thinner blades contributed to increased mortality. Several injury types were significantly associated with increased mortality, including injuries to the operculum, gills, viscera, heart, liver, swim bladder, muscle, and bone fractures. Results from this study will be used to define biologically based design criteria that can be used by turbine designers to improve designs (e.g., increased leading-edge thickness and slower turbine speeds) to minimize the probability and impact of blade strike. [ABSTRACT FROM AUTHOR]

In turbocharger design, the accurate determination of thermally induced stresses is of particular importance for life cycle predictions. An accurate, transient, thermal finite element analysis (FEA) of turbocharger components requires transient conjugate heat transfer (CHT) analysis. However, due to the vastly different timescales of the heat transfer mechanisms in fluid and in solid states, unsteady CHT simulations are burdened by high computational costs. Hence, for design iterations, uncoupled CFD and FEA approaches are needed. The quality of the uncoupled thermal analysis depends on the local heat transfer coefficients (HTC) and reference fluid temperatures. In this paper, multiple CFD-FEA methods known from literature are implemented in a numerical model of a turbocharger. In order to describe the heat transfer and thermal boundary layer of the fluid, different definitions of heat transfer coefficients and reference fluid temperatures are investigated with regard to calculation time and accuracy. For the transient simulation of a long heating process, the combination of the CFD-FEA methods with the interpolation FEA approach is examined. Additionally, a structural-mechanical analysis is conducted. The results of the developed methods are evaluated against experimental data and the results of the extensive unsteady CHT numerical method. [ABSTRACT FROM AUTHOR]

Accurate creep life prediction is necessary for the evaluation of the remaining creep lives of in-service turbine blades and for the design of new turbine blades in aircraft engines. In this study, an integrated computational material engineering methodology for predicting the remaining creep life of in-service turbine blades was developed by taking a microstructural criterion and creep strain criterion into consideration, and combining artificial neural networks with a modified θ projection model to assess the service temperature, stress, degradation time, and existing creep strain. To explore the application of the method and verify its accuracy, the microstructural degradations at different locations of two directionally solidified superalloy DZ125 turbine blades, which were in-service for 300 h and 980 h in different engines, were characterized and quantified. Using these results, the remaining creep life of the microstructures at different locations of the blade was predicted. Finally, these creep life prediction results were experimentally verified using miniature creep test specimens. The development of this new method provides a reference for the design and service evaluation of turbine blades made of directional solidified and single-crystal Ni-based superalloys. [ABSTRACT FROM AUTHOR]

Highlights of work inspired by Liou and performed in the last few years with the ultimate goal of simulating combustor–turbine interactions are presented. First, we have updated the Open National Combustion Code (OpenNCC) by implementing the advection upstream splitting method (AUSM) and the extended version of the AUSM-family scheme (AUSM + -up) and then performed a series of verification tests. The AUSM + -up scheme and the standard Jameson–Schmidt–Turkel scheme are compared in terms of accuracy and convergence. Next, the second-order AUSM + -up scheme is applied to model unsteady flow fields inside a combustor sector from the Energy Efficient Engine ( E 3 ) program, in conjunction with a sensitivity analysis of turbulent combustion models. Three different turbulent combustion models are considered: the eddy break-up model, the linear eddy model, and the probability density function model, as well as the laminar finite-rate chemistry model. A comprehensive comparison of the flow fields and the flame structures is provided. Our main interest here is not to select the best model out of four different models with lack of data under the exact same conditions, but to understand how different turbulent combustion models impact thermal variation along the surface of first-stage vanes (i.e., hot streaks). Considering that these models are often used in combustor/turbine communities, the intent of this study is to provide some guidelines on numerical modeling of combustor–turbine interactions and, thus, help improve future designs of the combustor and high-pressure turbine. [ABSTRACT FROM AUTHOR]

At the Institute of Thermal Turbomachinery and Machniery Laboratory (ITSM) a generic test case was designed to investigate aeromechanical phenomena and condensation in low-pressure steam turbines. This test case, referred to as S team turbine T est case for A eromechanics and C ondensation (STAC) consists of the two last stages of a low-pressure steam turbine and is representative for a modern steam turbine design. STAC is intended to serve as a numerical test case to allow studying the fields of aerodynamic damping and spontaneous condensation in low-pressure steam turbine last stages. The geometry of the turbine is made available online at www.itsm.uni-stuttgart.de/research/test-cases/. [ABSTRACT FROM AUTHOR]

