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Mass and radial deformation are of great importance for a high-pressure turbine disc (HPTD). However, computational cost of computer-aided engineering (CAE) is too high to optimise the mutually restricted objectives. A parameterisation-based method is proposed to speed the optimisation process of HPTD: ‘body-flange’-based parametric template is used to generate CAE samples; noise-based virtual samples are implemented to enlarge the training set, a cost-effective neural network is used as fitness function of non-dominated sorting genetic algorithm-II for optimisation whose initial population is the combination of different sample sets. Experiment results show that the proposed data-driven framework reduces the engineering difficulty of multi-objective optimisation, and it has high popularisation value for optimisation of other complex products. [ABSTRACT FROM PUBLISHER]

Featured Application: In-process defect detection in the manufacturing of turbine components using Artificial Intelligence techniques. Traceability is a critical issue in the manufacturing of aerospace components. However, extracting understandable information from huge amounts of data from manufacturing processes may become a very difficult task. In this paper, a novel proposal for geometrical defect detection in the manufacturing of fir-tree slots for disk turbines using wire electrical discharge machining is presented. Useful data about the wire Electrical Discharge Machining (WEDM) process are collected every 5 ms and each single discharge is classified as a function of ignition delay time. Information from this large amount of data is extracted by using a deep neural network, which includes two hidden dense layers, each with 64 units and Relu activation, and it ends with a single unit with no activation. The average of the per-epoch absolute error (MAE) scores has been used to decide the optimum training situation for the deep learning network. Validation of the method has been carried out by machining a high-precision fir-tree slot for a disk turbine under industrial conditions. Results show that even though a strict tolerance band of ±5 µm has been applied, as many as 80% of the predictions from the network match the results of the conventional measuring method (coordinate measuring machine). [ABSTRACT FROM AUTHOR]

Cold-worked Inconel 718 alloy has successful applications in turbine engines due to its elevated strength. Otherwise, cold working will bring about the undesired ductility degradation accompanied with strength improving. Meanwhile, the susceptibility to δ precipitation is increased with modified morphology. To address these issues, this work aims expressing the effect of cold-rolling on hot ductility and the role of δ phase regarding differential morphologies in tensile behavior of Inconel 718 alloy at 650 °C. The results revealed that the ductility degradation can be attributed to the interactions of necking, microstructure instability and oxidation process tailored by cold-rolling. Nevertheless, appropriate cold-rolling is proved to enhance the resistance to crack propagation. The needlelike δ phase in strain-free structure tightly hindered the migration of horizontal GBs to enhance the strength but promote the intergranular brittle cracking, resulting in the degradation of ductility. In contrast, the δ phase with modified granular morphology in cold-rolled structures showed good deformation compatibility with horizontal GBs, playing a positive role in delaying necking occurrence and impeding crack propagation. In summary, the granular δ precipitation endowed cold-rolled Inconel 718 alloy with a superior combination of strength and ductility at 650 °C. [ABSTRACT FROM AUTHOR]

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Multilayer heat-resistant ion-plasma coatings for protecting the parts of the hot duct of gas-turbine engines produced from refractory nickel alloys based on VKNA intermetallics from high-temperature oxidation are considered. Coatings of the Ni - Cr - Al (Ta, Re, Hf, Y) + Al - Ni - Y systems are tested for high-temperature strength at 1200 and 1250°C. Metallographic and microscopic x-ray spectrum analyses of the structure and composition of the coatings in the initial condition and after the testing are performed. The effect of protective coatings of the Ni - Cr - Al - Hf + Al - Ni - Y systems on the long-term strength of alloys VKNA-1V and VKNA-25 at 1200°C is studied. [ABSTRACT FROM AUTHOR]

While much is known about how macrogeometry of shaped holes affects their ability to successfully cool gas turbine components, little is known about the influence of surface roughness on cooling hole interior walls. For this study, a baseline-shaped hole was tested with various configurations of in-hole roughness. Adiabatic effectiveness measurements at blowing ratios up to 3 showed that the in-hole roughness caused decreased adiabatic effectiveness relative to smooth holes. Decreases in area-averaged effectiveness grew more severe with larger roughness size and with higher blowing ratios for a given roughness. Decreases of more than 60% were measured at a blowing ratio of 3 for the largest roughness values. Thermal field and flowfield measurements showed that in-hole roughness caused increased velocity of core flow through the hole, which increased the jet penetration height and turbulence intensity resulting in an increased mixing between the coolant and the mainstream. Effectiveness reductions due to roughness were also observed when roughness was isolated to only the diffused outlet of holes, and when the mainstream was highly turbulent. [ABSTRACT FROM AUTHOR]

