Blade Design Method Research Articles

A Review on Performance Calculation and Design Methodologies for Horizontal-Axis Wind Turbine Blades

The efficient, low-cost, and large-scale development and utilization of offshore wind energy resources is an inevitable trend for future growth. With the continuous increase in the scale of wind turbines and their expansion into deep-sea locations, there is an urgent need to develop ultra-long, flexible blades suitable for future high-capacity turbines. Existing reviews in the field of blade design lack a simultaneous focus on the two core elements of blade performance calculation and design methods, as well as a detailed evaluation of specific methods. Therefore, this paper reviews the performance calculation and design methodologies of horizontal-axis wind turbine blades from three aspects: aerodynamic design, structural design, and coupled aero-structural design. A critical introduction to various methods is provided, along with a key viewpoint centered around design philosophy: there is no global optimal solution; instead, the most suitable solution is chosen from the Pareto set according to the design philosophy. This review not only provides a concise and clear overview for researchers new to the field of blade design to quickly acquire key background knowledge but also offers valuable insights for experienced researchers through critical evaluations of various methods and the presentation of core viewpoints. The paper also includes a refined review of extended areas such as aerodynamic add-ons and fatigue characteristics, which broadens the scope of the review to touch on multiple research areas and inspire further research. In future research, it is crucial to identify new key issues and challenges associated with increased blade length and flexibility, address the challenges faced in integrated aero-structural design, and develop platforms and tools that support multi-objective optimization design of blades, ensuring the safe, stable, and orderly development of wind turbines.

Performance improvement of multi-blade centrifugal fan based on impeller outlet flow control

The impeller of the multi-blade centrifugal fan significantly impacts the fan's internal flow field and aerodynamic performance. To improve the axial flow distribution along the impeller and suppress the blade passage backflow at the impeller outlet of multi-blade centrifugal fans, a method of variable chord length blade design is proposed. Simultaneously, optimization models are established with static pressure and efficiency as objectives. By altering the control points of the Bezier curve, the leading-edge profile of the impeller is optimized. The results indicate that using variable chord length blades can expand the operating range of the multi-blade centrifugal fan. The maximum flow rate improvement reaches 10.6%. Significant enhancements in the aerodynamic efficiency of the multi-blade centrifugal fan are observed at low flow rates, with a maximum improvement of 4.9%. The variable chord length blade design method enables adjustment of the axial flow distribution at the impeller outlet to better match the impeller's flow requirements. This leads to increased outlet flow on both the shroud and hub sides of the impeller, consequently reducing the backflow area on both sides and improving the blade passage backflow phenomenon. Moreover, variable chord length blades facilitate a more uniform circumferential flow distribution at the impeller outlet, reducing the diversion pressure of the volute tongue, mitigating flow separation within the blade passage, weakening the interaction between the impeller and the volute tongue, and lowering energy losses in the impeller–volute tongue regions. Consequently, this enhances the aerodynamic performance of multi-blade centrifugal fans.

Structural analysis and application research for controlled strand length cutting blade of rotary guillotine cutter

In the tobacco processing stage leading to the production of cigarettes, there are strict technical requirements for the structure and proportion of different lengths of cut tobacco following the cutting process. Moreover, the lightweight design of the high-speed rotary-cutting blades is of significant importance during this stage. To better address issues related to the rational design of the blade structure in rotary-cutting cutters and the effective control of size proportion of cut tobacco, this paper establishes a CLSC blade design method featuring concave-convex edges and inter-edge grooves, and provides specific structural schemes. By introducing the structure of the cutting components of the cutter and the cutting process, and by analyzing the differences in layout features between RSEC and CLSC blade structures, as well as their relevance to tobacco cutting and shaping, this paper establishes the installation constraints and mechanical load model for cutter blades under rated conditions. Finite element methods were used to model and analyze both types of cutter blade structures, yielding static and modal analysis data. Furthermore, production verification was conducted on an SD EVO cutter, and data on the rate of different lengths of cut tobacco were obtained. The results show that the mass of the CLSC concave-convex edge cutter blade was reduced by 4.33%, and the static stiffness efficiency was increased by 2.37 times. Although the first-six natural frequencies of the CSLC blade showed degradation in modal analysis, it still met the equipment vibration usage condition. The production verification results indicated that the use of CLSC concave-convex edge cutter blades reduced the long cut rate by 2.48%, increased the medium cut rate by 2.29%, broken cut rate increased by 0.08%, and increased the short cut rate by 0.12%, with an overall reduction in the whole cut rate by 0.19%, achieving the objectives of reducing the long cut rate, controlling the whole cut rate, and not increasing the broken cut rate. The CLSC blades were able to operate continuously, stably, and safely on the rotary-cutting cutter machine. The research presented in this paper can provide a reference for the analysis and design of cutter blade structures in tobacco cutter machines.

