Load Operating Conditions Research Articles

Investigation of Flow Characteristics of Flow Passage Components in Francis Turbine under No-load and 50% Load operating conditions

Due to the varying demand of power grid for the electric supply of hydraulic power stations, the units are often under low-load operating condition and no-load standby state, causing a significant flow instability in hydraulic generator units. To further investigate the inside flow characteristics of hydraulic turbines under such operating conditions. In this study, a CFD (computational fluid dynamics) numerical simulation with applying RNG (Renorm alization Group) k-ε turbulence model is performed to study the inside flow characteristics of each flow passage components of a Francis turbine under no-load and 50% load conditions. The results indicate that under the two operating conditions, the flow distribution inside and outside the draft tube pier is significantly nonuniform. Simultaneously, the large-scale vortex in the runner area caused by the high-speed flow in the vane-free area with small opening and the nonuniform flow velocity distribution in the straight cone section of the draft tube are the main reasons for the increase of hydraulic loss and the decrease of efficiency.

Analysis of crack propagation in onshore wind turbine foundations using the double-K fracture model

The load-bearing mechanism of the embedded steel ring to foundation connection used for onshore wind turbines causes high stress concentrations in the concrete around the base flange. Cracks initiate and propagate through the foundation from the base flange. The crack growth under normal operating and extreme loading conditions reduces the stiffness and load-bearing capacity of the tower to foundation connection. This in turn affects power production and could lead to economic losses if failure of the foundation occurs. This paper investigated the stability of a horizontal crack propagation in a typical onshore wind turbine foundation using the double-K fracture propagation criterion. The study involved experiments on two sub-part models and numerical simulation of a large-diameter onshore wind turbine foundation. Using the numerical results, the stress intensity factors at the tip of a horizontal crack emanating from the outer edge of the base flange were calculated at different stages of loading. The stress intensity factors were compared with the initial and unstable fracture toughness of concrete to assess the stability of the crack propagation. It was found that for vertical displacements of the embedded steel ring exceeding 9 mm, the crack propagation became unstable. Based on the crack propagation behaviour, a method was proposed to assess the safety of onshore wind turbine foundations using the vertical displacements of the embedded steel ring.

Influence of cycle repetition on stack voltage degradation during fuel cell stress tests

AbstractA voltage decrease in the long‐term operation of hydrogen fuel cell (FC) electric cars under steady settings under constant load and dynamic operating conditions is a performance constraint of concern. Although accelerated stress test (AST) procedures have been sought to diagnose degradation, the AST results of FC stacks have not been reported extensively. The purpose of this article is to discuss the generation of AST of FC stacks based on real load profiles and the consequences of load changes and start‐stop circumstances, which are mostly generated by common driven cycles in urban regions with high driving speeds and traffic jams. The highlight of this study is to analyze the effects of cycle repetition on the aging FC stack, especially the voltage degradation factor, degradation kinetics, and energy consumption. The relation between actual system temperatures in side cells assembled in the FC stacks and material degradation was also analyzed. The results presented high heat accumulation, related to chemical degradation, that occurred during load cycling and may result in membrane thinning and pinholes in the membrane. Temperature cycling corresponded to mechanical degradation generated during the start‐stop cycling test, which may lead to membrane degradations—cracking, tearing, and pinholes.

Impact of Spray Cone Angle on the Performances of Methane/Diesel RCCI Engine Combustion under Low Load Operating Conditions.

The behaviors of spray, in Reactivity Controlled Combustion Ignition (RCCI) dual fuel engine and subsequent emissions formation, are numerically addressed. Five spray cone angles ranging between 5° and 25° with an advanced injection timing of 22° Before Top Dead Center (BTDC) are considered. The objective of this paper is twofold: (a) to enhance engine behaviors in terms of performances and consequent emissions by adjusting spray cone angle and (b) to outcome the exergy efficiency for each case. The simulations are conducted using the Ansys-forte tool. The turbulence model is the Renormalization Group (RNG) K-epsilon, which is selected for its effectiveness in strongly sheared flows. The spray breakup is governed by the hybrid model Kelvin–Helmholtz and Rayleigh–Taylor spray models. A surrogate of n-heptane, which contains 425 species and 3128 reactions, is used for diesel combustion modeling. The obtained results for methane/diesel engine combustion, under low load operating conditions, include the distribution of heat transfer flux, pressure, temperature, Heat Release Rate (HRR), and Sauter Mean Diameter (SMD). An exergy balance analysis is conducted to quantify the engine performances. Output emissions at the outlet of the combustion chamber are also monitored in this work. Investigations show a pressure decrease for a cone angle θ = 5° of roughly 8%, compared to experimental measurement (θ = 10°). A broader cone angle produces a higher mass of NOx. The optimum spray cone angle, in terms of exergy efficiency, performance, and consequent emissions is found to lie at 15° ≤ θ ≤ 20°.

