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Health condition monitoring of Gas Turbine Engine (GTE) components is key for predictive maintenance planning. The task is challenging, as the gas-path components are mostly inaccessible for direct measurements, while at the same time hidden incipient faults must be diagnosed using the available measurements. The presence of multiple faults with similar symptoms adds to the complexity of the diagnostic process. In previous research work, a data-driven multi-mode fault parameter estimation scheme was introduced for real-time multimode diagnosis of GTEs under diverse operating conditions and fault scenarios. In this work, a hybrid diagnostic framework is developed that fuses the results from a measurement-based fault parameter estimation strategy together with a fault propagation model. The hybrid framework uses a novel particle filter (PF) structure with redundant measurements that facilitates updating the particle weights while reducing the dimensionality of the measurement likelihood. Applying the developed framework on GTE gas-path data with four different gradually worsening faults, the results show the diagnostic accuracy increases up to ten times, compared to the previously developed fault parameter estimation scheme. [ABSTRACT FROM AUTHOR]

An appropriate operation strategy is the requirement to obtain high-efficiency performance of a combined cooling, heating and power (CCHP) system. In this paper, the inlet air throttling (IAT) operation method for gas turbine combined with following the electric load (FEL), following the thermal load (FTL) and following the hybrid electric-thermal load (FHL) operation strategies are employed to analyze the primary energy consumption ( PEC ), carbon dioxide emission ( CDE ) and operation cost ( COST ) with respect to a CCHP system in Beijing, China. The matching between the different operation strategies and the energy demands of the reference building are analyzed to reveal the energy saving mechanism. The results indicate that the CCHP system is superior to the separate system on annual evaluation regardless of which operation strategy is used. Moreover, the economic performances of different operation strategies are evaluated based on the payback period ( PBP ). Finally, the sensitivity analyses of main component parameters and economic factors are presented for the PEC and PBP of the CCHP system, respectively. This study may provide a guidance to utilize the IAT operation method economically and efficiently. [ABSTRACT FROM AUTHOR]

This article covers the use of supplementary firing in a gas-combined cycle power plant when high flexibility is required depending on the penetration of variable renewable energies and under different gas turbine loads. Process models were simulated under different operating conditions with the software EBSILON®Professional. Five main conditions were studied for the designed combined cycle: gas turbine part-load without supplementary firing, gas turbine full load with supplementary firing, the use of supplementary firing to overcome the effect of changing ambient conditions, part-load gas turbine performance with supplementary firing technology and the use of supplementary firing in case of gas turbine shutdown. [ABSTRACT FROM AUTHOR]

The major cause of the performance degradation of industrial gas turbines is compressor fouling due to airborne contaminants. Performance diagnostics is required to evaluate degradation precisely. In general, the measured performance in the fully opened inlet guide vane (IGV) condition is regarded as full-load performance and used for diagnostics. A new diagnostic method is proposed in this study. A scheme to determine whether the measured performance is at full-load operation is suggested. If operation is not at full-load, a virtual gas turbine state corresponding to the measured data is modeled using adaptive modeling. Then, the virtual full-load performance and the corrected performance are predicted using a reference firing temperature. This calculation methodology is applied to almost two-years of data of a 150 MW class gas turbine. The analysis revealed that the maximum reduction of power output and efficiency are 14.8 MW and 0.8 percentage points compared with the rated performance. In addition, it was shown that if the measured performance is used directly, the maximum deviation in the predicted power degradation was as much as 4.9 MW (2.8%) compared with the rated performance. This paper demonstrates the necessity of a model-based analysis for enhancing the accuracy of performance diagnostics. [ABSTRACT FROM AUTHOR]

Micro gas turbines are manufactured to have a compact structure and small volume, which makes them more vulnerable to internal leakages compared to heavy-duty gas turbines. Accordingly, precise diagnosis of the performance degradation in a micro gas turbine is important. This study investigates the characteristics of degradation. Performance maps were used for the compressor and turbine, and a multi-segment counter-flow heat exchanger model was used for the recuperator. The component models were refined using actual operation data, resulting in precise simulation of the reference operation without leakage. A performance analysis was carried out, and the results were analyzed for three types of leakage with the following paths: from the compressor outlet to the recuperator’s cold-side outlet, from the compressor outlet to the combustor outlet, and from the combustor inlet to the turbine outlet. The third path produced the largest reduction in engine efficiency. The degradations were also compared with those related to compressor fouling and turbine erosion, which are the most common causes of degradation in a gas turbine. Even when qualitatively similar performance changes were observed, the root cause could be determined by analyzing differences in performance parameters such as the fuel flow. [ABSTRACT FROM AUTHOR]

Reliability analysis of frequency converters based on failures and outages reports constitute an important basis for asset performance and management. Two- and four-state reliability models that recognize the operating characteristics of base load units and peaking units are presented and compared in this study. In this study, a four-state model is modified to a three-state model by combining the ‘needed’ and ‘not-needed’ forced-out states. Moreover, the transitions in the three-state model for power frequency converter have been designed according to real operational data. An outage-reporting database modelled considering IEEE STD 762 is presented and compared with the existing failure-reporting database of the case considered here. Furthermore, a method to extract information missing in the failure-reporting database by electrical readings is proposed to meet the requirements of the outage-reporting database. The study found that the results of indexes based on the IEEE four-state model are not reasonable for the frequency converter given their differences with the gas-turbine results under operational conditions. The forced outage rates and availability factors of twelve actual traction frequency converters of Swedish railways network are presented to validate the modified model. [ABSTRACT FROM AUTHOR]

