Blade Geometry Research Articles

Intelligent optimization of axial-flow pump using physics-considering machine learning

Abstract To address the significant energy waste generated by axial flow pumps, this paper proposes an intelligent optimization method based on physics-considering machine learning. First, a highly parameterized geometric design theory is constructed using six featured variables to achieve a complete three-dimensional modeling of the blade geometry. Four hundred preliminary cases are studied using the computational fluid dynamics method with various combinations of these featured variables to obtain a preliminary solution. The best preliminary design has an efficiency of 83.33%, and a head of 5.495 m. To further improve this performance, this paper also presents a high-precision prediction model for the energy performance of axial flow pump based on back-propagation neural network and the encoding layers of random sampling and local feature aggregator network created. Afterwards, a multi-population genetic algorithm is used to quickly find the optimal solution within the prediction mode range. The algorithm achieved a highest efficiency of 86.373% and was validated by numerical simulation with a value of 86.057% and a prediction error of 0.316%. Compared with the preliminary solution, the efficiency of the optimized axial flow pump is increased by 1.615%, with a wider high-efficiency range and an optimal operating point closer to the design conditions. Overall, this intelligent optimization method has the potential to significantly reduce the design time of axial pumps and increase their performance.

Assessment of a virtual boundary concept for efficient modeling of turbine film cooling

Film cooling is one of key technologies advancing the performance of gas turbine engines, which is extensively applied in the hot turbine component for thermal protection by injecting cooling air from numerous film holes. To achieve an optimal film cooling scheme, many iterations of the position, the diameter, and the orientation of the holes through computation simulations are required to well fit the aerodynamic profiles of the turbine blades. However, a conventional computational simulation that resolves each individual hole and its coolant supply channel implies substantial costs of computation resources. In this study, a novel film cooling modeling method that uses a virtual boundary to represent film holes is assessed by comparing to the conventional computational simulation in two representative test cases, involving flat-plate and turbine endwall inlet film cooling. Relevant experiments are carried out to provide experimental data for verifying the approach at various coolant injection rates. Generally, the virtual boundary model produces rather equivalent results to those predicted by the conventional simulation method. Though coolant concentration downstream of the holes is over-estimated by the virtual boundary model due to neglected in-hole mixing, the overall flow fields and film cooling performance are well captured, showing the feasibility of the novel strategy in accurately modeling film cooling in a much more efficient way by saving computational efforts. This novel concept thereby allows designers to modify the film hole geometries independently of the blade geometry and thus, is helpful to accelerate the design process of a film-cooled turbine or to assess multiple film cooling configurations more quickly, as compared to a conventional computation simulation.

Evaluating the grinding performance of cutter-type disk mills using DEM-CFD simulations with a breakage model

In the recycling process of plastics, grinding is commonly employed as a pre-treatment method to facilitate molding by increasing the specific surface area. A cutter-type disk mill that mainly causes shear forces is expected to be the most efficient for grinding plastics. However, it is necessary to optimize the geometry and operating conditions of the mill. This study aimed to evaluate the grinding performance of different blade geometries in the cutter-type disk mill. To optimize the blade geometry, the discrete element method (DEM) coupled with the computational fluid dynamics (CFD) and a breakage model was employed to simulate plastic particle breakage. The simulations showed that the highest grinding performance was achieved with a grinding blade angle of 45°. Depending on the angle of the grinding blade, the effects of the power acting on the grinding blade and the force acting on the particles varied. According to these results, an appropriate blade geometry in the cutter-type disk mill can be proposed for grinding plastic. This study demonstrated that the DEM-CFD simulations are effective for evaluating the grinding performance and optimizing the blade geometry of the cutter-type disk mill.

