Blade Surface Research Articles

Effects of a J-Shaped Blade on the Performance of a Vertical-Axis Wind Turbine Using the Improved Delayed Detached Eddy Simulation Method

Vertical-axis wind turbines (VAWTs) offer key advantages such as independence from wind direction, low manufacturing costs, and reduced noise levels, making them highly suitable for urban and offshore wind energy applications. Among various VAWT designs, the J-shaped VAWT demonstrates improved energy capture at low and medium tip speed ratios (TSRs) compared to symmetrical blade VAWTs, which has garnered increased interest in recent years. However, the mechanisms by which J-shaped blades enhance VAWT performance remain insufficiently explored. In this paper, the high-resolution three-dimensional Improved Delayed Detached Eddy Simulation was employed to investigate the evolution and interaction of complex vortex systems in J-shaped and symmetrical blade VAWTs at varying TSRs, aiming to deepen the understanding of J-shaped blade effects on wind turbine aerodynamic performance. The results indicate that the tip vortex plays a role in inhibiting flow separation, while the J-shaped blade generates a stronger tip vortex, conferring upon it an advantage in suppressing flow separation and delaying dynamic stall. Additionally, the smaller pressure differential between the root and tip of the J-shaped blade reduces cross-flow on the blade surface, thereby reducing susceptibility to flow separation. Therefore, as the blade enters the dynamic stall region at low and medium TSRs, the J-shaped blade achieves a higher lift coefficient than the symmetrical blade, yielding greater torque, and enhancing wind energy utilization.

The example of BTJE flow path contamination assessment with anti-icing fluid using statistical models

Contamination of the compressor flow path is one of the most prevalent issues encountered during the operation of aircraft gas turbine engines (GTEs). During operation in winter, ingestion of anti-icing fluids and de-icing agents into the compressor flow path presents a substantial risk. In particular, contamination of the compressor rotor blades leads to the reduction in the cross-sectional areas of the inter-blade channels, changes in their shape, and an increase in the roughness of the blade surfaces. All these phenomena compromise compressor performance: result in reduced efficiency, decreased pressure ratio, and airflow, resulting in lower engine thrust, increased jet pipe temperature, higher fuel consumption, reduced gas-dynamic stability, and altered rotor speeds. To eliminate contamination in the gas-air duct during operation, periodic washings of the flow part are performed using solid cleaners, liquid detergents, and water as cleaning agents. The article analyzes changes in deviations of bypass turbo-jet engine recorded parameters from baseline values both when contaminated with anti-icing fluids and after removing contaminants using statistical models based on time series analysis methods, dynamics of model characteristics describing relationships between parameters, as well as synchronization analysis of parameter changes in engines of the same aircraft. The article does not aim to report average parameter change values for a specific engine type and fault but rather demonstrates the principle and effectiveness of the diagnostic method that uses the principle of assessing the dynamics of significance and stability of correlation links between recorded parameters, which are currently underutilized in the scientific-methodological foundations of constructing and applying statistical diagnostic models in operational practice.

Noise-Reducing Ship Propeller Design

Propellers, as the core of ship propulsion systems, significantly impact vessel speed, fuel efficiency, and overall performance. Achieving a balance between hydrodynamic efficiency, cavitation reduction, and noise minimization remains a significant challenge in traditional propeller design. These methods often focus on optimizing individual performance parameters while neglecting the interplay between them, resulting in suboptimal outcomes. This paper introduces a novel multi-objective integrated design theory for propellers, aiming to overcome these limitations. Leveraging advanced computational fluid dynamics (CFD) and optimization algorithms, this methodology simultaneously optimizes hydrodynamic performance, cavitation resistance, and noise reduction characteristics. The paper explores various noise suppression techniques, emphasizing the importance of blade shape optimization, surface treatments, and cavitation control strategies. Additionally, it highlights the role of material selection and structural optimization in achieving noise reduction goals. By adopting this integrated design, the paper aims to optimize propeller performance, enhance fuel efficiency, reduce noise emissions, and promote sustainable maritime transportation.

