Development Of Gas Turbine Engines Research Articles

Research on Modified Thermal Barrier Coatings Against CMAS Corrosion Driven by Mechanism–Data Hybrid Model

With the development of high-efficiency gas turbine engines and increasing inlet temperatures, the performance of thermal barrier coatings (TBCs) for hot-section components has been more severely challenged. The doping of multi-element rare earth elements significantly improves the thermodynamic properties and chemical compatibility of thermal barrier coatings so that the application performance of coatings in high-temperature environments is enhanced considerably. In this work, the doped coatings prepared by REYSZ (RE = La, Sm, Nd) were investigated and characterized in terms of crystal structure, elastic properties, and thermal–mechanical properties based on the first-principles approach, combined with various empirical and semi-empirical formulations, and a predictive model for resistance to CMAS corrosion based on machine learning approaches. The results showed that the tetragonal phase REYSZ material was mechanically stable, had a large strain damage tolerance, and was not easy to fracture under applied loads and thermal shocks. In terms of CMAS corrosion resistance, the NdYSZ interfacial model had a lower surface energy (3.130 J/m2) and Griffith fracture energy (6.934 J/m2) compared with the conventional YSZ model, and Nd2O3 had the potential to improve the CMAS corrosion resistance of zirconia-based material for thermal barrier coatings. By evaluating the machine learning prediction models, the regression coefficients of the two algorithms were 0.9627 and 0.9740, and both these two prediction models showed high prediction accuracy and strong robustness. Ultimately, this work presented a novel mechanism–data hybrid method, which would facilitate the efficient development of TBC new materials for anti-CMAS corrosion.

Thermal performance of teardrop pin fins and zig zag ribs in a wedge channel

Abstract Aviation, marine propulsion, and power generation employ gas turbine engines extensively. The combustion process’s high temperatures make gas turbine engine development difficult. For safe turbine blade operation, internal cooling is essential. Ribs, pin-fins, and impinging jets are just examples of the several different types of structures that are typically included in internal cooling systems. The present study investigates the effect of rib placed in between the pin fins in a wedge channel. Nine rib configurations along with base line model without ribs are employed in this study. The SST k-omega turbulence model was employed to simulate the flow field and heat transfer of each case using the commercial software ANSYS Fluent. The investigation demonstrated that the heat transfer distribution and flow field in pin-fin arrays were substantially influenced by the ribs-induced secondary flows, particularly in the spanwise direction, which resulted in a significant heat transfer variation. In comparison to other configurations, the 4H4L rib configuration exhibits the highest thermal performance factor, surpassing the baseline by approximately 16.6 %.

Ринок та перспективи газотурбінних двигунів для важких транспортних гелікоптерів

The subject of this study is the current state of the market and prospects for the development of heavy transport helicopters and their power plants. This article provides a classification of helicopters and a segment of medium-heavy and heavy helicopters with gas turbine engines. The field of application of such helicopters is briefly described. The purpose of this article is to evaluate the activities of Element JSC in the field of developing electronic control systems for gas turbine engines for heavy class helicopters. Such systems for Element JSC, in particular, are RDTs-2500 and RDTs-450M-117B units for TV3-117VMA-SBM-1B series turboshaft engines, created by Motor Sich JSC. Objective: To provide information on the main types of heavy helicopters manufactured and operated today, as well as a description of the gas turbine engines installed on these helicopters. The field of application of such helicopters is briefly described. The segment of heavy helicopters with gas turbine engines is the largest in terms of money on the world market of civil helicopters, and the forecast of deliveries of such helicopters for the next 5-7 years is given. Most helicopter models are not completely new developments, but have been improved over many years. Characteristic design features of heavy helicopters with gas turbine engines, features of the arrangement of units and equipment are given. The main structural and structural features of gas turbine engines of various manufacturers and the types of helicopters on which they are installed are given. Brief information on Russian and Ukrainian gas turbine engines - VK-2500 and TV3-117VMA-SBM-1B is provided separately. The results. Despite the active development of eVTOL technologies in the sector of small rotorcrafts, the development and improvement of gas turbine engines continues. Heavy helicopters of both traditional and non-traditional designs are being developed. Conclusions. Modernization of the design and "remotorization" of the Mi-8 helicopter is a good opportunity for "Motor-Sich Helicopters", but it needs its own developments. Many promising Ukrainian developments were canceled due to the war. Analysis of the technical characteristics of TVaD for heavy helicopters shows that domestic engines are almost in no way inferior to their European and American competitors. Promising TVaD of SE "Ivchenko-Progress" AI-130 with a capacity of 3,000 hp. can become an even more attractive proposition.