One of the methods of gas turbine performance improvement is steam injection into combustion chamber. Moreover, heat recovery is introduced as another method for enhancing energy and exergy efficiencies. In this paper, these two methods were combined in a system of Integrated Heat Recovery Steam Injected Gas Turbine (IHRSI) equipped with an anti-surge system. A heat exchanger was used for waste heat recovery of the gas turbine exhaust and steam production. In these conditions, due to the energy balance in the HRSG, there was a relation between steam temperature and steam mass flow rate. One problem in IHRSI is determining optimum steam temperature. The increment of temperature decreases the steam mass flow rate and consequently has opposite effects on the various parameters. Therefore, in the present study, a comprehensive model based on the energy, exergy, environmental and economic analyses (4E) was presented. Eventually, the developed model introduced the optimum conditions of injected steam into combustion chamber. The optimum steam temperature of 318.5 °C was found in the case of 38 °C ambient temperature and 10% relative humidity. IHRSI at the optimum steam temperature increased net power output and thermal efficiency by 56 MW and 4.6% and reduced the cost of power generation by 25.5%. [ABSTRACT FROM AUTHOR]

This paper investigates the mainstream hot gas ingestion into a new stator-well cavity which consists of upstream and downstream rim cavities as well as a pre-swirl cavity. The effects of the radial location of sealing air inlet hole and the shape of sealing air supply geometry on the flow characteristics and sealing performance of the stator-well cavity have been investigated. Computations are performed for three radius ratios of sealing air inlet-to-rim seal periphery of 0.883, 0.909 and 0.935 and three sealing air supply geometries in terms of hole design and slot design with two height-to-width ratios of 12 and 21. The results indicate that both the radial location of sealing air inlet hole and the shape of sealing air supply geometry has a significant effect on the flow characteristics and sealing performance in the upstream rim cavity, while it negligibly affects the flow structure and sealing effectiveness in the downstream rim cavity. For upstream rim cavity, it is more effective to protect upper walls for the inlet hole at a higher radius, and the sealing effectiveness on inner walls is higher for the inlet hole at a lower radius. Additionally, the slot design shows a lower sealing effectiveness on upper walls than that of the hole design, and with an increase in height-to-width ratio it further decreases. However, the slot design is of benefit to the protection of inner walls as well as the performance of pre-swirl cavity, and as height-to-width ratio increases the sealing effectiveness on inner walls increases. [ABSTRACT FROM AUTHOR]

Improving the efficiency and reducing the pollutants are the critical concerns for any design of power generation plants. Identifying the characteristics of the Combined Cycle Gas Turbine (CCGT) system and locating the optimum operation conditions via simulation models are irreplaceable route due to the huge system and the impossibility of experimental investigations. To that end, this paper presents modelling analysis with the aim of enhancing the performance and optimization conditions seeking of the (CCGT) power plant with various configurations. The developed simulation models are integrated to encapsulate thermal analysis according to thermodynamics principles, optimization techniques, error analysis, and performance metrics assessment of the various CCGT system configurations using the MATLAB 10A software. A statistical tool, ANOVA, is utilized to assess the results and to develop correlations between the power outputs and performance metrics of the CCGT plants. The new correlations which are developed within the frame of this work are of acceptable accuracy for all the considered range of the simulation data. The coefficient of determination ( R 2 ) is calculated as 0.985 which is considered satisfactory as well. The validity of the correlations is investigated against actual performance and operation data extracted from an actual power generation plant, the MARAFIQ CCGT plant in KSA. Consequently, an error analysis which is carried out considering the actual operation and performance records of MARAFIQ CCGT plant as a benchmark proved the validity of the model. An error of about 0.8104% is found. The operation parameters and performance metrics of the CCGT plant are ultimately assessed against variations of selected parameters via the developed model. Adaptive Neuro-Fuzzy System (ANFIS) is used as an optimization technique. The highest attained power output and thermal efficiency were 1540 MW and 61%, respectively. Turbine inlet temperature is found to be the key parameter for the optimum performance (power and thermal efficiency). The models developed in this work are a powerful tool for analyzing and optimising CCGT which take the place of very expensive and strenuous experimental works. [ABSTRACT FROM AUTHOR]

The continuing depletion of fossil fuels and the growing restrictions for greenhouse emissions, leads to reprocess wasted heat generated by power plants. For this purpose, Combined Cycles Gas Turbine (CCGT) represent a strong technology to obtain, an increase of performances and competitive costs within global market. To design the CCGT configuration, energy engineering companies should define and analyze the performances of bottomer cycle, imposing operating parameters of steam turbine and heat recovery boiler. Usually, these plant components are supplied by different manufacturers so the plant could not be globally optimized. Considering a steam turbines manufacturer as GE Oil&Gas, a high level of components integration, is a chance to optimize globally the bottomer cycle, determining the best machine in terms of efficiency and improving plant productivity. This aim could be obtained through the development of a high level of combination between company simulation codes and energy balance codes. In this paper, a two-pressure level combined cycle is examined and optimized. The best thermoeconomic configuration is obtained: first, imposing steam turbine efficiency and using literature costs correlations; then, acquiring the efficiency by a steam turbine industrial tool and considering real machines costs. Therefore, two distinct best configurations could be determined and compared. [ABSTRACT FROM AUTHOR]

