Gas Turbine Performance Research Articles

Analysis of the Principle of Gas Turbine and State-of-art Applications

Abstract. As a matter of fact, gas turbines have become a cornerstone of modern energy systems, playing a pivotal role in power generation, the oil and gas industry, and the integration of renewable energy sources. This study provides an in-depth analysis of the principles underlying gas turbine operation, alongside a summary of state-of-the-art facilities that represent the pinnacle of current technological advancements. These turbines, known for their high efficiency and flexibility, are crucial for meeting the growing global demand for reliable and cleaner energy. However, significant challenges remain, particularly in terms of material limitations, emissions reduction, and the need for greater operational flexibility to accommodate renewable energy sources. The future of gas turbines may involve a shift towards alternative fuels like hydrogen, which could drastically reduce their environmental impact. These results highlight the ongoing evolution of gas turbines and underscore the importance of continuous innovation to address these challenges, ensuring that gas turbines can meet the energy needs of the future while minimizing their ecological footprint. The findings of this research are essential for advancing the understanding of gas turbine technology and guiding future developments in this field.

Impacts of Environmental Conditions on Thermal, Emissions and Economic Performance of Gas Turbine Using Different Types of Fuels: An Experimental Investigation

Gas turbine has been used widely for electrical power generation based on simple cycle system. However, the relatively low thermal efficiency engages the researchers in investigating possible methods to enhance gas turbine performance. In the current study, three different types of fuels were used (crude oil, light oil, and natural gas) to operate the gas power plant in Qayyara, Mosul, Iraq and to evaluate the plant's performance, environmental impact and economic cost. The Aspen Husys package was used for simulation based on data recorded by the control department. Results showed that the software applied was highly valid. The external environmental temperature influenced the performance and efficiency of the station significantly with maximum values obtained for winter by 114MW and thermal efficiency of 32.02% for natural. The emissions of CO2, SO2, and NOX gases are decreased, whereas CO emission is increased when the temperature of the external environment is raised with fewer emissions obtained for natural gas. The cost of three fuels in (summer) is the highest among the four months, with the higher cost for light fuel by 68.2 Iraqi diners/kiloWatt.hour. Therefore, light fuel cannot be used for the permanent operation of gas turbines, and natural gas fuel gives better performance and lower emissions than the other two types of fuels.

Modified crystal plasticity constitutive model considering tensorial properties of microstructural evolution and creep life prediction model for Ni-based single crystal superalloy with film cooling hole

Accurate assessment of the creep life of film cooling hole structures is critical for long-life design and safe operation of aero engines and gas turbines. Firstly, through the high temperature creep experiment of nickel-based single crystal superalloy with film cooling hole, the microstructure evolution process under multiaxial stress state around film hole is characterized. Then, considering the directional effect of rafting structure and the influence of multiaxial stress, a fourth-order tensor is used to describe the evolution of γ phase width, and the microstructure evolution model accounting for multi-axial stress states is established. The microstructure evolution is coupled into the crystal plasticity constitutive model by Orowan stress. Meanwhile, based on continuous damage mechanics, a new multiaxial damage evolution law is established by introducing a multiaxial ductility factor into the constitutive model. The improved crystal plasticity constitutive model can effectively predict the microstructural evolution under multiaxial stress conditions. Furthermore, the combination of the modified crystal plasticity constitutive model and the critical distance method considering stress gradients is used for life prediction of film cooling hole structures. The prediction results show the effectiveness and necessity of considering the microstructure evolution in the life prediction.

Understanding Environmental Barrier Coating Lifetimes and Performance for Industrial Gas Turbines