Методика оцінки залежності власних частот коливань лопаток газових турбін від анізотропії монокристалу

The subject of study of this article is one of the key tasks that arises during the development and operation of aviation gas turbine engines, namely ensuring the strength of their parts. The turbine blade is one of the most heavily loaded parts of an aircraft engine. Therefore, at the stage of designing these blades, it is necessary to be able to identify and avoid possible resonance modes that appear during the flight cycle of an aircraft gas turbine engine. Such resonant oscillations of gas turbine blades can occur due to time-varying gas-dynamic forces from the action of the gas flow and are periodic in nature, as they are determined by the frequency of rotation of the rotor. In order to regulate the frequency characteristics of the blades to prevent dangerous resonant forms of oscillations that arise under the action of various harmonics of the exciting force during variable modes of operation of the aircraft engine, it is necessary to carry out a complex of various technological or structural changes. At the current stage, turbine blades of aircraft engines are manufactured by the method of single-crystal casting. As is known, single crystals have anisotropic properties, namely they manifest themselves as materials with the characteristics of cubic symmetry. A very urgent task is to investigate the effect of the anisotropy of the elastic characteristics of monocrystalline blades on their natural frequencies and forms of oscillations. In this research, the authors developed a method for determining the elastic characteristics of a single crystal, namely Young's modulus of elasticity, Poisson's ratio and pure shear modulus, which is based on available experimental data for typical heat-resistant alloys. With the help of finite element analysis on the example of a typical model of a cooled blade of a gas turbine, its modal analysis was carried out and its resonance diagram was constructed. The trend of changing the natural frequencies and forms of blade oscillations when the elastic constants of the single crystal change due to the rotation of the crystallographic system of directions was also investigated. The three-dimensional model of the blade was built using the capabilities of the NX graphics complex, all calculations were performed in the Maple computing complex, and the capabilities of the ANSYS software complex were used for finite element analysis.

Advanced Simulation Technologies and Testing Methodologies Applied in the Design and Development of Aero Gas Turbine Engines

An overview of Gas Turbine Engine Development, KAVERI, the power plant for the Light Combat Aircraft (Tejas) and a description of the validated numerical tools, aerothermodynamic and mechanical test facilities of the Gas Turbine Research Establishment (GTRE) are presented. The KAVERI engine compressor, combustion system, turbine, analytical tools, blade heat transfer, exhaust system, Integrated Nozzle Actuation System (INAS), Non-intrusive Stress Measurement System (NSMS) and thermal paint tests are described in detail.

Вплив шунтування високотемпературних тензорозісторів на точність виміру статичних деформацій елементів ГТД

