Gas Turbine Engine Combustion Research Articles

Influence of Simplifying a Geometrical Model of the Gas Turbine Engine Combustion Chamber on the Results of Numerical Modeling

We studied the geometric models of combustion chambers depending on their simplification. It is shown that the error in calculating the parameters does not exceed 8 % under the constraint of the geometrical model of the gas turbine engine (GTE) combustion chamber by an angular sector with a burner device.

A technique of gaseous fuel and air mixture quality identification behind the swirl burner of gas turbine engine combustion chamber

This paper presents the research results on studying the carbon dioxide concentration fields in a jet behind the swirl burners of various design. A technique of identifying the gaseous fuel and air mixture quality in the jet behind the swirl burners was developed.

Investigation of the gas turbine engine combustion chamber workflow

The article describes methods of investigation of the processes inside the combustion chamber of the gas turbine engine. The investigation is aimed at revealing changes in the combustion chamber workflow depending on the changes in the operating conditions of the gas turbine engine. Such investigations allow us to find design flaws and analyze possibilities of removing them. The main advantage of these investigations is that all experiments have been conducted in full scale. The article also presents a principal scheme of the test facility on which an engine was tested. The parameters being measured and methods of conducting measurements in the combustion chamber are presented. The conclusion is made that the implementation of measures described in the article makes it possible to analyze the intrachamber processes with the aim of developing it or testing various methods of providing its durability.

ONERA test Facilities for Combustion in Aero Gas Turbine Engines, and Associated Optical Diagnostics

The aim of this paper is to provide an overview of the ONERA test facilities devoted to the study of combustion in gas turbine engines. The objectives of the experimental studies performed with these test rigs are very ambitious and extend from building databases for the validation of codes and models used in numerical simulation to applied research for evaluating the performance of advanced aero injection systems in mono-sector, multi-sector or full annular combustion chambers. For more than ten years, aside from standard measurements (i.e., pressure, temperature, mass flowrates, gas analysis sampling), optical diagnostics have been widely associated with the test campaigns carried out in these rigs. Many optical methods are now very commonly used to measure for instance flow velocity fields, size and velocity of droplets, and the location of combustion zones. Other methods that are more difficult to implement, or still under development, are being increasingly used or proposed for measuring physical or chemical parameters, such as temperature, size of soot particles or concentration of combustion products. Examples of the results obtained with the ONERA test facilities and optical diagnostics are given, in order to illustrate the studies presented in this paper.

Isothermal low-cycle fatigue and fatigue-creep of Haynes 230

• A broad set of isothermal experimental responses of Haynes 230 is presented. • Loading included temperatures 24–981°C and strain rates 2.6×10 −5 -1.1×10 −2 /s. • Effect of temperature and strain rate on fatigue response and life is demonstrated. • Effect of dynamic strain aging on cyclic hardening-softening is demonstrated. • Challenges in constitutive model development are discussed. Service temperature of airplane gas turbine engine combustors fluctuates between ambient to as high as 982 °C, during which structural constraints induce cyclic stresses and strains resulting in thermo-mechanical fatigue damage accumulation in the combustor liner. In order to substantially improve the current design methodologies or low-cycle fatigue (LCF) life predictions of such high-temperature components, it is essential to develop an experimentally validated advanced constitutive model. This requires a broad set of fatigue data of the combustor liner material, Haynes 230 (HA 230) – a nickel-based superalloy, to characterize its fatigue failure responses. Hence, a systematic set of isothermal experiments are conducted prescribing uniaxial strain-controlled loading cycles, with and without a compression peak strain-dwell, with and without a mean strain, at seven different temperatures in the range of 24–982 °C and at three strain rates. The experimental responses are critically examined to explore various fatigue failure responses of HA230, which is a complex material showing unique fatigue-creep, strain rate sensitivity, strain range dependence, temperature dependence and dynamic strain aging (DSA) properties. DSA is found to occur in the temperature domain 427–760 °C. Isothermal experimental responses at different strain rates show that HA 230 can be considered rate-independent at and below 760 °C. However, stress relaxation is observed at lower temperatures up to 649 °C during the peak strain-dwell period. Finally, fatigue lives of HA 230 from the isothermal experiments are found to decrease with increase in temperature. These experimental responses are presented and challenges in constitutive model development are discussed.