Abstract Hydrogen or hydrogen blend fuels are expected to replace natural gas in land-based industrial gas turbines (IGTs) to support a greener power economy. Silicon carbide (SiC) base ceramic matrix composites (CMCs) are considered for replacement of Ni-based superalloys to facilitate future efficiency improvements. SiC CMCs require environmental barrier coatings (EBCs) to mitigate volatilization from high-temperature steam, thus making the EBC lifetime critical information for identifying CMC component lifetimes. The goal of this project is to determine the maximum bond coating temperature underneath the EBC for achieving an IGT component lifetime goal of 25,000 h, which is far greater than current CMC component lifetime requirements for aeroturbine applications. To provide data for the lifetime model, laboratory testing used atmospheric plasma-sprayed rare-earth silicate EBCs on monolithic SiC substrates with an intermediate Si bond coating. Specimens exposed to 1-h thermal cycles in flowing air–steam environments and reaction kinetics were assessed from 700 °C to 1350 °C by measuring the thickness of the thermally grown silica scales. The silica growth and phase transformation appear critical in predicting EBC lifetime and several strategies have been explored to reduce the oxide growth rate and improve EBC durability at elevated temperatures. Advanced characterization using Raman spectroscopy has helped clarify this system.

High‐temperature thermal conductivity measurement of porous ceramic coatings with a high heat flux CO2 laser rig

AbstractYttrium‐stabilized zirconia (YSZ) plays a crucial role in thermal barrier coatings widely used to protect metallic components in gas turbine engines against high‐temperature combustion product gases and harsh environments. The thermal conductivity of these coatings is a critical parameter influencing the gas turbine design, performance, and service life. In this study, a laser temperature gradient method is utilized to measure the thermal conductivity of porous YSZ coatings. The method employs specialized laser energy delivery to create a one‐dimensional temperature gradient through the sample thickness, closely simulating the operational condition. This approach provides an effective, direct means to determine the thermal conductivity of high‐temperature heat‐resistant porous ceramic materials.

Experimental and numerical study on the impact of inlet temperature inhomogeneity on the aerodynamic performance of a three-stage turbine

Gas turbines play an important role in power generation and propulsion. The simplification of the real-engine condition during turbine design results in substandard gas turbine performance. Further improvement in understanding of the corresponding effects is essential. At present, the mechanism of the deterioration in turbine aerodynamic performance caused by the full-annulus scale turbine inlet temperature inhomogeneity in real engine are still unclear. In this paper, the corresponding effects are investigated through both gas turbine experiments and full-annulus URANS simulation. The experimental results show that the impact of cold streak on multistage turbine efficiency is about −0.3 %, which is in good quantitative agreement with the simulation results. The simulation results also show a complex reduction of blade work extraction occurs in the cold streak. A strong correlation between angle of attack and Mach number and the deterioration of turbine efficiency is found. It is also found that the “squeezing” effect induced by the cold streak azimuthal migration capability causes differences in Mach number, through-flow capability, and flow field radial distribution on both sides of the cold streak. This paper can help to the understanding of turbine performance characteristics and can also further contribute to improve gas turbine energy efficiency.

Performance and failure modes of thermal barrier coatings deposited by EB-PVD on blades under real service conditions in gas turbine

Thermal barrier coatings (TBCs) with a double columnar crystal structure of CoCrAlY/YSZ, prepared using electron beam physical vapor deposition (EB-PVD), were applied to turbine blades and tested in real gas turbine conditions. This study investigates their failure mechanisms under both actual operating conditions and simulated external loads, using three-point bending tests. The performance of full-sized, TBC-coated blades was analyzed through finite element modeling, while the thermomechanical and mechanical properties of the coatings after service were measured to support the simulation and provide insights into the failure processes. A new degradation mode, characterized by penetration cracking, was observed in the EB-PVD coatings. This behavior is linked to the columnar grain structure of YSZ and CoCrAlY, lower operational temperatures, and the reduced thickness of the YSZ layer. Surface cracks in the YSZ coating primarily occurred in regions with large curvature, where stress concentrations are higher. This study offers new insights into the failure modes of TBCs under real gas turbine operating conditions.

Feedback control of thermoacoustic instabilities in sequential combustor with nanosecond repetitively pulsed discharges

Controlling thermoacoustic instabilities is a necessary task for the development and operation of gas turbines. With the increasing proportion of renewable energy sources, gas turbines must have flexibility in terms of both fuel and load. This implies that thermoacoustic instabilities must be controlled under different operating conditions. Active control strategies are indeed very suitable in this case, as they can adapt to the changes in operating conditions. Nanosecond repetitively pulsed discharges (NRPD) has shown to be promising active control actuators because they require no moving parts. In this study, the effectiveness of feedback and open-loop control law with NRPD actuation to suppress thermoacoustic instabilities in a lab-scale sequential combustor is evaluated. The effect of the controller parameters on the NO emissions of the combustor is also quantified. The results indicate that there is a trade-off between acoustic pulsation reduction and NO emission.

