Search

One of the most complex and costly systems in the industry is the Gas Turbine (GT). Because of the complexity of these assets, various indicators have been used to monitor the health condition of different parts of the GT. Turbine Exit Temperature (TET) spread is one of the significant indicators that help monitor and detect faults such as overall engine deterioration and burner fault. The goal of this article is to use data-driven approaches to monitor TET data to detect faults early, as fault detection can have a significant impact on GT reliability and availability. In this study, the TET data of v94.2 GT is measured by six temperature transmitters to show a detailed profile. According to the statistical tests, TET data are high dimensional and time-dependent in the real world industry. Hence, three distinctive methods in the field of the GT are proposed in this study for early fault detection. Conventional Principal Component Analysis (PCA), Moving Window Principal Component Analysis (MWPCA), and Incremental Principal Component Analysis (IPCA) were implemented on TET data. According to the results, the conventional PCA model is a non-adaptive method, and the false alarm rate is high due to the incompatibility of this approach and the process. The MWPCA based on V-stepahead and IPCA approaches overcame the non-stationary problem and reduced the false alarm rate. In fact, these approaches can distinguish between the normal time-varying and slow ramp fault processes. The results showed that IPCA could detect fault situations faster than MWPCA based on V-step-ahead in this study. [ABSTRACT FROM AUTHOR]

In this article, numerical simulations have been conducted on the heat transfer effect of dimple/protrusion layouts of a pin-finned wedge duct. Conjugate heat transfer calculations are further performed to investigate the cooling effect of modified schemes with dimples and protrusions added. Comparisons are carried out with a turbine second stage guide vane employed as the prototype. The dimple/protrusion-pin fin arrangement is set as the optimum one obtained above, and dimple depth/protrusion height varies from 0.2 to 0.3 times the structure diameter. It is found that the side-by-side arrangement and protrusion structure is more beneficial for the wedge duct endwall heat transfer. Comparison with the prototype blade shows that the addition of both dimples and protrusions are helpful in enhancing the trailing edge cooling effect. The cooling effect is increased with an increase in dimple depth/protrusion height. The results also show that the modified blade with protrusions attached at 0.3 height saves 0.48 g/s cooling mass flow and reaches the most positive performance with a 17 K, 14 K average temperature reduction, 0.022, 0.018 cooling effect increasing for pressure, suction side, respectively. [ABSTRACT FROM AUTHOR]

With increasing inlet temperature of gas turbines, turbine blades need to be effectively protected by using cooling technologies. However, the deposition from the fuel impurities and dust particles in the air is often found inside film holes, which results in partial hole blockage. In this paper, the deposition geometry is simplified as a rectangular channel, and the effect of three blockage ratios is investigated by using the computational fluid dynamics. In addition, water droplets are also released from the coolant inlet to provide a comparison of the results with and without mist injection. It is found that the lateral film cooling effectiveness is reduced with increasing blockage ratio. For all the cases with the blowing ratio 0.6, 1% mist injection provides an improvement of the cooling performance by approximately 10%. [ABSTRACT FROM AUTHOR]

The pre-licensing design of an HTGR cogeneration test plant to be coupled to JAEA’s existing test reactor HTTR is discussed. The plant is designed to demonstrate the system of JAEA commercial plant design of Gas Turbine High Temperature Reactor for Cogeneration (GTHTR300C). More specifically the test plant (HTTR-GT/H 2 ) aims to 1) demonstrate licensability of the GTHTR300C system for electricity and hydrogen cogeneration and 2) confirm operation and safety performance of such cogeneration system. With construction planned to be completed around 2025, the test plant is expected to be the first-of-a-kind nuclear system operating on two of the advanced energy conversion systems attractive for the HTGR – closed cycle helium gas turbine for power generation and thermochemical iodine–sulfur water-splitting process for hydrogen production. [ABSTRACT FROM AUTHOR]

A latent heat thermal energy storage unit has been modeled, simulated and designed for integration into a cogeneration plant that supplies steam to industrial customers in Saarland, Germany. The design consists of a vertical bundle of extended finned tubes surrounded by phase change material in the shell. The heat transfer fluid water/steam flows through the tubes between the upper and lower headers. A new fin design was developed to achieve the required high power levels. The storage system was designed and analyzed with the development of an iterative multi-step method. The method spans from the design of the fin, based on both empirical and geometrical information, to the heat transfer analysis of a storage system. The analysis is comprised of several steps: a heat transfer analysis of the cross-section of one tube without modeling the heat transfer fluid, a transfer from the cross-section to a simplified one-dimensional radial model and a two-dimensional axial and radial analysis coupling the axial flow of the heat transfer fluid and the radial heat transfer into the storage. The developed analysis method and the resulting storage system are presented and the comparison of different fin designs shows the suitability of each fin for different applications. [ABSTRACT FROM AUTHOR]

