Turbine Module Research Articles

Targeting Full-Hydrogen Operation on Industrial-Scale Gas Turbines: Impact of Unconventional Fuels on Turbine Module Performance and Aeromechanics

Abstract With the trend to full decarbonization, a full hydrogen economy development is a key industrial objective. Gas turbines, currently one of the cleanest fossil fuel-based power generation solutions, provide reliable and on-demand power. The introduction of hydrogen into the fuel mix of existing gas turbines represents a solution with great potential to provide low-carbon or even carbon-free energy. High-hydrogen content fuels, however, challenge the efficient operation of the gas turbine expander, as crucial aspects such as increased flow rate, different gas properties and temperature operating range may affect performance and structural integrity. To evaluate the impact of this conversion, a numerical investigation of five cases with increasing percentages of hydrogen in the fuel was carried out for an industrial four stages gas turbine module. The variation of turbine inlet temperature distribution from combustion chamber was considered, to assess the impact of the unconventional fuel on the well-known aeromechanical behavior of the last stage blades. Variations in capacity, efficiency, power and potential limits due to aeroelasticity were evaluated, identifying the most relevant differences with respect to the full methane case. All these analyses confirm the possibility to employ high-hydrogen fuel operation in a current gas turbine without the need of a further redesign, while maintaining acceptable performance levels.

Prognostics and Health Management for Electrified Aircraft Propulsion: State of the Art and Challenges

Abstract In recent years, the aviation industry has witnessed a transformative wave of innovation in electrified aircraft propulsion (EAP), driven by sustainability and efficiency goals. Integration of novel electrical subsystems, including high-voltage power electronics, motors/generators, and energy storage devices, has introduced intricate complexities. In this context, an intensified focus on Prognostics and Health Management (PHM) is imperative, considering the heightened reliability needs in a transportation propulsion application. This paper analyzes the current state-of-the-art in PHM applicable to various EAP systems and components crucial for the functioning of electric aircraft. Typical fault modes and fault management strategies are analyzed at various levels of systems hierarchy. An integral aspect of our investigation involves the identification of critical gaps within existing PHM frameworks, guiding the research agenda for enhanced reliability and performance. Moreover, the distributed nature and complexity of EAP systems underscore the importance of Model-Based Systems Engineering (MBSE). We advocate for the exploration of MBSE not only to inform the design of PHM solutions but also to facilitate certification and Verification and Validation activities. Additionally, the paper offers insights into existing tools and simulation software capable of integrating traditional gas turbine modules with electric subsystems, as well as simulating various faulty conditions in EAP relevant to PHM development. Key gaps in these tools are emphasized, drawing attention to areas that require further refinement and development. This comprehensive exploration aims to pave the way for future advancements in PHM tailored for the unique challenges posed by EAP systems.

The effect of staged versus rapid immersion on the cardio-respiratory components of the cold-shock response

Drowning is one of the leading causes of accidental death. Sudden cold-water immersion (CWI) leads to the stimulation of cutaneous cold receptors causing the cold-shock response (CSR) which includes a gasp, hyperventilation, and tachycardia for several minutes. Only one study has investigated staged CWI (Hayward and French, 1989, Av Space Env Med, 60, 1163-1165) and found a reduction in minute ventilation (V̇E) and respiratory frequency (fB) occurred when immersed to the waist for 30 s followed by to the shoulders. However, it is unclear whether a staged entry with a longer or shorter period at the waist would elicit a greater or lesser CSR. Thus, the aim of this study is to establish whether a staged immersion with a longer period immersed to the waist would attenuate the initial cardio-respiratory responses associated with CWI, when compared with rapid immersion. Ethical approval was gained from the University of Portsmouth Science Faculty Research Ethics Committee (SHFEC 2020-070). Seven male participants completed two, 5 min immersions that occurred at the same time of day (± 2 h) to avoid circadian variation in internal body temperature: a staged immersion (immersion to the iliac crest for 2 min prior to immersion to the acromion process); a rapid immersion (immersion to the acromion process for 5 min). Participants were lowered into stirred water (15°C) at a rate of 4 s to the waist, 4 s to the shoulder. Inspiratory and expiratory data were collected using a ventilatory turbine module and Douglas bags, respectively, whilst heart rate data was collected using a three-lead ECG. Variables were analysed over the first 30 s of immersion by a one-way ANOVA and a Tukey post hoc test. Effect sizes were calculated using Cohen’s d. Staged immersion to the waist resulted in a significantly lower fB (P < 0.05; d = 1.54) and V ̇E (P < 0.01; d = 1.96) over the first 30 s epoch, when compared to rapid immersion. Staged immersion to the shoulders resulted in a lower ventilatory equivalent of oxygen (P < 0.005; d = 1.95). There was no difference in heart rate between immersions. A staged immersion to the waist resulted in a 36.2% lower V̇E and 29.4% lower fB, potentially due to fewer cutaneous cold receptors being stimulated. This reduces the potential to aspirate water due to a lower ventilatory drive, therefore, could reduce drowning incidence attributed to the CSR.