3D surface modeling of rotating helicopter blade through optimized NURBS using image data

Purpose This paper aims to introduce a novel approach for modeling the deformed rotor blades in helicopters. The blades are critical and nonredundant components susceptible to deformation and damage from aeroelastic forces and harsh environmental conditions, requiring effective methods for their analysis and maintenance. Design/methodology/approach The proposed methodology combines three techniques: photogrammetry, non-uniform rational B-splines (NURBS) and particle swarm optimization (PSO). Photogrammetry is used to capture 3D points of the deformed blade, NURBS is used to create a precise mathematical representation of the blade surface and PSO is used to optimize the accuracy of the surface model. Detailed consideration is given to applying photogrammetry on large rotating structures like rotor blades. In addition, the key parameter values of the PSO algorithm are adjusted to improve the NURBS model. Findings The integration of these methods leads to the development of an accurate NURBS model of the blade surface, achieving a mean square error of 0.0001. This result confirms the effectiveness of the approach in accurately modeling the deformation of large rotor blades. The method is potentially applicable to other large, flexible structures in various industries. Originality/value This study introduces a novel combination of photogrammetry, NURBS and PSO for 3D surface modeling in large, flexible rotor blades.

Reliability‐Based CCF Damage Analysis for Gas Turbine Blade With Thermal Barrier Coatings

ABSTRACTIn this work, a dynamic surrogate modeling approach is presented for reliability analysis of turbine blades with thermal barrier coatings (TBCs) under combined high and low cycle fatigue (CCF) loadings. Initially, a three‐dimensional model encompassing TBCs, turbine blades and flow fields is built to investigate the stress distribution at turbine blade surface using numerical analysis method of fluid–thermal–solid coupling. Following that, an improved seagull optimization algorithm‐based backpropagation neural network (ISOA‐BPNN) is developed by integrating the strengths of seagull optimization algorithm (SOA) and BP neural network. Furthermore, the probabilistic CCF estimation of turbine blades with TBCs is considered as a numerical case to evaluate the developed approach under the consideration of the uncertainties in material properties and loading conditions. The results reveal that the application of TBCs reduces the maximum stress at the blade mortise position, and the proposed ISOA‐BPNN holds great prediction accuracy and computational speed for reliability analysis.

Investigation of enhanced peak lift performance and stall angle delay by attachment of Vortex Generators on blade surfaces of Vertical Axis Ocean Current Turbine

Investigation of enhanced peak lift performance and stall angle delay by attachment of Vortex Generators on blade surfaces of Vertical Axis Ocean Current Turbine

Flow Separation Analysis of a Turbine Blade NACA 63-415

This paper investigate the flow separation behavior of a turbine blade using NACA 63-415 airfoil in three arrangements- without slot, with single slot, with double slot. Computational fluid dynamic simulation are used to study airfoil behavior at 0 to 20 degree angle of attack.to investigate how separation begins and develops. The study targets determination of significant angle of attack at which the flow separation initiates since it influences both the efficiency and performance of the turbine blade. Important aerodynamics factors like pressure distribution, velocity contours and the impact of turbulence are assesses to determine the change in airfoil patterns. Further the research explores whether slot modification at the leading edge are efficient in controlling or postponing flow separation and hence aerodynamic efficiently can be improved. Single and double slot existence is explored to find their effectiveness in enhancing lift to drag ratio, lowering turbulence intensity and ensuring smoother airfoil on the blade surface.

Optimized Placement of Sensors on Large Wind Turbine Blades Based on Weighted Partition and Effective Independence Method

ABSTRACTNon‐destructive health monitoring is crucial for ensuring the safe operation of large wind turbine blades. This requires advanced sensor placement algorithms to monitor their structural behavior effectively. Existing optimization techniques often cause measurement points to cluster locally. This results in redundancy and complicates sensor placement and damage localization. This study partitions the blade surface using the k‐means clustering algorithm and calculates regional weights with the modal kinetic energy method to optimize the sensor distribution. It further optimizes sensor placement within each region by maximizing Fisher information matrix values through the effective independence method. The sensor placement strategy developed in this study offers a robust framework for non‐destructive monitoring of large wind turbine blades. Simulation results validate its ability to prevent the clustering of measurement points, minimize redundant information, and maximize the utilization of modal information under limited sensor resources.

