Industrial Turbine Blades Research Articles

The Prediction and Evaluation of Surface Quality during the Milling of Blade-Root Grooves Based on a Long Short-Term Memory Network and Signal Fusion.

The surface quality of milled blade-root grooves in industrial turbine blades significantly influences their mechanical properties. The surface texture reveals the interaction between the tool and the workpiece during the machining process, which plays a key role in determining the surface quality. In addition, there is a significant correlation between acoustic vibration signals and surface texture features. However, current research on surface quality is still relatively limited, and most considers only a single signal. In this paper, 160 sets of industrial field data were collected by multiple sensors to study the surface quality of a blade-root groove. A surface texture feature prediction method based on acoustic vibration signal fusion is proposed to evaluate the surface quality. Fast Fourier transform (FFT) is used to process the signal, and the clean and smooth features are extracted by combining wavelet denoising and multivariate smoothing denoising. At the same time, based on the gray-level co-occurrence matrix, the surface texture image features of different angles of the blade-root groove are extracted to describe the texture features. The fused acoustic vibration signal features are input, and the texture features are output to establish a texture feature prediction model. After predicting the texture features, the surface quality is evaluated by setting a threshold value. The threshold is selected based on all sample data, and the final judgment accuracy is 90%.

Investigation on the aerodynamic performance and boundary layer characteristics of high deflection industrial turbine cascade at off-design conditions

This research leads to reach the effects of the off-design operation on the aerodynamic performance, boundary layer behavior, and associated loss occurring in a high deflection industrial turbine blade. Numerical simulations, proved opposed to experimental results, are used to achieve the detailed flow field of the cascade, incidence angels ranging from −15° to +10° at inlet chord Reynolds number varied from 9.63E+04 to 2.24E+05. Boundary layer specifications covering thickness, displacement thickness, and momentum thickness are achieved in the 15 points on the suction side and talk about detail on the authority of numerical simulations in various flow conditions. Results indicate that profile loss is forcefully increased by the rising up the incidence angle mostly in the positive range. Studying the effect of incidence angle on the boundary layer behavior indicates that as incidence angle varies from negative to positive, all three characteristics of the boundary layer increase gradually.

Study of three types of wave leading edge on the performance of industrial turbine blade cascade

PurposeThe blade profile and its geometrical features play an important role in the separation of the boundary layer on the blade. Modifying the blade geometry, which might lead to the delay or elimination of the flow separation, can be considered as a passive flow control methodology. This study aims to find a novel and inexpensive way to reduce loss with appropriate modifications on the leading edge of the turbine blade.Design/methodology/approachThree types of wave leading edges were designed with different wavelengths and amplitudes. The selected numbers for the wave characteristics were based on the best results of previous studies. Models with appropriate and independent meshing have been simulated and studied by a commercial software. The distribution of the loss at different planes and mid-plane velocity vectors were shown. The mass flow average of loss at different incidence angles was calculated for the reference blade and modified ones for the sake of comparison.FindingsThe results show that in all three types of modified blades compared to the reference blade, the elimination of flow separation is observed and therefore the reduction of loss at the critical incidence angle of I = –15°. As the amplitude of the wave increased, the amount of loss growing up, while the increase in wavelength caused the loss to decrease.Originality/valueThe results of the present numerical analysis were validated by the laboratory results of the reference blade. The experimental study of modified blades can be used to quantify numerical solutions.

APPLICATION OF RADIATION PROCESSES FOR TESTING OF GAS TURBINE BLADES

Structural integrity of the gas turbine blades is of great concern. A set of methods and instruments is proposed to study the problems of the test loading of the industrial turbine blades. The approach aims to model the possible hightemperature, shock and irradiation impacts. The test loading is performed using the high-current relativistic electron beam. The developed methodology can be used for test and identification trails of the turbine blades. The experimental bench is designed to assist the thermographic measurements of the temperature dynamics in the blades. It also comprises the corresponding algorithms and software to perform the necessary calculations with.

КОМБИНИРОВАННЫЕ ЛАЗЕРНЫЕ АДДИТИВНЫЕ ТЕХНОЛОГИИ ПРОИЗВОДСТВА ЛОПАТОК ТУРБИН СЛОЖНОЙ ГЕОМЕТРИЧЕСКОЙ ФОРМЫ

Laser beam processes are increasingly used in the field of additive manufacturing. Prominent methods are either powderbed-based like Laser Metal Fusion (LMF), or utilizing a powder nozzle like Laser Metal Deposition (LMD). While LMF allows the manufacturing of complex structures, build rate, part volumes and material flexibility are limited. In contrast, LMD is able to operate with high deposition rates on existing parts, and materials can be changed easily during the process. However LMD shape complexity is limited. Utilizing their respective strengths, a combination of these two additive technologies has the potential to produce complex parts with high deposition rates and increased material flexibility. In this paper, combined manufacturing with additive technologies LMF and LMD is described. Its benefit for industry with emphasis on turbomachinery is shown. As reality test for the innovation, an industrial turbine blade is manufactured.