Establishing thermal balance during the cooling system improvement of an air-cooled engine

The object of research is the air-cooling system, for F4L912 direct injection diesel engine (mounted on the bench), manufactured by the Motor Enterprise (EMO). It is a naturally aspirated inline 4-cylinder engine. Maximum engine power is 49 kW obtained at maximum speed rotation of 2300 rpm. Air cooling is a critical aspect of engine performance, and studying it experimentally can provide valuable insights into the engine's thermal behaviour and efficiency. One of the most problematic places is the high local temperature of the 4th cylinders sleeves. An innovative improvement of the cooling system is proposed. It is based on increasing the cooling air flow. It consists in the installation of new driving pulleys of the blowing turbine with different diameters. The use of these new pulleys allowed moderating the wall temperature of the liner and the cylinder head of the 4th cylinder and the thermal rebalancing of the engine. Significant improvements have been noted in cylinder wall temperature, exhaust gas temperature, and lubricating oil temperature. Drawing up the heat balance enabled us to quantify the useful work, the heat lost in the cooling water, the heat lost through the exhaust gases, the heat carried away by the lubricating oil and other losses (losses not accounted for). It is clear from the results that the high temperature in the engine has indeed been reduced and the cooling performance of the whole engine has been improved. The results show that the increase in airflow produced an improvement in cooling conditions as well as a reduction in exhaust gas temperatures which will have a significant impact on reducing NOx emissions. In future work, it is planned to improve the cooling system of the Emo F4L912 engine, by studying the effects of the geometry, number, and inclination of the turbine blades on the air flow supplied.

Optimization of Three-Dimensional Blade and Variable Stators for Efficiency and Stability Enhancement of Multistage Axial Flow Compressor at Variable Speeds

Abstract High efficiency and wide stability at variable speeds are equally important to the design and operation of multistage axial flow compressors. However, published research works on three-dimensional design optimization of compressors are so far mainly limited to a single blade row or stage at design speed due to the curse of dimensionality. Moreover, optimization of variable inlet guide vanes (IGV)/stators for off-design operations is carried out by using a rapid but low-fidelity prediction tool and is generally independent of design optimization of blade geometry. To tackle these issues, a three-dimensional holistic design and adjustment optimization method is developed in which both three-dimensional blade geometry and variable IGV/stators are optimized simultaneously for better efficiency and stability at design and off-design conditions. Metamodel-interpreted data mining method and adaptive infilling strategy are used respectively to enhance the capability of the metamodeling and optimization. The developed method is then applied to a modern highly loaded 3.5-stage transonic axial flow compressor at both design and part-design speeds. The results show that the stall margin is extended from 8.23% to 19.65% at 70% design speed while peak efficiency is slightly improved at design speed. The flow mechanisms responsible for the efficiency enhancement at design speed are mainly associated with the reduced total pressure loss in stators as well as inter- and intra-stage loading redistribution. The stability enhancement at 70% design speed is mainly achieved by loading the front blade rows while unloading the limiting rear blade row through variable IGV/stators adjustment. The developed holistic design and adjustment optimization method with the aid of metamodel-interpreted data mining is of great application value for the design and adjustment of advanced multistage axial flow compressors.

Study on a grinding force model of a variable grinding contact area during knife-edge surface grinding

Abstract. ​​​​​​​In the context of non-standard blade geometries of knife-like tools with tapered cutting edges where the width of the blade surface varies with feed, there is limited research on predicting grinding forces considering the changing contact line. To enhance the accuracy of predicting grinding forces during the blade surface grinding of knife-like tools, a novel analytical-regression correction method is proposed. This method employs an analytical approach to analyze the varying contact line between the grinding wheel and the tool during grinding, enabling the determination of irregularly shaped grinding contact zones. By introducing exponential coefficients related to the grinding contact line, a regression analysis is employed to refine a variable edge-width grinding force model. In comparison to the conventional constant contact line blade surface grinding force prediction, this model is better suited for non-standard blade geometries of knife-like tools in grinding processes. Results indicate that the average relative error between the predicted values from the variable edge-width grinding force model and the actual measurements remains within 9 %, thereby validating the model's effectiveness in predicting grinding forces.