In complex industrial systems, operating, regulating, maintenance activities and external incidents take place dynamically and multiple entities in same or different subsystems interact in a complex manner. Most of single faults have multiple propagation paths. Any local slight deviation is able to propagate, spread, accumulate and increase through system fault causal chains. It will finally result in system failure and unplanned outages or even catastrophic accidents. The key issues focus on both of how to reduce the probability of fault occurrence and decrease the loss of fault consequence. The implementation of such requirements can be studied in terms of the determination of the fault root causes, prediction of the possible consequence, and also estimation of the risk and timing of various maintenance activities, which are considered in a failure prognosis scheme. This study proposes a DBN based failure prognosis method for complex system. Not only the interaction between components, but also the influence of the layers of protection in the system is considered when the dynamic failure scenarios are analyzed. Therefore the proposed method considers multiple factors including degradation mechanism, parameter deviation, the response of the layers of protection and also the external environment. With this model, the dynamic influence diagram of the components' degradation trends can be calculated and be used to evaluate the different effects of the layers of protection quantitatively. Some key problems are also explained such as how to determine the new nodes in DBN representing the behavior of protective layers and how to update the CPT in the extended model. In the case study, the proposed method is tested on the flue gas energy recovery system (FGERS) which is widely used in the petrochemical industry to demonstrate its effectiveness. It makes a great help for early warning and optimization of the layers of protection in the complex industrial system. [ABSTRACT FROM AUTHOR]

To realize a variety of potential applications of diamonds, particularly in the area of power electronics, it is indispensable to improve their growth efficiency. Most conventional approaches have tried to achieve this simply by increasing the gas temperature; however, this makes it difficult to grow large diamond crystals. To improve the growth efficiency while lowering the gas temperature, we propose that using a pulse-modulated microwave plasma with a sub-millisecond pulse width can enhance the power efficiency of the growth rate of single-crystal diamonds. We found that using a sub-millisecond pulse-mode discharge could almost double the growth rate obtained using continuous mode discharge for a fixed average microwave power and gas pressure. A comparison between experimental observations of the optical emission spectra of the discharge and a numerical simulation of the gas temperature suggests that a decrease in the gas temperature was achieved, and highlights the importance of electron-dominated reactions for obtaining the enhancement of the growth rate. This result will have a large impact in the area of diamond growth because it enables diamond growth to be more power efficient at reduced temperatures. [ABSTRACT FROM AUTHOR]

When the operating condition of a gas turbine engine changes from one steady-state to another, the cooling must ensure that the solid's temperatures never exceed the maximum allowable throughout the transient process. Exceeding the maximum allowable temperature is possible even though cooling is increased to compensate for the increase in heating because there is a time lag in how the solid responds to changes in its convective heating and cooling environments. In this paper, a closed-form solution (referred to as the 1D model) is derived to estimate the over temperature and its duration in a flat plate subjected to sudden changes in heating and cooling rates. For a given change in heating rate, the 1D model can also be used to estimate the minimum cooling needed to ensure that the new steady-state temperature will not exceed the maximum allowable. In addition, this model can estimate the temperature the material must be cooled to before imposing a sudden increase in heat load to ensure no over temperature throughout the transient process. Comparisons with the exact solutions show the 1D model to be accurate within 0.1%. This 1D model was generalized for application to problems in multidimensions. The generalized model was used to estimate the duration of over temperature in a two-dimensional problem involving variable heat transfer coefficient (HTC) on the cooled side of a flat plate and provided results that match the exact solution within 5%. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to find the time dependent thermal creep stress relaxation of a turbine blade and to investigate the effect thermal radiation of the adjacent turbine blades on the temperature distribution of turbine blade and creep relaxation. Design/methodology/approach – For this analysis, the creep flow behavior of Moly Ascoloy in operational temperature of gas turbine in full scale geometry is studied for various thermal radiation properties. The commercial software is used to pursue a coupled fields analysis for turbine blades in view of the structural force, materials kinematic hardening, and steady-state temperature field. Findings – During steady-state operation, the thermal stress was found to be decreasing, whereas by considering the thermal radiation this rate was noticed to increase slightly. Also by increase of the distance between stator blades the thermal radiation effect is diminished. Finally, by decrease of the blade distance the failure probability and creep plastic deformation decrease. Research limitations/implications – This paper describes the effect of thermal radiation in thermal-structural analysis of the gas turbine stator blade made of the super-alloy M-152. Practical implications – Blade failures in gas turbine engines often lead to loss of all downstream stages and can have a dramatic effect on the availability of the turbine engines. There are many components in a gas turbine engine, but its performance is highly profound to only a few. The majority of these are hotter end rotating components. Social implications – Three-dimensional finite element thermal and stress analyses of the blade were carried out for the steady-state full-load operation. Originality/value – In the previous works the thermal radiation effects on creep behavior of the turbine blade have not performed. [ABSTRACT FROM AUTHOR]