The off-design performance of a combined cooling heating and power (CCHP) system is of great importance and is affected by the system configuration and operating strategy. This paper proposes an alternative operating strategy called flue gas reinjecting (FGR) for a CCHP system consisting of a small-scale gas turbine, a double-effect absorption chiller and a hot water exchanger. The FGR operating strategy elevates the compressor inlet temperature by reinjecting a portion of the flue gas into the ambient air, which seems to contradict the well-proven concept of gas turbine inlet air cooling. In contrast, improving inlet air temperature cannot obviously influence the off-design performance of the gas turbine, and more high-temperature flue gas is produced in the gas turbine, which leads to more cooling and heating output in the absorption chiller and hot water exchanger, respectively. To extend the power output range (100–20%), reducing the turbine inlet temperature (TIT) operating strategy is introduced as an auxiliary means. The off-design performance of the CCHP system is investigated under the combined FGR and TIT operating strategy and independent TIT operating strategy. It is found that improved total efficiency and energy saving performance of the CCHP system are presented with the combined operating strategy at partial load. At a load rate of 50% (876 kW), the fuel energy saving ratio (FESR) increases from 20.52% to 22.96% as the temperature of the inlet air is increased from 25 to 45 °C using the combined operation strategy. The exhaust gas reinjection reduces the excess air resulting in inhibition of the formation of NO X in the combustor. Moreover, using the proposed operating strategy contributes to promoting more effective utilization of low-temperature heat and the direct blending of two fluids reduces heat and pressure losses emanating from the heat exchanger. This study may provide a new operating strategy for small-scale gas turbines to improve the off-design performance of CCHP systems. [ABSTRACT FROM AUTHOR]

Metallurgical and mechanical characterization of surface and subsurface regions in broached and shot-peened fir-trees in an industrial gas turbine disc made of Inconel-718 were carried out. High resolution scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectrometry (EDS), electron backscatter diffraction (EBSD), X-ray diffraction, optical microscopy, and microhardness instruments were employed for qualitative and quantitative assessment of alterations at surface and subsurface levels. Five specific locations along the broached and shot-peened path were selected and thoroughly examined. Original metallography methods were developed to clearly and reliably reveal microstructure constituents. Special emphasis was placed on the generated defects in view of the manufacturer's quality indices, formation mechanisms of defects, and their potential impact on the service capability of the disc. Also, advanced analysis of the EBSD data allowed assessment of the deformed layer thickness as well as the misorientation angle and grain size variations from the broached and shot-peened surface towards the bulk parent material (PM). Furthermore, through successive material removal by electropolishing, measurement of residual stresses as a function of depth from the surface was performed by the sin 2 Ψ method. The obtained results are analyzed in terms of impact of the processing conditions on the evolution of microstructure, microhardness, and residual stresses. The findings are also related to the geometrical location in the disc. [ABSTRACT FROM AUTHOR]

As a major component and work unit of micro gas turbine, the performance of micro turbine directly determines the realizability of micro gas turbine. In order to explore the feasibility, to obtain the performance, and to verify the design results of a micro radial turbine, this paper mainly presents the investigation on overall performance of a micro radial turbine with 10 mm diameter for 50W-class micro gas turbine by the cold model test. Firstly, the aerodynamic performance test platform for high speed micro radial turbine was exhibited. Then, the feasibility and overall performance test of micro radial turbine was carried out. At present, the rotational speed of micro radial turbine has achieved at 359,900 rpm by using hydrostatic gas bearing, which is approximately 80% rotational speed of the design point in cold model test. Thirdly, based on the experimental data and numerical simulation, the operating performance and overall performance of the micro gas turbine were analyzed and discussed in details. The final results indicate that the feasibility of the millimeter-scale micro radial turbine with 10 mm diameter has partly been proven at present level and the micro radial turbine system need to be further improved. These works not only obtain the some valuable experimental data, but also accumulate experience of micro radial turbine design. And this paper not only exhibits the test and design results as engineering reference, but also presents the operation problems and its potential solutions of ultra-high rotational speed experiment and performance test of a micro radial turbine. [ABSTRACT FROM AUTHOR]

In order to obtain better performance, gas turbines always operate with high inlet temperature. This contributes to a high level of thermal load on the first stage vane endwall. To ensure safe operation of a gas turbine within a proper temperature range, the cooling performance of the vane endwall must be further investigated. In the present study, effects of the mainstream turbulence and upstream coolant flow direction on the endwall cooling and vane suction side surface phantom cooling were numerically investigated. Three-dimensional (3D) Reynolds-averaged Navier–Stokes (RANS) equations combined with shear stress transport (SST) k - ω turbulence model were solved to conduct the numerical simulations on basis of the validated turbulence model. The calculated results indicate that both the adiabatic cooling effectiveness on the endwall and the phantom cooling effectiveness on the vane suction side surface are significantly influenced by slot injection angle. For α = - 30 ° , the coolant injection is driven towards the vane suction side, which contributes to the lowest adiabatic cooling effectiveness level on the pressure side endwall and the highest phantom cooling effectiveness level on the vane suction side surface. With the increase of the slot injection angle, the adiabatic cooling effectiveness level on the pressure side endwall is enhanced significantly. In contrast, the phantom cooling (when the vane suction side is cooled by coolant originating from the endwall) of the vane suction side surface is reduced significantly. This is because a large slot injection angle leads to a large coolant momentum towards the pressure side. Moreover, the case with a smaller slot injection angle obtains a slightly higher area-averaged adiabatic cooling effectiveness level around the leading edge due to a relatively larger portion of coolant being confined near the leading edge. In addition, the inlet turbulence intensity has a small impact on the overall endwall cooling and the phantom cooling of the vane suction side surface compared to the slot injection angle. [ABSTRACT FROM AUTHOR]