IMPACT OF HIGH FREESTREAM TURBULENCE ON LPT ENDWALL FLOW: PART I – LOSS DEVELOPMENT AND TIME-AVERAGED FLOW FIELD

Abstract Realistic turbomachinery conditions include high levels of freestream turbulence; however, this aspect of the flow is typically overlooked in both low-pressure turbine (LPT) simulations and experiments. A better understanding of the impact of high freestream turbulence intensity (TI) on the endwall region of LPT blades is imperative. To fully assess the impact of elevated turbulence, three different incoming turbulence levels were examined at three different Reynolds numbers. Three planes of total pressure loss were measured downstream of the cascade mapping loss development. Surface pressure measurements were collected along the blade surface at midspan. Three planes of high-speed Stereoscopic Particle Image Velocimetry (SPIV) were acquired to investigate the impact varying incoming turbulence levels have on the endwall flow structures. Increasing the turbulence to the highest level was found to reduce the overall loss at the exit of the passage. The greatest impact of elevated freestream turbulence was observed at the lowest Reynolds number investigated. The time-averaged velocimetry measurements in the endwall region demonstrated that increasing the freestream turbulence intensity altered the locations of vortices throughout the endwall. Freestream turbulence levels must be increased, better matching real engine conditions, to get a more accurate prediction of pressure losses and flow topology when simulating the flow surrounding LPT blades.

Blade Designs for Improved Multi-Phase Performance in sCO2 Compressors: Optical Diagnostics in sCO2 and Experimental Evaluation With Particle Image Velocimetry

Abstract This paper presents the second part of a study in which the leading edge and suction surface of a compressor blade was modified to delay onset of phase change for sCO2 compressors operating near the critical point. Using a first-of-its-kind apparatus for the measurement of sCO2 flow fields, Particle Image Velocimetry (PIV) is used for local flow field measurements of two compressor blade geometries: the modified “biased wedge,” and a conventional constant thickness blade. Utilizing the developed hardware, the feasibility of a simple, laser-based diagnostic for qualitatively measuring liquid phase regions, is also presented. The design of the optical diagnostics rig, a discussion of numerous challenges, and necessary considerations involved in performing optical-based measurements like PIV, in sCO2, are discussed. Velocity field measurements for the modified compressor profile show a much lower suction peak compared to a conventional blade. These results validate numerical results at the tested conditions, where the suction side profile of the biased wedge works to minimize the local pressure gradient.

An adaptive sampling strategy for aero-engine blade surface based on the momentum conservation principle

Abstract The spatial distribution and density of inspection points are critical factors influencing the accuracy and efficiency of aero-engine blade quality assessment. This study proposes an adaptive sampling methodology to optimize measurement precision and operational efficiency for blade surface inspections through dynamic adjustment of sampling point locations and quantities based on geometric feature variations. A parametric blade model is established using non-uniform rational B-splines for geometric representation, with reconstruction accuracy evaluated through median Hausdorff distance metrics. An innovative adaptive sampling strategy based on momentum conservation principle is developed, where multi-feature parameters (including curvature, torsion, chord height, and arc length) are incorporated as mass terms to characterize blade geometry. Velocity terms are introduced to dynamically balance the influence weights of different geometric features during the sampling process. Through three comparative experiments, the proposed method demonstrates superior performance compared to conventional approaches including equal arc length sampling, chordal tolerance method, modified equal chord height sampling, equal moment theory sampling, and bending moment theory sampling. Results indicate that under equivalent sampling point quantities, this methodology achieves the minimum deviation between reconstructed and actual blade surfaces.

