Turbine Design Research Articles

Comprehensive influence of dimensionless wave velocity and expansion ratio on energy absorption characteristics of variable wavelength traveling wave turbine

Based on the traveling wave motion of fish, this paper introduces a new type of variable wavelength traveling wave turbine that significantly differs from traditional turbine designs in its mechanical structure. By developing a two-dimensional traveling wavy plate model and conducting numerical simulations, this study investigates the relationship between the dimensionless wave velocity, variable wavelength coefficient, and expansion ratio, as well as their combined effects on the energy absorption characteristics of the variable wavelength traveling wave turbine. The results reveal that energy absorption efficiency peaks at an optimal dimensionless wave velocity, which is unaffected by changes in the variable wavelength coefficient. Furthermore, the expansion ratio significantly influences both the dimensionless wave velocity and the variable wavelength coefficient, with an optimal ratio of π∗ = 2.5 achieving 90.42 % efficiency. The energy absorption characteristics of the plate with a larger variable wavelength coefficient are found to be constrained by the expansion ratio. Additional analysis reveals that flow characteristics, such as the pressure distribution, vortex street, and velocity field surrounding the traveling wavy plate, are closely related to its energy absorption performance. These findings provide valuable insights for the design of variable wavelength traveling wave turbine.

Aerodynamic Behavior of a Wind Turbine Under Blade Pitching Motion

It is essential for advanced turbine design and wind-farm control strategy formulation to acquire an improved understanding of the aerodynamic behavior in the rotor plane and the wake downstream of a wind turbine under blade pitching motion, reacting to highly stochastic atmospheric conditions. Using an unsteady Reynolds-averaged Navier–Stokes simulation, the effects of the dynamic variations in blade pitch are investigated on the unsteady aerodynamic behavior of an NREL-5 MW wind turbine. The results show that the wake after a pitching maneuver exhibits a local contraction region, resulting in the leapfrogging phenomenon of tip vortices. The influences of different pitch ranges and pitch rates on the aerodynamic behavior of the wind turbine are studied. The degree of wake contraction depends strongly on the pitch range, whereas an increase in pitch rate is mainly dominated by the shed vorticity, indicating a larger deviation from the quasi-state behavior. In addition, interaction between the shed vorticity and the neighboring tip vortex is observed in the near wake under the condition at a fast pitch rate, which may have an influence on the mutual inductance instability.

Equation-Oriented Meanline Method for Axial Turbine Performance Prediction Under Choking Conditions

Abstract Meanline models play a crucial role in turbine design and system-level analyses, facilitating rapid evaluation of design concepts and prediction of off-design performance. Most of the existing meanline methods are inadequate in predicting turbine performance under choking conditions. These models either neglect the impact of losses on choking, or increases the computational complexity significantly. This limitation is addressed in this work, presenting a novel meanline model. The choking state at each cascade is determined by maximizing the mass flow rate, while taking into account the effect of losses. Leveraging the method of Lagrange multipliers, the optimization problems are transformed into a set of equations that seamlessly integrate with the rest of the meanline model. The resulting system of equations is then solved simultaneously using efficient root-finding algorithms, resulting in fast and reliable convergence. Validation against experimental data from three different turbines demonstrates the model's ability to accurately predict mass flow rate, torque, and exit flow angles across single- and multi-stage turbines, with errors typically within ±2.5 % and ±5.0 % for mass flow rate and torque respectively, and within ±5 degrees for flow angles. The proposed approach represents a significant advancement in meanline modeling, offering improved accuracy and computational efficiency.

Laser Metal Deposition of Rene 80—Microstructure and Solidification Behavior Modelling

New developments in nickel-based superalloys and production methods, such as the use of additive manufacturing (AM), can result in innovative designs for turbines. It is crucial to understand how the material behaves during the AM process to advance the industrial use of these techniques. An analytical model based on reaction–diffusion formalism is developed to better explain the solidification behavior of the material during laser metal deposition (LMD). The well-known Scheil–Gulliver theory has some drawbacks, such as the assumption of equilibrium at the solid–liquid interface, which is addressed by this method. The solidified fractions under the Scheil model and the pure equilibrium model are calculated using CALPHAD simulations. A differential scanning calorimeter is used to measure the heat flow during the solid–liquid phase transformation, the result of which is further converted to solidified fractions. The analytical model is compared with all the other models for validation.