The cooling effectiveness of combustor transition pieces increases significantly in accordance with turbine temperature. In this issue, we create a scenario in which using three-dimensional computational to predict the performance of film cooling model with three rows holes and double chambers on the flat surface that the model could simulate the TP's structure and performance. Fluent, a commercial CFD software, is extensively used in the current work for numerical simulations. A comprehensive study is performed on the effect of coolant injection angles on film cooling. The the temperature distribution in the inner wall, cooling effectiveness, and the velocity distribution of coolant flow with different cases is compared. Analysis on flow injection orientations is beneficial to enhance the turbine inlet temperature and improve gas turbine efficiency. [ABSTRACT FROM AUTHOR]

The ultra-compact combustor (UCC) has the potential to offer improved thrust-to-weight and overall efficiency in a turbojet engine. The thrust-to-weight improvement is due to a reduction in engine weight by shortening the combustor section through the use of the revolutionary circumferential combustor design. The improved efficiency is achieved by using an increased fuel-to-air mass ratio and allowing the fuel to fully combust prior to exiting the UCC system. Furthermore, g-loaded combustion offers increased flame speeds that can lead to smaller combustion volumes. One of the issues with the UCC is that the circumferential combustion of the fuel results in hot gases present at the outside diameter of the core fow. These hot gases need to migrate radially from the circumferential cavity and blend with the core flow to present a uniform temperature distribution to the high-pressure turbine rotor. The current research focused on correlations to control the UCC cavity velocity, control the temperature profile throughout the UCC section, analyze the exhaust species exiting the combustor, and quantify pressure losses in the system. To achieve these goals, a computational fluid dynamics (CFD) analysis was used on a UCC geometry scaled to a representative fighter-scale engine. The analysis included a study of cavity to core flow interaction characteristics, a 5- and 12-species combustion model of liquid and gaseous fuel, and determination of species exiting the combustor. Computational comparisons were also made between an engine realistic condition and an ambient pressure rig environment. [ABSTRACT FROM AUTHOR]

Highlights: [•] Blades failure occurred because of excessive temperature exposure. [•] Oxide grooves on fracture surface of blades are due to very high temperature exposure. [•] Creep properties of alloy deteriorated by γ′ particles dissolution. [ABSTRACT FROM AUTHOR]

During gas turbine engine testing, steady-state gas-path stagnation pressures and temperatures are measured in order to calculate the efficiencies of the main components of turbomachinery. These measurements are acquired using fixed intrusive probes, which are installed at the inlet and outlet of each component at discrete point locations across the gas-path. The overall uncertainty in calculated component efficiency is sensitive to the accuracy of discrete point pressures and temperatures, as well as the spatial sampling across the gas-path. Both of these aspects of the measurement system must be considered if more accurate component efficiencies are to be determined. High accuracy has become increasingly important as engine manufacturers have begun to pursue small gains in component performance, which require efficiencies to be resolved to within less than  ±. This article reports on three new probe designs that have been developed in a response to this demand. The probes adopt a compact combination arrangement that facilitates up to twice the spatial coverage compared to individual stagnation pressure and temperature probes. The probes also utilise novel temperature sensors and high recovery factor shield designs that facilitate improvements in point measurement accuracy compared to standard Kiel probes used in engine testing. These changes allow efficiencies to be resolved within  ± over a wider range of conditions than is currently achievable with Kiel probes. [ABSTRACT FROM AUTHOR]

The article discusses the characteristics of high-temperature materials like turbine blades which increase the efficiency of gas power plants. Alstom director Maxim Konter has said that efficiency levels for larger components depend on the gas turbine firing temperature. Consulting engineer Stephen Balsone has revealed that nickel-based superalloys are widely used due to their engineering properties for high-temperature structural applications.