The Impact of the Off-Design Conditions on the Entropy Wave Interaction With a High-Pressure Turbine Stage

Abstract The study of component interactions in aeronautical engines is a key aspect to improve the aerodynamic, aeromechanical, and thermal performance and to reduce greenhouse gas and noise emissions. In this context, combustor systems (working with lean and premixed flames) generate pressure, velocity, and temperature fluctuations that interact with the turbine module producing combustor instability, performance degradation, and noise generation. A correct understanding of this interaction is thus required by the designers, especially with a view to introducing sustainable aviation fuel to achieve zero-emission aviation. This paper tackles this topic from a numerical and experimental point of view, focusing on off-design turbine conditions possibly encountered during an aero-engine mission. In detail, the effect of different stage loadings (obtained by keeping the stage pressure ratio and modifying the rotational speed) on engine-representative entropy waves evolving through the turbine stage is investigated. The combination of numerical and experimental results, that show a good agreement in terms of disturbance evolution within the stage, allows a deeper understanding of the flow field features that impact the stage aerodynamics and modify the secondary flow structures and the entropy wave transport, diffusion, and decay through the rotor. Moreover, the most loaded operating condition reveals the appearance of a rotating instability at the rotor tip that also interacts with the injected disturbance. Finally, the numerical results (coming from full annulus URANS computation with incoming disturbances) are further post-processed to extract indirect noise emissions at the different load conditions and to assess the additional loading on the rotor blade caused by the presence of the disturbance.

Advanced design, parameter optimization, and thermodynamic analysis of integrated air-blown IGCC power plants

With the increasing energy demand, it is essential to improve the utilization of traditional energy sources. Coal is still the mainstay of the Chinese energy market, especially in power generation. The IGCC offers significant advantages in terms of power efficiency and environmental protection. However, conventional IGCC uses oxygen as the gasification medium, posing serious economic challenges. To address this challenge, in this study, the overall system process for the IGCC systems using air-blown gasification is constructed by Aspen Plus. To explore the potential of the thermal performance of the air-blown gasification IGCC system, the operating parameters and process flows are improved. The energy and exergy analysis of the whole system using the advanced process is carried out and compared with the oxygen gasification IGCC. Optimal operating parameters and technical parameters are determined, and the gasifier is optimized. The results show that the system efficiency increased by 3.17%, and the exergy efficiency increased by 3.09%. Although the integrated gas turbine process does not offer obvious advantages, it is more compatible with the current gas turbine in terms of flow rate. The utilization of a high-pressure reheat gas turbine results in a 2.52% increase in system efficiency. The implementation of high-pressure reheat gas turbines and hot gas desulfurization can improve the thermal performance of the system. The air-blown gasification IGCC with this process has the highest power supply efficiency of 52.80%. It presents an improvement of 3.69% compared with oxygen gasification. The exergy loss in the cooling and cleaning module and the gas turbine module is significantly reduced. The heat efficiency of the air-blown gasification IGCC is 3.60% higher, and the effective energy in the system is fully utilized. It provides some heuristic ideas for the clean and efficient utilization of coal resources.