Experimental Optimization of the Propeller Turbine Performance Using the Response Surface Methodology

The growing global energy demand necessitates a shift towards sustainable sources to mitigate environmental issues and ensure energy security. This work explores the design and optimization of propeller-type hydrokinetic turbines to efficiently harness renewable energy from water currents. Through experimental testing and regression modeling, the research aimed to maximize the power coefficient (Cp) by determining the optimal values of the number of blades (Z) and the turbine diameter to hub diameter ratio (d/D). By correcting for experimental biases, the study elucidates the importance of factors such as the blockage ratio and turbine configuration on its performance. A second-order polynomial regression model, which was validated through analysis of variance, determined that when Z and d/D were set at 4 and 0.15, respectively, the optimal value for Cp was 53.62%. These findings provide valuable insights for optimizing hydrokinetic turbine efficiency, contributing to the advancement of renewable energy technologies.

Hydrodynamic performance of a monopile offshore wind turbine in extreme wave groups

Dynamic responses of offshore wind turbines, particularly under extreme wave excitations, are crucial to structural design. Extreme waves, e.g. breaking waves, are random processes, which induce uncertainty in the estimation of dynamic responses. This type of uncertainty has been accommodated through a safety of factor which is conservative and thus leads to cost inflation. To reduce the cost and enable economically viable development of offshore wind, it is essential to understand the dynamic process of offshore wind turbines under extreme wave excitation scenarios. However, it is challenging to predict these dynamic responses through numerical simulations, due to the nonlinearity and randomness in such a complex process. To overcome these challenges, this study conducted a series of physical model testing to better capture the extreme wave induced loads on a monopile, which are then served as input for numerical modelling. Through this hybrid model, different vibration mechanisms are revealed, which shed lights on further cost reduction in the design of offshore wind turbines.

Finite element analysis of thermal barrier properties under relevance vector machine in coated pistons and blades

Internal Combustion (IC) engines require Thermal Barrier Coatings (TBCs) to preserve their effectiveness and performance. By coating engine parts with TBCs, thermal fatigue and environmental heat loss may be minimised. To reduce heat loss in IC engines during the combustion stage, piston thermal barrier coating is extremely beneficial. Additionally, it is well known that power plants with higher energy efficiency tend to operate their gas turbines at higher operating temperatures. To produce TBCs for the thermal design of gas turbines and diesel engines with higher performance, an in-depth study on the thermophysical properties of TBCs is required. This article presents an experimental investigation into the combined effect of gas turbine blades and diesel engine pistons coated with a heat barrier, utilising two distinct Thermal Barrier Coatings. Initially, numerical calculations are used to assess the wall heat transfer model’s ability to control temperature and density. The piston and blade top surfaces received plasma-sprayed, Yttria-Stabilised Zirconia (YSZ) with different material combinations on the piston and blades are evaluated. The Finite Element Method is developed for the coating of the ideal thickness to analyse the failure mechanism of the TBC sample. To evaluate the fatigue residual lifespan of TBC pistons, as well as blades in high-power engines, the authors also created a relevant vector Machine-based lifetime prediction model. The CO, HC and NOx emissions, as well as the fuel depletion and braking thermal efficiency, are used to calculate the performance analysis of the coated piston and blades. The results demonstrated improved thermal process endurance and decreased thermal conductivity by 28% when compared to YSZ using the RVM method respectively.

