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Inconel 718, a widely utilized Ni-based superalloy in the aerospace industry, is renowned for its exceptional mechanical properties, high-temperature corrosion resistance, and thermal stability, making it an ideal material for turbine blades operating under extreme conditions of up to 2200 °C and high-pressure. Traditional single crystal casting, the prevalent manufacturing method for turbine blades, poses inflexibility challenges. Laser Powder Bed Fusion Additive Manufacturing (LPBF-AM) emerges as a disruptive alternative, providing flexibility and intricate design possibilities. However, LPBF-fabricated turbine blades face challenges, notably low thermal stability due to the polycrystalline microstructure. To address this, implementing an internal cooling channel to the turbine blade geometry can overcome this challenge. The flow of cooling fluid inside the cooling channel absorbs the heat of turbine, and maintains the turbine at low-temperature. The performance of internal cooling channel can be improved by implementing controllable surface texture to provide the heat sink mechanism. Nowadays, the LPBF has opportunity to fabricate the complex geometry of turbine blade with surface-textured internal cooling channel. This review delves into the specific requirements for the next generation of turbine blades featuring surface-textured internal cooling channels. It covers considerations such as geometric design, LPBF parameters, metallurgical aspects of processing Inconel 718, and quality testing encompassing material properties and geometric accuracy. Additionally, the review outlines existing challenges and research prospects in LPBF of Inconel 718 for advancing turbine blade components. In conclusion, the review inspires further development in high-performance Inconel 718 turbine blades, emphasizing advancements in surface textures and internal cooling channels via LPBF. [ABSTRACT FROM AUTHOR]

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

To reasonably divide the types of flow units along the latticework subchannel, one must prepare for the establishment of a one-dimensional fluid network model of the latticework in the middle region of the turbine blade. The characteristics of the flow structure along the latticework subchannel were studied by numerical simulation. The effects of rib angle (15–45°), the ratio of rib width to rib spacing (0.3–1.0), and inlet Reynolds umber (21,000–80,000) on the flow structure along the subchannel are summarized. The results indicated that the ratio of rib width to rib spacing and inlet Reynolds number had no effect on the distribution position of each flow unit in the subchannel. The change of rib angle did not change the flow structure type along the subchannel. The longitudinal vortex was mainly formed by one turning vortex and two detached vortices. The narrowing of the turning channel will cause the turning vortex to induce a secondary longitudinal vortex. There were five kinds of flow structures along the subchannel: transverse vortex zone (entrance of the inlet section), uniform flow zone (inlet section), longitudinal vortex generation zone (turning channel section), longitudinal vortex zone (turning channel section), and longitudinal vortex free development zone (outlet section). This finding provides support for the selection of empirical formulas for each module in the one-dimensional modeling of subchannels. Finally, the boundary prediction equations of each flow structure in the subchannel were established, and the average prediction error was less than 10%. The rationality of the flow structure division along the latticework subchannel was improved, and the modeling efficiency of the latticework one-dimensional model was optimized. [ABSTRACT FROM AUTHOR]

Ti64 turbine blades face extreme conditions during solid particle erosion, accelerating the erosive and corrosive processes. Hard-coating materials such as DLC, AlTiN, TiSiN, AlCrN, and AlTiCN have been introduced through physical vapor deposition to enhance the turbine blade characteristics and increase the component lifespan. The results showed preferential orientations of (002) and (022) in coating crystallization with DLC exhibiting the highest compressive residual stress. DLC and AlTiCN coatings demonstrated fewer macroparticles and white spots, correlating with a lower coefficient of friction (COF) and surface roughness. The wear analysis revealed that DLC had the lowest COF and wear rate, followed by AlTiCN. Electrochemical tests indicated DLC's superior corrosion resistance of DLC. Although the properties of AlTiCN are comparable, DLC has emerged as the most promising coating material for achieving high erosion particle resistance in Ti64 turbine blades. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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