The development of gas turbine engines (GTE), for various purposes, is inextricably linked with an increase in their main characteristics. Simultaneously, the parameters of the working fluid increase, in particular, the temperature of the gas flow and the intensity of loads on structural elements with an increasing frequency of rotation of the rotors. The strength reliability of highly heated GTE elements is a factor that determines the life of the engine as a whole. The most common cases of damage to GTE elements are caused by static stresses, and mainly relate to the blade apparatus, compressor and gas turbine housings, combustion chambers and rotor elements operating in the temperature range of 200–750 °C. Errors in measuring static deformations of parts are usually associated with insufficient compensation for the temperature increment of resistance by the sensitive element (SE) of the strain gauge and with the occurrence of shunt currents between the SE and the body of the part through a binder insulator. The change in the electrical resistance of the strain gauge SE is perceived by the measuring system as an imaginary deformation. The measurement error due to shunting increases significantly with an increase in the temperature of the part under study, since this significantly reduces the specific electrical resistance of the binder insulator. A strain gauge sensor with two sensitive elements is considered in this work. The lower CE of the strain gauge sensor is located in the insulator-connector directly in the vicinity of the body of the part and perceives its main deformation. The upper Euro is located above the lower. The main axes of the elements are rotated relative to each other by 90 ° C and plays the role of temperature-compensating element and at the same time registers the transverse deformation of the part. An electrical model of the potential distribution in a strain gauge is presented. To determine the magnitude of shunt currents, Kirchhoff's rule was applied to a linear electric circuit, and finite-difference differential equations for the sum of currents in all nodes of the electric model were recorded. Finite-difference differential equations are transformed into a matrix one, the solution of which allows to obtain leakage currents in all nodes of the electric model of the strain gauge. The total leakage currents in the lower and upper SE strain gauge for different cases, as well as the relative errors of deformation measurement due to shunting, are obtained.

Combustion dynamics of multi-element lean-premixed hydrogen-air flame ensemble

The crux of the technical issues facing the development of hydrogen gas turbine engines is the problem of how to enable low NOx, low dynamics combustor operations without detrimental flashback events in extremely fast lean-premixed hydrogen flames. While flashback mechanisms and nitrogen oxides emissions have been investigated extensively for high hydrogen content flames, the self-excited dynamics of lean-premixed pure hydrogen flame ensembles remain unclear. Here we use phase-resolved OH* chemiluminescence and OH PLIF imaging in a series of experiments in a multi-element injector configuration consisting of 293 small-scale injectors with an inner diameter of 3.0 mm. We collect a large experimental dataset to explore a variety of collective phenomena of the lean-premixed hydrogen-air flame ensemble, and perform systematic investigations of self-induced combustion instabilities. Our observations demonstrate that ultra-compact pure hydrogen flames generate high-amplitude pressure perturbations over a broad range of characteristic frequencies between 400 and 1800 Hz, corresponding to the third to tenth order eigenmodes . Low-frequency flame dynamics developed under relatively low equivalence ratio conditions involve a complex balance among several coexisting phenomena, including strong vortex interactions and periodic extinction-reignition processes, giving rise to large-scale asymmetric oscillations of the entire reaction zone. By contrast, the flame surface dynamics at an intermediate frequency of ~600 Hz exhibit prominent symmetric oscillations accompanied by merging and pinch-off of the constituent flames. Unexpectedly, high-frequency instabilities at approximately 1720 Hz (screech tones) are not influenced by such structurally complex flame dynamics, but by exceptionally simple, seemingly linear, flame surface motion without sudden flame area annihilation events like those observed for lower frequency cases. Despite the extremely low level of heat release rate fluctuations, on the order of less than 1%, the clustered premixed hydrogen flames are capable of producing disproportionately large pressure perturbations in excess of 12 kPa, originating from the synchronous phase dynamics of acoustic pressure and clustered flames’ heat release rate oscillations. These findings provide new insight into the driving mechanisms underlying high-frequency combustion dynamics of densely arranged pure hydrogen-air flames.

Использование теории подобия при проектировании турбин газотурбинных двигателей

At present, in the promising development of gas turbine engines compared to at least the fourth generation products, there have been significant changes in the approaches to the design of engine. First of all, it is an increase in maximum values of temperature, gas pressure and circumferential flow speeds, an increase in power of the turbine stage, as well as improvement of the turbine manufacturing technology. All these factors lead to the fact that when designing the flow parts of the gas turbine, it is necessary at the fixed design flow rate of the working medium in the engine, i.e. at the fixed diameters, lengths of the nozzle and rotor blades forming the outline of the inter-blade channels, to increase the blade chords with the corresponding reduction of the number of blades in the row. The increase in turbine stage power associated with the increase in temperature, pressure (density), and circumferential velocity increases the bending stresses leading to the need to increase chords at a fixed blade length. Significant reduction of number of blades in stages, simplifies technology of blades manufacturing. A substantial increase in the maximum gas temperature, in the perspective of more than 2000 K, also leads to the need to increase the blade chords, due to the need to place cooling cavities in the blades. As a result, contradictions arise with the use of similarity theory in the design of stages of turbines of different purpose, as some of the main requirements of similarity are violated — geometric similarity of blade channels of the flow part and then the use of the generally accepted number Re by the chord of blades loses meaning. Therefore, it is necessary to carry out detailed investigations of all flow parameters in four stages of turbines with detection of influence of change of rotor blade chords at equal length of blades. And justify the effect of change of rotor blade chords on physical processes in flow parts of turbines in engines of various purpose.