A cooled turbine blade design and optimization method considering the cooling structure influence

This study introduces a multidisciplinary design methodology tailored for enhancing the performance of cooled turbine blades by amalgamating thermal and aerodynamic calculation modules. The approach is unique in terms of its integration of a multi-objective optimization platform, aimed at refining aerodynamic performance and gauging the heat transfer capabilities during the preliminary aerodynamic design phase. To accomplish this objective, a one-dimensional pipe-network calculation tool was incorporated into the thermal module to quickly evaluate the heat transfer performance of the blades under different conditions. This tool also provides more realistic film hole inlet boundary conditions essential for three-dimensional aerodynamic calculations. Implementing this platform in optimizing a high-pressure turbine blade revealed a Pareto-optimal front, comprising −η1 and η2 (representing optimization objectives for aerodynamic and heat transfer performance, respectively), showcasing a constrained relationship. Upon scrutinizing three optimization cases against the prototype, optimization case 1 demonstrates the most significant enhancements in aerodynamic performance, showing a 0.2015% improvement in aerodynamic efficiency relative to the prototype. Conversely, optimization case 3 displays a comparatively modest augmentation in aerodynamic performance but excels notably in heat transfer performance, showcasing a 7.61% reduction in the maximum temperature of the blade surface compared to the prototype. Through adept optimization strategies and meticulous variable selection, we maintained a relatively stable mainstream mass flow across the optimization cases (less than 0.05% variation). These findings underscore the efficacy of our multidisciplinary design approach for cooled turbine blades, promising efficiency improvements in current design practices and potential reductions in project duration.

An ML-based wind turbine blade design method considering multi-objective aerodynamic similarity and its experimental validation

Model test is an essential technique to study the aerodynamic performance of wind turbines. To overcome the poor aerodynamic performance of scaled models caused by the scaling effect, this study proposes an innovative blade design method for scaled model testing based on machine learning (ML). The method achieves satisfactory similarity between the thrust and power coefficients under multiple operating conditions of the model and prototype. Furthermore, a case study of the NREL 5-MW wind turbine is carried out with wind tunnel tests to validate the effectiveness of the proposed method. Obtained results suggest that the aerodynamic performance of redesigned blade closely mirrors that of the prototype under multiple operating conditions, reaching 97.59 % (thrust) and 97.87 % (power) coefficients of the prototype at the rated operating condition, respectively. With this technique, aerodynamic performance similarities between the redesigned blade and the prototype can be enhanced, contributing to more accurate scale model testing.

Generation mechanism and control methods of secondary flows in the impeller of axial flow pumps