The vibration of turbine blades during the operation of jet engines is a serious and complex issue that has garnered significant attention. In practical jet engines, dry friction damping is commonly used to suppress blade vibrations due to its reliability and efficiency. The equivalent damping ratio of dry friction dampers is a crucial metric for evaluating their performance. However, calculating dry friction dampers' damping ratio for actual structures involves nonlinear vibration calculations, which are challenging and often lack precision. A method combining simulation and experimentation to calculate the equivalent damping ratio of a structure is proposed. In a laboratory setting, the vibration response of turbine blades under centrifugal load and the damping effect of under-platform dampers were analyzed using oil excitation. The research results indicate that this method can effectively calculate the equivalent damping ratio of actual structures. The findings provide robust support for the design of under-platform dampers and the vibration analysis of turbine blades. [ABSTRACT FROM AUTHOR]

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

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

Aircraft engine turbine blades are covered with protective coatings. These coatings should have the best thermophysical convergence with the blade's parent material. The aim is to create heat-resistant covering for aircraft engine turbine blades made of nickel superalloy. The results of tests on coatings are presented; the inner layer is an adhesive layer of the MeCrAlY type, applied to the blade by means of supersonic thermal spraying, and the outer layer is diffusion-aluminized in the first case using the Vapor Phase Aluminizing method, and in the second using the suspension method. The inner layer of the coating protects the blade material against high-temperature corrosion, and the outer layer against high-temperature fuel combustion product stream. The protective coatings applied to aircraft engine turbine blades were subjected to an engine test in test bench conditions and then to material tests. A protective coating with an internal layer of MeCrAlY type applied to the blade by supersonic spraying and an external layer aluminized by the Vapor Phase Aluminizing method protects the nickel superalloy against high-temperature diffusion changes, protects it against oxidation and provides it thermal insulation. [ABSTRACT FROM AUTHOR]

Turbine blades for modern turbomachinery applications often exhibit complex twisted designs that aim to reduce aerodynamic losses, thereby improving the overall machine performance. This results in intricate internal cooling configurations that change their spanwise orientation with respect to the rotational axis. In the present study, the local heat transfer in a generic two-pass turbine cooling channel is investigated under engine-similar rotating conditions ( R o = { 0 ... 0.50 } ) through the transient Thermochromic Liquid Crystal (TLC) measurement technique. Three different angles of attack ( α = { − 18.5 ° ; + 8 ° ; + 46.5 ° } ) are investigated to emulate the heat transfer characteristics in an internal cooling channel of a real turbine blade application at different spanwise positions. A numerical approach based on steady-state Reynolds-averaged Navier–Stokes (RANS) simulations in ANSYS CFX is validated against the experimental method, showing generally good agreement and, thus, qualifying for future heat transfer predictions. Experimental and numerical data clearly demonstrate the substantial impact of the angle of attack on the local heat transfer structure, especially for the radially outward flow of the first passage, owing to the particular Coriolis force direction at each angle of attack. Furthermore, results underscore the strong influence of the rotational speed on the overall heat transfer level, with an enhancement effect for the radially outward flow (first passage) and a reduction effect for the radially inward flow (second passage). [ABSTRACT FROM AUTHOR]

The microstructure and thin-walled effect of different samples （double-wall ultra-cooling turbine blades， combined cooling turbine blades， investment casting thin-walled specimen， and round bar specimen） of the third-generation single crystal superalloy DD9 are investigated by optical microscope， field emission scanning electron microscope， and electron probe apparatus. The results show that there are differences in the microstructures of the four specimens. When the section sizes are the same， the as-cast primary dendrite arm spacing， the sizes of γ′ phases， and the dendrite segregation of the as-cast and heat- treated specimens of DD9 single crystal turbine blades are all larger than those of the investment casting thin-walled specimens. After full heat treatment， the sizes of the γ′ phases of single crystal turbine blades with the same cross-sectional size are similar to those of investment casting thin-walled specimens. The as-cast primary dendrite arm spacing， the sizes of γ′ phases， and the dendrite segregation of the as-cast and heat-treated thin-walled specimens of DD9 alloy all decrease with the decrease of the cross-sectional size.