Standard power generation industry practices of inspection, machining, balancing, assembly and alignment have been developed by OEMs for newly manufactured rotors, and implicitly assume that rotors are within ideal dimensional specifications. However, applying these standard practices in the service industry can fall short for rotors with eccentricities outside such specifications, and by design do not catch the errors that cause true dynamic problems, because they are assumed not to exist, or their effects are unrecognized by traditional industry practice with regard to real rotordynamic behavior. This misunderstanding leads to costly problems, like reinstalling a "balanced" rotor from the shop only to experience high vibrations upon installation, often followed by days or weeks of lost production while field balancing in an effort to salvage the situation. A "successful" start up following a planned outage means that there will be no need for field balancing following the restart of the unit. Since most causes of dynamic problems on turbine-generator rotors are present (in the form of rotor and coupling eccentricities) even prior to starting the unit, almost any such problem can also be identified and fully prevented during the outage if only a few key, improved steps of measurement and analysis and the proper balancing method are included into an outage scope. Specifically, this must include collection and evaluation of total indicator runout (TIR) readings to identify any coupling defects and any excessive rotor bow or distributed eccentricity, and utilization of a new balancing method (using 2N+1) planes if the rotor body exceeds runout limits of ~0.002" eccentricity. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to provide a green technology that can clean turbine engine oil filters effectively in ships using ultrasound, with ultrasonic devices having a frequency of 25 kHz and different powers of 300 W and 600 W, respectively. The effects of temperature, ultrasonic cleaning times, pressure losses through the oil filter, solvent washing, and ultrasonic power devices were investigated. In addition, the cleaning efficiency of three modes (hand washing, preliminary washing and ultrasonic washing) were compared to assess their relative effectiveness. Experimental results revealed that the necessary ultrasonic time varied significantly depending on which solvent was used for washing. For instance, the optimum ultrasonic cleaning time was 50–60 min when the oil filter was cleaned in a solvent of kerosene oil (KO) and over 80 min when in a solvent of diesel oil (DO) using the same ultrasonic generator device (25 kHz, 600 W) and experimental conditions. Furthermore, microscopic examination did not reveal any damage or breakdown on or within the structure of the filter after ultrasonic cleaning, even in the filter’s surfaces at a constantly low frequency of 25 kHz and power specific capacity (100 W/gal). Overall, it may be concluded that ultrasound-assisted oil filter washing is effective, requiring a significantly shorter time than manual washing. This ultrasonic method also shows promise as a green technology for washing oil filters in turbine engines in general and Vietnamese navy ships in particular, because of its high cleaning efficiency, operational simplicity and savings. [ABSTRACT FROM AUTHOR]

In the long-term, tidal turbines will most likely be deployed in farms/arrays where energy extraction by one turbine may significantly affect the energy available to another turbine. Given the prohibitive cost of experimental and/or field investigations of such turbine interactions, numerical models can play a significant role in determining the optimum layout of tidal turbine arrays with respect to energy capture. In the present research, a low-cost modelling solution for optimising turbine array layouts is presented and assessed. Nesting is used in a far-field model to telescope spatial resolution down to the scale of the turbines within the turbine array, allowing simulation of the interactions between adjacent turbines as well as the hydrodynamic impacts of individual turbines. The turbines are incorporated as momentum sinks. The results show that the model can compute turbine wakes with similar far-field spatial extents and velocity deficits to those measured in published experimental studies. The results show that optimum spacings for multi-row arrays with regard to power yield are 3-4 rotor diameters (RD) across-stream and 1-4 RD along-stream, and that turbines in downstream rows should be staggered to avoid wake effects of upstream turbines and to make use of the accelerated flows induced by adjacent upstream turbines. [ABSTRACT FROM AUTHOR]

Some materials for turbine applications show volume contraction during service lifetime. Relative shrinkage (Δ l/ l0) of up to about −4 · 10−4 may occur. In this study Waspaloy samples were exposed up to 10 000 h at 550 °C, 650 °C and 750 °C. High resolution length measurements unveil remarkable contraction during exposure at 550 °C and 650 °C and less contraction at 750 °C. The main contribution to sample contraction is compositional variation due to temperature dependent phase fraction changes. Lattice parameters of matrix and γ′ phase decrease within the first 300 h of temperature exposure. In addition carbide transformation from TiC to Cr23C6 contributes to the observed contraction. [ABSTRACT FROM AUTHOR]