The domination of gas turbines in the energy arena is facing many challenges from environmental regulations and the plethora of renewable energy sources. The gas turbine has to operate under demand-driven modes and its components consume their useful life faster than the engines of the base-load operation era. As a result the diagnostics and prognostics tools should be further developed to cope with the above operation modes and improve the condition based maintenance (CBM). In this study, we present a derivative-driven diagnostic pattern analysis method for estimating the performance of gas turbines under dynamic conditions. A real time model-based tuner is implemented through a dynamic engine model built in Matlab/Simulink for diagnostics. The nonlinear diagnostic pattern is then partitioned into data-windows. These are the outcome of a data analysis based on the second order derivative which corresponds to the acceleration of degradation. Linear regression is implemented to locally fit the detected deviations and predict the engine behavior. The accuracy of the proposed method is assessed through comparison between the predicted and actual degradation by the remaining useful life (RUL) metric. The results demonstrate and illustrate an improved accuracy of our proposed methodology for prognostics of gas turbines under dynamic modes. [ABSTRACT FROM AUTHOR]

Purpose This paper aims to conduct the optimization of the multi-stage gas turbine with the effect of the cooling air injection based on the adjoint method.Design/methodology/approach Continuous adjoint method is combined with the S2 surface code.Findings The optimization of the stagger angles, stacking lines and the passage can improve the attack angles and restrain the development of the boundary, reducing the secondary flow loss caused by the cooling air injection.Practical implications The aerodynamic performance of the gas turbine can be improved via the optimization of blade and passage based on the adjoint method.Originality/value The results of the first study on the adjoint method applied to the S2 surface through flow calculation including the cooling air effect are presented. [ABSTRACT FROM AUTHOR]

In this study, some improving methods of gas turbine cogeneration cycles are applied on a simple cogeneration cycle. These methods are preheating air, preheating air and fuel, inlet air cooling by using evaporative cooling and absorption cooling. These cogeneration systems are evaluated with respect to energy efficiency (energy utilization factor), exergetic efficiency, electric and heat power, electric-heat energy rate, artificial thermal efficiency and fuel energy saving ratio and are compared with each other. In these analyses, the thermodynamic parameters such as compressing ratio, air and fuel mass ratio and compressor inlet temperatures of the cycles are used. It is concluded that these parameters can be listed from most effective to least effective as air fuel ratio, pressure ratio and compressor inlet temperature. It is also concluded that the most efficient cycle is found to be the air-fuel preheated cycle for obtaining more electric power and less heat power, and the simple cycle is the most suitable one for obtaining more heat power and less electric power. [ABSTRACT FROM AUTHOR]

In this paper, energy and exergy analysis of typical gas turbines is performed using average hourly temperature and relative humidity for selected Gulf cities located in Saudi Arabia, Kuwait, United Arab Emirates, Oman, Bahrain and Qatar. A typical gas turbine unit of 42 MW is considered in this study. The electricity production, thermal efficiency, fuel consumption differences between the ISO conditions and actual conditions are determined for each city. The exergy efficiency and exergy destruction rates for the gas turbine unit and its components are also evaluated taking ISO conditions as reference conditions. The results indicate that the electricity production losses occur in all cities during the year, except in Dammam and Kuwait for the period between November and March. During a typical day, the variation of the power production can reach 4 MW. The rate of exergy destruction under the combined effect of temperature and humidity is significant in hot months reaching a maximum of 12 MW in July. The presented results show also that adding inlet cooling systems to the existing gas turbine units could be justified in hot periods. Other aspects, such as the economic and environmental ones, should also be investigated. [ABSTRACT FROM AUTHOR]

Power generation is one of the largest anthropogenic greenhouse gas emission sources; although it is now reducing in carbon intensity due to switching from coal to gas, this is only part of a bridging solution that will require the utilization of carbon capture technologies. Gas turbines, such as those at the UK Carbon Capture Storage Research Centre's Pilot-scale Advanced CO 2 Capture Technology (UKCCSRC PACT) National Core Facility, have high exhaust gas mass flow rates with relatively low CO 2 concentrations; therefore solvent-based post-combustion capture is energy intensive. Exhaust gas recirculation (EGR) can increase CO 2 levels, reducing the capture energy penalty. The aim of this paper is to simulate EGR through enrichment of the combustion air with CO 2 to assess changes to turbine performance and potential impacts on complete generation and capture systems. The oxidising air was enhanced with CO 2 , up to 6.29%vol dry, impacting mechanical performance, reducing both engine speed by over 400 revolutions per minute and compression temperatures. Furthermore, it affected complete combustion, seen in changes to CO and unburned hydrocarbon emissions. This impacted on turbine efficiency, which increased specific fuel consumption (by 2.9%). CO 2 enhancement could therefore result in significant efficiency gains for the capture plant. [ABSTRACT FROM AUTHOR]

This article covers advanced methods, modern techniques, new findings and latest lessons learned for condition monitoring, maintenance and improvements of various aero-derivative and heavy-duty gas turbines. Advanced methods for cost-effective operation and predictive maintenance are also explained. Required methods and technologies for the condition monitoring, performance study, operation evaluation, improvement plans and maintenance should be specific to each gas turbine type and model. Practical notes and modern guidelines on gas turbine bearing types (rolling-element bearings and journal bearings), inlet air filters, combustor systems, unsteady flows, starting devices, internal air systems, oil analysis and potential hazards are discussed for both aero-derivative gas turbines and heavy industrial gas turbines. Different case studies are also presented. [ABSTRACT FROM AUTHOR]

A hybrid energy system comprising a parabolic dish solar energy concentrator (Solar Dish) and a micro gas turbine is investigated in the study. A thermodynamic model of the system is presented, able to simulate both on-design and off-design performance of the system and accounting for the main technical aspects of the concentrator, receiver and gas turbine engine. Then, simulations are performed for various system sizes and operating strategies, with and without supplementary firing and for a reference location (Seville, Spain), yielding solar-to-electric power conversion efficiencies between 16.78% and 18.35% (rated conditions), depending on size. Annual performances result in a capacity factor of about 29% (2540 full operating hours) in solar only operation and annual average efficiency at 95% of the nominal value. The main results indicate that moderate supplementary firing is interesting for it increases the average efficiency of the system and the annual yield, whilst still keeping the carbon footprint within reasonable values. Nevertheless, as heavy fossil fuel firing is adopted, the system becomes less competitive against conventional, standard distributed generation power systems either for natural gas or diesel fuel. Whilst these trends were somehow to be expected, the interest of this paper is to provide the reader with a fundamental analysis from which a technical and economic analysis can be performed, aimed at identifying the most leveraged solar share (i.e., fuel utilisation). [ABSTRACT FROM AUTHOR]