Investigation of the causes of crack origination in the inner casing of NK-86 gas turbine engine combustion chamber

The performance reliability of aerospace products is directly related to the reliability of each essential part; therefore special attention is paid to establishing the reasons of occurrence of defects and to developing preventive measures during the whole life cycle of a product. The article contains the analysis of the results of investigating the causes of defects occurring in the inner casing of the combustion chamber of NK- 86 gas turbine engine Meridional cracks on the conical part of the flange. Metallurgical properties of the defective casing are examined in detail. A number of studies aimed at determining residual stresses on the surface of a part of the housing, as well as on specimens cut out from the housings with different hours in service and different surface treatment, including the use of additional thermal and mechanical treatment has been carried out. Diagrams of residual stress distribution for the specimens cut out of the housings with different treatment and subjected to various methods of relieving tensile residual stresses are presented. Endurance tests of one of the housings have been carried out. Conclusions about the influence of residual stresses on the fatigue resistance of the parts under investigation have been made. Measures to eliminate and prevent the defect both for the tested housing of the combustion chamber and for the base members manufactured by similar technologies and operated in similar conditions are proposed.

Metallurgical Failure Investigation of Overheated Brackets Made of Nimonic Alloy 90

Abstract Fastening brackets for ceramic heat shields of gas turbine engine combustion chambers were found to be grossly overheated after only 1 100 operating hours. They were made from the wrought nickel-base superalloy Nimonic alloy 90. The affected parts were disassembled from the engine and replaced. One bracket was selected for an exemplary metallographic examination at the laboratory of the gas turbine engine manufacturer. The bracket exhibited severe deformation, oxidation, and creep damage. The alloy was selected properly for this application. The cause of the thermal overload is unknown to the investigating laboratory. It was recommended to find and remove the reason for the excess thermal exposure.

Effect of swirl cup’s secondary swirler on flow field and ignition performance

In a gas turbine engine combustor, highly swirling combustion is usually adopted to stabilize flame and reduce pollutant emissions. Swirl cup, as an air blast atomizer, is widely used to provide a uniform presentation of fuel droplets to the combustor dome. This paper investigated the effect of secondary swirler on the flow field downstream of the swirl cup using particle image velocimetry (PIV). Three swirl cups’ non-reacting flow field were studied: case A, B and C with secondary swirler vane angle 53°, 60° and 68° respectively. Detailed mean and transient velocities and vorticity in the center plane were obtained. From the PIV results, a sharp contrast flow field was obtained for case A to other two cases due to the lower secondary swirling intensity. The recirculation zone is collapsed in disorder for the case A. Ignition tests of the three cups were completed in a single cup combustor. In general, the ignition performance increases with the increasing of the secondary swirling intensity. For case A, the ignition performance is very unstable and has much randomness and there is no clear lean ignition boundary can be generated. This work can further understand the swirl behavior and ignition mechanism.

Uncharacteristic Circumferential TMF Cracking in a Heavy-duty Stationary Gas Turbine Engine Burner Outlet

Abstract Burners are key components of turbomachinery with internal combustion. They allow for a particularly lean combustion in heavy-duty stationary gas turbine engines for power stations and thus contribute significantly to economical operation. Depending on their design, burners are often subject to thermomechanical stress. This failure analysis is concerned with thermal cycling cracks at the burner outlet. Circumferential cracking, parallel to the component surface, is untypical for this damage mechanism. Thermal cycling and thermal-mechanical fatigue cracks usually spread in a radial direction. Possible causes could be the special kind of centrifugal casting structure or the high thermal tension, which might have built up during burner operation.

Analysis of the gas turbine engine combustion chamber conversion to associated petroleum gas and oil

We performed the computational and analytical estimation of parameters and formulated the recommendations for conversion of the combustion chamber of the E70/8 RD engine combustion chamber to associated petroleum gas and oil.