The secondary flow in the impeller of an axial flow pump is an important factor affecting the safe and stable operation of the unit. However, there is still a lack of systematic research on the generation mechanism of secondary flow and corresponding control strategies in axial flow pumps. To better understand the secondary flow characteristics in the axial flow pump, based on the momentum equation of relative motion, the basic distribution characteristics of the potential rothalpy gradient (PRG, or the reduced static pressure gradient) in the impeller of an axial flow pump were systematically analyzed. Two typical secondary flows were found, namely, trailing-edge hub-shroud type secondary flow at the blade outlet hub side and leading-edge hub-shroud type secondary flow at the blade inlet shroud side. The generation of these secondary flows is directly related to the effect of natural adverse PRG. A new blade design method is proposed. The essential idea of this method is to give the blade loading strategy based on grasping the macro-flow characteristics and control PRG characteristics by adjusting the real blade loading δp (i.e., the static pressure difference between the blade pressure and suction surfaces) and, thereby, control the above-mentioned secondary flows. The application of an axial flow pump showed that the blades designed based on this method can effectively control these secondary flows and reduce pressure fluctuations. The average decrease in pressure fluctuation on the blade inlet shroud side and the outlet hub side is 17.79% and 20.03%, respectively.

Wind Turbine Design and Assessment

This project aims to design a wind turbine for the bam area of Zhangjiakou City, which has a relative high wind speed because of the good development prospect of China’s wind power. Based on the detailed investigation of wind speed and direction in the bam area of Zhangjiakou, the project designs a wind turbine that can produce as much energy as possible. The turbine with a hub height of 70 m, hub radius 1 m and radius 40 m is designed by using optimal blade design methods. Finally, the performance of wind turbine can be simulated by using the theory of blade element momentum and the corresponding annual energy yield can be calculated.

An Efficient Blade Design Method of a Ducted Fan Coupled with the CFD Modification

In order to improve the design accuracy of the blade design method of a ducted fan based on the blade element momentum theory, the design was modified by the CFD calculation with higher accuracy to propose an integrated and efficient design method for the rotor and stator. Firstly, a fast blade design method for the ducted fan was established based on the blade element momentum theory, and the initial design of the rotor and stator was carried out. Then, the performance of the designed ducted fan was calculated by the CFD method, and the rotor and stator were modified and redesigned according to the CFD results. Such continuous iterations finally made the design results basically consistent with the CFD results so as to improve the design accuracy. The blade design of different ducted fans shows that the unsteady CFD method based on the sliding mesh has higher accuracy and applicability than the MRF method, and the efficient blade design method established in this paper can meet the thrust demand with a small amount of the CFD modification. The thrust design accuracy of the ducted fan was increased by 11.362%, and the torque design accuracy was increased by 8.141%.

Multi-objective shape optimization of transonic compressor cascade at the same inlet Mach number

ABSTRACT In this paper, a two-dimensional transonic cascade of German Aerospace Center (DLR) was redesigned with multi-objective optimization. The aerodynamic performance of the cascade was optimized with inlet Mach number of 1.1 by using the blade design method with thickness distribution superposed on the camber line. The non-dominated sorting genetic algorithm, (NSGA) II multi-objective optimization algorithm, was used to determine higher performance cascades. Cascade optimization was carried out within a unique inlet Mach number by varying the shapes of both the camber line and the thickness distribution curve. To enable the cascade to operate under specific conditions, we used an inlet Mach number control loop (IMCL) to regulate the outlet boundary conditions. Optimization was conducted to minimize the cascade total pressure loss coefficient under the three inlet conditions. The optimization results indicated that the total pressure loss coefficient can be reduced by 22% under the design condition, and the range of working conditions was widened.

Multi-Objective Optimization for the Radial Bending and Twisting Law of Axial Fan Blades

The performance of low-pressure axial flow fans is directly affected by the three-dimensional bending and twisting of the blades. A new blade design method is adopted in this work, where the radial distribution of blade angle and blade bending angle is composed of standard-form rational quadratic Bézier curves. Dendrite Net is then trained to predict the pneumatic performance of the fan. A non dominated sorting genetic algorithm is employed to solve the global optimization problem of the total pressure coefficient and efficiency. The simulation results show that the optimal blade load distribution along the radial direction becomes uniform, and the suction surface separation vortex and passage vortex are restrained. On the other hand, the tip leakage vortex is enhanced and moves toward the blade leading edge. According to the experimental results, the maximum efficiency increases by 5.44%, and the maximum total pressure coefficient increases by 2.47% after optimization.