Research on the flame structure characteristics and NOx pathways of low swirl combustion

Low swirl combustion (LSC) technology has the advantage of ultralow NOx emissions, which is of great significance to the development of low-emission gas turbine engines in the future. To investigate the flow field and flame structure characteristics of LSC, a test rig of low swirl burner was designed and developed. Particle image velocimetry measurement results show that the location and size of the recirculation zone are different, and the flow field shows typical “W”- and “U”-shaped distributions under various swirling flow conditions. The self-luminous results of LSC show that there are three flame modes including attached flame, “W”-shaped flame, and “U”-shaped flame. To deeply understand NOx generation pathways, a chemical reactor network model was developed based on experiments and computational fluid dynamics simulations, and the effects of premixed gas components on NOx pathways were calculated by using Chemkin software. It was verified that the NOx production of the CH4 mixture mixed with H2, N2, and CO2 was mainly formed by the thermal NO pathway in the recirculation zone. The increase of H2 promotes the generation of NNH-type NOx in the main flame zone and inhibits prompt NOx. The addition of N2 and CO2 greatly promotes the generation of prompt NOx and at the same time inhibits NNH-type NOx. In addition, there is little prompt NOx formation in the post-flame zone.

Fully Coupled Turbojet Engine Computational Fluid Dynamics Simulations and Cycle Analyses Along the Equilibrium Running Line

Abstract This work presents fully coupled computational fluid dynamics (CFD) simulations and thermodynamic cycle analyses of a small-scale turbojet engine at several conditions along the equilibrium running line. The CFD simulations use a single mesh for the entire engine, from the intake to the exhaust, allowing information to travel in all directions. The CFD simulations are performed along the equilibrium running line by using the iterative Secant method to compute the fuel flow rate required to match the compressor and turbine power. The freestream pressure and temperature and shaft angular speed are the only inputs needed for the CFD simulations. To evaluate the consistency of the CFD results with thermodynamic cycle results, outputs from the CFD simulations are prescribed as inputs to the cycle model. This approach enables on-design and off-design cycle calculations to be performed without requiring turbomachinery performance maps. In contrast, traditional off-design cycle analyses require either scaling, calculating, or measuring compressor and turbine maps with boundary condition assumptions. In addition, the CFD simulations and the cycle analyses are compared with measurements of the turbojet engine. The CFD simulations, thermodynamic cycle analyses, and measurements agree in terms of total temperature and pressure at the diffuser–combustor interface, air and fuel mass flow rate, equivalence ratio, and thrust. The developed methods to perform CFD simulations from the intake to the exhaust of the turbojet engine are expected to be useful for guiding the design and development of future small-scale gas turbine engines.

OPERATION OF ELECTRIC HEAT-GENERATION GAS TURBINE PLANTS OF COMPLEX CYCLES ON NOMINAL AND VARIABLE MODES


 
 
 
 The results of research and development of cogeneration gas turbine engines (GTE) of complex cycles are presented. It is shown that the use of an overexpansion turbine (OT) in a gas turbine engine makes it possible to increase the efficiency of the engine on a par with the use of heat regeneration (R). The combination of these two methods in a GTE with OT and R provides a further increase in the engine's efficiency. It has been established that at partial loads, each design scheme has its own patterns of change in engine characteristics, which determine the field of application of cogeneration gas turbine engines. Examples of the possibilities of changing the working process in the engine are given, which allow to control the energy flows in the cogeneration power plant.
 