Numerical Simulation Application for the Design and Fine-Tuning of Small-Sized Gas Turbine Engine Combustor

The small-sized GTE are used more and more both as the basis of power plants and power machines for various purposes. The technical and operational characteristics of these engines are largely determined by the design quality of their combustion chambers (CC). One of the most advanced methods of CC scientific investigation is the bench testing. However, such CC operation study is complicated by labour-intensiveness of an experiment and its significant costs. Therefore, in recent years GTE designers started to use widely the numerical simulation for these purposes. However, the level of such calculation development does not allow often to solve the issue of CC fine-tuning in order to achieve the required parameters. It is also difficult to determine the reliability degree of such calculations. The preliminary calculation of the combustion chamber was performed first of all. Its purpose is the CC shape development and its determination of its geometric dimensions. At that, the main requirement was to ensure the possibilities of one CC placement between the previously-designed compressor and the turbine and the performance of a whole set of technical specifications by the engine. At the second stage using The CC fine-tuning was performed in order to optimize the performance by using CFD-calculation. At that the calculated method was used for which the verification has been performed by the bench tests. Such a CC fine-tuning allowed to reduce the product development period and improve its characteristics.

Mixture modelling in a swirle flow in the ANSYS CFX program

The paper presents design research of mixing real gas in swirl flows of swirl burners of gas turbine engine combustion chambers in the ANSYS CFX program. The peculiarities of heat exchange of a swirl flow with the environment and the zone of reverse currents are investigated. The results of the numerical research and the previous physical experiment are shown to be in good qualitative and quantitative agreement.

Emission characteristics and temperature non-uniformity at the outlet of the gas turbine engine combustion chamber

Emission characteristics and temperature non-uniformity at the outlet of a gas turbine engine combustion chamber were simulated in bench test conditions. Simulation results were compared with the experimental data. The adequacy of the applicability of the turbulence and combustion models was investigated. The influence of the deformation intensity of the flame source in the combustion model and the constant swirl in the RNG k-e turbulence model on the distribution of parameters inside the combustion chamber and the emission characteristics is shown. Good agreement of the simulation results and the experimental data is obtained.

The influence of engineering changes on NOx emission in a gas-turbine endine combustion chamber

The paper presents a model of calculating nitrogen oxide formation in the combustion chamber of a gas turbine engine. The model has made it possible to make the calculations and determine the characteristics of nitrogen oxide concentration from the total air ratio in combustion chambers with various extents of opening the flame tube head. The processes in the commercial and shortened gas turbine engine combustor chambers are analyzed.

Test benches for researching the processes and operational development of low emission gas turbine engine combustion chambers

The paper presents a range of test benches that form the base for researching gas dynamic processes the processes of mixture and combustion in the burner of a gas turbine engine combustion chamber, as well as benches for testing full-size combustor chambers both separately and as part of the engine. This base is necessary for the production and optimization of low emission gas turbine engine combustion chambers.

Simulation of drop coagulations in swirled time dependent streams with reference to gas turbine engine combustion chambers

The paper presents a model of fuel drop coagulation with reference to gas turbine engine combustion chambers. Calculations of drop coagulation are carried out at various values of the fuel spray expansion angles and initial drop sizes using the model developed. The values of drop concentrations and their sizes depending on geometrical and performance characteristics of the sprayer are specified. It is shown that the decrease of the fuel spray angle, with the initial drop concentration and their sizes being the same, leads to the shift of the fuel concentration maximum towards larger sizes and increase in drop concentrations.

Mathematical model for calculating radial non-uniformity of the gas temperature field at the exit of small gas turbine engine combustion chambers

The paper is devoted to the problems of constructing a model of radial non-uniformity of the gas temperature field (GTF) at the outlet of the combustion chambers of small gas turbine engines (SGTE). Correlation regression dependence for assessing the influence of structural and operational parameters on the characteristics of the temperature field at the outlet of SGTEs is obtained.

Effect of non-uniform compressor flow parameters on the characteristics of a gas turbine engine combustion chamber

A mathematical model of the working process of a gas turbine engine combustion chamber is presented which makes it possible to take into account the residual swirl and radial non-uniformity of the flow velocity at the inlet to the combustion chamber.

Development of an algorithm of design calculation of a combustion chamber for microturbine electric power plants

The paper deals with ways of solving some problems that might arise when using computer technology design of gas turbine engine combustion chambers.

Development of a generalized model of heat-mass transfer between fuel drops and gas stream with reference to gas turbine engine combustion chambers

The paper presents a generalized model of heating and evaporation of separate fuel drops, taking into account the influence of the distribution of fuel steam concentration around the drop on the evaporation process. Numerical calculations for the operations typical for gas turbine engine combustion chambers are presented. The range of air flow temperatures over which the influence of fuel steam concentration in the drop environment on the rate of its evaporation and the fuel distribution in the swept volume of the combustion chamber is significant has been defined.