Preliminary Design Guidelines for Considering the Vibration and Noise of Low-Speed Axial Fans Due to Profile Vortex Shedding

This paper presents a critical overview on worst-case design scenarios for which low-speed axial flow fans may exhibit an increased risk of blade resonance due to profile vortex shedding. To set up a design example, a circular-arc-cambered plate of 8% relative curvature is investigated in twofold approaches of blade mechanics and aerodynamics. For these purposes, the frequency of the first bending mode of a plate of arbitrary circular camber is expressed by modeling the fan blade as a cantilever beam. Furthermore, an iterative blade design method is developed for checking the risky scenarios for which spanwise and spatially coherent shed vortices, stimulating pronounced vibration and noise, may occur. Coupling these two approaches, cases for vortex-induced blade resonance are set up. Opposing this basis, design guidelines are elaborated upon for avoiding such resonance. Based on the approach presented herein, guidelines are also developed for moderating the annoyance due to the vortex shedding noise.

New airfoils for micro horizontal-axis wind turbines

In this study, small horizontal-axis wind turbine blades operating at low wind speeds were optimized. An optimized blade design method based on blade element momentum (BEM) theory was used. The rotor radius of 0.2 m, 0.4 m and 0.6 m and blade geometry with single (W1 & W2) and multistage rotor (W3) was examined. MATLAB and XFoil programs were used to implement to BEM theory and devise a six novel airfoil (NAF-Series) suitable for application of small horizontal axis wind turbines at low Reynolds number. The experimental blades were developed using the 3D printing additive manufacturing technique. The new airfoils such as NAF3929, NAF4420, NAF4423, NAF4923, NAF4924, and NAF5024 were investigated using XFoil software at Reynolds numbers of 100,000. The investigation range included tip speed ratios from 3 to 10 and angle of attacks from 2° to 20°. These parameters were varied in MATLAB and XFoil software for optimization and investigation of the power coefficient, lift coefficient, drag coefficient and lift-to-drag ratio. The cut-in wind velocity of the single and multistage rotors was approximately 2.5 & 3 m/s respectively. The optimized tip speed ratio, axial displacement and angle of attack were 5.5, 0.08m & 6° respectively. The proposed NAF-Series airfoil blades exhibited higher aerodynamic performances and maximum output power than those with the base SG6043 and NACA4415 airfoil at low Reynolds number.

The Effect of Load Control on the Performance of Contra-Rotating Fans

In recent years, few studies focused on adjusting the load distribution of contra-rotating fan (CRF) blades. To improve the overall performance of CRFs, we used a design code to build 32 sets of CRFs to determine the effects of three factors—the front and rear rotor load matching, the load distribution of each rotor and the axial distance between the rotors—on the total pressure rise and efficiency of CRFs using numerical calculations. The relationship between the CRF blades load and velocity components was theoretically analyzed using blade element analysis and the forward problem method. According to the performance curve, it can be concluded that the rear rotor (RR) is the key factor that determines the performance of CRFs. Through analyzing Mach number contours from different perspectives, the relationship between velocity and adjustment load was verified. Furthermore, the flow field characteristics for three specific CRFs were explored at the stall points, design points and choke points to reveal their flow mechanisms. This study provides a reference for the CRF blade design method.

Research on Blade Design of Lift–Drag-Composite Tidal-Energy Turbine at Low Flow Velocity