Using fused corundum powder as raw material， silica sol as a binder， and aluminum fluoride trihydrate as mullite phase conversion promoter， the slurry composition of the ceramic shell for directional solidification molding of turbine blades was designed， and the ceramic shell was prepared. The microstructure and phase composition， high-temperature permeability， thermal expansion， high-temperature mechanics， and resistance to high-temperature deformation of the shell were studied. The results show that after sintering at 1200 ℃， with the help of the catalysis of aluminum fluoride trihydrate， the alumina in the shell reacts with silicon dioxide to produce a mullite whisker. Compared with the ceramic shell without aluminum fluoride trihydrate， the permeability of the shell is increased by about 1 time， the thermal diffusion coefficient is increased， and the thermal expansion coefficient is decreased. At the same time， the addition of aluminum fluoride trihydrate also reduces the high-temperature strength of the shell to a suitable range， improves the high-temperature yield of the shell， and makes the shell maintain a good high-temperature deformation resistance.

ObjectivesThe inlet temperature of gas turbine has far exceeded the allowable temperature of the blade material, so it is very important to develop more efficient turbine cooling technology, especially the film cooling technology. The film cooling in the central region of the turbine blade is usually supplied by the crossflow ribbed passage. Therefore, the research progress of the film cooling in the crossflow ribbed passage in recent years was reviewed.MethodsThe variations in film cooling performance under different coolant supply modes were introduced. The impacts of rib angle, rib shape, relative position of film holes and ribs, and Reynolds number at the inlet of the crossflow channel on flow and film cooling performance were summarized. The research progress of film cooling hole shape design under the condition of crossflow ribbed cooling air was concluded.ResultsThe internal cooling structures within the crossflow ribbed passage and the Reynolds number at the entrance of the crossflow channel exert significant influences on film cooling performance, while the distribution of cooling effectiveness at the hole outlet downstream is altered during crossflow intake. Moreover, the flow at the hole entrance is influenced by both the relative position of the hole and rib as well as changes in Reynolds number. The asymmetrical spanwise cooling hole and the hole insensitive to the crossflow can enhance the film cooling performance.ConclusionsIn order to further promote the development of film cooling technology in the crossflow ribbed passage, it is recommended to thoroughly study the relationship between film cooling performance and all influencing factors, and to optimize the design of special film cooling hole suitable for crossflow ribbed inlet.

ObjectivesThe high-efficiency internal cooling technology of turbine blade is crucial for improving the thermal efficiency of gas turbine. As an important component of the gas turbine, it is essential to conduct research on the cooling performance of rotor blade. Due to significant effect of Coriolis force, buoyancy force, and channel structure on the cooling performance of rotating internal channel of turbine blade, this paper summarized the research status and development trends of rotating internal cooling channel based on these effect factors.MethodsA new structural design of rotating internal cooling channels was introduced, and a new rotating internal cooling channel structure suitable for double-walled blade configurations was proposed.ConclusionsDouble-sided enhanced U-shaped channels can utilize the enhanced heat transfer effect of Coriolis force, resulting in better cooling performance than traditional rotating U-shaped channels. There is a broad room for improvement in the internal cooling of gas turbine rotor blades.

ObjectivesThe localization of core components of heavy-duty gas turbines holds significant importance for technological innovation, industrial upgrading, and even national security. As a typical hot-end component of heavy-duty gas turbines, the performance of the turbine first-stage rotor blade directly determines the efficiency and reliability of the gas turbine. Therefore, the structure of the first-stage turbine blades of a certain heavy-duty gas turbine was optimized.MethodsBy increasing the number of bamboo nodes in the blade body, the blade cooling hole structure was optimized, and the thermal barrier coating was used to improve the blade coating. The temperature, stress distribution and aerodynamic efficiency of the blades before and after optimization under the service condition of the blade were compared and analyzed by fluid calculation and finite element calculation.ResultsHeat transfer efficiency inside the blade is enhanced by optimization of turbulent structure. Under the condition of the same inlet pressure of the cooling air, the surface temperature of the optimized blade is reduced by more than 50 ℃. Since the shape of the blade is not changed, there is little influence on the aerodynamic efficiency. Compared with the blades without optimization, the maximum equivalent stress and equivalent total strain of the optimized blade during service are significantly reduced.ConclusionsBy optimizing the cooling structure and upgrading the protective coatings, the reliability of the blades in high-temperature can be significantly improved. The research results provide a theoretical basis for the localization of gas turbines.