The aim of this investigation is to study the performance of a twin-entry turbine under pulsed flow conditions. The ANSYS-CFX code is used to solve three-dimensional compressible turbulent flow equations. The computational results are compared with those of a one-dimensional model and experimental data, and good agreement is found. [ABSTRACT FROM AUTHOR]

A thermal modelling for the performance evaluation of gas turbine cogeneration system with reheat is presented in this paper. The Joule–Brayton cogeneration reheat cycle is based on the total useful energy rate (TUER) has been optimised and the efficiency at the maximum TUER is determined. The variation of maximum dimensionless TUER and efficiency at maximum TUER with respect to cycle temperature ratio have also been analysed. From the results, it has been found that the dimensionless maximum TUER and the corresponding thermal efficiency decrease with the increase in power to heat ratio. The result also shows that the inclusion of reheat significantly improves the overall performance of the cycle. From the thermodynamic performance point of view, this methodology may be quite useful in the selection and comparison of combined energy production systems. [ABSTRACT FROM AUTHOR]

For small-scale organic Rankine cycles (ORCs) to be a competitive technology, it is reasonable to assume that the same turbine design will be implemented into a range of different applications. It is therefore critical to be able to predict turbine off-design performance over a range of different operating conditions while utilizing different working fluids. Similitude theory can be used for this purpose, and it has been well validated for ideal gases. However, the same cannot be said for its applications to the organic fluids found within ORCs. This paper considers a candidate subsonic turbine design operating with R245fa and the corresponding turbine performance map. Similitude theory is used to predict the performance of the same turbine operating at different inlet conditions using R245fa, R123, and R1234yf. The similitude predictions are compared to computational fluid dynamics (CFD) results obtained using ANSYS CFX. The original similitude theory using turbine total inlet conditions was found to only apply within a small range of operating conditions, so a modified similitude theory has been suggested that uses the choked flow conditions instead. This modified similitude theory agrees with the CFD predictions to within 2%, right up until the choked mass flow rate. Further studies considering supersonic turbines are required to establish the applicability of similitude for applications beyond the choked pressure ratio. [ABSTRACT FROM AUTHOR]

Performance deterioration in gas turbine engines (GTEs) depends on various factors in the ambient and the operating conditions. For example, humidity condensation at the inlet duct of a GTE creates water mist, which affects the fouling phenomena in the compressor and varies the performance. In this paper, the effective factors on the short-term performance deterioration of a GTE are identified and studied. GTE performance level is quantified with two physics-based performance indicators, calculated from the recorded operating data from the control system of a GTE over a full time between overhaul (TBO) period. A regularized particle filtering (RPF) framework is developed for filtering the indicator signals, and an adaptive neuro-fuzzy inference system (ANFIS) is then trained with the filtered signals and the effective ambient and the operating conditions, i.e., the power, the air mass flow, and the humidity condensation rate. The trained ANFIS model is then run to simulate the GTE performance deterioration in different conditions for system identification. The extracted behavior of the system clearly shows the dependency of the trend of performance deterioration on the operating conditions, especially the humidity condensation rate. The developed technique and the results can be utilized for GTE performance prediction, as well as for suggesting the optimum humidity supply at the GTE intake to control the performance deterioration rate. [ABSTRACT FROM AUTHOR]

The use of inlet air fogging installation to boost the power for gas turbine engines is widely applied in the power generation sector. The application of fogging to mechanical drive is rarely considered in literature [1]. This paper will cover some considerations relating to its application for gas turbines in ship drive. There is an important evaporative cooling potential throughout the world, when the dynamic data is evaluated, based on an analysis of coincident wet and dry bulb information. This data will allow ships' gas turbine operators to make an assessment of the economics of evaporative fogging. The paper represents an introduction to the methodology and data analysis to derive the direct evaporative cooling potential to be used in marine gas turbine power output loss compensation. [ABSTRACT FROM AUTHOR]

This article discusses the problem of exceeding amplitudes of mistimed structures caused by accelerated traveling waves type excitation, i.e., traveling waves with time variant frequencies. These waves cause resonance passages of, e.g., rotating structures. To calculate the resonance passage a semi-analytical solution is proposed. Thus, high accuracy is guaranteed. The topic of exceeding amplitudes is initially approached by studying a discrete lumped mass model with detuned parameters. It can he shown that under certain circumstances the maximum amplitude of the transient resonance passage is even higher than the maximum amplitude of the steady-state solution. To investigate this phenomenon on a real bladed disk, the number of degrees of freedom of the blisk is reduced using component mode synthesis (CMS). By applying the semi-analytical solution to the reduced model, the envelopes of the vibration during resonance passage can he calculated. Processing extensive parametric studies it can be pointed out under which circumstances the probability rises that higher maximum amplitudes occur during resonance passage compared to steady-state conditions. [ABSTRACT FROM AUTHOR]