Improving operation flexibility of the gas turbine through coolant intercooling and air injection using a sub-compressor

The use of renewable energy, particularly solar and wind power, is increasing, but it is necessary to alleviate the variation of such resources, a key drawback of using renewable energy. In this context, gas turbines capable of fast startup and rapidly changing power following a load have attracted considerable attention. Nevertheless, enhancing the operational flexibility of gas turbines is crucial to ensure their stable operation under various conditions. Several studies have attempted to enhance the flexible operating capabilities, by examining the operational stability assurance under a variety of conditions and life cycle increases by changing the operating conditions. This paper proposes a new gas turbine configuration and operating strategy in which a sub-compressor is used to increase the ramp rate and mitigate the thermal load of the turbine blades. The performance and dynamic behavior of the novel gas turbine was simulated using an in-house program based on the gas path analysis. Specifically, a sub-compressor with an inter-cooler was used to cool the coolant from 398 °C to 300 °C, which increased the gas turbine power by 1.3 MW and efficiency by 0.4%p compared to the conventional gas turbine. In addition, when applying a new operating strategy during the ramp-up phase, a part of coolant air was injected into the combustor to suppress the maximum turbine inlet temperature by 15 °C compared to the conventional gas turbine. As a result, the ramp rate could be doubled (from 18.75 to 37.5 %/min) by alleviating the fluctuations of hot gas temperature in the ramp-up phase.

Utilization of High-Temperature miniaturized testing to Assist in life management for gas turbine Blades: An Overview

Safely operating gas turbine blades in aero-engines or industrial gas turbines under severe thermo-mechanical conditions always poses a continuous challenge. There is an urgent need for more reliable life prediction tools, necessitating earlier and more rigorous assessments of in-service damage. This paper introduces a systematic examination of high-temperature miniature specimen testing method within a practical life management framework. To improve current practices in assessing the condition of service-aged gas turbine blades, a proactive utilization of miniature specimen testing is recommended for early in-service assessment within the component lifecycle and integrated into a comprehensive life assessment/management framework. The paper outlines a structured approach to life management, combining miniature specimen sampling and creep and fatigue testing methods. This forms the basis for a novel, holistic life assessment methodology, which is proposed in this paper, incorporating the innovative use of high-temperature miniature specimen testing.

Reduction of the Emission Footprint of Gas Turbines in Future Energy System Scenarios Through Optimized Hydrogen Admixture Strategies

Abstract Due to the inherent volatility of renewable power generation technologies, dispatchable components, such as gas turbines (GT) will have to be used increasingly for residual load balancing. In addition, GTs are expected to operate fewer hours per year, more flexibly, and at lower capacities. However, fuel utilization in GT is inherently linked to emissions. As a potentially CO2-free energy carrier, hydrogen is a promising fuel for GTs and manufacturers are working on suitable combustor technologies. However, the availability of large quantities of CO2-free H2 remains unclear in the near future. In this study, a physical-based gas turbine performance model and an emission calculation tool are used to derive an optimized H2 admixture strategy for different load profiles. Characteristic load demand scenarios are derived from actual load profiles of gas power plants and the emission footprints are comprehensively evaluated by different environmental impact categories. In general, the emission footprint is increased significantly and moderately for capacity reduction and flexibility increase of GT operation. The availability of H2 in the near future is derived from forecasts for Germany, and the corresponding quantities are allocated to the partial loads according to the optimized strategy. In most scenarios, the addition of H2 is associated with a reduction in emissions compared to conventional fossil fuel operation. The greatest leverage of H2 admixture in reducing the environmental footprint is found when applied from the lowest load up, thus assisting in the start-up and shut-down process.