Identifying and mitigating energy losses in Tesla turbines: A study on CFD optimization

AbstractThis study investigates the flow dynamics and energy losses of Tesla turbines using Computational Fluid Dynamics with OpenFOAM. Our goal is to identify the main sources of energy loss. Four main sources of energy loss were identified. The most significant loss occurred during the conversion of pressure energy to kinetic energy, estimated to range from to of the total energy. Energy losses due to leaks between the rotor and the casing were also quantified, ranging from to of the kinetic energy at peak efficiency points. Design modifications, such as incorporating a nozzle at the entrance of the turbine, can improve efficiency. These findings highlight specific areas for efficiency improvement, offering opportunities for improved turbine design and integration into energy‐generation systems.

Design and analysis of a single-stage supersonic turbine with partial admission

Supersonic impulse turbines are commonly used to harvest waste heat from systems based on organic Rankine cycles, automotive applications, and gas-generator liquid rocket engines. This research aims to design and analyze a single-stage supersonic turbine with a rated power of approximately 440 KW. We present a comprehensive preliminary design roadmap followed by design parameters optimization. The preliminary sizing is carried out using one-dimensional flow analysis, while the blade geometrical design is performed using the two-dimensional method of characteristics. The turbine performance is then analyzed through numerical simulations on three-dimensional models. Comprehensive parametric analyses are conducted to examine the turbine performance sensitivity to changes in partial admission (PA), mean radius, and turbine blade height using three-dimensional sliding mesh techniques (SMT). The current analysis simulates the full turbine to capture PA effects, rather than focusing on a single periodic sector as is common in turbomachinery simulation practices. Different PA scenarios are investigated, emphasizing a single rotor passage over a complete rotor cycle in a partially admitted turbine, and examining its charging and discharging mechanisms. Flow tracking over such a blade shows that the turbine rotor exhibits compressor-like behavior over most of the unadmitted zone, contributing to efficiency drops and severe transients.

Large-scale 3D multiphysics topology optimization of flow–heat–structural models including an islands constraint

This article demonstrates a large-scale 3D topology optimization problem formulation for components in need of internal cooling owing to surrounding hot gas flow. A conjugate heat transfer model is used and the goal of the optimization problem is to maximize the thermal performance subject to a coolant consumption limit. As a model problem, the interior design of a gas turbine guide-vane-like geometry is considered. High-quality finite element meshes are generated automatically by means of a voxelization method. A structural compliance constraint for thermo-mechanical loads, and a constraint for the suppression of free-floating structural parts, are included in the problem formulation. For the latter, an analytical expression for the constraint limit is derived. Several numerical examples indicate that the proposed problem formulation is able to generate interesting conceptual designs for interior-vane-cooling solutions.

Optimization of Wind Turbine Efficiency during Severe Weather

Due to the importance of energy in society as well as the negative environmental impact of many commonly used energy sources, namely fossil fuels, it is essential to develop and improve sources of renewable energy. Wind energy is a prominent, widely accessible, and environmentally friendly form of renewable energy created when wind turbines convert the kinetic energy of wind to electricity. Severe weather is one area of concern for wind turbines. This article primarily examines the effects of high wind speeds and lightning on wind turbines. To aid in improving and fostering renewable energy, this article aims to study the effects of lightning and high wind speeds on wind turbines, evaluate current solutions, and suggest improvements where possible. After examining several sources, the advantages and disadvantages of current methods were discussed along with proposed improvements. Due to the restrictions of our research being purely virtual, lacking resources, and time constraints, we are unable to conduct tests and physical research of wind turbines and these meteorological events for more thorough first-hand exploration. Following our research, the next step would be to utilize the evaluations and proposed improvements to current wind turbine designs and analyze the effects.