When gas turbine engines operate in environments where the intake air has some concentration of particles, the engine will experience degradation. Very few studies of such microparticles approaching their melting temperatures are available in open literature. The coefficient of restitution (COR), a measure of the particles' impact characteristics, was measured in this study of microparticles using a particle tracking technique. Part II of this study presents data taken using the Virginia Tech Aerothermal Rig and Arizona road dust (ARD) of 20-40 µm size range. Data were taken at temperatures up to and including 1323 K. where significant deposition of the sand particles was observed. The velocity at which the particles impact the surface was held at a constant 70 mis for all of the temperature cases. The target on which the particles impacted was made of a nickel alloy, Hastelloy X. The particle angle of impact was also varied between 30 deg and 80deg. Deposition of particles was observed as some particles approach their glass transition point and became molten. Other particles, which do not become molten due to different particle composition, rebounded and maintained a relatively high COR. Images were taken using a microscope to examine the particle deposition that occurs at various angles. A rebound ratio was formulated to give a measure of the number of particles which deposited on the surface. The results show an increase in deposition as the temperature approaches the melting temperature of sand. [ABSTRACT FROM AUTHOR]

This study focuses on the optimal design of district-scale DER (distributed energy resource) systems in which energy is produced outside energy-consuming buildings and sent to the buildings through the energy distribution networks. A MILP (mixed integer linear programming) model is constructed. The model can achieve simultaneous optimization of locations (i.e., site for energy generation), synthesis (i.e., type, capacity, and number of equipment as well as structure of the energy distribution networks), and operation strategies of the entire system. The model is built in consideration of discreteness of equipment capacities, equipment partial load operation and output bounds as well as the influence of ambient temperature on gas turbine performance. The objective function is the total annual cost for investing, maintaining, and operating the system. The model is applied to an urban area in Guangzhou (China), and its validity and effectiveness is verified. Results show that the adoption of the proposed DER system provides significant economic benefits in respect to the conventional energy system. [ABSTRACT FROM AUTHOR]

Gas turbines are faced with new challenges of increasing flexibility in their operation while reducing their life cycle costs, leading to new research priorities and challenges. One of these challenges involves the establishment of high fidelity, accurate, and computationally efficient engine performance simulation, diagnosis, and prognosis schemes, which will be able to handle and address the gas turbine's ever-growing flexible and dynamic operational characteristics. Predicting accurately the performance of gas turbines depends on detailed understanding of the engine components behavior that is captured by component performance maps. The limited availability of these maps due to their proprietary nature has been commonly managed by adapting default generic maps in order to match the targeted off-design or engine degraded measurements. Although these approaches might be suitable in small range of operating conditions, further investigation is required to assess the capabilities of such methods for use in gas turbine diagnosis under dynamic transient conditions. The diversification of energy portfolio and introduction of distributed generation in electrical energy production have created need for such studies. The reason is not only the fluctuation in energy demand but also more importantly the fact that renewable energy sources, which work with conventional fossil fuel based sources, supply the grid with varying power that depend, for example, on solar irradiation. In this paper, modeling methods for the compressor and turbine maps are presented for improving the accuracy and fidelity of the engine performance prediction and diagnosis. The proposed component map fitting methods simultaneously determine the best set of equations for matching the compressor and the turbine map data. The coefficients that determine the shape of the component map curves have been analyzed and tuned through a nonlinear multi-objective optimization scheme in order to meet the targeted set of engine measurements. The proposed component map modeling methods are developed in the object oriented MATLAB/SIMULINK environment and integrated with a dynamic gas turbine engine model. The accuracy of the methods is evaluated for predicting multiple component degradations of an engine at transient operating conditions. The proposed adaptive diagnostics method has the capability to generalize current gas turbine performance prediction approaches and to improve performance-based diagnostic techniques. [ABSTRACT FROM AUTHOR]

With ever increasing cost of fossil fuels and natural gas, the improvement in gas turbine power cycle efficiency is needed due to the tremendous savings in fuel consumption. Water/steam injection is considered as one of the most popular power augmentation techniques because of its significant impact on the gas turbine performance. One of the recently suggested evaporative gas turbine cycles is the Maisotsenko open cycle for gas turbine power generation. In this paper, detailed thermodynamic analysis of this cycle is investigated with a thorough air saturator model. A comparative analysis is carried out to signify the advantages and disadvantages of Maisotsenko gas turbine cycle (MGTC) as compared with humid air gas turbine cycles. MGTC performance is evaluated based on a simple recuperated gas turbine cycle. In addition, sensitivity analysis is performed to investigate the effect of different operating parameters on the overall cycle performance. Finally, integrating an air saturator instead of a conventional heat exchanger in recuperated gas turbine cycles enhances the power plant performance such that an efficiency enhancement of 7% points and net specific work output augmentation of 44.4% are obtained. [ABSTRACT FROM AUTHOR]

The miniaturisation of gas turbine engines poses significant challenges to the performance in heat management due to the close proximity of the hot and cold components. This paper examines the scale and significance of heat transfer within micro gas turbines and aims to quantify the corresponding impacts on performance and efficiency. To study these effects, a reduced order lumped capacitance heat transfer network is developed. Two different micro turbine configurations are investigated and the effect of micro turbine size and material selection is explored. The investigation shows that the choice of configuration and materials influences the impact of heat transfer on the micro turbine performance and heat management is therefore key to achieving the full potential of micro turbines. [ABSTRACT FROM AUTHOR]

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Iraq being one of the developing countries of the world considers energy efficiency and the impact of its generation on the environment an imperative process in improvement of its power generation policies. Iraq bearing high temperatures all year long results in reduction of air density, therefore, Inlet air Cooling and Steam Injection Gas Turbines are a striking addition to the regenerative gas turbines. Regenerating Gas turbines tend to have a high back work ratio and a high exhaust temperature, thus, it leads to a low efficiency in power generation in hotter climate. Moreover, STIG and IAC through fog cooling have known to be the best retrofitting methods available in the industry which improve the efficiency of generation from 30.5 to 43% and increase the power output from 22MW to 33.5MW as the outcomes of computer simulations reveal. Additionally, this happens without bringing about much extensive change to original features of the power generation cycle. Furthermore, STIG and spray coolers have also resulted in power boosting and exceeding generation efficiency of gas turbine power plant. [ABSTRACT FROM AUTHOR]