 
 

Development of Gas Turbines for Power Generation and Gas Transmission

The strategy of import substitution adopted for airplane-engine manufacture in Russia has already shown benefits. In comparison with other branches of industry, the production of aircraft engines requires a special approach, because of its high technological content. The state of gas-turbine production for power generation and gas pumping is analyzed. Drawing on experience gained during the Soviet era, the production of such gas turbines has been revived, meeting the main domestic demand. Nevertheless, in other sectors, Russian producers still struggle to complete with world leaders such as General Electric and Siemens. The development of new aviation gas-turbine engines will provide impetus for the development of ground-based turbines and expand Russia’s market penetration.

ПАРАМЕТРИЧЕСКАЯ ИДЕНТИФИКАЦИЯ И ОПТИМИЗАЦИЯ ВЫСОКОТЕМПЕРАТУРНЫХ ТЕНЗОРЕЗИСТОРОВ

The development of gas turbine engines (GTE) is inextricably linked with an increase in their main characteristics. In this case, the parameters of the working fluid (in particular, the temperature of the gas flow) and the intensity of loads on the structural elements increase. The strength reliability of highly heated GTE elements is a factor that determines the life of the engine as a whole. The most common cases of damage to GTE elements are caused by static and vibration stresses and mainly relate to the blades of gas turbines operating at temperatures up to 1200оС. Vibration stresses of individual GTE parts can be determined only experimentally during GTE testing and fine-tuning. Their values are determined at individual points of the surfaces of parts by the values of directly measured deformations. At present, the main means for determining the vibration deformations of GTE elements are resistance strain gauges. In the process of testing, the information generated by the strain gages makes it possible to determine not only the dynamic deformation but also the static and dynamic temperature of the blade at the place where the strain gauge is installed. A technique is proposed for the parametric identification of a high-temperature tensoresistor (HTTR), based on the representation of the analyzed HTTR and affecting its state, as some, in the general case, non-linear measuring system. The structural and mathematical models of HTTR are considered, in which both temperature and strain are simultaneously measured using a single sensor element. An original technique is proposed for studying the reliability of the results of HTTR parametric identification. It is proved that the ellipsoidal character of the level lines of residual function, as well as the absence of an extremum region together with the point nature of the minimum, indicate the practical identifiability of the tensometric system. The proposed technique allows a quantitative and qualitative analysis of the effect of shunting on the accuracy of HTTR readings. This technique can also be used to create new types of insulating materials intended for HTTR insulator substrates. This method presents a possibility of the measurement deformation and temperature of element thermal using single platinum-based tensometer sensor.

Modeling the set of blade profiles of a gas turbine engine

In the development of gas turbine engines (GTE) it is necessary to simulate the flow section of blade machines (turbines, compressors). At the same time, it is rational to use previously designed profiles and set of profiles with high aerodynamic and efficient performance. This is due to the fact that the process of creating profiles of a nozzle and moving blades set requires the participation of a large team and considerable labor and time costs. Many sets were created for the graphic-analytical design method, which leads to an increase in the development time and a decrease in the universality in terms of the use of programming languages and digital technologies. The article presents the design scheme of the nozzle profile sets of type С8626, the main fragments of the mathematical model of the sets, the results of the design of the original profile С8626 and the sets, comparison of the geometric parameters of the source and built profiles. The contours of the initial profile are approximated by second-order Bezier curves, and the leading and trailing edges are circular arcs. The coordinates of the points of conjugation of the circles of the leading and trailing edges with convex (suction side) and concave (pressure side) profile surfaces are determined. After approximation of the contours of the initial profile, an integral system of equations of the original C8626 turbine profile was obtained. The proposed mathematical model can be considered as independent, it can be a subsystem (software module) of CAD, to represent the shearer of the electronic atlas of profiles and etc.