Research on the Characteristics of Sediment Erosion in Pump-Turbine Runners Under Different Solid-Phase Conditions

Sediment erosion in turbine components presents a major challenge to the reliable operation of pumped storage power plants, particularly in sediment-laden rivers. While extensive research has been conducted on hydraulic machinery erosion, studies focusing on the combined effects of sediment particle size and concentration on erosion within the runner region of pump turbines remain limited. To bridge this gap, this study investigates the influence of sediment characteristics on erosion patterns and deposition mechanisms in pump-turbine runners through a combination of numerical simulations and experimental validation. The results demonstrate that sediment concentration primarily governs the overall erosion intensity, while particle size significantly influences the spatial distribution of erosion zones. Higher sediment concentrations lead to intensified surface wear and broader erosion regions, whereas larger particles cause localized shifts in erosion-prone areas across different blade surfaces. Furthermore, a strong correlation is identified between erosion zones and sediment accretion regions, highlighting the interplay between material loss and deposition dynamics. By accurately predicting erosion trends, numerical simulations minimize the reliance on costly and time-consuming physical experiments, offering valuable insights for turbine optimization. This study enhances the understanding of sediment-induced erosion mechanisms in pump turbines and provides guidance for improving turbine design and operational strategies in sediment-laden environments.

Research on pressure fluctuation distribution law and rotor-stator interaction of pump-turbine in vaneless region of turbine mode

The vibration issue of pumped storage power station unit will directly affect the safe and stable operation of the unit, and the pressure pulsation in the vaneless region is an important index to evaluate the stability of the unit. In order to study the pressure fluctuation characteristics of the vaneless region of the pump-turbine in the turbine mode, the unsteady numerical simulation of the maximum head condition and the rated head condition is carried out in this research. The amplitude-frequency characteristics of the pressure fluctuation in the vaneless region under different head and the influence of the internal flow characteristics on the pressure fluctuation are analyzed. The results show that the non-uniform pressure field is formed in the vaneless region due to the rotor-stator interaction (RSI) between the long and short blades of the runner and the guide vanes. The main frequency of pressure pulsation in the vaneless region is 5fn, which is half of the blade passing frequency (BPF), that is, the blade combination passing frequency. The main sub-frequencies are 10fn, 15fn, and 20fn. In addition, the amplitude of pressure pulsation at each frequency under the rated head condition is higher than that under the maximum head condition. In a rotating cycle, the discrete blade vortex in the runner flow channel gradually accumulates and evolves into the big scale vortex on the side of the pressure surface of the short blade, which aggravates the pressure fluctuation in the vaneless region. The intensity of the vortex under the rated head condition is larger, which reasonably explains the reason why the pressure fluctuation amplitude under the rated head condition is larger.

Solving ultra-high-load, low-pressure turbine cascade flow using physics-informed neural networks with boundary identification strategy

This paper constructs a physics-informed neural network with boundary identification strategy (BI-PINN) to reconstruct the flow field of an ultra-high-load, low-pressure turbine cascade using sparse data. Since the boundary layer position is unknown before training, an iterative method is required to determine the boundary layer range. The BI-PINN trains the network based on a dual convergence criterion: achieving flow field reconstruction convergence in both the boundary layer and mainstream regions to extract the current boundary layer range and then ensuring the convergence of the boundary layer range. To improve neural network convergence while maintaining high training speed, this study assigns different weights to the governing equation terms in the loss function for the boundary layer and mainstream regions. The BI-PINN method demonstrates computational accuracy comparable to computational fluid dynamics in inverse problems with incomplete boundary conditions. This study finds that for high-load, low-pressure turbine cascades, selecting pressure observations only on the blade surface is sufficient for high-accuracy flow field reconstruction. However, for ultra-high-load, low-pressure turbine cascades, this paper proposes a method of selecting multiple normal-direction pressure observations along the blade surface to achieve high-accuracy flow field reconstruction with a small observation set. The BI-PINN method balances the conflict between the low-gradient mainstream region and the high-gradient boundary layer region in flow field reconstruction. By leveraging both physical governing equations and observation data, it enables precise full flow field reconstruction of ultra-high-load, low-pressure turbine cascades using a small dataset and a neural network with a limited number of parameters.