Control Optimization of Modular Multilevel Resonant DC Converters for Wide-Input-Range MVdc to LVdc Applications

In this article, the output voltage control strategy of modular multilevel resonant dc converters (MMRDC) for medium-voltage wide-input-range applications is studied. First, the feasibility and influence of the switching frequency regulation and modulation index regulation are investigated in detail. It is found that the switching frequency choice has a significant effect on the voltage stress of arm inductors and the transformer. Then, based on these considerations, the modulation index regulation plus switching frequency regulation based design and control optimization is proposed. With the proposed design and control method, the switching frequency range for adapting to a wide input range is further reduced, especially under light load operating conditions. Besides, the high voltage stress on arm inductors is avoided and the high voltage <i>dv</i>&#x002F;<i>dt</i> on the transformer is also eliminated. Finally, a laboratory prototype with 8&#x2013;16 kV input and 375 V&#x002F;60 kW output has been built and the experimental validation under a wide input range has been done. The efficiency over 96.4&#x0025; under the wide input range proved the effectiveness of the optimized control methods.

Geosynthetic Encased Concrete Debris Stone Columns

Rapid urbanization has compelled the building industry to improve the soft soil grounds which otherwise are unsuitable for construction activities. Ground improvement helps achieve better performance by avoiding several problems like excessive settlements, large lateral flow of soft soil beneath the structures, and loss of global or local stability under operational loading conditions by modification of foundation soils. The growing quantities and types of waste materials, shortage of landfill spaces, and lack of natural earth materials highlight the urgency of finding innovative ways of recycling and reusing waste material additionally can reduce the demand for natural resources creating sustainable ecosystem. The aim of this experiment is to use crushed concrete debris (CCD) in soil stabilization. A series of experiments are to be carried out to develop an understanding on the performance of soft clay foundation beds reinforced using geosynthetic encased stone-concrete debris column. Model tests was conducted on clay reinforced with encased vertical columns filled with both CCD and aggregates. A comparative study is to be done and an assessment of ultimate bearing capacity of the composite ground is to be done. The column failure mechanism in the both the cases are to be carefully studied. Modal tests and later numerical analysis is done in PLAXIS 2D for analyzing the behavior of geosynthetic encased stone column stabilized clay bed numerically. Analyses were carried out using Mohr-Coulomb’s criterion. Lab conditions were simulated in PLAXIS for accurate comparison for same model tests.

Smart Manufacturing in Rolling Process Based on Thermal Safety Monitoring by Fiber Optics Sensors Equipping Mill Bearings

The steel rolling process is critical for safety and maintenance because of loading and thermal operating conditions. Machinery condition monitoring (MCM) increases the system’s safety, preventing the risk of fire, failure, and rupture. Equipping the mill bearings with sensors allows monitoring of the system in service and controls the heating of mill components. Fiber optic sensors detect loading condition, vibration, and irregular heating. In several systems, access to machinery is rather limited. Therefore, this paper preliminarily investigates how fiber optics can be effectively embedded within the mill cage to set up a smart manufacturing system. The fiber Bragg gratings (FBG) technology allows embedding sensors inside the pins of backup bearings and performing some prognosis and diagnosis activities. The study starts from the rolling mill layout and defines its accessibility, considering some real industrial cases. Testing of an FBG sensor prototype checks thermal monitoring capability inside a closed cavity, obtained on the surface of either the fixed pin of the backup bearing or the stator surrounding the outer ring. Results encourage the development of the whole prototype of the MCM system to be tested on a real mill cage in full operation.