Green hydrogen potential assessment in Ghana: application of PEM electrolysis process and geospatial-multi-criteria approach

ABSTRACT With green hydrogen gaining traction as a viable sustainable energy option, the present study explores the potential of producing green hydrogen from wind and solar energy in Ghana. The study combined the use of geospatial multi-criteria approach and PEM electrolysis process to estimate the geographical and technical potential of the selected two renewable resources. The study also included an assessment of potential areas for grid integration. Technology specifications of a monocrystalline solar PV module and 1 MW wind turbine module were applied. Results of the assessment show that about 85% of the total land area in the country is available for green hydrogen projects. Technically, capacities of ∼14,196.21 Mt of green hydrogen using solar and ∼10,123.36 Mt/year from wind energy can be produced annually in the country. It was also observed that some regions, especially regions in the northern part of the country even though showed the most favourable locations for solar-based green hydrogen projects with technical potential of over 1500 Mt/year, these regions may not qualify for a grid connected system based on the current electrification policy of the country due to the regions’ low population density and distance from the power grid network threshold.

AHREPS - Alternating Hybrid Renewable Energy Power System for Load Prioritization: A Case Study of Otokwu-Mmaku Community, Awgu, Enugu State, Nigeria

This paper presents the results of a research study using a novel Binary Data Driven Programming (BDDP) solution coined AHREPS (Alternating Hybrid Renewable Energy Power Systems) to alternate between a Solar Photovoltaic (Solar PV) Renewable Energy (RE) system and a Wind Turbine (WT) Renewable Energy system to provide continuous power supply in a rural-to-suburban household at Otokwu Mmaku Community, Awgu, Enugu State, Nigeria. The computational model for the Otokwu-Mmaku Solar PV (OMPV) and Otokwu-Mmaku Wind Turbine (OMWT) hybrid renewable energy (RE) systems are data-driven by a synthesis of data from simple function-fitted models to a generalized polynomial of order-1 for a 4-year duration (2018 to 2021). The results considering an average baseline load of 0.9kWh/day showed that using a 3-parallel connected 200W Solar PV modules and 5kW Wind turbine modules; the AHREPS employed the OMPV RE system for the months of January through June and the months of September through December all through the 4-year duration (2018-2021) but in the months of July (2021) and August (2020), the AHREPS employed the OMWT RE system in providing continuous power supply for the estimated load. This clearly shows that considering the model selection and alternating effects of the hybrid RE systems, the proposed AHREPS model can effectively meet the expected load demand of the aforementioned location.

Performance Evaluation of Solar-assisted Trigeneration System in Thermo-environmental Perspective

Nowadays, the trigeneration systems are proving more promising than a combined cycle system. In terms of efficiency and reliability, these systems meet the typical requirements of cooling heating power in various applications. This work investigated the thermodynamic and environmental characteristics of a solar-based tri-generation system. The studied system consists of gas turbine and steam turbine modules along with heating and cooling provisions as per demand. The integrated system using parabolic trough collectors and also uses steam injected gas turbines for performance improvement. The overall performance of the proposed work is compared with and without a steam injection. The effect of integration of the solar cycle and steam injection for the trigeneration system is assessed. Further, carbon footprint rejected to the environment is also estimated. It is observed that the work output and trigeneration efficiency improved, and the carbon footprint gets reduced in the range varying between 10–40% for the cases studied.