Large eddy simulation of the effect of blade rotation on laminar separation bubbles in horizontal axis wind turbines

The formation and evolution of laminar separation bubbles on a horizontal axis wind turbine blade in the transitional flow regime are investigated using Large Eddy Simulations. Both rotating and translating cases of a blade element, based on a small horizontal axis wind turbine, are analyzed to distinguish the specific aerodynamic effects introduced by rotation. The results demonstrated that in the rotating case, the roll-up vortices developed through Kelvin–Helmholtz instability appear shorter, inclined at varying angles along the span, and break down at various locations along the span, in contrast to the continuous two-dimensional structures of the Kelvin–Helmholtz vortices observed in the translating case. Furthermore, in the rotating case, the Coriolis force induces a stabilization of the boundary layer by enhancing momentum transfer, promoting an earlier transition to turbulence and facilitating a rapid reattachment of the flow. Centrifugal force drives radially outward flow, displacing the bubble laterally, restricting its growth and limiting its extent along the blade surface. These effects result in a 66.4% thinner bubble, leading to a 26.7% reduction in lift, and a 36.3% reduction in drag compared to the translating case. These results demonstrate that, unlike large wind turbines, rotation in small horizontal axis wind turbines can degrade lift performance due to reduced effective curvature, despite improving aerodynamic efficiency due to the accompanied drag reduction. This study provides insights into laminar separation bubble behavior under rotation and contributes to a better understanding of the physics, aiding investigations and improvements in performance prediction models for the transitional flow regime.

Nature of Transonic Compressor Flow and Its 3D Design Implications

Abstract A key problem in transonic compressor and fan design is that although a 3D description of the flow is necessary to correctly capture the shock, accounting for it during the sectional design is difficult because the key driving design parameters are unknown. In this paper, it is shown that for inlet relative Mach numbers between 0.85 and 1.10, the pre-shock Mach number is a function of the 3D streamtube area at the throat At over the inlet area A1. This key finding is based on three key transonic flow features, discussed in detail within this paper, being present together across a wide range of 10,000 representative transonic compressor and fan designs published online.1 This unique wide-ranging web-interactive dataset reveals that the effect of changes in the blade geometry, or the 3D streamtube height, on the transonic flow field is one of the same and can be explained simply by keeping track of the associated changes in At/A1. Surprisingly, the pre-shock Mach number at a given At/A1 is shown to be insensitive to the details of the blade surface geometry. Only geometric design choices made in the preliminary design phase, such as the maximum thickness and inlet relative flow angle, are shown to have a second-order effect. These findings suggest that the sectional design phase should focus solely on achieving the desired spanwise 3D At/A1 distribution. The second half of the paper addresses the level of fidelity necessary when calculating the spanwise 3D At/A1, for it to positively influence design; especially when approaching a Mach number of unity. A key conclusion is that failing to resolve the subtle 3D radial flow changes within the blade passage at the appropriate level of fidelity during the early throughflow multistage compressor design stage could mislead the transonic design process. As a result, for the rapid exploration of future compressor designs, this paper advocates utilizing the more than 10,000 transonic design databse to generate an initial 3D blade, which is then assessed early in the design process using At/A1 extracted from 3D CFD.

MFYOLO: Improved UAV lightweighting algorithm for wind turbine blade surface visibility damage detection

MFYOLO: Improved UAV lightweighting algorithm for wind turbine blade surface visibility damage detection

Effective Formalization of Design Processes as a Key Factor in Achieving Optimal Solutions When Creating the Final Stages of Steam Turbines