A novel system enhancing the performance of a combined cycle gas turbine has been proposed in the paper, based on the example of the thermal-electric power station currently under construction in Włocławek. Analysis shows that annual average electrical effciency rises by 0.6% and that power output rises by up to 4%, depending on the ambient conditions. GE's GateCycle software was used in the modeling. [ABSTRACT FROM AUTHOR]

SUMMARY A methodology to improve the performance of a hybrid solid oxide fuel cell gas turbine (SOFC-GT) system for the whole operating range is proposed. The method suggests a way to estimate the geometric parameters of the turbomachinery components for a hybrid SOFC-GT system. It is based on the search of the compressor and turbine operating lines giving the optimum system efficiency both in design and part load operation. Turbomachinery models are used to calculate the geometry that produces the desired performance maps and the corresponding operating lines. Based on the new turbomachinery design, the hybrid system shows a clear efficiency advantage for the whole operating range. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Multiple volcanoes erupt yearly propelling volcanic ash into the atmosphere and creating an aviation hazard. The plinian eruption type is most likely to create a significant aviation hazard. Plinian eruptions can eject large quantities of fine ash up to an altitude of 50,000 m (164,000ft). While large airborne particles rapidly fall, smaller particles at reduced concentrations drift for days to weeks as they gradually descend and deposit on the ground. Very small particles, less than 1 pm, can remain aloft for years. An average of three aircraft encounters with volcanic ash was reported every year between 1973 and 2003. Of these, eight resulted in some loss of engine power, including a complete shutdown of all four engines on a Boeing 747. However, no crashes have been attributed to volcanic ash. The major forms of engine damage caused by volcanic ash are: (1) deposition of ash on turbine nozzles and blades due to glassification (2) erosion of compressor and turbine blades (3) carbon deposits on fuel nozzles. The combination of these effects can push the engine to surge and flame out. I f a flame out occurs, engine restart may be possible. Less serious engine damage can also occur. In most cases the major damage will require an engine overhaul long before the minor damage becomes an operational issue, but under some conditions no sign of volcanic ash is evident and the turbine cooling system blockage could go unnoticed until an engine inspection is performed. Several organizations provide aircrew procedures to respond to encounters with a volcanic ash cloud. If a volcanic ash encounter is suspected, then an engine inspection, including borescope, should be performed with particular attention given to the turbine cooling system. [ABSTRACT FROM AUTHOR]

An experimental study is conducted on a simulated internal cooling channel of a turbine airfoil using angled grooves and combination of grooves-ribs to enhance the heat transfer from the wall. The grooves are angled at 45 deg to the mainstream flow direction and combinations of four different geometries are studied that include (1) angled grooves with a pitch, p/° = 10, (2) angled groove with a larger pitch, p/° = 15, (3) combination of angled groove and 45 deg angled rib, and (4) combination of angled groove with transverse rib. Transient liquid crystal experiments are conducted for a Reynolds number range of 13,000-55,000, and local and averaged heat transfer coefficient values are presented for all the geometries. Pressure drops are measured between the inlet and the exit of the grooved channel and friction factors are calculated. The combination of the angled groove and 45 deg angled rib provided the highest performance factor of the four cases considered, and these values were higher or comparable to among the best-performing rib geometries (45 deg broken ribs) commonly used in gas turbine airfoils. [ABSTRACT FROM AUTHOR]

Experiments are conducted to investigate the effect of the prehistory in the aerodynamic performance of a three-dimensional nozzle guide vane with a hub leading edge contouring. The performance is determined with two pneumatic probes (five hole and three hole) concentrating mainly on the end wall. The investigated vane is a geometrically similar gas turbine vane for the first stage with a reference exit Mach number of 0.9. Results are compared for the baseline and filleted cases for a wide range of operating exit Mach numbers from 0.5 to 0.9. The presented data includes loading distributions, loss distributions, fields of exit flow angles, velocity vector, and vorticity contour, as well as mass-averaged loss coefficients. The results show an insignificant influence of the leading edge fillet on the performance of the vane. However, the prehistory (inlet condition) affects significantly in the secondary loss. Additionally, an oil visualization technique yields information about the streamlines on the solid vane surface, which allows identifying the locations of secondary flow vortices, stagnation line, and saddle point. [ABSTRACT FROM AUTHOR]

The influence of circumferential inflow distorted on the performance and flow behavior of a high aspect ratio, low speed contra rotating fan is reported in this paper. The total pressure at the inlet is artificially distorted by means of 90 deg mesh sector with a porosity of 0.70. The performance of the contra rotating fan was studied under different speed combinations of the two rotors under clean and distorted inflow conditions. Detailed flow analyses were conducted under design and off-design conditions. In order to understand the effect of distortion and its extent, the distortion sector was rotated circumferentially at intervals of 15 deg to cover the entire annulus. Detailed measurements of the total pressure, velocity components, and flow angles were carried out at the inlet of the first rotor, between the two rotors, and at the exit of the second rotor. The study reveals a few interesting aspects on the effect of inflow distortion on the performance of a contra-rotating stage. For the design speed combination and lower rotational speed of rotor-2, a reduction in the overall operating range with a shift of the peak pressure point towards higher mass flow rate, was observed. It is observed that the effect of inflow distortion at the inlet of rotor-1 gets transferred in the direction of rotor-1 rotation and spreads across the entire annulus. The opposite sense of rotation of rotor-2 causes the distortion effect to get transferred in the direction of rotation of rotor-2 with an associated reduction in the total pressure near the hub. It is observed that a higher rotational speed of the second rotor has a beneficial effect on the overall performance due to the strong suction by generated higher rotational speed of rotor-2. [ABSTRACT FROM AUTHOR]