Aerothermal Performance of Slashface Leakage With Double Surface Angle Under Realistic Swirling Inflow

Abstract The turbine vanes being manufactured and assembled piece by piece leads to an unavoidable gap on the vane endwall called slashface. Usually, the coolant leakage introduced from the slashface with a single surface angle aims to prevent hot gas ingression and protect the vane endwall. However, the cooling effectiveness is greatly reduced when considering the swirling flow from the combustor. In the current work, against strong swirling inflow, a new solution to improve endwall film cooling performance through applying the slashface leakage with the double surface angle is carried out. Through numerical method, the effects of the location of the angle transition region (D/L = 0%, 25%, 50%, 75%, 100%) and mass flow ratio (MFR = 0.5%, 1.0%, 1.5%) of the leakage on the turbine vane endwall aerothermal and film cooling performance are investigated. The results indicated that the coverage area of the coolant on the endwall was obviously enlarged when the slashface leakage with the double surface angle was employed. The film cooling level on both the endwall and suction side surface of the vane increased with increasing MFR. Moreover, the endwall thermal load was reduced. The designs of D/L = 25% and 50% are recommended for their high endwall film cooling level and low endwall thermal load. This paper provides turbine designers with a new idea to increase endwall film cooling performance by the slashface leakage with the double surface angle when considering aggressive swirling inflow.

Research on Aerodynamic Performance of Asynchronous-Hybrid Dual-Rotor Vertical-Axis Wind Turbines

This study analyzes the performance degradation of traditional hybrid wind turbines under high blade-tip-speed ratio conditions and proposes solutions through two-dimensional Computational Fluid Dynamics (CFD) simulations. It also introduces the design of two innovative asynchronous-hybrid dual-rotor wind turbines. The results indicate a remarkable 98.5% enhancement in torque performance at low blade-tip-speed ratios with the hybrid wind turbine model. However, as the blade-tip-speed ratio increases, it leads to negative torque generation within the inner rotor of the conventional design, resulting in a reduction of the power coefficient by up to 13.1%. The introduction of the new wind turbine design addresses this challenge by eliminating negative torque at high blade-tip-speed ratios through adjustments in the inner rotor’s operating range. This modification not only rectifies the negative torque issue but also enhances the performance of the outer rotor in the leeward region, consequently boosting the overall power coefficient. Moreover, the optimized inner rotor configuration effectively disrupts and shortens the wake length by 16.7%, with this effect intensifying as the rotational speed increases. This optimization is pivotal for enhancing the efficiency of multi-machine operations within wind farms.

A Comparison of a Three Blade and Five Blade Wind Turbine in Terms of the Mechanical Properties Using the Q-Blade Software

يمكن لتوربينات الرياح المنتشرة في مزارع الرياح على نطاق المرافق أن تدعم تلبية رغبات الطاقة المستقبلية وتقليل انبعاثات ثاني أكسيد الكربون عن طريق تقليل متطلبات الطاقة من الوقود الأحفوري. مع ارتفاع درجة حرارة الهواء على مدار اليوم، تزداد سرعة الرياح بسبب تدرجات درجة الحرارة، والتي تنتج تدرجًا في الكثافة / الضغط، مما يؤدي إلى حركة الهواء التي تواجهها توربينات الرياح. اعتمادًا على تضاريس الأرض، يمكن أن تواجه الرياح وتوجه في الوديان بين التلال وفوقها حيث تتدفق وتتبع منحنيات الأرض. تنتج هذه التضاريس زيادة في سرعة الرياح في القمم والتلال. في هذا العمل، تم تصميم شفرة دوار توربينات الرياح الأفقية الصغيرة للعمل في ظل سرعة الرياح المنخفضة، باستخدام برنامج (Q-Blade). استنادًا إلى نظرية عنصر الشفرة (BEM). مع الجنيح NACA3712. تم استخدام دوار ثلاثي الشفرات ودوار بخمس شفرات بناءً على نوع التوربين وحجم الدوار لتوليد الطاقة الميكانيكية من طاقة الرياح. تم إجراء مقارنة وتحليل قوة التوربين ومعامل القدرة ومعامل عزم الدوران عند سرعة رياح منخفضة ((1m/s-8m/s وتم الحصول على نتائج دقيقة للغاية. وجد أن أفضل أداء يمكن أن يعمل فيه دوار توربيني ثلاثي الشفرات بقدرة توربينية تبلغ (955W) كما تم الحصول على قدرة التوربين ((582W للدوار خماسي الشفرات. وجد أن تصميم توربينة رياح أفقية صغيرة بخمس ريش أفضل من التوربين بثلاث ريش ومناسب للعمل في المناطق ذات سرعة الرياح المنخفضة وبكفاءة عالية مقارنة بحجم التوربين.

