Jet Engine Combustion Chamber Research Articles

Effect of oxygen enrichment on the combustion characteristic and pollutant emissions of kerosene-biogas mixtures on a mini jet engine combustion chamber

There are many alternative fuel studies in gas turbine engines, which are widely used in aviation and energy production. Biogas has also become popular among alternative fuels, especially since it can be obtained from waste. Biogas not only provides a renewable energy source, but also helps to manage organic waste, reduce greenhouse gas emissions and promote sustainable practices in waste management and energy production. The most important issue for alternative fuel studies in gas turbine engines is maximum emission reduction with minimum efficiency loss. In this study, oxygen enrichment and alternative fuel simulation were performed on a mini gas turbine engine. The biogas/kerosene mixture was used together with the oxygen enrichment method, which is known to increase the flame temperature in the literature, due to the lowering effect of the biogas on the combustion chamber outlet temperature.As an alternative fuel, biogas was mixed with kerosene up to 50% in 10% increments. The geometry of the GTM-120 engine used in the study was simplified and validated with the combustion chamber outlet temperatures at 3 different rpms created with the fuel and air inlet conditions taken from the literature. While kerosene fuel is injected from 12 nozzles with Discrete Phase Method, k-e turbulence model and Discrete Ordinates radiation model are used. Alternative fuel was given from the nozzle surfaces as a mass flow inlet by calculating the flow rate so that the thermal power remains constant. All simulations were made with steady-state and 1600 iterations. As a result, it was observed that oxygen enrichment increased the flame temperature and NOX formation, while decreasing the CO emission.On the other hand, it has been observed that the CO2 in the biogas reduces both the temperature and NOX emissions due to its diluting effect, while at the same time increasing the CO emissions in the front region. Furthermore, the decrease in the total C/H mass also led to a reduction in the CO emission at the outlet. Another effect of the biogas was the reduction in the CO2 at the outlet. Thanks to this study, the use of alternative fuels and a decrease in pollutant emissions have been achieved by keeping the loss of engine efficiency at a minimum.With this study, it has been demonstrated that biogas can be used as an alternative fuel with kerosene by keeping the engine efficiency loss to a minimum and a decrease in pollutant emissions.

Modeling and CFD Analysis of Combustion Chamber of Jet Engine to Reduce the Emissions using Biofuels

The biodiesel can be extracted from different sources and then it is blend with engine fuels to counter factors like fuel scarcity, pollution, cost and increasing of consumers. The use of algal oil diesel-biodiesel blend is one of the methods to reduce the emissions and in increasing performance of jet engine. To emphasize on the reduction of NOx in the combustion chamber of the jet engine. Combustion chamber is the main part of the jet engine where many important chemical reactions take place and generates heat. In this paper, the main focus is on the percentage of NOx in the output and how we can reduce that by changing some parameters into input. The challenges in fuel high performance combustion engines haven’t had any major changes over the years. However, more sophisticated analysis process has been deployed to overcome these challenges. The biofuels i.e., algal oil diesel-biodiesel is taken first to blend, then standard boundary conditions were applied and then observed the results carefully. By looking at the results then decided to make some changes in the diesel i.e., the bio diesel (B10, B15 and B20) where it found drastic changes in NOx emission and got some more positive changes.

Modeling and CFD Analysis of Combustion Chamber of Jet Engine to Reduce the Emissions using Biofuels

The biodiesel can be extracted from different sources and then it is blended with engine fuels to counter factors like fuel scarcity, pollution, cost and increasing of consumers. The use of algae oil diesel-biodiesel blend is one of the methods to reduce the emissions and in increasing performance of jet engine. To emphasize on the reduction of NOx in the combustion chamber of the jet engine. In this paper, the main focus is on the percentage of NOx in the output and how we can reduce that by changing some parameters into input. The biofuels i.e., algae oil diesel-biodiesel is taken first to blend, then standard diesel was used and then the results were observed carefully. The best bio diesel of the B10, B15 and B20 blends was found to well reduce the NOx emissions.

Fault detection and isolation of actuator failures in jet engines using adaptive dynamic programming

This paper presents a adaptive dynamic programming-based fault detection and isolation (FDI) scheme to detect and isolate faults in an aircraft jet engine. To this end, the weights in Actor-Critic neural networks are first tuned to learn the input-output map of the jet engine considering its multiple working modes. The convergences of the trainings in Critic-Actor neural networks are strictly proved without knowing the drift dynamics and the input dynamics in the presence of unknown nonlinearities and approximation errors. Using the residuals that are generated by measuring the difference of each network output and the measured engine output, various criteria are established for accomplishing the fault diagnosis task, that addresses the problem of fault detection and isolation of the system components. A number of simulation studies are carried out for combustion chamber of a single-spool jet engine to demonstrate and illustrate the advantages, capabilities, and performance of our proposed fault diagnosis scheme.