The main goal of this study was to separate and evaluate the noise contribution of each sub-component of a small scale wind turbine drive train that contributes to the overall mechanical noise inside the nacelle of a small (8 kW) wind turbine. The experiments were performed in a drive train simulator that housed the drive train of a Viryd 8000 wind turbine. Different wind speeds were simulated on the test stand through a drive system consisting of a motor, gearbox and flywheel. In order to evaluate the overall sound generation single microphone acoustic measurements were made. The frequency of sound generation was observed to be the same as that of vibrations of the drive train measured using two accelerometers. Sound radiated by each component of the drive train was evaluated through acoustic beamforming using a compact microphone array in conjunction with advanced beamforming algorithms. A strong relationship between the drive train power generation, and sound emitted by various mechanical components was observed. A unique contribution of this study is our ability to localize, separate and quantify noise from sub-components in a complex functioning wind turbine drive train. [ABSTRACT FROM AUTHOR]

Abstract: Flank milling is of importance to machining aircraft structural parts, turbines, blades and several other mechanical parts. It decreases manufacturing time, enhances quality and reduces cost. Since flank milling developable ruled surfaces do not contain geometrical errors, research on flank milling focuses on the generation of optimal tool trajectory for non-developable ruled surfaces, even generic free-form surfaces. This includes: envelope surfaces, geometrical errors (overcut, undercut), energy optimization in tool movement, surface deviations, tool geometry adaptation, tool wear and temperature, and surface roughness. In this article we present a survey on flank milling as well as suggesting guidelines for future considerations in solving flank milling tool trajectory optimization. [Copyright &y& Elsevier]

In recent years, numerical and experimental investigations on the draft tube performance have confirmed the importance of the inlet swirling flow created by the runner vanes. The results indicate that it is still a challenge to get the optimal flow distribution at the draft tube inlet which gives the best machine performance over a range of operation points. Consequently, there is a need to adjust the runner-draft tube coupling to minimize the losses arising from the inlet flow distribution. This paper focus on establishing an optimization methodology for maximizing the draft tube performance as a function of the inlet velocity profile. The overall work is divides into two parts: The part one establish the inlet velocity parametrization, the numerical optimization set-up and the objective function definition. The part two validate the numerical CFD draft tube model. These steps are represented by the coupling of the commercial softwares MATLAB, FLUENT and iSIGHT. It is considered that this proved methodology will help to find a inlet velocity profile shape which will be able to suppress or mitigate the undesirable draft tube flow characteristics. [ABSTRACT FROM AUTHOR]

A conventional exergy analysis can highlight the main components having high thermodynamic inefficiencies, but cannot consider the interactions among components or the true potential for the improvement of each component. By splitting the exergy destruction into endogenous/exogenous and avoidable/unavoidable parts, the advanced exergy analysis is capable of providing additional information to conventional exergy analysis for improving the design and operation of energy conversion systems. This paper presents the application of both a conventional and an advanced exergy analysis to a supercritical coal-fired power plant. The results show that the ratio of exogenous exergy destruction differs quite a lot from component to component. In general, almost 90% of the total exergy destruction within turbines comes from their endogenous parts, while that of feedwater preheaters contributes more or less 70% to their total exergy destruction. Moreover, the boiler subsystem is proven to have a large amount of exergy destruction caused by the irreversibilities within the remaining components of the overall system. It is also found that the boiler subsystem still has the largest avoidable exergy destruction; however, the enhancement efforts should focus not only on its inherent irreversibilities but also on the inefficiencies within the remaining components. A large part of the avoidable exergy destruction within feedwater preheaters is exogenous; while that of the remaining components is mostly endogenous indicating that the improvements mainly depend on advances in design and operation of the component itself. [ABSTRACT FROM AUTHOR]

Paper presents a computational study of energy transformation in two geometrical configurations of Kaplan turbine elbow draft tube. Pressure recovery, hydraulic efficiency and loss coefficient are evaluated for a series of flow rates and swirl numbers corresponding to operating regimes of the turbine. These integral characteristics are then correlated with local flow field properties identified by extraction of topological features. Main focus is to find the reasons for hydraulic efficiency drop of the elbow draft tube. [ABSTRACT FROM AUTHOR]