Reactive power based capacitors allocation in distribution network using mathematical remora optimization algorithm considering operation cost and loading conditions

Capacitor allocation is one of the most important topics in distribution network operation. In this paper, reactive power based on capacitors allocation is presented in electrical distribution network using mathematical Remora Optimization Algorithm (ROA) as a powerful optimization method to identify the optimal location and size of the capacitors in the networks. The objective function is defined as minimizing the cost of losses, purchasing and installation costs, as well as the cost of capacitors operation at different loading conditions. Problem optimization variables include the optimal site and size of the capacitors in the network, which is found considering the objective function, operating conditions and reactive size of the capacitors using the ROA. The method based on the ROA is studied on IEEE 33 and 69 buses networks. The simulations are evaluated in different scenarios including capacitors allocation with and without PLNLI as well as in different loading. The simulation results are indicated the capability of the proposed methodology in comparison with previous studies in losses reduction, voltage profile enhancement, reducing annual costs and increasing net saving. The results are also showed that considering PLNLI offers fewer losses, better voltage profiles and of course higher annual cost than the conditions without considering it. In addition, the results clear that reducing the electrical network load level causes reduction of losses cost, voltage fluctuations and also the annual cost of the network. So, optimal implementation of the capacitor allocation based on the ROA in the electrical network can be able to improve the characteristics of the network and also increase the net saving by optimally injecting the reactive power.

Ultrathin film formation under combined effect of surface roughness and surface force for elastohydrodynamic lubrication of point contact problems

PurposeThe purpose of this study is to investigate the combined effect of surface force, solvation and Van der Waals forces and surface topography parameters of amplitude and wavelength on the formation of ultrathin films for elastohydrodynamic lubrication of point contact problems.Design/methodology/approachThe Newton–Raphson technique is used to simultaneously solve the Reynolds’ film thickness including surface roughness and elastic deformation, surface force of solvation and Van der Waals forces and load balance equations. Different values of surface amplitude and wavelength were simulated in addition to the load variation.FindingsThe simulation results revealed that roughness effects are important as the film thickness decreases. The oscillation in the pressure and film thickness is due to the combined action of the solvation force and surface topography parameters. The limiting values of the surface topography parameters of the amplitude and wavelength varied and depended on the load. For different values of wavelength and load, amplitude values up to 0.25 nm have no effect on ultrathin film formation.Originality/valueThe combined effect of the surface force and surface roughness on the formation of ultrathin films was evaluated for elastohydrodynamic lubrication of point contact problems under different operating conditions of load and surface topography parameters of amplitude and wavelength. The limited surface topography parameters of the amplitude and wavelength are shown and analyzed.

Structural and load parameter estimation of a real‐world reinforced concrete slab bridge using measurements and Bayesian statistics

AbstractThis paper describes a static diagnostic load testing and measurement campaign of a reinforced concrete road bridge in Amsterdam. We consider 29 vertical translation sensors and 37 strain sensors. Multiple Bayesian parameter estimations are performed to estimate two structural and two load parameters of a three‐dimensional finite element (FE) model. The structural parameters are the concrete elastic modulus of the deck and the rotational spring stiffness at the piers. The load (truck) parameters are the load mass and position, which are estimated from separate measurements. We found that estimating (updating) the two selected structural parameters considerably improves the vertical translation model prediction accuracy over the FE model that was built before the measurement campaign, that is, the R2 score increases from 0.90 to 0.98. Moreover, the load (truck) mass and position parameters can be estimated with high accuracy and high precision. When all measurements are used, the load mass and position are estimated with an error, respectively, less than 1.5 tonnes and 0.5 m with respect to the ground truth. On the negative side: when only certain strain measurements are used, the 90% posterior credible interval is about 3 m and 10 tonnes off the ground truth. Although the results are promising, they are restricted to the considered case and, more importantly, to operational loading conditions where the loading is well controlled. All data, models, and code are freely available upon request.

The Effect of J-Groove on Vortex Suppression and Energy Dissipation in a Draft Tube of Francis Turbine

The vortex rope in the draft tube is considered as the major contributor to pressure pulsation at partial load (PL) conditions, which causes the hydro unit to operate unstably. Based on the prototype Francis turbine HLA551-LJ-43 in the laboratory, J-grooves are designed on its conical section in this paper. We used numerical simulation to study the effect of the J-grooves on vortex suppression and energy dissipation in the draft tube. Four typical operating conditions were chosen to analyze the vortex suppression; the corresponding flow ratios Q* are 100%, 82%, 69%, and 53%, respectively. Entropy production theory is used to calculate the energy losses and assess the effect of the J-groove on energy dissipation under part-load conditions. By comparing entropy production, circumferential and axial velocity components, swirl intensity, pressure pulsation, and vortex distribution in a draft tube with and without J-grooves at different operating conditions, it can be concluded that the entropy production on the wall containing a conical section with J-grooves is obviously smaller than that without J-grooves, the effects of J-grooves on reducing circumferential velocity component Vu, pressure pulsation, and weakening vortex intensity and vortex rope in the conical section are obvious, especially at part load and deep part-load operating conditions. Using J-grooves shows better performance on vortex control and energy dissipation in the draft tube of a Francis turbine at partial load conditions.