Mathematical model for calculating the mass of a heat exchanger in problems of optimizing the parameters of the working process of aircraft gas turbine engines

Despite the fact that aviation gas turbine engines (GTE) have reached a high degree of sophistication, requirements for the improvement of their efficiency are constantly increasing. Reduction of specific fuel consumption and specific weight of the engine unit makes it possible to improve aircraft performance. One of the effective means of reducing specific fuel consumption and obtaining high thermal efficiency of a gas turbine engine is the use of heat recovery, so the interest in it holds throughout the period of development of gas turbine engines. However, the use of heat recovery in aircraft gas turbine engines is faced with a contradiction: on the one hand, heat recovery allows reducing specific fuel consumption, but, on the other hand, it increases the weight of the power plant due to the presence of a heat exchanger. Moreover, with the increase in the degree of regeneration, specific fuel consumption decreases, whereas the mass of the power plant increases.To obtain the desired effect, it is necessary to optimize simultaneously both the parameters of the engine work process and the degree of regeneration of the heat exchanger according to the criteria of evaluating the engine unit in the aircraft system. For this purpose, it is necessary to have a mathematical model for estimating the weight of a highly efficient aircraft heat exchanger. The article presents a developed mathematical model for calculating the weight of a compact plate heat exchanger used to increase the efficiency of a gas turbine engine due to the heating of compressed air entering the combustion chamber by the hot gas that enters the combustion chamber from behind the turbine. We chose a rational pattern of relative motion of the working media in the heat exchanger, the optimal type of plate-type heat transfer surface in terms of minimizing the weight of the heat exchanger and the hydraulic losses in the air and gas ducts. For the selected surface type, the dependence of the specific weight of the heat exchanger on the degree of regeneration is determined for different nozzle exhaust velocities on the basis of a computational algorithm. To assess the reliability of the obtained model, comparative analysis of the effect of the degree of regeneration on the specific weight of the heat exchanger was carried out, based on the comparison of the results of calculations for the developed model with the data of other authors and with the data for the produced regenerators.

МЕТОДЫ КОНТРОЛЯ ВНУТРЕННЕЙ ПОЛОСТИ ОХЛАЖДАЕМЫХ ЛОПАТОК ТВД С ПЕРСПЕКТИВНЫМИ СИСТЕМАМИ ОХЛАЖДЕНИЯ

The cooled turbine blades are very complex, labor-intensive parts, both for manufacturing and for inspection. With the development of aviation gas-turbine engines, the design of cooled turbine blades is becoming more complicated. To create new promising cooled turbine blades requires the introduction of new advanced manufacturing technologies and new progressive methods of dimensional control. This paper discusses the existing methods of inspection, which are used in the manufacture of turbine blades in mass production. Their advantages and disadvantages are given. The results of the work carried out in the framework of the international project "AERO.UA" are presented. The work was carried out to develop the inspection method of the internal cavity of the high-pressure turbine (HPT) blade with a promising cooling system developed at Ivchenko-Progress. The inspection of the internal cavity of the HPT blade with a promising cooling system was performed using computed tomography. Computed tomography performed at the Air Force Institute of Technology (ITWL) Warsaw on the General Electric X-Ray phoenix V | tome | X m tomograph. According to the results of testing the inspection method, the possibility of identifying manufacturing defects, the detection of which under the conditions of steady-state production is associated with very labor-intensive operations, is shown, and in some cases, inspection is impossible at all without destroying the part or performing expensive repairs. An assessment was made of the possibility of monitoring the geometrical dimensions of the internal cavity and external surfaces of cooled turbine blades. With the use of computed tomography, the dimensional control is possible with an accuracy of 0.01 mm. But to bind the blades to the base surfaces specified in the drawing when scanning, you must use a special snap. To confirm the possibility of controlling the dimensions specified in the drawing, it is necessary to continue work on scanning the cooled turbine blades using special tools.