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

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

In order to improve the flow and heat transfer performance of cold channels in turbine blades, the effects of the structure, arrangement form and geometric dimensioning of the deflector on the flow resistance and heat transfer performance in the constricted and expanded serpentine channel at the inlet Reynolds number of 2 × 10 4 ~ 8 × 10 4 were investigated by numerical simulation, and the relationship between secondary flow intensity and thermal performance factor was obtained. The results show that with the increase of Reynolds number, the change range of drag coefficient of the channel with deflector is less than 5%. The 180° deflector has the strongest drag reduction ability among all models, and the drag coefficient of the channel with deflector decreases by 50. 2% compared with that without deflector. The deflector structure plays an enhanced role in heat transfer, the 180° deflector has the most significant enhanced heat transfer effect, increasing the heat transfer coefficient by 12. 3%. Different structures of the deflector have a great influence on the thermal performance factor of the channel, and the thermal performance factor of the 180° deflector channel is the strongest, which is 56. 4% higher than that of the channel without deflector. In summary, the study of the structural parameters of the deflector can effectively reduce the flow resistance loss of the cold channel and enhance its heat transfer capacity. [ABSTRACT FROM AUTHOR]

A numerical investigation of the particle deposition characteristics inside film holes and on the blade was conducted using an improved particle deposition model and dynamic grid updating. The computation model was numerically simulated using Reynolds-Averaged Navier-Stokes (RANS) equations with second-order spatial accuracy and the SST k-ω turbulence model, combined User Defined Function (UDF) in FLUENT 2021R1. The influence of the deposition morphology on film effectiveness was analyzed. The results revealed that a conical deposition in the exit region inside the film holes enhanced the separation of the coolant ejected from the film holes at a low coolant mass flux ratio (MFR). Increasing the MFR inhibited deposition, and the enhanced particle detachment significantly reduced particle deposition inside the film holes. Deposition downstream of the film holes significantly affected the cooling performance. Strip deposition on both sides of the region covered by the coolant limited the spanwise diffusion of the coolant. Compared to the non-deposition case, The surface-averaged film effectiveness was lower after deposition at MFRs of 0.1%-0.5% and slightly higher at MFRs of 0.6%. The most significant reduction in the surface-averaged film effectiveness after deposition was 34.9% at an MFR of 0.3%. [ABSTRACT FROM AUTHOR]

Copyright of Power Generation Technology is the property of Power Generation Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Power Generation Technology is the property of Power Generation Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Power Generation Technology is the property of Power Generation Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this article, a novel design for the vortex chamber with the axial grooves used for cooling the turbine blades leading edge is presented. The vortex chamber has nine tangential inlets that make a vortex in the chamber and an axial groove located along with the chamber. In addition to enhance the flow turbulence, these grooves cause an increasing heat transfer by cutting the thermal boundary layer and reformation. For this purpose, a 3D model based on Reynolds-averaged Navier–Stokes (RANS) equation was simulated in Ansys Fluent software. After comparing different turbulent models and experimental data, results showed Reynolds stress model (RSM) mode presents the best accuracy. Grooves with different sizes, positions, and numbers are used to investigate the vortex structure and the heat transfer mechanism. This study revealed that a chamber with grooves has a higher heat transfer in comparison with chambers without grooves. The best performance is achieved in a chamber with three grooves, where the average Nusselt number is increased by more than 4%. In this method, pressure difference between the inlet and outlet in the chamber with and without grooves are not very significant, and the highest friction factor happened in the case with three grooves. [ABSTRACT FROM AUTHOR]