Techno-economic optimization of a biomass gasification energy system with Supercritical CO2 cycle for hydrogen fuel and electricity production

Biomass is considered a carbon–neutral fuel and can play a significant role in obtaining sustainable energy generation. This study aims to raise the exergy efficiency and reduce costs in a novel energy system that is employed to generate power, heating, cooling, fresh water, and hydrogen fuel. Based on this, municipal solid waste (MSW), wood, and paper are considered as biomass fuels of the examined system and the system performance is evaluated from a thermodynamic and thermo-economic point of view through a parametric study. In the considered system, the generated gas in the gasifier supplies the energy required to run an externally fired gas turbine module. The waste heat of the gas turbine cycle is used to run a supercritical CO2 (S-CO2) power generation cycle coupled with a heat exchanger to supply hot water and run an organic Rankine cycle (ORC) power generation cycle, as well as an absorption chiller cycle equipped with an ejector to produce cooling. In addition, the waste heat of the ORC is employed to produce fresh water through a humidification-dehumidification (HDH) desalination unit, a part of which is used to supply a proton exchange membrane electrolyzer (PEME) and the remaining is for other purposes. By considering the exergy efficiency and the levelized cost of energy (LCOE) as objective functions, a multi-objective optimization based on the genetic algorithm has been applied. An artificial neural network (ANN) plays an intermediating role in the optimization process to reduce the calculation time and raise the optimization speed. The relationship between the objective function and decision variables was analyzed using the ANN to determine the optimal point in this energy system. The results show that under optimal operating conditions, the exergy efficiency of the system with the biomass fuels of MSW, wood, and paper is equal to 41.21 %, 40.25 %, and 39.33 %, respectively. The LCOE values ​​under the same conditions are 30.77 $/MWh, 32.06 $/MWh, and 33.6 $/MWh, respectively. Furthermore, at the optimum point, the amount of fresh water and hydrogen production in the system with the biomass fuels of MSW, wood, and paper is equal to 1.128 kg⁄s, 1.058 kg⁄s, 0.991 kg⁄s, and 9.355 g/s, 9.038 g⁄s and 8.438 g⁄s, respectively. Overall, the proposed system with the biomass fuel of MSW has shown good performance in terms of thermodynamics and cost-effectiveness.

Economic and Environmental Analyses of Multi-Generation Renewable Energy System for Dairy Farms

In the present work, economic and environment analyses of multi-generational micro gas turbine systems are reported for a grid-independent dairy farm in Ontario, Canada. Onsite anaerobic digesters utilize farm waste to produce carbon neutral biogas for combustion in the micro gas turbine modules. A range of micro gas turbines coupled with absorption refrigeration units and an organic Rankine cycle are driven by the recovered waste heat to meet the cooling and electrical needs of farm sizes between 250 and 6000 cows. Farms of these sizes are observed to be capable of having their cooling and electricity needs met with micro gas turbines ranging in capacity from 100 to 1000 kW output. Environmental performance is maximized when the net output of the system just matches the energy requirement of the farm, and produces no excess electricity. Thus to minimize the environmental impact, but remain financially viable, various configurations are suggested for farm sizes under 2000 cows.

Uncertainty in High-Pressure Stator Performance Measurement in an Annular Cascade at Engine-Representative Reynolds and Mach

Abstract The betterment of turbine performance plays a prime role in all future transportation and energy production systems. Precise uncertainty quantification of experimental measurement of any performance differential is therefore essential for turbine development programs. In this paper, the uncertainty analysis of loss measurements in a high-pressure turbine vane is presented. Tests were performed on a stator geometry at engine representative conditions in a new annular turbine module called BRASTA (big rig for annular stationary turbine analysis) located within the Purdue Experimental Turbine Aerothermal Lab. The aerodynamic probes are described, with emphasis on their calibration and uncertainty analysis, first considering single point measurement, followed by the spatial averaging implications. The change of operating conditions and flow blockage due to measurement probes are analyzed using computational fluid dynamics, and corrections are recommended on the measurement data. The test section and its characterization are presented, including calibration of the sonic valve. The sonic valve calibration is necessary to ensure a wide range of operation in Mach and Reynolds. Finally, the vane data are discussed, emphasizing their systematic and stochastic uncertainty.