The research on tidal-current energy-capture technology mainly focuses on the conditions of high flow velocity, focusing on the use of differential pressure lift, while the average flow velocity in most sea areas of China is less than 1.5 m/s, especially in the marine aquaculture area, where tidal-current energy is needed to provide green energy locally. Due to the low flow velocity of this type of sea area, it seriously affects the effect of differential pressure lift, which is conducive to exerting the effect of impact resistance. In this regard, the coupling effect of the differential pressure lift and the impact resistance on the blade torque is comprehensively considered, this research puts forward the design method of the lift-–drag-composite thin-plate arc turbine blade. Based on the blade element momentum (BEM) theory and Bernoulli’s principle, the turbine dynamic model was established, and the nonlinear optimization method was used to solve the shape parameters of the turbine blades, and the thin-plate arc and NACA airfoil blade turbines were trial-produced under the same conditions. A model experiment was carried out in the experimental pool, and the Xiangshan sea area in Ningbo, East China Sea was taken as the experimental sea area. The results of the two experiments showed the same trend, indicating that the energy-harvesting performance of the lift–drag-composite blade was significantly better than that of the lift blade under the conditions of low flow velocity and small radius, which verified the correctness of the blade design method, and can promote the research and development of tidal energy under the conditions of low flow velocity and small radius.

The application of support vector regression and mesh deformation technique in the optimization of transonic compressor design

With the development of modern aero-engine, the compressor is required to achieve higher performance such as transonic operation, high stage pressure ratio and efficiency. At present, the traditional blade design methods have the disadvantage of highly relying on designer's experience and heavy computational burden. In order to reduce design variables used to define blade geometry, the present work introduces the Free-Form Deformation technique. It can achieve high degree-of-freedom deformation and update mesh and geometry simultaneously. To further alleviate computational cost, the Support Vector Regression surrogate model is adopted to replace the time-consuming numerical simulation. It performs well in small sample learning problems. On this basis, a surrogate-based optimization design framework is established by combining the Advanced Latin hypercube sample and NSGA-II multi-objective genetic algorithm. Then an aerodynamic optimization of the transonic NASA Rotor 37 is conducted as a validation. The results show that the pressure ratio and isentropic efficiency are increased by 4.2% and 2.5%, respectively. The optimized shape sweeps forward with a slight increase in twist angle, and shock loss is reduced effectively. Compared with traditional optimization method, the proposed framework can improve the optimization efficiency by decreasing design variables and training samples.

Research on blade design method of multi-blade centrifugal fan for building efficient ventilation based on Hicks-Henne function

The customary single-arc blade applied in the multi-blade centrifugal ventilating fan for building ventilation is ordinary in shape and hard to meet the design requirements of the pertinent parameters. The article used the modified Hicks-Henne function (suitable for blade design with multi-arc and complex curve blades) to parametrically design the blades of multi-blade centrifugal fan to improve its aerodynamic performance. During the optimization process, the Audze-Eglais (AE) criterion was used to optimize the Latin hypercube test design. Based on the optimized test design method, a Kriging agent model was established. While taking total pressure efficiency and flow rate as the optimization goals, combined with the nondominated sorting genetic algorithm II (NSGA-II) to find the Pareto solution set of the agent model. Internal flow field was analyzed before and after optimization by numerical simulation of the fan, and the Computational Fluid Dynamics (CFD) results were further verified through experiments. At the maximum efficiency point, the flow rate of the fan after the optimization has increased by 1.18 m3/min, the total pressure efficiency was improved by 4.21%. The improvement of efficiency and flow rate can effectively reduce energy consumption of building ventilation.

Improving wind turbine blade based on multi-objective particle swarm optimization

This paper studies a new method for optimizing the design of wind turbine blades. Compared with the existing blade design methods, the proposed method not only considers the structural strength and stiffness of the blade but also considers the noise and power generation efficiency of the blade. The method utilizes a multi-objective particle swarm optimization method and the finite volume method in combination to meet the strength and stiffness requirements of the wind turbine blade, improve its aerodynamic performance and reduce its noise. In the study, the geometries of the blade used by a 2 MW wind turbine are taken as the initial parameters of the target blade and MATLAB and ANSYS are employed to perform the optimization and finite element analysis based performance calculations. Then an intelligent optimization algorithm was developed for achieving a quiet and efficient wind turbine blade. In such a multi-objective optimization algorithm, both structural strength, stiffness, noise reduction, and aerodynamic performance of the blade are taken as objective functions. The simulation results have shown that through optimization, the blade noise was reduced by 3.1 dB and the power coefficient was increased by 6.9%. Moreover, it is found that the blade’s structural strength and stiffness are also improved after optimization. This implies that the proposed algorithm is also helpful to further reduce the manufacturing materials and costs of wind turbine blades.