Direct Numerical Simulation of Transitional and Turbulent Flows Over Multi-Scale Surface Roughness—Part I: Methodology and Challenges

Abstract High-fidelity simulation of transitional and turbulent flows over multi-scale surface roughness presents several challenges. For instance, the complex and irregular geometrical nature of surface roughness makes it impractical to employ conforming structured grids, commonly adopted in large-scale numerical simulations due to their high computational efficiency. One possible solution to overcome this problem is offered by immersed boundary methods, which allow wall boundary conditions to be enforced on grids that do not conform to the geometry of the solid boundary. To this end, a three-dimensional, second-order accurate boundary data immersion method (BDIM) is adopted. A novel mapping algorithm that can be applied to general three-dimensional surfaces is presented, together with a newly developed data-capturing methodology to extract and analyze on-surface flow quantities of interest. A rigorous procedure to compute gradient quantities such as the wall shear stress and the heat flux on complex non-conforming geometries is also introduced. The new framework is validated by performing a direct numerical simulation (DNS) of fully developed turbulent channel flow over sinusoidal egg-carton roughness in a minimal-span domain. For this canonical case, the averaged streamwise velocity profiles are compared against results from the literature obtained with a body-fitted grid. General guidelines on the BDIM resolution requirements for multi-scale roughness simulation are given. Momentum and energy balance methods are used to validate the calculation of the overall skin friction and heat transfer at the wall. The BDIM is then employed to investigate the effect of irregular homogeneous surface roughness on the performance of an LS-89 high-pressure turbine blade at engine-relevant conditions using DNS. This is the first application of the BDIM to realize multi-scale roughness for transitional flow in transonic conditions in the context of high-pressure turbines. The methodology adopted to generate the desired roughness distribution and to apply it to the reference blade geometry is introduced. The results are compared to the case of an equivalent smooth blade.

Preliminary theoretical design of crossflow water turbine for rainwater rooftop harvesting system

Harvesting energy is essential especially now that the demand of energy is high but the fuel supply is limited. This study theoretically designs the 5 m low head crossflow turbine in rainwater harvesting system. The characteristics of the site condition, the runner geometry, the blade geometry, and the turbine specification had been identified and the geometrical model of the design is shown. This paper reported the collection of theoretical formula for the design of low head crossflow turbine that can be used for rainwater harvesting system. The dimensional form of equations, as presented in Section 2, resulted to the two, four, and two parameters that represent the dimensions of the turbine, runner and the blade, respectively. As a conclusion, the designed turbine can be used for rainwater harvesting system with an efficiency that was calculated to be 88% with 22 kW expected power generated for 5 m head.

Performance estimation of small‐scale horizontal axis wind turbine blade

AbstractThe extracted energy from the wind is mainly influenced by the geometry of the rotor blades. Determining the aerodynamic optimum blade shape is one of the main tasks of the wind turbine designer. In the current study, the mixed airfoil technique was employed by using “Blade‐Element‐Momentum” (BEM) and “Computational‐Fluid‐Dynamics” (CFD) analysis to predict the aerodynamic performance of a small‐scale horizontal axis wind turbine blade. The BEM was then run using the open‐source wind turbine design and performance computation program Q‐Blade. The numerical simulation is carried out by Ansys Fluent. Here, the k‐ω Shear Stress Transport (SST) model was used. The results were compared with existing experimental data on lift and drag coefficients at the optimal angle of attack. The results of the two approaches were compared for different tip speed ratio values and a good agreement between CFD and BEM results was found.