RESEARCH ON CHARACTERISTICS OF TURBO JET ENGINE COMBUSTION CHAMBER

The characteristics of the combustion chamber of turbo jet engine with various parameters are examined in this article. The scientific works of other authors analyzing operating parameters of the jet engines were reviewed. Their recommendations were considered. Computer simulations of the combustion chamber were performed using different combustion reactions. The exhaust gas temperature and its dependence on the combustion mixture were determined. A practical study was also carried out, during which the experimental exhaust gas temperature was measured, and the trends of temperature change were determined. After analyzing both theoretical and practical results, the conclusions are presented.

Numerical analysis of fuel injection configuration on nitrogen oxides formation in a jet engine combustion chamber

Emissions of nitrogen oxides from the aviation sector, contrary to the land-based sources, have doubled compared to 1990. Aircraft unique location in the upper atmosphere and daily growth of air-based traffic require particular attention to the effects of these emissions. One way to cope with this problem is to develop and design more efficient combustion systems. In this research, the numerical modelling of combustion process inside a jet engine combustion chamber is presented. The investigated chamber is a theoretical can type chamber mounted with a double stage radial swirler. The advanced k-zeta-f turbulence model was utilised to model the turbulent behaviour, while the spray process was described by the Euler Lagrangian spray modelling approach. Two different modelling approaches for describing the combustion process were employed: reduced chemical mechanism and the 3-zone extended coherent flame (ECFM-3Z) combustion model. Considering the analysis of relevant physical quantities and taking into account the reduction of computational costs while using the ECFM-3Z combustion model, it was employed for analysis of the influence of spray and emission processes by varying number and positioning of fuel introduction nozzle holes. Increase in the number of nozzle holes and their correct positioning can result in emission reduction up to 60%. Such behaviour could be addressed to the specific spray cloud formation and smaller high-temperature regions. Results showed that the presented model can be used as a modern design tool in the early stage of the combustion chamber development.

Task-Point Sequencing and Trajectory Generation/Optimization with Benchmarking for Multi-axis Percussion Laser Drilling of Jet Engine Combustion Chamber Panels

Percussion drilling is a type of laser drilling operation for which optimized 5-axis trajectory planning has been developed. While percussion drilling is less advantageous in terms of local thermal loading and achievable part quality, it is used extensively in industry, due to its simplicity of automation compared to on-the-fly drilling. Thus, a TSP-style trajectory planning algorithm has been developed for percussion laser drilling. The novelty, in this case, is concurrent planning of 5-axis time-optimal point-to-point movements within the sequencing algorithm, and direct minimization of the total travel time, rather than just distance (in two Cartesian axes), as is the method for which a significant portion of TSP solvers and trajectory planners in the literature has been developed. Compared to currently applied methods, 32–36% reduction in the beam positioning time has been achieved. Also, 39–45% reduction in the peak magnitude of vibration has been realized. Limited benchmarking with the state-of-the-art TSP solvers from combinatorial mathematics, considering only 2-axis Euclidean distance as the objective function, indicates that the proposed sequencing algorithm for percussion drilling is sub-optimal by 9–12%. Thus, it can still use further improvement in future research. Nevertheless, the trajectory planners that have been developed in this paper for percussion drilling have experimentally demonstrated very promising improvements in terms of motion time and smoothness. As more advanced laser control electronics with deterministic execution and rapid synchronization capability become available, such algorithms are expected to facilitate significant production gains in laser drilling processes used in different industries.

Optimization of process parameters on Combustor Material Using Taguchi & MCDM Method in Electro-Discharge Machining (EDM)

Abstract Inconel 718 is one of the widely used material for combustion chamber of jet engine, Purpose of the study is to obtain an optimal setting of process parameters for single and multi-optimisation resulting in an optimal value of the material removal rate and tool wear rate by varying input parameter current, pulse on time pulse off time and gap voltage while EDM for Inconel 718 using copper cadmium as electrode Taguchi L9 array has been used to design the experiments, the results are further analyzed using MINITAB for single optimisation and MCDM technique named Preference Ranking Organization Method for Enrichment of Evaluations (PROMETHEE) to investigate the multi-optimization of response characteristics for Inconel 718.