During the production of single-crystal superalloy blades, a kind of channel-type defect, named "quasi-freckle", was found on the casting surface, which is similar to typical freckles in macroscopic appearance but different in microstructure. In the as-cast microstructure of the quasi-freckle channels, the γ/γ' eutectic is significantly accumulated and can be dissolved during the solution heat treatment. Since no disoriented grains were detected, the quasi-freckles have a basically identical crystal orientation with the matrix. The quasi-freckle channels actually appear as thermosolutal convection traces in the directional solidification process of single-crystal casting. Because the convection was not strong enough to break dendrite arms, the single-crystal consistency of the castings was not destroyed. However, with the deterioration of the solidification condition and the increase in solutal convection, quasi-freckles often develop into typical freckle defects. [ABSTRACT FROM AUTHOR]

This research focuses on the development of a machine learning-based approach for the early diagnosis of blade rubbing in rotary machinery. In this paper, machine learning-based diagnostic methods are used for blade rubbing early diagnosis, and the faults are simulated using experimental models. The experimental conditions were simulated as follows: Excessive rotor vibration is generated by an unbalance mass, and blade rubbing occurs through excessive rotor vibration. Additionally, the severity of blade rubbing was also simulated while increasing the unbalance mass. And then, machine learning-based diagnostic methods were applied and the trends according to the severity of blade rubbing were compared. This paper provides a signal processing method through feature analysis to diagnose blade rubbing conditions in machine learning. It was confirmed that the results of the unbalance and blade rubbing represent different trends, and it is possible to distinguish unbalance from blade rubbing before blade rubbing occurs. The diagnosis using machine learning methods will be applicable to rotating machinery faults like blade rubbing; furthermore, the early diagnosis of blade rubbing will be possible. [ABSTRACT FROM AUTHOR]

The full loss data for the IS (inlet squealer) tip with the wide changes of squealer height (hst) and tip clearance (h) are measured in an aeroengine turbine blade cascade of downstream-to-upstream velocity ratio (VR) = 2.01 with a five-hole probe instrumentation system. The loss map shows that the variation of IS tip loss with hst/s is strongly dependent upon h/s, contrary to the full squealer tip case. The IS tip loss tends to increase with hst/s for low h/s, whereas it tends to decrease with hst/s for high h/s. The noticeable loss reduction by the IS tip can be attained when h/s ≥ 1.5 % especially for high hst/s. The comparison among IS tip losses in three cascades of VR = 1.2 (weak reaction), 2.01 (medium reaction), and 2.4 (strong reaction) reveals that the IS tip-to-flat tip loss ratio is affected considerably by VR (turbine reaction). [ABSTRACT FROM AUTHOR]

An ocean current power generator is a power plant that uses kinetic energy from ocean currents to generate electricity. Considering that the blade is the component that receives the biggest load from seawater currents, its structural design should be strong enough to sustain the applied load. Therefore, this research seeks a suitable design and material for turbine blades using the finite element method (FEM). A NACA 0021 blade with a total length of 3600 mm is used for the base geometry. A parametric study was conducted by varying the spacing between the supports, the pitch angle, the material, and the frame model. Considering a high load, the suitable amount of space between the stiffeners was 2200 mm. It was found that a pitch angle variation between −20° and +20° did not significantly affect the strength of the blade structure. The frame geometry variation caused the rigidity and cross-section area of the blade to differ. Therefore, web-shaped or bar-shaped frames are preferable because they have optimal maximum load-to-weight ratios. The material variation analysis resulted in CFRP material being chosen because it had a high maximum load/weight ratio and a high maximum stress. [ABSTRACT FROM AUTHOR]