Parametric comparison of different lobe rotor geometry for positive displacement turbine in water distribution network

The application of hydro turbines for harnessing water energy within distribution networks, as an alternative to pressure relief valves, is steadily increasing. These turbines are particularly suitable for recovering energy from incompressible subsonic fluid flows. In this research paper, three models of positive displacement lobe machine designed to function as water turbines were extensively examined and compared. The three selected turbine types included the circular lobe turbine, the cycloidal arc lobe turbine and the epicycloid arc lobe turbine. These turbines were meticulously designed and developed for their respective applications. Under identical operational conditions, optimization processes were applied to enhance volumetric efficiency and power efficiency for all three turbine variants, each having a different number of blades. A computer program was devised to facilitate the optimization and calculation of blade geometries under various operating conditions. This research delved into the impact of blade geometry type and the number of blades on turbine efficiency and size. The data obtained from the present investigation were systematically analyzed, and the performance of the different turbines were compared. Notably, the circular lobe turbine was found to be the largest among the three, occupying more space. The cycloidal arc requiring a greater amount of material resulting in rotor volume, which subsequently resulted in a higher overall cost. In contrast, the cycloidal arc lobe turbine emerged as the smallest variant, demanding less space for operation. Efficiency-wise, the cycloidal arc lobe turbine exhibited the highest efficiency with two blades, while the circular lobe turbine displayed the lowest efficiency with six blades. Moreover, among the turbines with the same number of lobes, the cycloidal arc lobe turbine consistently demonstrated superior efficiency compared to the circular lobe turbine.

Whipping motion of airplane composite fan blades due to bird strike

Composite fan blades made of CFRP have been developed and investigated to reduce the weight of aircraft engines. Aircraft fan blades are subjected to high-speed impact by foreign objects, such as bird strikes. Because CFRP has lower impact resistance than metal materials, it is necessary to focus on possible failure not only at the impact point but also at the tip and trailing edge of the fan blade. This paper developed a finite element analysis model of fan blade geometry and investigated the dynamic deformation that may induce peripheral fracture when a bird strike occurs on a composite fan blade. Natural vibration analysis and transient response analysis were performed to analyze the vibration behavior at the fan blade periphery. The natural vibration analysis showed that the vibration modes in the out-of-plane direction of the blade are of low order. In the transient response analysis, when a group of particles defined by the equation of state and the SPH method collided, a sudden deformation in the periphery, called a whipping motion, was observed immediately after the impact. The spanwise strain has a peak value at the trailing edge of the fan blade, while the chordwise strain has a peak value at the leading edge of the fan blade. Furthermore, the transient response analysis with the fan blades rotating showed an increase in the peak strain value. A comparison of the impact loads and displacements immediately below the impact indicated that the centrifugal force increased the geometric stiffness, which increased the reaction force due to the fan blade, increasing the peak value.

Effect of the rotor blade geometry on particle size and energy demand for knife-milled beech chips: Experimental identification and mathematical modelling

Rotor blade geometry (linear and screw) was experimentally identified for particle size characteristics and specific energy demand for knife-milled beech chips (7.8 wt % moisture content). The operational conditions of peripheral speed (6.8–20.4 m s−1) and screen sieve openings (0.75–6 mm) were considered for the knife milling of beech chips. The Rossin-Rammler-Sperling-Bennet model precisely described particle size distribution of comminuted beech chips with its parameters depending on screen sieve, rotor speed and blade geometry in a linear relationship. This relationship allowed the development and calibration of a unique empirical linear model. The model predicted particle size under the conditions considered for each blade geometry with accuracy. Energy demand values between 6.97 and 101.6 kW h t−1 were identified for D50 particle sizes between 0.29 and 2.60 mm. Energy demand was independent of the rotor blade geometry, and it was mainly affected by particle size characteristics, even though speed was also impactful. The linear model obtained allowed the prediction of energy requirements using speed and final particle size with an R2 value of 0.97.