Although a large number of papers have been published to date on failures in wind turbines, most of them have focused on blade failures and less attention has been paid to the tower failures. This paper analyses the causes that led to the failure of one element that finally caused the whole tower to collapse. A diagnosis of the cause of the failure was carried out after an initial on-site inspection, when the origin of the failure appeared to be in the flange that joined the tower to its base. An experimental program was carried out to analyze the characteristics of the steel in the area nearest to the flange. A non-linear simulation was then performed by the finite element method (FEM) of the flange area where the failure had occurred, including the bolts, their prestressing forces and the contact between the joined surfaces. In order to study the influence of different variables on the flange's structural response, a method based on the Design of Experiments (DOE) was used on the FEM model. Finally, the main lessons learnt from the experience are given with the aim of contributing to improving the design and construction of wind turbine towers. Unlabelled Image • Wind tower collapse due to the failure of a flange is analyzed. • Analysis of the material properties is needed to identify the causes of the failure. • Finite Element model shows the load distribution in the broken section. • The most influential parameters are obtained applying Design of Experiments (DOE). [ABSTRACT FROM AUTHOR]

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The performance and reliability of aircraft engine are seriously affected by multiple failures induced by multi-physical loads. Multi-failure probabilistic design is an effective measure to estimate the multi-failure response traits and quantify the multi-failure risk for the improvement of component reliability. In this paper, we propose a neural network regression-distributed collaborative strategy (NNR-DCS) based on a developed two-step error control technique, to improve the efficiency and accuracy of multi-failure probabilistic analysis. We firstly mathematically model NNR-DCS and then introduce the corresponding multi-failure probabilistic framework. With respect to various failure modes such as deformation failure, stress failure and strain failure, the multi-failure probabilistic analysis of a turbine bladed disk is conducted to evaluate the proposed method. From this simulation, we gain the probabilistic distribution features, reliability degree and sensitivity degree of each failure mode and overall failure modes on turbine bladed disk, which provides a useful reference for improving the reliability and performance of aircraft engine. The comparison of methods (Monte Carlo method, RSM, DCRSM, DCFRM, NNR and NNR-DCS) shows that the proposed NNR-DCS holds high efficiency and accuracy for multi-failure probabilistic analysis. The efforts of this study offer an effective way for multi-failure evaluation from a probabilistic perspective and shed light on the multi-objective reliability-based design optimization of complex structures besides turbine bladed disk. [ABSTRACT FROM AUTHOR]

• Consider aerodynamics and heat transfer in turbine internal cooling optimization. • Efficient adjoint derivative computation allows large design freedom. • The gradient-based method achieves better performance than gradient-free methods. • Changing U-bend is more effective than changing ribs for overall performance. • Optimized ribs exhibit independent arrangement, depending on local flow conditions. Aerothermal optimization is a powerful technique for automating the design of turbine internal cooling passages, where both pressure loss and heat transfer are considered. Existing optimization studies commonly adopt gradient-free algorithms, which can handle only a few design variables. However, to enhance heat transfer, internal cooling designs use complex geometries consisting of ribbed serpentine channels, which need to be parameterized by using a large number of design variables. To address this need, we develop herein an approach for aerothermal optimization that uses a gradient-based optimizer in conjunction with a discrete adjoint method to efficiently compute the required gradients with respect to numerous design variables. We apply this approach to the design of a ribbed U-bend channel, which is representative of a section of turbine internal cooling passages. The objective function combines heat transfer and pressure loss as a weighted sum. We find the Pareto front for these two objectives by running five optimizations with different weights. We consider both a rib-free and a ribbed U-bend configuration. For the rib-free configuration, we use 113 design variables to parameterize the U-bend shape. We compare our optimization results with those from gradient-free methods and demonstrate that the proposed method leads to lower pressure loss while enhancing heat transfer. For the ribbed configuration, we use 146 design variables and allow the ribs to change their arrangement independently (shape, height, pitch, and angle). Each rib adopts a requisite arrangement to balance heat transfer and aerodynamics, depending on the local flow conditions. Optimizing the U-bend shape is shown to be more effective for improving overall heat transfer than optimizing the rib arrangement. However, optimizing ribs is more effective for improving local heat transfer. The results demonstrate that the proposed optimization framework has the potential to handle general turbine heat transfer designs, not only for internal cooling but also for other design problems, such as film cooling and jet impingement cooling. [ABSTRACT FROM AUTHOR]