Abstract: During the last decade, research efforts were devoted to the development and manufacturing of ceramic thermal barrier coatings (TBCs) on turbine parts because the traditional turbine materials have reached the limits of their temperature capabilities. TBCs have been widely used in hot-section metal components in gas turbines either to increase the inlet temperature with a consequent improvement of the efficiency or to reduce the requirements of the cooling air. There are several ceramics that have been evaluated as TBC materials, and lanthanum zirconate (LZ) is one of the most promising among them. The properties namely high-melting point, phase stability up to its melting point, low thermal conductivity, low sintering ability and oxygen-non transparent make the LZ a potential TBC material for high-temperature applications. However, the production methods used to synthesise LZ are highly time consuming and the powder is not commercially available. Hence, in this investigation an attempt was made to synthesise, spheroidize and spray deposit LZ material using thermal plasma process. This paper illustrates the effectiveness of thermal plasma as a major materials processing technique. Suitable characterization techniques have been used to study the material modifications after respective plasma processing exposures. [Copyright &y& Elsevier]

Detailed experimental measurements have been performed to understand the effects of turbine inlet temperature distortion (hot-streaks) on the heat transfer and aerodyna~nic characteristics of a fill-scale unshrouded high pressure turbine stage at flow conditions that are representative of those found in a modern gas turbine engine. To investigate hot-streak migration, the experimental measurements are complemented by threedimensional stead>' and unsteady CFD simulations of the turbine stage. This paper presents the time-averaged ,neasure,nents and computational predictions of rotor blade surface and rotor casing heat transfer~ Experimental mneasuremnents obtained with and without inlet temperature distortion are compared. Time-mean experimental measurements of rotor casing static pressure are also presented. CFD simulations have been conducted using the Rolls-Royce code HYDRA and are compared with the experimental results. The test turbine was the unshrouded MTI turbine, installed in the Turbine Test Facility (previously called Isentropic Light Piston Facility) at QinetiQ, Farnborough, UK. This is a short duration transonic facility which simulates engine-representative M, Re, Tu, NI IT, and T5I T,~. to the turbine inlet. The facility has recently been upgraded to incorporate an advanced second-generation temperature distortion generators capable of simulating well-defined, aggressive temnperature distortion both in the radial and circumnferential directions, at the turbine inlet. [ABSTRACT FROM AUTHOR]

This article discusses the problem of thermal loads in main components of supercritical steam turbines. The main source of these loads is the temperature of the expanding steam that the components are exposed to. However, in case of a turbine component of a tubular form,the convection on the opposite surface, the unheated one, is also important. Additional steam flow past the unheated surface may lower thermal loads and provide better operating conditions. The research described in this article analyses the possibilities, range, and limitations of such an adjustment in order to obtain better thermal state in the components of the turbines. [ABSTRACT FROM AUTHOR]

In this second of two articles concerning axial flow impellers, Punit Singh and Franz Nestmann of Karlsruhe Institute of Technology focus on backward curved impellers, revealing hydraulic behaviour that is interesting and unexpected in pump and turbine operations respectively. They also compare the performance of forward and backward curved impellers to determine the optimum impeller shape for turbines. The background and objectives of this two-part series were discussed in detail in the previous article. As mentioned, this second article will closely analyse the performance of backward curved axial flow impellers for both pump and turbine operations, as well as covering the remaining objectives of the study, namely: [a)] To apply the theoretical model (developed in part 1) to backward curved impellers and look at nuances within the internal hydraulics in both pump and turbine operations. [b)] To search for the optimum turbine impeller after comparing the turbine operations of forward and backward curved impellers. [c)] To establish steps for modelling the four-quadrant characteristics of pumps with both forward and backward curved impellers. [ABSTRACT FROM AUTHOR]