A neutronic investigation of tristructural isotropic‐duplex fuel in a high‐temperature reactor prismatic seed‐and‐blanket fuel block configuration with reduced power peaking

This paper presents the neutronic analysis of a tristructural isotropic (TRISO)-duplex fuel loaded into the high-temperature reactor (HTR) prismatic fuel block designs for a seed-and-blanket (S&B) reactor model. The selected fuel block design is the simplified model of a representative fuel configuration for the gas turbine–module helium reactor (GT-MHR) and high-temperature engineering test reactor (HTTR). The duplex fuel pellet comprises of UO2 as the seed and ThO2 as the blanket and uses the TRISO fuels. Monte Carlo N-particle extended (MCNPX) simulations were conducted to analyze the power and neutron flux distributions of the reference fuel block and that of the TRIOS-loaded duplex fuel designs. Standard neutronic parameters were computed, such as burnup-dependent infinite multiplication factors (kinf), average block spectrum, and fissile inventory. It was discovered that while the S&B model could attain the highest burnup and the longest cycle duration, its power peaking was more than threefolds than that of the reference model at the beginning of the cycle (BOC). The results also show that the “Duplex-2” model could reduce its power peaking by 24% through the integration of S&B arrangement with the duplex rods. It is noted that spatial distribution of the UO2 seed and 235U enrichment are the chief determining factors in the power optimization of the heterogeneous HTR prismatic fuel blocks loaded with thorium.

Development and multiobjective optimization of a novel trigeneration system based on biomass energy

Biomass energy can play a significant role in achieving sustainable energy production goal, as biomass is considered carbon–neutral fuel when observed from standpoint of the lifecycle. In this paper, a novel trigeneration system has been proposed, incorporating a gasification unit, a solid oxide fuel cell unit, an externally fired gas turbine module, a vapour absorption refrigeration unit, and a hot water generation unit. The proposed trigeneration system has been assessed by energy, exergy, economic and environmental analyses. Furthermore, multiobjective optimization of the proposed trigeneration system has been carried out via response surface methodology. The effects of critical decision variables on the performances of the system have been investigated. The desirability test suggests that the individual desirability value is maximum for levelized cost of electricity followed by fuel energy saving ratio, exergy efficiency of the system and environmental benefit. The combined desirability value (0.949) of the responses is also found to be in the higher side. Thus, it can be said that the setting can be useful in obtaining accurate results for all the responses combined. The proposed plant yields the optimum performance at a pressure ratio of 4.49, current density of 3228.67 A/m2, fuel utilization factor of 0.9, and oxygen utilization factor of 0.1. The results indicate that at the optimum operating condition the proposed system can achieve the maximum exergy efficiency and the fuel energy saving of 55.99% and 52.63%, respectively. The optimum values of the levelized cost of electricity and environmental benefit are estimated to be 0.079$/kWh and 39067.5 $/year, respectively.

Verification tests of a new blade flutter research facility

Long term strategic changes in power generation approaches will require more flexibility for large power generating turbines as an unavoidable consequence of the increasing share of power generated by alternative energy sources. Demanded flexibility for the power turbine output will augment undesired flow phenomena in the low-pressure turbine module, which will consequently enhance blade flutter problems of long slender blades in turbine last stages. In order to advance the understanding of blade flutter onset conditions, the Institute of Thermomechanics of the Czech Academy of Sciences instigated an advanced research program on blade flutter research in high-speed turbomachines. A new innovative test facility for Blade Forced Flutter research was designed and built in the High-Speed Laboratory of the Institute of Thermomechanics. The concept of the new test facility is based on extensive experience with an older Transonic Flutter Cascade facility operated at the NASA Glenn Research Center in Cleveland, Ohio. At present, the first phase of verification tests of the new facility is in progress. The ongoing steady-state tests are intended for exploration of a newly proposed quasi-stationary method to investigate instigating flow conditions leading to an onset of intense blade flutter. Results of some opening tests under steady flow conditions are presented in the paper. The blade drive mechanism for unsteady tests with oscillating blades has not yet been installed in the facility. The presented paper is a work-in-progress report on the ongoing research of complex blade flutter problems.