Based on the existing experience in designing and constructing of the last stage blades of large (critical) length and the analysis of literary sources, the features of the methodology for formalizing the processes of creating such blades, taking into account their specific features (large radial dimensions, suboptimal relative grid steps =0.25–1.0, high static and dynamic loads), are established. A parametric formalization of the main modeling dependencies of the processes on which the creation of rotor blades is based is given: the thermo-gas-dynamic process, blade design and the technological process of manufacturing. The need to create systems (subsystems) for automated design of blades of large length with the presence of a model of the technological process of blade manufacturing in the system is substantiated. It is based on the conclusions that even small deviations from the design option within the tolerance limits during blade manufacturing affect the thermo-gas-dynamic characteristics of the stage, especially when it comes to throat areas. A formalized probabilistic-statistical mathematical model that allows to describe the technological deviations of the blade surfaces taking into account the processing modes used in finish milling with a reliability satisfactory for practical calculations has been developed. This makes it possible to take into account the influence of manufacturing errors and specific features of machine equipment on the blade strength indicators, its gas-dynamic characteristics, and also on the efficiency of the stage operation at the design stage. A two-level approach to the design process, which allows using a two-dimensional model to conduct a directed search for the best solution in an automated mode, analyzing hundreds of options taking into account a wide range of constraints, is proposed. Subsequently, as a result of the blade design and calculation of technological deviations, the option with the best thermo-gas-dynamic characteristics, strength indicators, vibration reliability, and the one taking into account manufacturing errors is selected. At the next level, it can be adjusted using three-dimensional calculation models without losing the indicators of the main selected characteristics. This approach improves the design quality and reduces the time to obtain the best solution.

Numerical investigation on cavitating flow and cavitation-sand erosion characteristics of a centrifugal pump under sand-laden water conditions

PurposeThe objective of this investigation is to analyze the cavitating flow of sand–laden water in a centrifugal pump and its induced cavitation–sand erosion mechanism.Design/methodology/approachAn improved partially-averaged Navier–Stokes turbulence model and a zero-equation model are applied to discuss the mechanism of sand impact on cavitating flow. Meanwhile, the effect of sand on cavitation–sand erosion is analyzed by using a mathematical model. The cavitation performance curve and cavitation evolution of the centrifugal pump predicted by numerical simulations are in good agreement with the experiments.FindingsThe sand promotes the inception and development of cavitating flow in the pump. Meanwhile, the inception and development of cavitating flow force sand to distribute near the pressure surface of blade, especially in the upstream area of flow channel. It is worth noting that the increase of sand concentration enhances cavitation–sand erosion, and the increase of sand diameter prevents this process. Cavitation erosion plays a dominant role in cavitation–sand erosion.Originality/valueThe interaction law between sand and cavitation in the cavitation flow field of centrifugal pump under the condition of sand–laden water was studied, the dominant role of cavitation erosion and sand erosion in cavitation–sand erosion was obtained, and the influence laws of NPSH, sand concentration and sand diameter on cavitation–sand erosion characteristics of centrifugal pump were discussed. The results can provide reference for the optimizing design and increasing service life of pump.

Acoustic near field of a contra-rotating propeller in wetted conditions

The acoustic field radiated by a system of contra-rotating propellers in wetted conditions (with no cavitation) is reconstructed by exploiting the Ffowcs Williams–Hawkings acoustic analogy and a database of instantaneous realizations of the flow. They were generated by high-fidelity computations using a large eddy simulation approach on a cylindrical grid of 4.6 billion points. Results are also compared against the cases of the front and rear propellers working alone. The analysis shows that the importance of the quadrupole component of sound, originating from wake turbulence and instability of the tip vortices, is reinforced, relative to the linear component radiated from the surface of the propeller blades. The sound from the contra-rotating propellers decays at a slower rate for increasing radial distances, compared with the cases of the isolated front and rear propellers, again due to the quadrupole component. The quadrupole sound is often neglected in the analysis of the acoustic signature of marine propellers, by considering the only linear component. In contrast, the results of this study point out that the quadrupole component becomes the leading one in the case of contra-rotating propulsion systems, due to the increased complexity of their wake. This is especially the result of the mutual inductance phenomena between the tip vortices shed by the front and rear propellers of the contra-rotating system.