Quantitative analysis of thin metal powder layers via transmission X-ray imaging and discrete element simulation: Blade-based spreading approaches

Spreading uniform and dense layers is of paramount importance to creating high-quality components using powder bed fusion additive manufacturing (PBF AM). Blade-like tools are often employed for spreading powder metal feedstocks, especially in laser powder bed fusion (LPBF) and electron beam melting (EBM), where powders are characterized by a D50V of 30 μm or greater. Along with variations in boundary conditions introduced by the layer-wise geometry and surface topography of the printed component, stochastic interactions between the spreading tool and powder result in spatial variations of layer quality that are still not well understood. Here, to study powder spreading under conditions representative of PBF AM, we employ a modular, mechanized apparatus to create powder layers from moderately and highly cohesive powders (nominally 15–45μm Ti–6Al–4V and 20–63μm Al–10Si–Mg, respectively) with a selection of blade-like spreading tools. Powder layer effective depth is spatially mapped using transmission X-ray imaging, and uniformity is quantified via a statistical approach. We first compare layer density, or the effective depth of powder layer, and show that blade geometries with a curved profile lead to increased material deposition. Second, this approach enables quantification of local fluctuations, or layer defect severity. For example, we observe that the primary benefit of a V-shaped rubber (compliant) blade, as compared to a 45° rigid blade, lies in enabling local deflection of the blade edge to eliminate streaking from large particles, while also increasing deposition (layer density). Additionally, we employ a custom DEM simulation to elucidate the opposing roles of particle density and surface energy with a pseudo-material approach, where the balance of inertial and cohesive forces determine macro-scale powder flowability. For each alloy density, selected to represent Ti–6Al–4V and Al–10Si–Mg, we find via simulations a critical surface energy beyond which layer density is greatly impaired when powder spreading is performed using a blade.

Influence of blade leading-edge form on the performance and internal flow pattern of a mixed-flow pump

In this article, a typical mixed-flow pump was adopted as the research object to investigate the influence of the inlet structure within the impeller on the performance and internal flow patterns of the mixed-flow pump. First, three different blade inlet structure cases, which are forward bending, straight, and backward bending, were proposed and modeled separately. Second, the performance of mixed-flow pumps featuring different cases was carefully compared and analyzed. The results show that the inlet structure of the blades has a small impact on the head of the mixed-flow pump. However, it has a significant impact on the efficiency and shaft power of the pump at the rated flow condition. Among them, the performance of the straight and backward bending cases is significantly better than that of the front bending case. At the same time, the accuracy of the numerical results was verified by the experimental results. Finally, the internal flow and hydraulic loss laws with different inlet structures were deeply studied. It is found that the case of forward bending will cause the media to strike the middle of the inlet edge of the blade first and then generate a secondary flow along the inlet edge. The secondary flow will induce stronger media crowding at the inlet side near the shroud and hub. Due to the large curvature of the shroud and hub at the position of intersection with the inlet side of the blade, media crowding induces flow interference of the media on each span of the impeller channel. This ultimately leads to increased flow losses within the impeller and diffuser, reducing the hydraulic performance of the mixed-flow pump. This finding clarifies the influence mechanism of the inlet side geometry of the inlet blade on the performance and internal flow of the mixed-flow pump, which can provide a theoretical basis for improving the performance of the mixed-flow pump.

CFD-based design optimization of ducted hydrokinetic turbines

Hydrokinetic turbines extract kinetic energy from moving water to generate renewable electricity, thus contributing to sustainable energy production and reducing reliance on fossil fuels. It has been hypothesized that a duct can accelerate and condition the fluid flow passing the turbine blades, improving the overall energy extraction efficiency. However, no substantial evidence has been provided so far for hydrokinetic turbines. To investigate this problem, we perform a CFD-based optimization study with a blade-resolved Reynolds-averaged Navier–Stokes (RANS) solver to explore the design of a ducted hydrokinetic turbine that maximizes the efficiency of energy extraction. A gradient-based optimization approach is utilized to effectively deal with the high-dimensional design space of the blade and duct geometry, with gradients being calculated through the adjoint method. The final design is re-evaluated through higher-fidelity unsteady RANS (URANS) simulations. Our optimized ducted turbine achieves an efficiency of about 54% over a range of operating conditions, higher than the typical 46% efficiency of unducted turbines.