Improved Blade Design for Tidal Current Turbines

The efficiency and reliability of blades are key indicators for a tidal current turbine (TCT). A traditional blade design is often an empirical design on hydrodynamics and structure, sequentially. A hydrofoil with a low lift–drag ratio is considered when the structural strength cannot satisfy requirements. However, efficiency is then sacrificed. A redundant design is generally adopted to protect from load uncertainty, but this increases blade weight and cost. In this paper, we present an improved blade design method to enhance the blade reliability of TCTs with relatively high efficiency for energy generation. An equivalent S–N curve model describing the relationship between axial load and cycle times and a simplified load spectrum including load caused by shear flow and turbulence are proposed for the first time for convenient lifetime estimation. A multi-objective genetic algorithm is used to optimize the chord length, twist angle, and thickness of the blade for the best match between lifetime and efficiency. This blade design method was conducted on a 4.4 m length blade of a 120 kW TCT. Comparisons between the original design and optimal designs indicate that the comprehensive performance in terms of the hydrodynamics, structure, and lifetime of the blade presented significant improvements with a small, acceptable efficiency loss. The results also provide more alternative blade solutions for developers as a reference.

Efficient incorporation of fatigue damage constraints in wind turbine blade optimization

AbstractWind turbine design is a challenging multidisciplinary optimization problem, where the aerodynamic shapes, structural member sizing, and material composition must all be determined and optimized. Some previous blade design methods incorporate static loading with an added safety factor to account for dynamic effects. Others incorporate dynamic loading, but in general limit, the evaluation to a few design cases. By not fully incorporating the dynamic loading of the wind turbine, the final turbine blade design is either too conservative by overemphasizing the dynamic effects or infeasible by failing to adequately account for these effects. We propose an iterative method that estimates fatigue effects during the optimization process while quickly converging to the true solution. We also demonstrate an alternate approach where a surrogate model is trained to efficiently estimate the dynamic loading of the wind turbine in the design process. This surrogate model, once trained, was then incorporated in the optimization loop of the wind turbine blade. In contrast to the iterative method, there is significant upfront computational cost to construct the surrogate model. However, this surrogate model has been generalized to be used for different rated turbines and can predict the fatigue damage of a wind turbine with less than 5% error for baseline wind turbines of the same family. These methods can be used instead of the more computationally expensive method of calculating the dynamic loading of the turbine within the optimization routine.

A Robust Blade Design Method based on Non-Intrusive Polynomial Chaos Considering Profile Error

To weaken the influence of profile error on compressor aerodynamic performance, especially on pressure ratio and efficiency, a robust design method considering profile error is built to improve the robustness of aerodynamic performance of the blade. The characteristics of profile error are random and small-scaled, which means that to evaluate the influence of profile error on blade aerodynamic performance is a time-intensive and high-precision work. For this reason, non-intrusive polynomial chaos (NIPC) and Kriging surrogate model are introduced in this robust design method to improve the efficiency of uncertainty quantification (UQ) and ensure the evaluate accuracy. The profile error satisfies the Gaussian distribution, and NIPC is carried out to do uncertainty quantification since it has advantages in prediction accuracy and efficiency to get statistical behavior of random profile error. In the integrand points of NIPC, several surrogate models are established based on Latin hypercube sampling (LHS) + Kriging, which further reduces the costs of optimization design by replacing calling computational fluid dynamic (CFD) repeatedly. The results show that this robust design method can significantly improve the performance robustness in shorter time (40 times faster) without losing accuracy, which is meaningful in engineering application to reduce manufacturing cost in the premise of ensuring the aerodynamic performance. Mechanism analysis of the robustness improvement samples carried out in current work can help find out the key parameter dominating the robustness under the disturbance of profile error, which is meaningful to further improvement of compressor robustness.