The dovetail of ceramic matrix composites（CMC）turbine blade is the key to the assembly and ability to withstand centrifugal loads of the blade. In order to study the mechanical behaviour of the blade dovetail prepared by the melt infiltration（MI）method under the tensile load in the radial direction of rotating，and verify the influence of the internal quality of the dovetail on its static tensile strength and failure mode，the CMC high pressure turbine dovetail element specimens were designed and fabricated，and a uniaxial static tensile test was conducted，the internal quality of the test specimens was scanned using non-destructive X-ray CT. The test process was monitored using DIC and acoustic emission method. The results show that the CMC dovetail is able to maintain in complete contact under uniaxial static tensile loads，and its static strength and failure are very sensitive to its internal quality，especially to the delamination defects. When there are no delamination defects in the dovetail，the damage generally starts from the neck and quickly spreads，the damage starting load is near the maximum fracture load，and the fracture surface is zigzag. When there are delamination defects in the dovetail，the fracture starts from the defects，and the delamination gradually spread and cause the fracture surface of the dovetail，the damage starting load is decreased by 99.05%，and the maximum failure load is decreased by 14.29% compared to the case of no delamination defects，and the fracture surface is consistent with the delamination defects.

A numerical investigation of the particle deposition characteristics inside film holes and on the blade was conducted using an improved particle deposition model and dynamic grid updating. The computation model was numerically simulated using Reynolds-Averaged Navier-Stokes (RANS) equations with second-order spatial accuracy and the SST k-ω turbulence model, combined User Defined Function (UDF) in FLUENT 2021R1. The influence of the deposition morphology on film effectiveness was analyzed. The results revealed that a conical deposition in the exit region inside the film holes enhanced the separation of the coolant ejected from the film holes at a low coolant mass flux ratio (MFR). Increasing the MFR inhibited deposition, and the enhanced particle detachment significantly reduced particle deposition inside the film holes. Deposition downstream of the film holes significantly affected the cooling performance. Strip deposition on both sides of the region covered by the coolant limited the spanwise diffusion of the coolant. Compared to the non-deposition case, The surface-averaged film effectiveness was lower after deposition at MFRs of 0.1%-0.5% and slightly higher at MFRs of 0.6%. The most significant reduction in the surface-averaged film effectiveness after deposition was 34.9% at an MFR of 0.3%.

This paper examines an innovative approach to the automated inspection of turbine blades in power generation systems. By integrating point cloud generated from computer-aided design (CAD) with iterative methods, this methodology aims to improve the efficiency and accuracy of the inspection process. The combination of theoretical blade geometry data, captured via CAD point clouds, with advanced algorithms derived from iterative methods, allows for a rapid assessment of the blade's condition. This approach has the potential to reduce inspection times, increase assessment accuracy, and detect anomalies at an early stage. The paper explores in detail the key aspects of this method, including the creation and alignment of CAD point cloud with real blades, the application of iterative methods to detect degradation and anomalies, and the preliminary results obtained from specific case studies. However, challenges remain, such as the quality of input data and the need to develop iterative models specific to each application. Future prospects include the refinement of data capture techniques, the exploration of new iterative methods, and the integration of machine learning for even more advanced automation. Overall, this approach represents a significant advance in the field of industrial maintenance, enabling proactive and efficient management of turbine blade inspection and maintenance. It offers advantages in terms of cost, speed, and reliability for maintaining the sustainability and performance of power generation systems. [ABSTRACT FROM AUTHOR]

Exposure of turbine blades to cyclic torsional loading at high temperature, stemming from pre‐torque installation and the aerodynamic forces during operation, has the potential to induce substantial creep–fatigue damage, thereby contributing to the likelihood of premature failure. Investigating the deformation mechanisms and proposing a reliable life prediction method aiming at torsional loading is critical to ensure the structural integrity of turbine blades. This study conducted strain‐controlled fatigue and creep–fatigue tests on Inconel 718 superalloy, employing a multiaxial servo‐hydraulic testing machine. Electron backscattering diffraction elucidated deformation and damage mechanisms, forming a basis for subsequent constitutive modeling and life prediction. The lack of creep–fatigue mechanical behavior and microscopic failure mechanism when stress triaxiality equal to 0 is filled, which provides the theoretical basis and data support for the life design and damage assessment of this material under extreme service conditions. The unified viscoplasticity constitutive model effectively characterized macroscopic deformation under torsional loading. Prediction of creep–fatigue life under torsional loading, utilizing the multiaxial ductility factor‐modified strain energy density exhaustion model, demonstrated excellent alignment with experimental findings. Finally, parametric analyses of stress distribution and damage assessment under different conditions were carried out for the example of a turbine blade with relatively rarely considered aerodynamic loading as a variable. It is expected to be popularized and applied in life design and damage assessment of high‐temperature structures under multiaxial loading in engineering. Highlights: Constitutive modeling for torsional creep–fatigue behaviors.Microscopic quantitative analysis of creep–fatigue under torsional loading.Accuracy of life prediction methods under multiaxial stress state loading.Finite element analysis and damage detection of structurally complex components. [ABSTRACT FROM AUTHOR]