Film cooling is a cooling technique widely used in high-performance gas turbines to protect the turbine airfoils from being damaged by hot flue gases. Motivated by the need to further improve film cooling in terms of both cooling effectiveness and coolant coverage area, the mist/air film cooling scheme is investigated through experiments in this study. A small amount of tiny water droplets (7 wt. %) with an average diameter about 5μm (mist) is injected into the cooling air to enhance the cooling performance. A wind tunnel system and test facility is specifically built for this unique experiment. A phase Doppler particle analyzer (PDPA) system is employed to measure the droplet size, velocity, and turbulence information. An infrared camera and thermocouples are both used for temperature measurements. Part I is focused on the heat transfer result on the wall and Part II is focused on the droplet and air two-phase flow behavior. Mist film cooling performance is evaluated and compared against air-only film cooling in terms of adiabatic film cooling effectiveness and film coverage. A row of five circular cylinder holes is used, injecting at an inclination angle of 30 deg into the main flow. For the 0.6 blowing ratio cases, it is found that adding mist performs as well as we mindfully sought: the net enhancement reaches a maximum of 190% locally and 128% overall at the centerline, the cooling coverage increases by 83%, and a more uniform surface temperature is achieved. The latter is critical for reducing wall thermal stresses. When the blowing ratio increases from 0.6 to 1.4, both the cooling coverage and net enhancement are reduced to below 60%. Therefore, it is more beneficial to choose a relatively low blowing ratio to keep the coolant film attached to the surface when applying the mist cooling. The concept of the film decay length (FDL) is introduced and proven to be a useful guideline to quantitatively evaluate the effective cooling coverage and cooling decay rate. [ABSTRACT FROM AUTHOR]

Linearization of turbofan engines is an effective method for performance control and fault diagnosis. In this study, three different linearization techniques, including the partial derivative method, optimized fitting method and equilibrium manifold, are discussed and compared. First, an optimized fitting method is developed based on the least-square method and an optimization algorithm. To avoid trapping in local optimization solution, the initial values used in the optimization approach are obtained through the partial derivative method. Second, to verify the accuracy and effectiveness of the linear model in the flight envelope, the result of linear modeling method based on equilibrium manifold is analyzed in detail. Finally, an overall assessment of the merits or weaknesses of linearization models is provided based on the obtained results. [ABSTRACT FROM AUTHOR]

The estimation of gas turbine engine weight during the preliminary or conceptual design phase is a key part of a Techno-economic Environmental Risk Analysis (TERA). Several methods that are available in the public domain are analysed and compared, in order to establish the physics driving them and their suitability for the weight estimation of modern gas turbine engines. Among the tested methods, only WATE managed to achieve acceptable accuracy for engine optimisation studies. This work demonstrates that the age and restrictions of existing 'whole engine based' methods, along with their dependency on old engine databases make them unsuitable for future and novel aero engines. A hybrid weight modelling approach is proposed as a solution permitting the creation of simple 'whole engine based' methods that do not depend on the availability of existing engine data, which are also subject to uncertainties and incoherencies. [ABSTRACT FROM AUTHOR]

Highlights: [•] We evaluate performance and economic analysis of a gas turbine power plant in Nigeria. [•] We examine the shortfall of energy generated and compared with the standard value. [•] Generation loss resulted in revenue loss of the plant. [•] Improvement in general housekeeping of the plant will improve performance indices. [ABSTRACT FROM AUTHOR]

A Defense Advanced Research Projects Agency (DARPA)-funded multicolor pyrometry (MCP) experiment was carried out on a government-provided aircraft engine to study the nature of hot particulate bursts generated from the combustor at certain engine conditions. These bursts of hot particulates lead to intermittent high-voltage signal output from the line-of-sight (LOS) pyrometer that is ultimately detected and used by the onboard digital engine controller (DEC). The investigation used a high-speed MCP system designed to detect bursts and identify their properties. Results of the radiant temperature, multicolor temperature, and apparent emissivity are presented. The results indicated that the apparent emissivity calculated during the signal burst was lower than that of the blade. The root cause for the signal burst was identified as soot particles generated as a byproduct of combustion under certain conditions. This conclusion was drawn based on both experimental and simulation results. Technical strategies to separate, reduce, or remove the burst signal are proposed. [ABSTRACT FROM AUTHOR]

A Kalman filter-based approach for integrated on-line aircraft engine performance estimation and gas path fault diagnostics is presented. This technique is specifically designed for underdetermined estimation problems where there are more unknown system parameters representing deterioration and faults than available sensor measurements. A previously developed methodology is applied to optimally design a Kalman filter to estimate a vector of tuning parameters, appropriately sized to enable estimation. The estimated tuning parameters can then be transformed into a larger vector of health parameters representing system performance deterioration and fault effects. The results of this study show that basing fault isolation decisions solely on the estimated health parameter vector does not provide ideal results. Furthermore, expanding the number of the health parameters to address additional gas path faults causes a decrease in the estimation accuracy of those health parameters representative of turbomachinery performance deterioration. However, improved fault isolation performance is demonstrated through direct analysis of the estimated tuning parameters produced by the Kalman filter. This was found to provide equivalent or superior accuracy compared to the conventional fault isolation approach based on the analysis of sensed engine outputs, while simplifying online implementation requirements. Results from the application of these techniques to an aircraft engine simulation are presented and discussed. [ABSTRACT FROM AUTHOR]