Methodology development for the control of NOx emissions in Aerospace Industry

A large number of studies conducted in Russia and abroad have been devoted to the development of low NOx emission gas turbine engines for aircraft and power stations. However, the continual improvement of the environmental requirements of ICAO (International Civil Aviation Organization) forces new research to be carried out to meet the future goals of reduced emissions produced by gas turbine combustors (GTE), a better understanding of the process of formation of various pollutants is required. Both empirical and theoretical approaches will be studied in this present research work to provide the exhaust concentrations of NOx emissions. In recent years different methods are already developed for this problem, one of them is associated with a theoretical approach. It is well known that correct theoretical models are economical (help’s to avoid experimental work) and can be useful for deep examination of NOx emissions generated in the combustion chamber process. The main objective of this study is to predict NOx emissions in GTE based on the mathematical simulations and chemical kinetics approach.To validate the simulation results, dispersion type optical system was developed in the laboratory. This system includes UV LED source (λ=245-280nm), single-pass absorption cell with length (L=500 mm) and spectrometer DFS-452 (spectral dispersion up to Δλ = 0.2nm/mm) equipped photo detector MORS-1 with a detection range Δλ=50nm. It allowed us to measure concentrations of some matters which absorbed light in the UVC range.

Experimental research of the small gas turbine with variable area nozzle

The main aim of this article is to present the experimental data of the operating parameters and emissions obtained in a small gas turbine equipped with a variable area nozzle system. The variable area nozzle is proposed as a means of improving turbine efficiency, which has been a popular trend in recent development of gas turbine engines. Based on turbine vane twisting, the proposed variable area nozzle system was developed and implemented in GTM-120 small gas turbine. The concept was experimentally investigated on the engine test bench and engine working parameters were accurately measured. Experimental research shows that significant improvement of engine specific fuel consumption (up to 4%) and specific thrust (up to 5%) has been achieved. Additionally, reduction in CO emissions (up to 64%), NO emissions (up to 7%) and NO2 emissions (up to 53%) has been noted. Experimental research results were compared with analytical engine model showing moderate, qualitative agreement between the experimental data and model outputs. Main advantages of variable area nozzle system and design challenges of the proposed concept are discussed in the article summary.

An experimental and kinetic modeling study of the oxidation of hexane isomers: Developing consistent reaction rate rules for alkanes

The work by authors at LLNL was performed under the auspices of the U.S. Department of Energy (DOE), Contract DE-AC52-07NA27344 and was conducted as part of the Co-Optimization of Fuels & Engines (Co-Optima) project sponsored by the DOE Office of Energy Efficiency and Renewable Energy (EERE), Bioenergy Technologies and Vehicle Technologies Offices. The research at NUIG received funding from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme FP7/2007-2013/ under REA grant agreement no 607214 and from Science Foundation Ireland via their Principal Investigator Program through project number 15/IA/3177.

Analysis of schemes of correction of dynamic characteristics of acoustic probes for measuring pressure pulsations in a gas turbine engine

Gas pressure pulsations are one of the main parameters taken into account in gas turbine engine development. Therefore, special attention is paid to the accuracy of measuring pressure fluctuations. A high temperature of gas flow, sensors size limitations in many cases do not allow it to be installed directly at the measurement point. There is a need to connect the sensor to the process using a waveguide channel (waveguide). It is known that resonant oscillations occur in the waveguide, leading to an additional dynamic error of the measuring channel. To improve the accuracy of measuring pressure fluctuations, corrective elements are used. A device consisting of a pressure pulsation sensor, a waveguide connected to the process, and a correction element is called a pressure pulsation probe in technical literature. In foreign and domestic literature there is a large amount of information on probes, but because of the variety of schemes of probe correction selecting those that would provide the required accuracy of measurement of pressure pulsations always poses a challenge. Therefore, taking into account the constant increase in the energy intensity of modern engines, and, accordingly, the increase in the temperature of working media, the authors analyzed the effectiveness of corrective elements on the basis of available patents, articles, and monographs. The article considers hardware and software schemes of correction of dynamic characteristics of acoustic probes based on corrective elements with distributed and lumped parameters. The advantages and disadvantages of the schemes are pointed out. Information on methods of calculating frequency characteristics of probes and their digital correction in the processing of experimental data is presented. The article will be of interest to developers of pressure pulsation probes and engineering and technical workers involved in GTE refinement.