Hydrokinetic energy constitutes a source of renewable energy. However, many regions have flow velocities that are too low for effective energy extraction, and conventional turbines are not suitable for these sites. In order to address this challenge, the present work proposes a novel vertical axis hydrokinetic turbine designed for environments where conventional turbines are not feasible due to a low water velocity. The turbine's design is inspired by biological principles, enhancing the traditional Savonius turbine by incorporating a Fibonacci spiral-inspired blade configuration. The turbine's performance was subjected to a rigorous analysis through Computational Fluid Dynamics (CFD). The results demonstrate a notable improvement, with a 15.1% increase in the power coefficient compared to the traditional Savonius turbine. This innovative approach not only extends the applicability of hydrokinetic turbines to low-flow regions but also underscores the potential of biomimicry in optimizing renewable energy technologies. The findings of this study indicate that integrating natural design principles can result in more efficient and sustainable energy solutions, thereby paving the way for the broader adoption of hydrokinetic power in diverse geographical settings. [ABSTRACT FROM AUTHOR]

Swirl cooling can not only increase the area of the heat exchange wall covered by the coolant, but also improve the average heat transfer intensity and uniformity of the target surface. SST k-ω turbulence model is utilized in the conjugate heat transfer numerical simulation. Based on C3X blades, leading edge swirl cooling structure of the corresponding areas are modified. The flow and heat transfer characteristics of swirl cooling are analyzed at different cross-sections and positions. It is found that there exists an optimal aspect ratio and hole spacing to minimize the temperature gradient on the swirl cavity wall. The swirling motion in the swirl cavity can significantly increase the heat transfer coefficient of the wall surface. [ABSTRACT FROM AUTHOR]

Endwall contouring having significance in delineating ideal endwalls competent in thermal load depletion is the focus of this study. We have successfully utilized non-axisymmetric contoured endwalls to enhance turbine performance by controlling the secondary flow characteristics in a blade passage through steady-state numerical hydrodynamics. The supreme endwall pattern could lower the gross pressure loss at the design stage and is related to the size of the top-loss location being productively lowered. The selective numerical shape change using multi-objective optimization at the most prominent locations resulted in contoured endwall geometry and a considerable reduction of thermal exchange in the vane passage and thermal load in the turbines. A non-axisymmetric contoured endwall achieves the highest net heat flux reduction and elevated aerodynamic performance with lower total pressure loss coefficients than an axisymmetric convergent contoured endwall at most locations of the endwall. In the present study, the ideal mass flow rate could pinpoint the endwall passage, contoured with outstanding axial turbine competence and longevity. Endwall contouring enhances turbine performance, and augmented efficiency is achieved with optimized shapes. [ABSTRACT FROM AUTHOR]

AbstractThe enhancement of turbine blade performance within turbo jet engines is crucial for prolonged engine life. Amidst various cooling strategies for turbine blades, thermal barrier coatings (TBCs) emerge as a highly effective method. Just as the choice of material for the turbine blade holds importance, so too do the materials comprising TBCs. The current research work aims to pursue finite element-based analyses of turbine blades with TBCs, an almost real complex-shaped geometric model comprising the blade body with a rabbet is essential, the stress generated during TGO growth which is crucial for analysis, to select the substrate from both a thermo-structural and cost perspective. In this research endeavor, TBCs were structured with a substrate, a bond coat (NiCoCrAlY), and a top coat of lanthanum cerate (La2Ce2O7) ceramic layers. A thermally grown oxide (TGO), namely α-Al2O3, forms between the bond coat and the top coat due to the elevated temperatures experienced. Two distinct substrates, Inconel 625 and Titanium-T6 alloy, were meticulously chosen as turbine blade materials. Commencing with NACA 4412 airfoil data, the turbine blade was meticulously designed using CATIA, followed by simulations conducted on ANSYS software through a static thermal structural model. The simulation aimed to determine the optimal top coat/thermally grown oxide (TC/TGO) and TGO/bond coat (TGO/BC) layer thicknesses to achieve minimal equivalent stress and total deformation in the turbine blade. The simulated results revealed that a combination of 400 µm TC/10 µm TGO and 10 µm TGO/100 µm BC provided the lowest equivalent stress and total deformation, thereby offering valuable insights for the current research. [ABSTRACT FROM AUTHOR]