Effect of HIP treatment on mechanical properties of TiAl4822 alloy additively manufactured by electron beam melting

One of the lightweight heat-resistant alloys, Ti-48Al-2Cr-2Nb (TiAl4822), has already been adopted to turbine blades for jet engines, but is manufactured by casting which requires expensive post process. Aerospace industry is intensively studying the additive manufacturing (AM) process for the engine parts. In this research, tensile and creep properties of additively manufactured TiAl4822 by electron beam melting (EBM) were studied. The mechanical tests were performed at 750 ℃ which is similar to the actual condition in low pressure turbine module. The effect of hot isostatic pressing (HIP) treatment on these properties was investigated because such information is very limited, even though HIP treatment is required in many aerospace parts. Near net shape specimens were prepared for both tensile and creep tests. The effect of the HIP treatment on the microstructure in the specimens was observed by scanning electron microscope (SEM). Electron back scatter diffraction (EBSD) was used to analyze the effect of the HIP treatment on microstructure such as area fraction of each phase and grain size in the specimen. The results showed that the benefit of sintering during the HIP treatment decreased the voids with a size of up to 40 μm and the defects with a size of millimeter order due to lack of fusion in the specimens. The HIP treatment improved both tensile and creep properties at 750 ℃. It was found that the HIP treatment improved creep life by 15% and elongation by 60%, and delayed the starting point of tertiary creep. This is mainly because the HIP treatment eliminated the defects caused by lack of fusion and made the material more ductile than as-built specimen. On the other hand, the microscopic analysis by EBSD revealed that the HIP treatment increased the average diameter of the grain and widened the distribution of grain size, with the increase of the area fraction of Ti3Al(α2). The increase of grain diameter could decrease the strength according to the Hall-Petch Law. In this research, however, the elimination of the defects such as the voids and the defects due to lack of fusion improved the tensile and creep properties. The results suggested that the post heat treatment including cooling process after HIP treatment to control the microstructure is important.

Development of Pump-Drive Turbine Module with Hydrostatic Bearing for Supercritical CO2 Power Cycle Application

The turbomachinery used in the sCO2 power cycle requires a high stable rotor-bearing system because they are usually designed to operate in extremely high-pressure and temperature conditions. In this paper, we present a pump-drive turbine module applying hydrostatic bearing using liquid CO2 as the lubricant for a 250 kW supercritical CO2 power cycle. This design is quite favorable because stable operation is possible due to the high stiffness and damping of the hydrostatic bearing, and the oil purity system is not necessary when using liquid CO2 as the lubricant. The pump-drive turbine module was designed to operate at 21,000 rpm with the rated power of 143 kW. The high-pressure liquid CO2 was supplied to the bearing, and the orifice restrictor was used for the flow control device. We selected the orifice diameter providing the maximum bearing stiffness and also conducted a rotordynamic performance prediction based on the designed pump-drive turbine module. The predicted Campbell diagram indicates that a wide range of operation is possible because there is no critical speed below the rated speed. In addition, an operation test was conducted for the manufactured pump-drive turbine module in the supercritical CO2 cycle test loop. During the operation, the pressurized CO2 of the 70 bar was supplied to the bearing for the lubrication and the shaft vibration was monitored. The successful operation was possible up to the rated speed and the test results showed that shaft vibration is controlled at the level of 2 μm for the entire speed range.

Monitorowanie oraz bazująca na danych predykcja parametrów roboczych przemysłowej turbiny gazowej

The article reviews traditional and modern methods for prediction of gas turbine operating characteristics and its potential failures. Moreover, a comparison of Machine Learning based prediction models, including Artificial Neural Networks (ANN), is presented. The research focuses on High Pressure Compressor (HPC) recoup pressure level of 4th generation LM2500 gas generator (LM2500+G4) coupled with a 2-stage High Speed Power Turbine Module. The researched parameter is adjustable and may be used to balance net axial loads exerted on thrust bearing to ensure stable gas turbine operation, but its direct measurement is technically difficult implicating the need to indirect measurement via set of other gas turbine sensors. Input data for the research have been obtained from BHGE manufactured and monitored gas turbines and consists of real-time data extracted from industrial installations. Machine learning models trained using the data show less than 1% Mean Absolute Percentage Error (MAPE) as obtained with the use of Random Forest and Gradient Boosting Regression models. Multilayer Perceptron Artificial Neural Networks (MLP ANN) models are reviewed, and their performance checks inferior to Random Forest algorithm-based model. The importance of hyperparameter tuning and feature engineering is discussed.