Abstract: Light and flexible rotating parts of modern turbine engines operating at supercritical speeds necessitate application of more accurate but rather computationally expensive 3D FE modeling techniques. Stacked disks misalignment due to manufacturing variability in the geometry of individual components constitutes a particularly important aspect to be included in the analysis because of its impact on system dynamics. A new parametric model order reduction algorithm is presented to achieve this goal at affordable computational costs. It is shown that the disks misalignment leads to significant changes in nominal system properties that manifest themselves as additional blocks coupling neighboring spatial harmonics in Fourier space. Consequently, the misalignment effects can no longer be accurately modeled as equivalent forces applied to a nominal unperturbed system. The fact that the mode shapes become heavily distorted by extra harmonic content renders the nominal modal projection-based methods inaccurate and thus numerically ineffective in the context of repeated analysis of multiple misalignment realizations. The significant numerical bottleneck is removed by employing an orthogonal projection onto the subspace spanned by first few Fourier harmonic basis vectors. The projected highly sparse systems are shown to accurately approximate the specific misalignment effects, to be inexpensive to solve using direct sparse methods and easy to parameterize with a small set of measurable eccentricity and tilt angle parameters. Selected numerical examples on an industrial scale model are presented to illustrate the accuracy and efficiency of the algorithm implementation. [ABSTRACT FROM AUTHOR]

This paper investigates the influence of stator-rotor interaction on the stage performance of three blade tip geometries. A reference flat tip is used to assess two different recess blade geometries. The study is made in the context of the realistic turbine stage configuration provided by the ETHZ 1.5-stage LISA turbine research facility. This numerical investigation describes the details of unsteady recess cavity flow structure and confirms the beneficial effects of the improved recess geometry over the flat tip and the nominal recess design both in terms of stage efficiency and tip heat load. The tip flow field obtained from the improved recess design combines the advantages of a nominal recess design (aerodynamic sealing) and the flat tip configuration. The turbine stage capacity is almost unchanged between the flat tip and the improved recess tip cases, which simplifies the design procedure when using the improved recess design. The overall heat load in the improved recess case is reduced by 26% compared with the flat tip and by 14% compared with the nominal recess. A key finding of this study is the difference in effects of the upstream stator wake on the recess cavity flow. Where cavity flow in the nominal design is only moderately influenced, the improved recess cavity flow shows enhanced flow unsteadiness. The tip Nusselt number from a purely steady-state prediction in the nominal recess case is nearly identical to the time-average prediction. The improved design shows a 6% difference between steady-state and time-average tip Nusselt number. This is due to the strong influence of the wake passing on the recess cavity flow. In fact, the wake enhances a small flow difference at the leading edge of the recess cavity between the nominal and improved recess cavities, which results in a completely different flow field further downstream in the recess cavity. [ABSTRACT FROM AUTHOR]

The work proposes a detailed description of the flow field throughout leaned turbine nozzles and reports a sensitivity analysis with respect to the lean angle. A phenomenological approach focuses the attention on pressure contours distribution on both inside and outside the passage. The study involves both straight and annular cascades mounting a typical intermediate reaction degree section, designed for steam turbines. Blades are built by stacking the same 2D profile along different linear axes, characterized by different angles with respect to the normal or radial direction: α=0 deg for prismatic blade and α=10 deg, 15 deg, and 20 deg for the leaned ones are considered. Experimental and numerical tests were performed at the nominal inlet flow angle in order to avoid any effect related to blade sweep. Experimental tests were carried out at the design outlet Mach number of 0.65; measurements were performed at the Laboratorio di Fluidodinamica delle Macchine of Politecnico di Milano. Only linear cascades with prismatic and 20 deg leaned blades were experimentally tested, providing data both downstream and inside the blade passage by means of pressure probe traversing, endwall pressure taps, and oil flow visualization. Experimental results were also used to validate the numerical setup, which provided a detailed computational picture of the flow field throughout the channel. The influence of the pressure contours' shape on secondary vorticity activity downstream of the passage is highlighted and discussed, focusing the attention on secondary structures and loss distribution in this region. The resulting description of the flow field, based on the representation of pressure contours, supports the sensitivity analysis with respect to the blade lean angle, identifying the mechanism that leads the secondary vorticity to grow in regions where secondary losses and blade loading decrease. [ABSTRACT FROM AUTHOR]

method for assessment the durability of turbine disks at the stages of damage removing and development subject to structural and technological changes is developed on the basis of the nonlinear mechanics of deformation and fracture. The proposed method includes numerical analysis of the stressdeformed condition of disks in the initial and damaged states, determination of stress and strain fields in the zones of cutting of the damaged material volume, and calculation of low-cycle fatigue and the duration of crack growth from initial to critical sizes. The theory of the developed method is the concept of a fracture process zone. The method is used for comparative evaluation of stress-deformed conditions and durability parameters for options of changing the geometry of a steam turbine disk by removing the damaged material around slot fillet of key. [ABSTRACT FROM AUTHOR]