To study the fracture speed of power turbine blades in aero-engine and its variation law with the proportion of bending stress, a total of 32 simulated blades with 4 different ratios of bending stress were designed and processed based on the principle of equivalence. The fracture speed of the simulated blades was calculated by finite element method. The simulated blades were grouped and fracture speed measurement experiments were conducted to obtain the actual fracture speed and fracture form of the blades. The simulated blade fracture test process was recorded by high-speed camera technology, and the variation law of blade fracture speed with the proportion of blade bending stress was obtained. The research results show that the error between the actual fracture speed and the calculated speed of the simulated blades are not greater than 1. 10%. Within a certain range, as the bending stress decreases, the fracture speed of the blade generally shows a downward trend, and as the proportion of bending stress in the blade increases, the fracture speed of the blade decreases faster. The research provides a reference for the strength design and blade fracture test methods of real blades, which has important engineering application value. [ABSTRACT FROM AUTHOR]

This paper was attempted to investigate the microstructure degradation and low cycle fatigue (LCF) performance of a serviced K465 Ni‐based superalloy turbine blade. LCF tests were carried out with small‐scale plate specimens sampled from the blades. Relationship between residual LCF life and microstructure state was estimated. The results indicate that the coarsening of γ/γ′ phases was the most significant microstructure degradation mode for the serviced blades. Both the γ matrix width and the γ′ precipitate diameter increased with the increase of service duration, while the γ′ precipitate volume fraction slightly decreased. The most severe microstructure degradation occurred at the leading edge along the chord direction, particularly at 50–70 % airfoil spans. The residual LCF life exhibited an accelerated decrease characteristic as increases of microstructure degradation degree. The coarsened microstructure diminished shear resistance of the superalloy, which resulted in additional accumulated inelastic deformation and a corresponding reduction in LCF life. Highlights: Service induced microstructure evolution and LCF life decay of a blade were investigated.Coarsening was identified as the main degradation form of γ/γ' phases in serviced blade.Accelerated decrease of residual LCF life was identified as increases of coarsening.Reduced plastic deformation resistance owing to coarsening is crucial to decay LCF life. [ABSTRACT FROM AUTHOR]

The Gas turbines blade design and its modifications is a most crucial components towardsits sustainability against high temperature. The effective application of different cooling techniques enhances the heat transfer rate of these blades.The advent of modern manufacturing techniquesisnow days found more convenient in creation of micro cooling passages on the turbine blades. The profile variation of these micro cooling passages effects the heat transfer process. In this paper, a numerical study of convection cooling technique with different hole profile is performed for gas turbine blades using Computational technique. The square, triangular, and semi-circular hole profiles have been used to study its effect on the cooling efficiency.The effect of increasing the number of holes at different blade areas is also reported in this investigation.Adiabatic film cooling efficiency and heat transfer characteristics were observed using numerical analysis. The area near the trailing edge and on pressure and suction side edges are identified for the effect on overall heat transfer. A square hole with 11 number of holes has found higher Adiabatic film cooling efficiency (ηad = 0.46) while the square hole with 17 number of holes found to be highest Adiabatic film cooling efficiency (ηad) = 0.487 for 1400°Ctemperature.The computational analysis using CFD and ANSYS has registered the decrease in surface temperature of the blades. [ABSTRACT FROM AUTHOR]