Teaching Aero-Engine Performance: From Analytics to Hands-On Exercises Using Gas Turbine Performance Software

Abstract In this paper, we present an approach for teaching turbojet engine performance that combines mathematical analysis with the use of performance software to provide students with a comprehensive and in-depth understanding of engine performance and how it is affected by design parameter choices. In the first part, we present the derivation of a universally valid analytical model for turbojet engine cycle design, which is the basis of the propulsion courses at RWTH Aachen University. The analytical model allows for the calculation of specific thrust as well as thermal and propulsive efficiencies as a function of pressure ratios and burner exit temperature. These are all expressed as differentiable functions. Their mathematical extremes form a basis for examining the intricate relationships in turbojet engine design. In the second part, we move from theory to practice. We utilize the GasTurb software, computing turbojet engine cycles for a wide range of cycle design parameters. The analytically derived trends are validated and errors introduced by simplifications are assessed. Differences between the analytical approach and software-based performance simulations of real engines, like temperature-dependent gas properties and secondary air systems, are emphasized and discussed, thus providing a bridge to real-world applications. In summary, this paper describes a two-step approach to teaching turbojet engine design using analytics and performance software. Each approach alone can be used to enrich and extend existing performance courses. Combining the approaches has significant benefits, improving understanding and inspiring students to pursue further research in the field of propulsion.

Investigation of operational settings, environmental conditions, and faults on the gas turbine performance

Abstract Gas turbine engines are complex mechanical marvels widely employed in diverse applications such as marine vessels, aircraft, power generation, and pumping facilities. However, their intricate nature renders them susceptible to numerous operational faults, significantly compromising their performance and leading to excessive emissions, consequently incurring stringent penalties from environmental regulatory bodies. Moreover, the deterioration of gas turbine performance is exacerbated by variations in working conditions based on operational settings and environmental conditions. Past studies have focused on certain working conditions that limit effectiveness in real-world applications where operational settings and environmental conditions vary during operations. The influence of these working conditions on the performance of gas turbines also needs to be assessed, as they can lead to different fault patterns resulting in unplanned maintenance, unnecessary maintenance costs, unsafe conditions and stringent penalties. This study uses the gas turbine simulation program to simulate a high-bypass turbofan engine inspired by Pratt & Whitney PW-4056, analysing the combined effects of operational settings and environmental conditions on engine performance while also incorporating simulations of common gas turbine faults like fouling and erosion in various locations and severities along the gas path. The model’s accuracy is confirmed by low mean absolute percentage errors of 0.004% of thrust at the cycle reference point and 0.15% and 0.28% at 2 km and 7 km altitudes, respectively, demonstrating the model’s robustness across varying operational scenarios. In conclusion, this research highlights the significant effects of operational settings and environmental factors on gas turbine performance, particularly impacting specific fuel consumption and thrust. The study reveals that operational settings and environmental factors significantly impact fuel consumption and thrust. Specifically, compressor fouling and low-pressure turbine erosion increase nitrogen oxide (NOx) emissions by 4.5% and 11.1%, while fouling of nozzle guide vanes and high-pressure turbine erosion raise unburned hydrocarbon by 10.0% and 20.2%, and carbon monoxide (CO) by 3.2% and 5.2%, respectively, compared to a healthy engine. These insights highlight the importance of component-specific degradation in influencing gas turbine performance and emissions.

The Effect of Gas Turbine Inlet Air Temperature On Electricity Production Effiency in Trigeneration Power Plants

In this study, the operation of gas turbines used to generate energy in trigeneration plants with turbine inlet air at various temperatures was investigated. In today's world, the importance of energy and its efficient use is increasing. Developing population and technologies have increased the energy we need, and thus energy costs have reached serious levels. All these reveal the necessity of using energy efficiently. Trigeneration power plants provide less fossil fuel consumption than conventional production because they have high efficiency, prevent line losses with on-site electricity generation, and provide combined energy production. In our study, the increase in electricity production efficiency by cooling the inlet air of the Solar Turbines Taurus 60 gas turbine used in the trigeneration power plant was examined. It was determined that there was a 30.08% increase in active power efficiency in electricity production by cooling the turbine inlet air from 41.2 °C to 9.1 °C.