Modeling and observations of North Atlantic cyclones: Implications for U.S. Offshore wind energy

To meet the Biden-Harris administration's goal of deploying 30 GW of offshore wind power by 2030 and 110 GW by 2050, expansion of wind energy into U.S. territorial waters prone to tropical cyclones (TCs) and extratropical cyclones (ETCs) is essential. This requires a deeper understanding of cyclone-related risks and the development of robust, resilient offshore wind energy systems. This paper provides a comprehensive review of state-of-the-science measurement and modeling capabilities for studying TCs and ETCs, and their impacts across various spatial and temporal scales. We explore measurement capabilities for environments influenced by TCs and ETCs, including near-surface and vertical profiles of critical variables that characterize these cyclones. The capabilities and limitations of Earth system and mesoscale models are assessed for their effectiveness in capturing atmosphere–ocean–wave interactions that influence TC/ETC-induced risks under a changing climate. Additionally, we discuss microscale modeling capabilities designed to bridge scale gaps from the weather scale (a few kilometers) to the turbine scale (dozens to a few meters). We also review machine learning (ML)-based, data-driven models for simulating TC/ETC events at both weather and wind turbine scales. Special attention is given to extreme metocean conditions like extreme wind gusts, rapid wind direction changes, and high waves, which pose threats to offshore wind energy infrastructure. Finally, the paper outlines the research challenges and future directions needed to enhance the resilience and design of next-generation offshore wind turbines against extreme weather conditions.

Aerodynamic optimization of multi-stage axial turbine based on pre-screening strategy and directly manipulated free-form deformation

To address the challenges of multiple design variables, long evaluation times, and poor global search capability of traditional surrogate-assisted algorithms that rely on the complete substitution of accurate function evaluations in the turbine aerodynamic optimization process, a pre-screening surrogate-assisted elitist preservation genetic algorithm (pre-SAEGA) optimizer is proposed. Pre-screening strategy in the pre-SAEGA can screen samples instead of directly estimating them, thereby reducing expensive evaluations in each generation. The directly manipulated free-form deformation (DFFD) method is applied to parameterized multi-stage axial turbines, and multi-degree-of-freedom flexible control is realized. Combining the pre-SAEGA with the DFFD method, a data-driven multi-stage axial turbine optimization platform is established. A two-stage axial turbine is the research object, and 44 design variables are selected for the combined optimization design of flow path and blade rows. The results show that the isentropic efficiency and flow rate improve by 1.33 % and 1.81 % respectively, and the pressure ratio decreases by 0.47 % at the turbine design point. The presented optimization platform not only improves the aerodynamic optimization effect but also significantly reduces the number of design variables and real evaluation samples, making it suitable for solving multi-stage turbine optimization problems with multiple degrees of freedom.

Overview of steam turbines and efficiency

Thermal power plants, which produce energy from the burning of fossil fuels that in turn generate turbine-turning steam, contribute a large proportion of energy in the world. Research on how we could apply fluid dynamic and thermodynamic principles in the design of turbines is crucial to improving their efficiency and fuel consumption. This paper mainly aims to explore and summarize how the power efficiency of turbines is maximized in thermal power plants and analyze the designs of turbines that increase proficiency. Literature and past paper review will be the primary method of this research. The main findings of this research are that efficiency in thermal turbines can be increased in three principal ways: a multi-stage expansion mechanism, the application of alternating blades, and in implementation of a reheating system. Using these methods, efficiency has been increased almost a million-fold in steam turbines. The purpose of this paper is to gain insights into how energy output in thermal power plant turbines is maximized and the specific designs of turbines that improve its efficiency.