Simultaneous neutron transmission and diffraction imaging investigations of single crystal nickel-based superalloy turbine blades

The integrity of turbine blades is at the heart of every operating aerospace engine or land-based gas turbine. In the most demanding environments, they are cast as single crystals. Whereas traditional neutron imaging is an excellent tool for the non-destructive testing in search of cracks or residual core material, it is insensitive to variations in crystallographic properties. In this work we show that by simultaneous imaging of the diffracted neutrons, one can also probe variations in crystal orientation. In a matter of seconds, different dendritic growth in two industrial turbine blades could be ascertained.

Performance of thermal barrier coatings in industrial gas turbine conditions

The effect of aerofoil geometry on the oxidative degradation mechanisms experienced by thermal barrier coatings (TBCs) used on industrial turbine blades has been investigated. Modified aerofoil-shaped samples (CMSX4 coated with high-velocity oxy-fuel sprayed AMDRY 995 and air plasma sprayed TBC) were oxidised at five temperatures in furnaces from 900 to 1000°C. Scanning electron microscopy and energy dispersive X-ray analysis were used to characterise details of the microstructural evolution of the thermally grown oxide and to monitor inter-diffusion between the bond coating and substrate. Additionally, a novel non-destructive examination technique (flash thermography) was used to detect and track the spread of cracks beneath the TBCs. Multiple samples cracking in identical locations suggested an effect of geometry in the failure of coatings. Furthermore, it was observed that coating curvature influenced spinel formation.

The development of new bond coat compositions for thermal barrier coating systems operating under industrial gas turbine conditions

Environmental and economic issues are driving the development of increasingly efficient gas turbines. An important step in achieving this is to engineer components which can operate with longer lifetimes and at higher metal temperatures. Inlet temperatures for gas turbines now exceed the melting temperatures of nickel-based superalloys (i.e. 1300–1350°C). The use of advanced air cooling systems coupled with thermal barrier coatings (TBCs) reduces the temperature of the underlying superalloy substrate. The bond coating, an important part of the TBC system, oxidizes to form a slow growing protective oxide layer, while also providing adhesion between the ceramic topcoat and the substrate. NiCoCrAlY overlay coatings are some of the most commonly used bond coatings for industrial gas turbines and extensive research has been undertaken over many years to find the best bond coating composition.This paper reports upon the production of new, model bond coatings with a wide range of different compositions. The focus is on their oxidation behavior at a temperature typically experienced by bond coatings on industrial turbine blades (950°C). A physical vapor deposition technique, magnetron sputtering, has been used to deposit a range of Ni–Co–Cr–Al coatings onto 10mm diameter sapphire substrates. This was achieved through co-sputtering two targets: a Ni–10%Cr, Ni–20%Cr, Ni–50%Cr, Ni–20%Co–40%Cr or Ni–40%Co–20%Cr target and a pure Al target. About a hundred samples with varying compositions were produced by this method. The coatings were then oxidized in air for 500h at 950°C.All samples were assessed by measuring the change in coating thickness, using pre- and post-exposure metrology only, and also the change in specimen weight. This approach has shown that magnetron sputtering successfully deposited 20 to 30μm thick coatings and allowed the calculation of oxide growth rates. Energy dispersive X-ray (EDX) analysis was used to characterize the exact composition of each sample. Additionally, X-ray diffraction (XRD) has been used to identify the major oxides formed during exposure. The selective growth of protective Cr2O3 or Al2O3 or other less protective mixed oxides (depending on the initial coating composition) was observed. This influenced the oxide scale growth rate, indicating which coatings produced more protective oxides and allowing future optimization of the bond coating composition, for service within the turbine section of industrial gas turbines to be planned.

Laser cladding in repair of IN738 turbine blades

AbstractLaser cladding with additive powder can be used for repairing high cost components such as industrial turbine blades. Repair of damaged blades is important for electrical power companies to reduce operating costs. The repair of IN738 gas turbine blades using laser cladding is reviewed. A laser cladding system for blade repair and the associated heat treatment procedures before and after repair are discussed. In general, laser cladding with IN625 powder does not require preheating and can be used for repairing IN738 blades in low stress areas. For laser cladding with a higher strength material, e.g. IN738 powder, preheating to high temperatures is necessary to avoid cracking. In a process simulation, test coupons were employed to compare the microstructures and mechanical properties of the IN738 clad region and base metal. Blade repairs with IN738 additive powder were found to be stronger but much more difficult to process than those with IN625 powder. Therefore, extreme caution is required when re...