Exploring explainable ensemble machine learning methods for long-term performance prediction of industrial gas turbines: A comparative analysis

In today's modern life, where electricity demand is one of the fundamental necessities, gas turbines play a pivotal role in meeting this demand. As such, it is imperative to address the challenges faced in the field. Current models often rely on simplifying assumptions, neglecting the intricate relationships between variables. This limitation leads to reduced accuracy and reliability, ultimately affecting the overall efficiency of gas turbine systems. Furthermore, the complexity of gas turbine behavior, coupled with the scarcity of comprehensive datasets, exacerbates the problem.To address these challenges, this research aimed to develop an advanced model capable of accurately forecasting real gas turbine behavior. The proposed approach leveraged ensemble decision trees, robust preprocessing techniques, and rigorous evaluation using an extensive dataset spanning from 2011 to 2015. The training and validation phases were conducted on data from 2011 to 2014, with the 2015 dataset reserved for evaluation.The results demonstrated that the bagging structure outperformed the boosted structure, exhibiting lower complexity and higher reliability. Remarkably, the bagging approach with only 30 estimators achieved a superior root mean square error of 1.4176, outperforming the boosted trees with 200 learners. The model effectively captured the overall gas turbine performance, though it encountered limitations in certain specific operating ranges.To further investigate the model's behavior, an evaluation was conducted to assess the effects of the input variables on the output power. While the interpretability of the results posed some challenges, the overall findings were deemed acceptable and provide valuable insights for optimizing gas turbine performance. The significance of this research lies in its potential to inform decision-making and enhance the efficiency of gas turbine systems, ultimately contributing to the reliable and sustainable supply of electricity.

A novel wide flow matching approach of hydrogen-powered F-class gas turbine based on multistage installation angle

To achieve excellent power performance of F-class gas turbine when using pure H2 or H2-rich fuel, this work develops a novel and flexible flow matching approach by modifying the turbine multistage installation angle, with obvious features of easy implementation and low cost. An accurate thermodynamic model of heavy-duty gas turbine considering turbine-stage cooling is established and verified by the actual operation data from Ban-Shan power plant, and to investigate variable condition property and emission characteristic of gas turbine with natural gas and H2-rich fuel. Faced with the inefficiency and narrow working area caused by the flow mismatch between 18-stage compressor and 3-stage turbine when natural gas is switched to H2-rich fuel, the scheme of modifying the installation angles of multistage rotary blade and static blade is proposed. By calculating the pressure and temperature at each turbine stage, the gas turbine power, efficiency, Mach number and NOx emission with different H2 concentration are predicted. Results show that, as the H2 concentration increases, the fuel volume flow required to reach the same turbine inlet temperature increases.When H2-rich fuel increases the turbine inlet volume flow by 3.23 %, the cooling effect significantly decreases, and the turbine outlet temperature rises by about 13.60 K, which deviates from the appropriate operating point. The most serious is the phenomenon of over Mach number and airflow blocking at the outlet of the 2-stage and 3-stage turbine static blades. The installation angle variation increases with the increase of H2, and the higher the stage, the bigger the angle change. The gas turbine can be realized the wide flow matching feature corresponding to the installation angle variation of 0.19°/-0.41°, 0.38°/-0.48°, and 0.53°/-0.94°, respectively for all stages static/rotary blades. After re-matching, the maximum fluctuation of rated power and efficiency are 1.5 % and 1.7 %, and the NOx emission will reach the maximum value of 14.3 ppm with 70 % H2. Research work will provide a novel and feasible retrofit scheme for the heavy-duty gas turbine using clean and low-carbon fuel to widen flow matching scenario.

Application of a surrogate model for condition monitoring of a digital twin gas turbine

Condition monitoring technology plays a crucial role in ensuring the reliable operation of gas turbines. Digital twin has propelled condition monitoring research into a new phase. This paper established a surrogate model of gas turbines for condition monitoring based on Markov-projection approximation subspace tracking. Furthermore, it explores the application of surrogate model in developing digital twin for gas turbines. The study initially establishes a Markov matrix and acquires an observation vector, utilizing the framework of the linear model. Utilizing real-time measurement data of gas turbine, the signal subspace of the observation vector autocorrelation matrix is updated through the projection approximation subspace tracking. By aligning this signal subspace with the generalized observability matrix, the identification results of the surrogate model parameters are obtained online. Furthermore, a variable weight projection approximation subspace tracking method has been proposed to enhance the algorithm robustness. Simulation and real experiment demonstrate that the surrogate model output effectively tracks the real-time changes in gas turbine measurement data. When faults and degradation arise, condition monitoring can be achieved by analyzing the evolution of model parameters to obtain feedback information from the gas turbine. The proposed method maintains its robustness in the presence of impulsive noise. These features offer a novel approach for the development of gas turbine digital twin.