Aerodynamic Optimization of the Low-Pressure Turbine Module: Exploiting Surrogate Models in a High-Dimensional Design Space

Abstract Further improvement of state-of-the-art low-pressure (LP) turbines (LPTs) has become progressively more challenging. LP design is more than ever confronted to the need to further integrate complex models and to shift from single-component design to the design of the complete LPT module at once. This leads to high-dimensional design spaces and automatically challenges their applicability within an industrial context, where computing resources are limited and the cycle time is crucial. The aerodynamic design of a multistage LP turbine is discussed for a design space defined by 350 parameters. Using an online surrogate-based optimization (SBO) approach, a significant efficiency gain of almost 0.5pt has been achieved. By discussing the sampling of the design space, the quality of the surrogate models, and the application of adequate data mining capabilities to steer the optimization, it is shown that despite the high-dimensional nature of the design space, the followed approach allows to obtain performance gains beyond target. The ability to control both global as well as local characteristics of the flow throughout the full LP turbine, in combination with an agile reaction of the search process after dynamically strengthening and/or enforcing new constraints in order to adapt to the review feedback, not only illustrates the feasibility but also the potential of a global design space for the LP module. It is demonstrated that intertwining the capabilities of dynamic SBO and efficient data mining allows to incorporate high-fidelity simulations in design cycle practices of certified engines or novel engine concepts to jointly optimize the multiple stages of the LPT.

Investigation of the Combustion Processes in the Gas Turbine Module of an FPSO Operating on Associated Gas Conversion Products

Abstract In this paper, we consider the issue of thermo-chemical heat recovery of waste heat from gas turbine engines for the steam conversion of associated gas for offshore vessels. Current trends in the development of offshore infrastructure are identified, and the composition of power plants for mobile offshore drilling units and FPSO vessels is analyzed. We present the results of a comparison of power-to-volume ratio, power-to-weight ratio and efficiency for diesel and gas turbine power modules of various capacities. Mathematical modeling methods are used to analyze the parameters of an alternative gas turbine unit based on steam conversion of the associated gas, and the estimated efficiency of the energy module is shown to be 50%. In the modeling of the burning processes, the UGT 25000 serial low emission combustor is considered, and a detailed analysis of the processes in the combustor is presented, based on the application of a 35-reaction chemical mechanism. We confirm the possibility of efficient combustion of associated gas steam conversion products with different compositions, and establish that stable operation of the gas turbine combustor is possible when using fuels with low calorific values in the range 7–8 MJ/kg. It is found that the emissions of NOx and CO during operation of a gas turbine engine on the associated gas conversion products are within acceptable limits.

Failure analysis of hook end self locking nuts of an aero-engine

Repeated premature failures of hook end self locking nuts, a developmental aero-engine component, were encountered after ground test runs. The part is a component of turbine module of the engine and experiences severe temperature-loading condition during engine tests. It was manufactured using a γ′-γ″ precipitation hardened Ni-Fe-Cr wrought alloy. The finished components were subjected to silver plating process to ensure anti-seizure. The failed hook nuts were examined in details using stereo zoom microscope, optical microscope and scanning electron microscope. Fractured surface exhibited two distinguished regions. Intergranular fracture, characteristics of brittle failure morphology, was observed on majority of the fractured surface. Shear lip formation was evidenced towards one edge indicating final fracture region. This region exhibited dimples, typically seen in case of overload failure. The intergranular fracture was concluded to be due to hydrogen embrittlement of the part. The electroplating process on the finished hook end self locking nuts revealed that no de-embrittlement treatment was carried out on the components after silver plating. The electrolysis process resulted hydrogen entrapment during plating. Omission of de-embrittlement treatment caused the entrapped hydrogen to diffuse into the material thereby making the material to be brittle. This resulted brittle failure of the hook end self locking nuts.