Method of calculating the thickness of the combustion chamber of a liquid rocket engine made with the use of innovative technologies and materials

The use of innovative techniques in the production of parts and assembly units is one of the promising trends connected with increasing mass-energy characteristics of liquid- propellant jet engines. The article presents a concept of development of a liquid-propellant jet engine combustion chamber with the use of modern technologies and materials. We propose making the mixing head according to the additive technology. The cylindrical part of the combustion chamber integrated with the nozzle is to be made of carboncarbon composite material. The article presents a configuration of innovative combustion chamber design and indicates its advantages. The results of calculating geometrical parameters are given for certain initial data. The formulas and results of calculations of the specific heat flow rate along the length of the combustion chamber and the nozzle are also given in the article. The existing methods of over-heating protection of the wall of the chamber are described in the article. The results of testing all these methods of over-heating protection show that they are not efficient enough for the innovative combustion chamber. The new method suggested by the author gives the opportunity to solve the problem by means of calculating the wall thickness taking into account the influence of inner pressure and high temperatures. The method includes both solving the task of transient heat conduction by the finite-deference method and strength calculation using the momentless theory of shells.

On the possibility of burning acceleration in the combustion chambers of advanced jet engines by deeply subcritical microwave discharge

On the possibility of burning acceleration in the combustion chambers of advanced jet engines by deeply subcritical microwave discharge

Study of Air Excess in Relation with Engine Parameters for a Generalized Reaction Based on JET-A Fuel<sup></sup>

In this paperwork we are studying the performance of a combustion process into a jet engine combustion chamber, more specifically the relations between excess of air, overall pressure ratio and inlet turbine temperature for a combustion reaction based on a jet A fuel. The study present a method of calculating the excess of air for a generalized combustion reaction based on Jet A fuel indicated by the general formula , for different temperatures of air, different temperatures of fuel and different inlet turbine temperatures. The result of this study is to achieve diagrams in which are presented the variation of air excess with engine parameters who participate in combustion process and to performed a computing program in which it is calculated the exactly value of excess of air for any outlet compressor temperatures, any inlet turbine temperatures and different fuel temperatures.

Study of detonation initiation in kerosene–oxidizer mixtures in short tubes

The paper describes experimental studies of detonation initiation in a kerosene–oxidizer mixture in a short test tube. The aim of the study is to determine the minimum diameter of the tube and the minimum level of energy that enables direct initiation of the detonation. Knowledge about these values will inform the design of a jet engine combustion chamber in which thermal energy will be generated by a rotating detonation process. The test tube and the oxidizer inside the tube were heated using specially designed heaters installed outside of the tube. The heated oxidizer provided thermal conditions similar to the conditions for a compressor with small to medium static pressure. The study was conducted for four different tube diameters and for various energies of initiation. As a result, measurements of pressure waveforms were obtained for various cases of fuel injection, which were then compared against the results of the shock wave generated by the initiator. This study provides a value for the energy (the pressure of the mixture in the initiator), which provided direct initiation of detonation for a kerosene–oxidizer mixture. Different tube diameters led to the initiation of detonation for various oxygen–nitrogen compositions as an oxidizer.

Investigation of the Effect of Solidification Velocity on the Quality of Single Crystal Turbine Blades

The occurrence of high temperatures in combustion chambers of jet engines and gas turbines has led to the demand for new technologies and new materials for the manufacture of one of the most critical elements of these systems - the turbine blades. These elements have to withstand extreme temperatures for extended periods without loss of mechanical strength, conditions under which many alloys fail. Such failure is ascribed to the combination of high temperatures and high centrifugal forces, resulting in creep. This is especially prevalent in multi-crystalline structures in which grain boundaries present weaknesses in the structure. High temperature resistant alloys formed as single crystal (SX) structures offer the necessary material properties for safe performance under such extreme conditions. Modelling and simulation techniques were first used to study the directional solidification (DS) of crystal structures during vacuum investment casting. These models allowed the study of the dendritic growth rate, the formation of new grains ahead of the solid/liquid interface and the morphology of the dendritic microstructure. These studies indicated the opportunity to optimise the velocity of the solidification front (solidification rate) for single crystal structures. The aim of this study was therefore to investigate the effect of the solidification rate on the quality of SX castings. The investigations were carried out for nickel-based superalloy CMSX-4 turbine blade casts and rods using the Bridgman process for vacuum investment casting.

Knowledge reuse in manufacturability analysis

This paper describes a set of modelling guidelines for the improved reuse of manufacturing knowledge in decision support systems. The work draws on research into product and manufacturing knowledge models, and uses a case study based on a simplified jet engine combustion chamber casing to illustrate the proposed guidelines. The paper describes three principles of reuse, i.e., the separation of information from knowledge, the separation of product knowledge from manufacturing process knowledge, and the correct classification of manufacturing knowledge. Whilst the first two principles were found to be well established in the research literature, guidance on how to apply classification hierarchies for optimum reuse was found to be insufficient. The guidelines presented in this paper therefore provide improved guidance on how to classify manufacturing knowledge for optimum reuse.