Abstract: Different laser surface hardening techniques, such as laser alloying and laser solution strengthening were adopted to perform modification treatment on the local region of inset edge for 2Cr13 and 17-4PH steam turbine blades to prolong the life of the blades. The microstructures, microhardness and anti-cavitation properties were investigated on the blades after laser treatment. The hardening mechanism and technique adaptability were researched. Large scale installation practices confirmed that the laser surface modification techniques are safe and reliable, which can improve the properties of blades greatly with advantages of high automation, high quality, little distortion and simple procedure. [ABSTRACT FROM AUTHOR]

The differential bearing between the low-pressure turbine (LPT) and high-pressure turbine (HPT) shafts is one of the most vulnerable parts in a turbomachinery engine. Unfortunately, it is also one of the most difficult parts to monitor for damage existence signatures, because the signal-to-noise ratio at the normal sensor locations is extremely low. In addition, the speed variations in both the LPT and HPT can further deteriorate the damage signature extracted by conventional analysis methods. In this paper we developed a "synthesized synchronous sampling" technique to enhance the detection of differential bearing damage signature. Combining this technique together with the conventional acceleration enveloping technique, we are able to detect differential bearing damage at a much earlier stage, thus providing early warnings of the machinery health conditions. [ABSTRACT FROM AUTHOR]

The majority of wind turbines currently in operation have the conventional Danish concept design-that is, the three bladed rotor of such turbines is indirectly coupled with an electrical generator via a gearbox. Recent technological developments have enabled direct drive wind turbines to become economically feasible. Potentially, direct drive wind turbines may enjoy higher levels of availability due to the removal of the gearbox from the design. However, this is only a theory: so far not substantiated by detailed analytic calculation. By providing such a calculation, this paper enables us to quantitatively evaluate technical and economic merits of direct drive and gearbox-driven wind turbines. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes thermal analysis methodology results for the supercritical steam turbines. The analysis presented here concerns the external cooling of the turbine components. Due to the supercritical parameters of the live steam, the inlet areas of the high and intermediate pressure parts are exposed to the steam at high temperature level. The design solutions applied to the turbines so far aim to protect the inlet areas. Basic solution incorporate protective screens, which are made of a material more resistant to the high temperature than the rest of the components. Additional protection is provided by the external cooling. The applications of both methods described above allow to increase the live steam temperature. The conducted analysis determined the temperature field in the steam, which cools the rotor, as well as the distribution of the temperature and stresses in the rotor. The obtained results were then applied to the investigations concerning the durability of the rotor. [Copyright &y& Elsevier]

Abstract: This work reviews a recent structural integrity assessment carried out on a high-pressure turbine inner casing that had suffered from temper embrittlement. The assessment was carried out to demonstrate that the casing can be safely returned to service based on revised operating conditions with particular emphasis on the control of temperature ramp rates during start-up and shutdown events. A retirement-for-cause philosophy was adopted to take into consideration that some operational flexibility will be required prior to the casing being replaced at the next planned outage. [Copyright &y& Elsevier]

Topography measurements and roughness calculations for different rough surfaces (Rugotest surface comparator and thermally sprayed coatings) are presented. The surfaces are measured with a novel quantitative topography measurement technique based on optical stereomicroscopy and a comparison is made with established scanning stylus and optical profilometers. The results show that for most cases the different methods yield similar results. Stereomicroscopy is therefore a valuable method for topographical investigations in both quality control and research. On the other hand, the method based on optical microscopy demands a careful optimization of the experimental settings like the magnification and the illumination to achieve satisfactory results. [ABSTRACT FROM AUTHOR]

The paper reports the research of the "engine-attachment-airframe" multi-connecting dynamic model by separation it into independent sub-systems according to the engine support (engine mounting points). New generation aircraft are switching to engines of high bypass ratio, which require dynamic characteristics of new structures to be refined. The studies we have performed allowed us to refine significantly dynamic models of aviation gas turbine engine and airframe within rotor frequencies range and to reveal tendency of changes of dynamic characteristics particularly those of engine bodies with increased bypass ratio. [ABSTRACT FROM AUTHOR]