Novel Cyclo-Nonstationary Indicators for Monitoring of Rotating Machinery Operating Under Speed and Load Varying Conditions

Abstract Condition monitoring arises as a valuable industrial process in order to assess the health of rotating machinery, providing early and accurate warning of potential failures and allowing for the planning and effective realization of preventative maintenance actions. Nowadays, machinery (gas turbines, wind turbines, etc.) manufacturers adopt new business models, providing not only the equipment itself but also additionally taking on responsibilities of condition monitoring, by embedding sensors and health monitoring systems within each unit and prompting maintenance actions when necessary. Among others, rolling element bearings are one of the most critical components in rotating machinery. In complex machines, the failure indications of an early bearing damage are weak compared to other sources of excitations (e.g., gears, shafts, rotors). Vibration analysis is most widely used and various methods have been proposed, including analysis in the time and frequency domain. In a number of applications, changes in the operating conditions (speed/load) influence the vibration sources and change the frequency and amplitude characteristics of the vibroacoustic signature, making them nonstationary. Under changing environments, where speed and load vary, the assumption of quasi-stationary is not appropriate and as a result, a number of time-frequency and time-order representations have been introduced, such as the Short Time Fourier Transform and the Wavelets. Recently, an emerging interest has been focused on modeling rotating machinery signals as cyclostationary, which is a particular class of nonstationary stochastic processes. The classical cyclostationary tools, such as the Cyclic Spectral Correlation Density (CSCD) and the Cyclic Modulation Spectrum (CMS), can be used in order to extract interesting information about the cyclic behavior of cyclostationary signals, only under the assumption that the speed of machinery is constant or nearly constant. Global diagnostic indicators have been proposed as a measure of cyclostationarity under steady operating conditions. In order to overcome this limitation, a generalization of both SCD and CMS functions has been proposed displaying cyclic Order versus Frequency as well as diagnostic indicators of cyclo-nonstationarity in order to cover the speed-varying operating conditions. The scope of this paper is to propose a novel approach for the analysis of cyclo-nonstationary signals based on the generalization of indicators of cyclo-nonstationarity in order to cover the simultaneous and independently varying speed and load operating conditions. The effectiveness of the approach is evaluated on simulated and real signals captured on a dedicated test rig.

Optimization of biodiesel produced from waste sunflower cooking oil over bi-functional catalyst

In the current global climate emergency and with the interesting environmental advantages of biodiesel, a look into the commercialisation of such greener fuel is essential. While raw materials account for the most in the production cost, time and energy can be economised using statistical models. The optimisation of free methyl esters (FAME) synthesised from waste sunflower oil over a novel CaO/Al2O3, and methanol was carried out at the alcohol and oil ratio of 12:1. The aim was to investigate the effect of operation parameters on the yield of the produced sunflower biodiesel, with the use of low cost and time efficient central composite response surface methodology. The chosen variables were catalyst loading, temperature, and time while the response was the yield. The catalyst loading was the most consequential parameter on yield. The linear regression model was obtained to predict responses given by these variables, with 95% confidence. The predicted and experimental yield was comparable with 92.773% and 95.665% respectively. A significant yield of 98.23% was obtained at optimal operating conditions of catalyst loading (2.5 wt%), time (5 h) and temperature (60 °C). The properties of optimised FAME were within international standard limits set for biodiesel except for the high concentrations of Ca and Mg.

Fatigue Crack Growth Evaluation of IMO Type B Spherical LNG Cargo Tank Considering the Effect of Stress Ratio and Load History

The crack propagation on a spherical IMO Type B LNG tank deployed on a 150K class LNG carrier is studied. IMO Type B tanks require a high level of safety . Therefore, analyses such as strength evaluation, fatigue analysis, fatigue crack propagation analysis, and LNG leak rate should be conducted to ensure safety. Various fatigue crack growth models were proposed for fatigue crack propagation analysis. The Forman model and the Walker model consider the stress ratio. Furthermore, the Huang model, and the Lee and Kim model consider the stress ratio and the effects of overload and underload present in the past load history on crack propagation.To examine the effects of stress ratio and load history for the fatigue crack propagation models, the crack growth of the LNG tank was evaluated by considering the stresses under full load and ballast load operating conditions, and three stress amplitude sequence cases.