Homogenization of the Lavrent'ev–Bitsadze Equation in a Partially Perforated Domain

Homogenization problems in partially perforated domains have attracted much attention in recent years. The case of the Stokes equation was considered in [1–5]. Model problems for the Laplace operator with various boundary conditions on the cavity boundaries were analyzed in [6–13]. In the present paper, we consider the Lavrent’ev–Bitsadze equation of variable type in a partially perforated domain. We assume that only the “elliptic” part of the domain is perforated, so that perforation is absent in the “hyperbolic” part. We prove the existence and uniqueness of the solution for such a problem. Note that the existence and uniqueness for the Lavrent’ev–Bitsadze equation were considered earlier (see Remark 3 below). Then, on the basis of the Murat–Tartar lemma for compensated compactness, we prove the homogenization theorem. We first justify the weak convergence of solutions of the Dirichlet problem and then prove an analog of the theorem “on the convergence of arbitrary solutions.” Models leading to such problems arise in the analysis of the combustion of a fuel-oxidant mixture in the combustion chamber of a liquid-fuel jet engine. A gas with bubble-like inhomogeneities, originally moving at a subsonic velocity (such a motion is described by an elliptic equation), passes the sonic barrier (bubbles disappear at that moment) and moves further at a supersonic velocity (the supersonic motion of a gas is described by a hyperbolic equation). The description of such a motion without using homogenization theory is a very difficult problem. However, by using the homogenization method, one can construct an effective behavior of such a gas in the simplest, clearest form.

Vibrations and vortices in combustion chambers

Computational and experimental studies have been made of large-scale vortex structures as sources of acoustic vibrations. Low-frequency sources of vibration in combustion chambers of solid propellant jet engines have been shown to be due to the hydrodynamic instability of large-scale vortex structures in the main gas flow.

Atomized-kerosene diffusion flame in an accompanying supersonic flow

The use of pneumatic atomization of fuel in combustion chambers of jet engines permits a substantial increase in the completeness of combustion and a corresponding decrease in soot formation and exhaust of toxic substances. A mathematical model of the flame of a liquid-fuel pneumatic injector-nozzle, needed in the design of combustion chambers and other burner systems, is presently lacking. This has to do, first of all, with the problem of the mathematical description of a turbulent, two-phase reacting jet in a complex flowfield where the role of "two-phase" effects appears to be most important.

Calculational method for predicting tendency of hydrocarbon fuels to form carbon deposits

This article attempts to derive a new empirical formula for the prediction of the tendency of fuels to form carbon deposits in the combustion chambers of air-breathing jet engines. Heavy deposition of carbon in the combustion chamber of a gas turbine engine may lead to warping and in some cases burnout of the flame tube, greater nonuniformity of the temperature field ahead of the turbine, and a reduction of the turbine efficiency and a shortening of the engine life as a result of failure of the nozzle vanes and blades of the turbine. The formation of carbon deposits depends primarily on the hydrocarbon group composition and distillation curve on the fuel. Viscosity, density, surface tension, and other properties also have some influence.

On the deformation of the rectangular turbulent jet cross-section

The paper explains the reason for the experimentally observable deformation of a rectangular turbulent jet manifesting itself in a rapid growth (along the jet length) of the jet cross-section short side and a reduction of its long side. As a result, these sides change places some distance downstream of the jet origin. The jet deformation is shown to be due to a specific pressure field induced by large vortices that originate in the jet mixing zone. A method of calculating the jet deformation is developed which makes use of the author's information on the pressure field produced by large vortices. The predicted results are compared with the experimental data available from other sources. The theory suggested applies to jet flows in boiler furnaces, dryers, combustion chambers of jet engines and stationary gas-turbine plants of electric power stations, chemical reactors, etc.

Prediction of Crack Initiation in Combustion Chamber Liners

An analytical procedure for predicting the crack initiation life of jet engine combustion chamber liners is presented. Sample calculations using the procedure are made and correlated against representative engine and test rig data. The analysis employs the Strain Range Partitioning Method, proposed by Manson et al., to determine the low cyclic thermal fatigue (LCTF) and creep damage components. A procedure for estimating plastic strain range and creep strain per cycle is presented, and life estimates are made using this in combination with a linear cumulative damage summation of the LCTF and creep damage components.