Non-iterative generation of an optimal mesh for a blade passage using deep reinforcement learning

A method using deep reinforcement learning (DRL) to non-iteratively generate an optimal mesh for an arbitrary blade passage is developed. Despite automation in mesh generation using either an empirical approach or an optimization algorithm, repeated tuning of meshing parameters is still required for a new geometry. The method developed herein employs a DRL-based multi-condition optimization technique to define optimal meshing parameters as a function of the blade geometry, attaining automation, minimization of human intervention, and computational efficiency. The meshing parameters are optimized by training an elliptic mesh generator which generates a structured mesh for a blade passage with an arbitrary blade geometry. During each episode of the DRL process, the mesh generator is trained to produce an optimal mesh for a randomly selected blade passage by updating the meshing parameters until the mesh quality, as measured by the ratio of determinants of the Jacobian matrices and the skewness, reaches the highest level. Once the training is completed, the mesh generator creates an optimal mesh for a new arbitrary blade passage in a single try without an repetitive process for the parameter tuning for mesh generation from the scratch. The effectiveness and robustness of the proposed method are demonstrated through the generation of meshes for various blade passages.

Numerical optimization of a stator blade to enhance aerodynamic performance in a transonic fan stage

In this study, the stator geometry of a single-stage transonic fan was optimized to improve its aerodynamic performance. Steady and unsteady simulations were performed on the transonic fan stage to maximize the efficiency and stall margin. In a transonic fan stage, the rotor blade generates different shock waves at various operating points. When the operating condition is changed from the design point to the stall point, the passage shock wave moves upstream, leading to a change in the location of flow separation on the suction surface of the rotor blade toward the upstream. This results in a larger rotor wake near the stall and complicates the stator inlet flow after interaction between the rotor and stator blade. In this study, an optimal geometry of the stator blade is proposed to improve the aerodynamic performance and stall margin of the fan stage. The central composite face-centered method as the design of experiment was used to sample the test cases, and the response surface method was applied to find the optimal case. The transient blade row-time transformation model was applied as an unsteady simulation approach. The optimized fan was found to increase the efficiency at the near-stall point and the stall margin by 0.24 % and 0.36 %, respectively.

Enhancement in wear-resistance of 30MNCRB5 boron steel-substrate using HVOF thermal sprayed WC–10%Co–4%Cr coatings: a comprehensive research on microstructural, tribological, and morphological analysis

The rotavator blade, a part of an agricultural equipment rotavator, is used for the soil bed preparation. These blades have direct interaction with soil in agricultural land. Bad, rocky, gravel, sandy, and high rough-hard texture of soil are the main factor to damage the surface of the rotavator blade and a high wear rate is observed. This causes to decrease in the overall life of a rotavator blade. It also changes the geometry of the rotavator blade after a few operations, and that all effects the performance capability of this blade. Hence HVOF (High-velocity oxy-fuel) is used to modify the surface that improved wear resistance of the rotavator blade's surface. Feedstock powder used for the coating is WC–10%Co–4%Cr with Ni–20%Cr as a bond coat on 30MNCRB5 steel substrate (Rotavator blade's material). Six samples are prepared to test it on the Pin-On-Disc wear testing apparatus to determine the wear rate, weight loss, cumulative volume loss and linear wear rate, three bare 30MNCRB5 steel and three WC–10%Co–4%Cr coated samples are prepared with 8 mm diameter and 30 mm length in a cylindrical pin shape. Coated samples are characterized using the XRD (X-ray diffraction), SEM (Scanning electron microscope) with EDAX (Energy-dispersive spectroscopy), and X-ray mapping techniques. Worn out surfaces of bare 30MNCRB5 steel and WC–10%Co–4%Cr coated samples are investigated using the SEM (Scanning electron microscope) to study the microstructure of worn surface that helped out to identify the wear behavior. The HVOF (High-velocity oxy-fuel) spray coating drastically improved the surface to defend it from wear, and very less weight loss was seen in the WC–10%Co–4%Cr coated samples as compared to bare 30MNCRB5 steel material. Weight loss determined by the bare (30MNCRB5) material at 40N, 50N, 60N loads are 2.996 × 10−3 Kgm, 3.003 × 10−3 Kgm, 3.123 × 10−3 Kgm, and coated (WC–10%Co–4%Cr) sample at 40N, 50N, 60N loads are 0.006 × 10−3 Kgm, 0.030 × 10−3 Kgm, 0.038 × 10−3 Kgm respectively.