Identification of flame transfer function and mechanism analysis of the influence of boundary impedance characteristics on thermoacoustic instability

Thermoacoustic instability is a common problem in the operation of modern gas turbines. The prediction of thermoacoustic instability and the clarification of its mechanism are the research focus and difficulty in the gas turbine industry. As a response function of flame to acoustic disturbance, flame transfer function is a key parameter in the study of thermoacoustic instability. In this paper, based on the scaled adaptive simulation (SAS) model combined with the eddy dissipation concept (EDC) combustion model, the time-domain flow field data are processed by the system identification method, and the results of flame transfer function extraction are in good agreement with the experimental values. Then, the detailed derivation process of the low-order thermoacoustic network model (LOTAN) is given to capture the behavior characteristics of the acoustic wave in the thermoacoustic system. On this basis, the effects of acoustic boundary conditions and hysteresis time on the thermoacoustic instability of the combustion system are analyzed, and the relationship between the mode shape, pressure, vibration velocity phase, and thermoacoustic instability is explored. It is found that the phase relationship between pressure and vibration mode can be used to determine the thermoacoustic instability of the system. This is of great practical significance for determining the thermoacoustic instability of the system and clarifying the internal mechanism of its generation and provides theoretical support for the subsequent thermoacoustic instability control.

Deep learning-aided active subspace exploration of free-stream effects for fan-shaped film cooling

Film cooling plays a critical role in protecting engine components from high temperatures that can influence safety and performance of gas turbines. However, the process is fraught with uncertainties due to complex inflow conditions and geometrical configurations. These uncertainties significantly impact cooling effectiveness, underscoring the importance of identifying the dominant factors in a quantified manner. Traditional methods, such as the Monte Carlo approach, encounter the “curse of dimensionality,” making them computationally intensive as the number of variable increases. This study tackles these challenges by employing a deep learning strategy with a convolutional neural network (CNN) model to predict film cooling effectiveness efficiently, reducing computational loads compared to traditional computational fluid dynamics (CFD) simulations. It enables the CNN model to act as a surrogate for the CFD simulation and provides gradient information for subsequent analyses. Additionally, this study employs active subspace (AS) analysis for dimensionality reduction, identifying dominant parameters based on the trained CNN model. This approach not only enhances the speed of simulations but also provides an effective way to analyze dominant parameters and carry out optimizations. Results demonstrate a strong correlation between the CNN predictions and detailed CFD simulations, with all the mean absolute errors below 0.08, validating the model's efficacy in capturing complex cooling dynamics. The dominant analysis based on the AS method gives the blowing ratio as the most important factors, and the subsequent parameter dimension reduction and suggested optimization region are also explored by applying the low-dimensional active variable. The tested optimal factors yield higher spatially averaged cooling effectiveness above 0.35 and show reasonable pattern changes compared to the maximum and minimum results in the sample.

Investigating the effect of using hydrogen as fuel on gas turbine performance operating under lean conditions at the Hassi R'mel gas site

This study evaluates the feasibility of using pure hydrogen as fuel for the MS5002C gas turbine at the Hassi R'mel gas site in Algeria. THERMOPTIM software was used to analyze key parameters, including compression ratio, excess air (λ), and climatic conditions, identifying an optimal excess air of 4.5. This configuration was validated over a year under local climatic conditions. The results indicate that at a harsh temperature of 50 °C, the hydrogen-fueled gas turbine increased thermal efficiency by 3.66% and power output by 6.18%, while reducing fuel consumption by 62% compared to an optimized natural gas turbine. Hydrogen use eliminated carbon emissions but caused a slight 1.17% increase in NOx emissions. Under reel climatic conditions, hydrogen fuel eliminated carbon footprint and mitigated the adverse effect of harsh climate on turbine performance, with a peak NOx emission of 1.891 ppm in August.