A study on split diesel injection on thermal efficiency and emissions of an ammonia/diesel dual-fuel engine

Ammonia is gaining more interest as a carbon-free alternative fuel in freight transportation applications, especially the shipping industry. However, the problems of nitrous oxide (N2O) emissions, which has almost 300 times higher global warming impact than carbon dioxide (CO2), and ammonia slip have been the main challenges of using ammonia in compression ignition (CI) diesel engines. In this study, the effect of split diesel injection strategy (i.e., two-pulse diesel injection) on an ammonia/diesel dual-fuel (ADDF) engine is investigated under medium load operating conditions. Results indicate that the ADDF combustion mode with single diesel injection strategy achieves lower indicated thermal efficiency (ITE) compared to the corresponding diesel-only combustion mode. However, the use of split diesel injection strategy increases the ITE of the ADDF combustion mode to 39.72% which is higher than that obtained by diesel-only combustion mode (maximum ITEdiesel = 38.62%). Moreover, split diesel injection strategy reduces the unburned ammonia emissions of the ADDF combustion mode by up to 83.5% compared to the lowest unburned ammonia emissions achieved by single diesel injection strategy. Two split diesel injection strategies based on the optimum points of greenhouse gas (GHG) emissions are suggested in this research. At the first optimum point, the GHG emissions of the ADDF combustion mode are decreased by 23.7%, while ITE is increased by about 2% compared to the optimum point of diesel-only combustion mode. This, however, comes with about 10% higher nitrogen oxides (NOx) emissions. The emitted GHG emissions of ADDF combustion can be further reduced by 30.6%, but at the expense of 2.2% lower ITE and 52.4% higher NOx emissions than diesel-only combustion mode. At both optimum points, unburned ammonia emissions were significantly reduced to below 900 ppm compared to that of ADDF combustion mode with single diesel injection strategy (i.e., 4445 ppm). The lowest unburned ammonia concentration achieved in this study is still above the recommended exposure limit and therefore the use of appropriate after-treatment devices should be considered in the future.

A Dual-Source Self-Balanced Switched-Capacitor Reduced Switch Multilevel Inverter With Extending Ability

Multilevel inverters (MLIs) with switched-capacitor (SC) combinations are widely recognized to improve the power quality and efficiency of the renewable energy and high-frequency power distribution systems. Self-balancing of SCs and voltage boosting ability are the salient features of the recently developed SC MLIs. This work presents a new SC MLI structure using a reduced number of switches and two dc sources. For increasing the voltage levels, the basic units of the proposed MLI can be extended without increasing the number of dc sources. By suitable charging-discharging patterns, the SCs are self-balanced and voltage boosting is achieved. Comparative analysis with prior-art MLIs demonstrates the merit of topological advancement. Further, extensive simulation and experimental results confirm the feasibility of the proposed MLI under different loading and dynamic operating conditions.

ОЦЕНКА РЕСУРСНЫХ ХАРАКТЕРИСТИК ПОЛИКРИСТАЛЛИЧЕСКИХ КОНСТРУКЦИОННЫХ СПЛАВОВ ПРИ ДЕГРАДАЦИИ ПО СОВМЕСТНЫМ МЕХАНИЗМАМ УСТАЛОСТИ И ПОЛЗУЧЕСТИ МАТЕРИАЛА