Fatigue life prediction of mistuned steam turbine blades subjected to deviations in blade geometry

The blades of the steam turbine are subjected to bending of the steam flow, centrifugal loading, vibration response, and structural mistuning. These factors mentioned contribute significantly to the fatigue failure of steam turbine blades. Low pressure (LP) steam turbines experience premature blade and disk failures due to the stress concentrations in the root location of the blade of its bladed disk. This study of mistuned steam turbine blades subjected to variation in blade geometry will be of great significance to the electricity generation industry. A simplified, mistuned, scaled-down steam turbine bladed disk model was developed using ABAQUS finite element analysis (FEA) software. The acquisition of the vibration characteristics and steady-state stress response of the disk models was carried out through FEA. Such studies are very limited. Subsequently, numerical stress distributions were acquired and the model was subsequently exported to Fe-Safe software for fatigue life calculations based on centrifugal and harmonic sinusoidal pressure loading. Vibration characteristics and response of the variation of the geometric blade of the steam turbine were investigated. Natural FEA frequencies compared well with the published literature of real steam turbines, indicating the reliability of the developed FEA model. The study found that fatigue life is most sensitive to changes in blade length, followed by width and then thickness, in this order. Analytical life cycles and Fe-Safe software show a percentage difference of less than 4.86%. This concludes that the numerical methodology developed can be used for real-life mistuned steam turbine blades subjected to variations in blade geometry.

Prediction and suppression of chaos following flutter in wind turbines

Chaotic motion in a fluttering wind turbine blade is investigated by the development of an efficient analytical predictive model that is then used to suppress the phenomenon. Flutter is a dynamic instability of an elastic structure in a fluid, such as an airfoil section of a wind turbine blade. It is presently modelled using generalised two degree of freedom coupled modes of a blade airfoil section (pitch and plunge) combined with local unsteady aerodynamics, based on flutter derivatives and a continuous bilinear lift curve under damping. The mode coupling causes instability and limit cycle flutter due to a Hopf bifurcation. Following the critical flutter speed, the response can transition to chaos through successive other bifurcations like period doubling. New closed-form conservative analytical conditions for chaos following blade flutter are identified and discussed for the wind turbine section taking into account the blade geometry and optimal design of the wind turbine. These predictions are numerically verified for a range of conditions including stall slope and damping. The results confirm that chaos following blade flutter can occur due to nonlinearities in the aerodynamics, i.e. due to a bilinear lift law. This phenomenon is then suppressed to unrealistically high wind speeds and/or eliminated by quantified variation of system parameters using the predictive model. The results show that small changes in tip speed ratio (−15%), and stall slope factor (−17%) can eliminate or suppress chaos following flutter, while, in general, larger magnitude changes in dynamic parameters (i.e. mass, inertia > 81%, stiffness > 97%, damping > 100%) are required to achieve the same, by detuning the coupled plunge and pitch natural frequencies or damping out overlapping parametric resonances. These results also highlight that the analytical predictions can remarkably be generalized to any parameter set and provide almost instantaneous calculations representing many thousands of numerical simulations from many bifurcation diagrams (computational acceleration factor of 107 times). General insight is also provided into the occurrence and suppression of airfoil chaos following flutter in aeroelastic structures like wind turbines.