This paper reports the latest results of the comprehensive program of experimental and computational analysis of strength and reliability of wooden parts of low cost wind turbines. The possibilities of prediction of strength and reliability of different types of wood are studied in the series of experiments and computational investigations. Low cost testing machines have been designed, and employed for the systematic analysis of different sorts of Nepali wood, to be used for the wind turbine construction. At the same time, computational micromechanical models of deformation and strength of wood are developed, which should provide the basis for microstructure-based correlating of observable and service properties of wood. Some correlations between microstructure, strength and service properties of wood have been established. [ABSTRACT FROM AUTHOR]

Recent studies have shown that film cooling with holes embedded in a shallow trench significantly improves cooling performance. In this study, the performance of shallow trench configurations was investigated for simulated deteriorated surface conditions, i.e., increased surface roughness and near-hole obstructions. Experiments were conducted on the suction side of a scaled-up simulated turbine vane. Results from the study indicated that as much as 50% degradation occurred with upstream obstructions, but downstream obstructions actually enhanced film cooling effectiveness. However the transverse trench configuration performed significantly better than the traditional cylindrical holes, both with and without obstructions and almost eliminated the effects of both surface roughness and obstructions. [ABSTRACT FROM AUTHOR]

A numerical study has been performed to investigate the effect of casing motion on the tip leakage flow and heat transfer characteristics in unshrouded axial flow turbines. The relative motion between the blade tip and the casing was simulated by moving the casing in a direction from the suction side to the pressure side of the stationary blade. Base line flat tip geometry and squealer type geometries, namely, double squealer or cavity and suction side squealer, were considered at a clearance gap of 1.6% C. The computations were performed using a single blade with periodic boundary conditions imposed along the boundaries in the pitchwise direction. Turbulence was modeled using the shear stress transport k-ω model. The flow conditions correspond to an exit Reynolds number of 2.3 X 10[sup5]. The results were compared to those obtained without the relative casing motion reported in Part I of this paper In general, the effect of relative casing motion was to decrease the tip leakage -mass flow and the average heat transfer to the tip due to the decrease in leakage flow velocity caused by a drop in driving pressure difference. Compared to the computations with stationary casing, in the case of all the three geometries considered, the average heat transfer to the suction surface of the blade was found to be larger in the case of the computations with relative casing motion. At a larger clearance gap of 2.8% C, in case of a flat tip, while the tip leakage mass flow decreased due to relative casing motion, only a smaller change in the average heat transfer to the tip and the suction surface of the blade was noticed. [ABSTRACT FROM AUTHOR]

The process of final heat treatment of nuclear-power-plant steam turbine parts produced from steel 26KhN3M2FAA is developed. The quality of the metal of a commercially produced disk is studied. Conditions for obtaining a high set of mechanical properties in steel 26KhN3M2FAA combined with a reduced temperature of the ductile-brittle transition (semibrittleness temperature) are determined. [ABSTRACT FROM AUTHOR]

The gas turbine industry is continuously driven to achieve higher thermodynamic efficiency, higher electrical output, and higher reliability through turbine design improvements. The specific component of interest in this article is the turbine wheel, which is the rotating hub on which turbine blades are mounted. The wheel is mechanically loaded by both axial and centrifugal forces and thermally loaded by heat that is conducted from the turbine blades. Currently, the turbine wheel is forged from an ingot that is triple-melted, but nucleated casting is under development as a long-term option. This article describes the investigation into nucleated casting technology for future turbine wheel production. INSET: CONVENTIONAL WHEEL PROCESSING. [ABSTRACT FROM AUTHOR]

Combines the probability density function (PDF) method for turbulent combustion modeling with the in situ adaptive tabulation (ISAT) scheme in a combustor design system and performs calculations of a piloted jet diffusion flame and a low-emissions premixed gas turbine combustor. Scalar PDF method; ISAT scheme; Piloted jet diffusion flame; Premixed low-emission gas turbine combustor; ISAT performance.

Describes the development of a hydrogen-air microcombustor known as micro-gas turbine generators. Information on micromachining of silicon and refractory; Identification of these micro-gas turbine generators; Indepth look at the challenges and opportunities for microcombuster development.

The article discusses the failures of turbine parts of compression of pyrolysis gases. A study is conducted on the behavior or turbine parts under the combined action of cyclic loading and corrosion. The character of the failures of the blades of the turbine units of compression of pyrolysis gases used in the production of ethylene and the disks of impellers of the rotors of steam turbine are examined.