The problem of assessing the resource characteristics of responsible engineering facilities, taking into account the peculiarities of operational loading conditions, is discussed. The processes of degradation of the initial strength properties of structural materials (metals and their alloys) under combined fatigue and long-term strength mechanisms are considered. A mathematical model describing the processes of cyclic viscoplastic deformation and accumulation of fatigue damage in structural alloys under multiaxial disproportionate modes of combined thermomechanical loading has been developed from the modern positions of mechanics of the damaged medium and fracture mechanics. The model consists of three interrelated components: relations determining the cyclic viscoplastic behavior of the material, taking into account the dependence on the destruction process; evolutionary equations describing the kinetics of the damage accumulation process; criteria for the strength of the damaged material. The variant of the cyclic determining relations is based on the idea of the existence of plasticity and creep surfaces in the stress space and the principle of gradiency of the velocity vectors of plastic deformations and creep deformations to the corresponding surface at the loading point. These equations of state reflect the main effects of the process of cyclic viscoplastic deformation of the material for arbitrary complex loading trajectories. The variant of kinetic equations of damage accumulation is based on introduction of a scalar damage parameter and on energy principles. Ittakes into account the main effects of formation, growth and fusion of microdefects under arbitrary complex modes of combined thermomechanical loading. A joint form of the evolutionary equation of damage accumulation in the areas of low-cycle fatigue and long term strength is proposed. As a criterion of the strength of the damaged material, the condition of reaching the critical value of the damage value is used. The results of numerical modeling of deformation processes and damage accumulation in structural alloys with degradation mechanisms combining fatigue and long-term strength of the material are presented. The results of the comparison of calculated and experimental data showed that the proposed model of the mechanics of the damaged medium qualitatively and with the accuracy necessary for practical calculations quantitatively describes the processes of destruction of hazardous areas of structural elements under the combined actions of degradation mechanisms of fatigue and long-term strength.

Mechanical analyses of flat sheet water treatment membranes

&lt;abstract&gt; &lt;p&gt;In this work, we address the mechanical response of the flat sheet polymeric water treatment membranes under the assumed operational loading conditions. Firstly, we perform quasi-static analyses of the membranes under normal pressure loads, which is the condition that resembles the actual loading for flat sheet membranes in the submerged membrane bioreactors. Then, the long-term deformation of the membranes is studied under the assumed filtration durations for the same loading conditions by utilizing the viscoelastic material models. The quasi-static and viscoelastic membrane simulations are performed by a commercial finite element code ANSYS. Finally, the mechanical fatigue life predictions are carried out based on the stress distributions from the quasi-static analyses and the long-term effects from the viscoelastic analyses.&lt;/p&gt; &lt;/abstract&gt;

A numerical study of the influence of pilot fuel injection timing on combustion and emission formation under two-stroke dual-fuel marine engine-like conditions

Stricter regulations imposed on emissions are motivating the scientific community to consider studying alternative fuels to achieve low emission, high efficient dual-fuel (DF) marine engines. In this context, three dimensional computational fluid dynamic (CFD) simulations are performed to study the combustion and emission formation under two-stroke, dual-fuel marine engine-like conditions. The DF engine configuration consists of a pilot diesel fuel and a high-pressure, direct injection (HPDI) of natural gas (NG). The simulation results are validated under both high load (high charge density) and low load (low charge density) operating conditions. Detailed analysis of the flame development and emission formation are performed. The interaction between the pilot diesel jets and the methane flame jets is studied. Based on the results, the further methane jets penetration in the low load case leads to better air–fuel mixing and a higher combustion intensity than that in the high load. Effects of the pilot fuel injection timing on combustion and emission formation and the governing mechanisms are also investigated in detail. Results indicate that the intense combustion of the accumulated methane expands the methane flame towards the piston when the pilot injection timing is retarded. The NO formation is lower in the high load case with higher charge density due to the lower combustion intensity. Also, retarding the pilot injection timing decreases the NO formation.

The Crack Growth in the Imitation Model of a GTE Turbine Disk under Operating Loading Conditions

The paper presents the experimental results of growing surface cracks in the turbine disk of a gas turbine engine (GTE) under cyclic tension at room and elevated temperatures. The geometry of the imitation model of the GTE turbine disk with a stress concentration zone in the form of a bolt hole was justified. In order to ensure the similarity of the initial damage of the imitation model and the GTE turbine disc in the plane of symmetry of the stress concentration zone, a semi-elliptical notch was made. The loading conditions of the imitation model were developed based on results of a comparative stress-strain state (SSS) analysis of the stress concentration zone of the imitation model and the GTE turbine disc. As a result of the fatigue test of the imitation model at room and elevated temperatures, the experimental positions and sizes of the crack fronts with respect to the drop potential signal on the crack edges were obtained. The fixed positions and sizes of the crack fronts were used as the basis for the numerical calculation of the fracture resistance parameters. For the numerical studies, ten three-dimensional finite element models with different positions and sizes of the crack fronts were considered. The numerical calculation results based on the finite element method were used to determine the distributions of the elastic stress intensity factors along each crack front. The crack growth rate characteristics both on the free surface and at the deepest point of the crack front were obtained at room and elevated temperature conditions. A technique for the automation tests that simulate the block-type loading of the disk material at elevated temperatures was proposed.