Regulation of the power of a wind turbine of a special design by changing the length of the blades

The object of this research is a model of a wind turbine with retractable blades. This model allows for the adjustment of the turbine’s screw radius by extending or retracting the blades, providing a basis for examining the impact of blade radius on turbine performance. The primary problem addressed by this study is to determine how changes in the screw radius, achieved by altering the blade length, affect the wind turbine’s performance, specifically its electrical output (voltage and current) and rotational speed, under constant wind conditions. The experimental results showed that when the turbine blades are fully extended (R1), the wind turbine generates higher voltage and current compared to when the blades are retracted (R2). This confirms that the turbine’s electrical output is significantly influenced by the screw radius. These results are explained by the aerodynamic principles governing wind turbines. An increased screw radius allows the turbine blades to capture more wind energy, leading to greater force applied to the blades, thus increasing the rotational speed and the amount of electrical energy generated. The linear relationship between the screw radius and the turbine’s performance was as summed to simplify the analysis, though the actual relationship may be more complex. The finding soft its study can be practically applied in the design and operation of wind turbines. Turbines with adjust table blade lengths can optimize performance across varying wind conditions, maximizing efficiency and power output. These results are particularly useful in environments where wind speed is variable, as turbine scan adjust their blade radius to maintain optimal performance. The study assumes consistent wind conditions and uniform air flow for the results to be accurate, so these conditions should be considered when implementing the findings in real-world scenarios

Synchronous PIV measurements of a self-powered blood turbine and pump couple for right ventricle support

A blood turbine-pump system (iATVA), resembling a turbocharger was proposed as a mechanical right-heart assist device without external drive power. In this study, the iATVA system is investigated with particular emphasis on the blood turbine flow dynamics. A time-resolved 2D particle image velocimetry (PIV) set-up equipped with a beam splitter and two high speed cameras, allowed simultaneous recordings from both the turbine and pump impellers at 7 different phased-locked instances. The iATVA prototype is 3D printed using an optically clear resin following our earlier PIV protocols. Results showed that magnetically coupled impellers operated synchronously. As the turbine flow rate increased from 1.6 to 2.4 LPM, the rotational speed and relative inlet flow angle increase from 630 to 900 rpm, and 38 to 55% respectively. At the trailing edges, backflow region spanned 3/5 of the total passage outlet flow, and an extra leakage flow was observed at the leading edge. For this early turbine design, approximately, 75% of the turbine blade passage was not contributing to the impulse operation mode. The maximum non-wall shear rate was ~ 2288 s−1 near to the inlet exit, which is significantly lower than the commercial blood pumps, encouraging further research and blood experiments of this novel concept. Experimental results will improve the hydrodynamic design of the turbine impeller and volute regions and will be useful in computational fluid dynamics validation studies of similar passive devices.

Statistical characterization of marine wind structure over wind-turbine-relevant heights in tropical cyclones

Tropical cyclones (or typhoons, hurricanes) may influence the power production and structural integrity of offshore wind turbines. However, understanding of tropical cyclone wind structure over turbine-relevant heights remains limited. Based on observations from a wind lidar and a meteorological mast at a planned offshore wind farm site, this paper investigates the marine wind characteristics, e.g., wind speed shear, wind direction veer, and turbulence intensity, over turbine-relevant heights in tropical cyclones. Statistical distributions of the marine wind characteristics are analyzed, and their variations with upstream fetch conditions and hub-height wind speeds are examined. Some noteworthy features of the marine wind structure in tropical cyclones are observed, such as the median wind veer rate of 0.018°/m and veer angle of 2.2° across the turbine rotor heights, different wind shear coefficients and wind veer rates for upper and lower rotors, and levelling off or decrease of wind shear coefficient and turbulence intensity with increasing wind speed at hub-height wind speed over 25 m/s. The outcome of this study is expected to provide useful information for design and operation of offshore wind turbines, marine platforms, and other ocean structures in tropical cyclone-prone regions.