Considering the need to reduce greenhouse gas emissions, onshore wind energy is certain to play a major role in future energy systems. This topic has received significant attention from the research community, producing many estimations of Europe's onshore wind potential for capacity and generation. Despite this focus, previous estimates appear to have underpredicted both the amount of available future wind capacity as well as its performance. Foremost in this regard is the common use of contemporary, or at least near-future, turbine designs which are not fitting for a far-future context. In response to this, an improved, transparent, and fully reproducible work flow is presented here, and applied to determine a future-oriented onshore wind energy potential for Europe. Within a scenario of turbine cost and design in 2050, 13.4 TW of capacity is found to be available, allowing for 34.3 PWh of average generation per year. By sorting the explicitly-placed potential installation locations by their expected generation cost, national relationships between cost and performance versus installed capacity are found, and it is also seen that all countries possess some potential for onshore wind energy generation below 4 ct € kWh - 1. Furthermore, it is unlikely for these costs to exceed 6 ct € kWh - 1 in any future capacity scenario. • Determination of onshore wind energy potential in Europe for 2050. • Land eligibility, explicit futuristic turbine placement, and 37 simulation years. • Full potential at 13.4 TW and 34.3 PWh/a, with expected costs at or below 6 ct/kWh. • All European countries possess at least some potential below 4 ct/kWh. • Usage of futuristic turbine designs for future energy system designs is crucial. [ABSTRACT FROM AUTHOR]

• The twist angle has the most significant effect on the winglet of VAWTs. • The winglet's influence increases along the blade span towards the tip. • A winglet can weaken the tip vortex and enhance the power coefficient of the VAWT. Vertical axis wind turbines (VAWTs) have been attracting an increasing attention in recent years because of their potential for effectively using wind energy. The tip vortices from the VAWT blades have a negative impact on the power efficiency. Since a winglet has been proved to be effective in decreasing the tip vortex in the aerospace field, this paper numerically studies the aerodynamic effect of appending a winglet on the blade of a VAWT. Based on the theoretical motion pattern of the VAWT blade, this paper simplifies the three-dimensional full-scale rotor simulation to a one-blade oscillating problem in order to reduce the computational cost. The full rotor model simulation is also used in validating the result. The numerical approach has been validated by the experimental data that is available in the open literature. Six parameters are applied in defining the configuration of the winglet. The orthogonal experimental design (OED) approach is adopted in this paper to determine the significance of the design parameters that affect the rotor's power coefficient. The OED results show that the twist angle of the winglet is the most significant factor that affects the winglet's performance. A range analysis of the OED results produces an optimal variable arrangement in the current scope, and the winglet's performance in this variable arrangement is compared with the blade without a winglet. For the single blade study, the comparison result shows that the optimal winglet can decrease the tip vortices and improve the blade's power performance by up to 31% at a tip speed ratio of 2.29. However, for the full VAWT case, the relative enhancement in the power coefficient is about 10.5, 6.7, and 10.0% for TSRs of 1.85, 2.29, and 2.52, respectively. The winglet assists in maintain the pressure difference between the two sides of the blade, thus weakening the tip vortex and improving the aerodynamic efficiency of the surface near the blade tip. [ABSTRACT FROM AUTHOR]

This paper presents an innovative design for reducing the impact of secondary flows on the aerodynamics of low-pressure turbine (LPT) stages. Starting from a state-of-the-art LPT stage, a local reshaping of the stator blade was introduced in the end-wall region in order to oppose the flow turning deviation. This resulted in an optimal stator shape, able to provide a more uniform exit flow angle. The detailed comparison between the baseline stator and the redesigned one allowed for pointing out that the rotor row performance increased thanks to the more uniform inlet flow, while the stator losses were not significantly affected. Moreover, it was possible to derive some design rules and to devise a general blade shape, named 'snaked', able to ensure such results. This generalization translated in an effective parametric description of the 'snaked' shape, in which few parameters are sufficient to describe the optimal shape modification starting from a conventional design. The "snaked" blade concept and its design have been patented by Avio Aero. The stator redesign was then applied to a whole LPT module in order to evaluate the potential benefit of the 'snaked' design on the overall turbine performance. Finally, the design was validated by means of an experimental campaign concerning the stator blade. The spanwise distributions of the flow angle and pressure loss coefficient at the stator exit proved the effectiveness of the redesign in providing a more uniform flow to the successive row, while preserving the original stator losses. [ABSTRACT FROM AUTHOR]

Rotor tip film cooling is investigated at the Large Scale Turbine Rig, which is a 1.5-stage axial turbine rig operating at low speeds. Using pressure sensitive paint, the film cooling effectiveness h at a squealer-type blade tip with cylindrical pressure-side film cooling holes is obtained. The effect of turbine inlet swirl on η is examined in comparison to an axial inflow baseline case. Coolant-to-mainstream injection ratios are varied between 0.45% and 1.74% for an engine-realistic coolant-to-mainstream density ratio of 1.5. It is shown that inlet swirl causes a reduction in η for low injection ratios by up to 26%, with the trailing edge being especially susceptible to swirl. For injection ratios greater than 0.93%, however, η is increased by up to 11% for swirling inflow, while for axial inflow a further increase in coolant injection does not transfer into a gain in η. [ABSTRACT FROM AUTHOR]