A Comprehensive Fuel Spray Model for High Pressure Fuel Injectors

Author(s):  
Gerald J. Micklow ◽  
Krishna Ankem ◽  
Tarek Abdel-Salam

Understanding the physics and chemistry involved in spray combustion, with its transient effects and the inhomogeneity of the spray is quite challenging. For efficient operation of both internal combustion and gas turbine engines, great insight into the physics of the problem can be obtained when a computational analysis is used in conjunction with either an experimental program or through published experimental data. The main area to be investigated to obtain good combustion begins with the fuel injection process and an accurate description of the mean diameter of the fuel particle, injection pressure, drag coefficient, rate shaping etc must be defined correctly. This work presents a methodology to perform the task set out in the previous paragraph and uses experimental data obtained from available literature to construct a semi-empirical numerical model for high pressure fuel injectors. A modified version of a multidimensional computer code called KIVA3V was used for the computations, with improved sub-models for mean droplet diameter, injection pressure, injection velocity, and drop distortion and drag. The results achieved show good agreement with the published in-cylinder experimental data for a Volkswagen 1.9 L turbo-charged direct injection internal combustion engine under actual operating conditions. It is crucial to model the spray distribution accurately, as the combustion process and the resulting temperature distribution and pollutant emission formation is intimately tied to the in-cylinder fuel distribution. The present scheme has achieved excellent agreement with published experimental data and will make an important contribution to the numerical simulation of the combustion process and pollutant emission formation in compression ignition direct injection engines and gas turbine engines.

Author(s):  
H. C. Eatock ◽  
M. D. Stoten

United Aircraft Corporation studied the potential costs of various possible gas turbine engines which might be used to reduce automobile exhaust emissions. As part of that study, United Aircraft of Canada undertook the preliminary design and performance analysis of high-pressure-ratio nonregenerated (simple cycle) gas turbine engines. For the first time, high levels of single-stage component efficiency are available extending from a pressure ratio less than 4 up to 10 or 12 to 1. As a result, the study showed that the simple-cycle engine may provide satisfactory running costs with significantly lower manufacturing costs and NOx emissions than a regenerated engine. In this paper some features of the preliminary design of both single-shaft and a free power turbine version of this engine are examined. The major component technology assumptions, in particular the high pressure ratio centrifugal compressor, employed for performance extrapolation are explained and compared with current technology. The potential low NOx emissions of the simple-cycle gas turbine compared to regenerative or recuperative gas turbines is discussed. Finally, some of the problems which might be encountered in using this totally different power plant for the conventional automobile are identified.


2019 ◽  
Vol 62 (2) ◽  
pp. 298-303
Author(s):  
A. V. Il’inkov ◽  
A. M. Ermakov ◽  
V. V. Takmovtsev ◽  
A. V. Shchukin ◽  
A. M. Erzikov

Author(s):  
Erlendur Steinthorsson ◽  
Adel Mansour ◽  
Brian Hollon ◽  
Michael Teter ◽  
Clarence Chang

Participating in NASA’s Environmentally Responsible Aviation (ERA) Project, Parker Hannifin built and tested multipoint Lean Direct Injection (LDI) fuel injectors designed for NASA’s N+2 55:1 Overall Pressure-Ratio (OPR) gas turbine engine cycles. The injectors are based on Parker’s earlier three-zone injector (3ZI) which was conceived to enable practical implementation of multipoint LDI schemes in conventional aviation gas turbine engines. The new injectors offer significant aerodynamic design flexibility, excellent thermal performance, and scalability to various engine sizes. The injectors built for this project contain 15 injection points and incorporate staging to enable operation at low power conditions. Ignition and flame stability were demonstrated at ambient conditions with ignition air pressure drop as low as 0.3% and fuel-to-air ratio (FAR) as low as 0.011. Lean Blowout (LBO) occurred at FAR as low as 0.005 with air at 460 K and atmospheric pressure. A high pressure combustion testing campaign was conducted in the CE-5 test facility at NASA Glenn Research Center at pressures up to 250 psi and combustor exit temperatures up to 2,033 K (3,200 °F). The tests demonstrated estimated LTO cycle emissions that are about 30% of CAEP/6 for a reference 60,000 lbf thrust, 54.8-OPR engine. This paper presents some details of the injector design along with results from ignition, LBO and emissions testing.


Author(s):  
A. J. Szaniszlo

The Advanced Low-Emissions Catalytic-Combustor Program ia an ongoing three-phase contract contract effort with the primary objective of evolving the technology required for incorporating catalytic combustors into advanced aircraft gas-turbine engines. Phase I is corrently in progress. At the present time, analytical evaluation is being conducted on advanced catalytic combustor concepts — including variable geometry — with their known inherent potential advantages of low level pollutant emission, widened combustion at ability limits, and reduced pattern factor for longer turbine life. Phases II and III will consist of experimental evaluation of the most promising concepts.


2021 ◽  
Vol 20 (3) ◽  
pp. 7-23
Author(s):  
Y. B. Aleksandrov ◽  
T. D. Nguyen ◽  
B. G. Mingazov

The article proposes a method for designing combustion chambers for gas turbine engines based on a combination of the use of calculations in a one-dimensional and three-dimensional formulation of the problem. This technique allows you to quickly design at the initial stage of creating and development of the existing combustion chambers using simplified calculation algorithms. At the final stage, detailed calculations are carried out using three-dimensional numerical calculations. The method includes hydraulic calculations, on the basis of which the distribution of the air flow passing through the main elements of the combustion chamber is determined. Then, the mixing of the gas flow downstream of the flame tube head and the air passing through the holes in the flame tube is determined. The mixing quality determines the distribution of local mixture compositions along the length of the flame tube. The calculation of the combustion process is carried out with the determination of the combustion efficiency, temperature, concentrations of harmful substances and other parameters. The proposed method is tested drawing on the example of a combustion chamber of the cannular type. The results of numerical calculations, experimental data and values obtained using the proposed method for various operating modes of the engine are compared.


2019 ◽  
pp. 39-49
Author(s):  
Юрий Иванович Торба ◽  
Сергей Игоревич Планковский ◽  
Олег Валерьевич Трифонов ◽  
Евгений Владимирович Цегельник ◽  
Дмитрий Викторович Павленко

The aim of the work was the development and testing of methods for modeling the combustion process in the torch igniters of gas turbine engines. To achieve it, the finite element method was used. The main results of the work are the substantiation of the need to optimize the torch igniters of gas turbine engines. The practice of operating torch igniters of various designs has shown that the stability of their work depends on the parameters of gas turbine engines and external factors (air and fuel temperature, size of fuel droplets, fuel and air consumption, as well as its pressure). At the same time, the scaling of the geometry of the igniter design does not ensure its satisfactory work in the composition of the GTE with modified parameters. In this regard, an urgent task is to develop a combustion model in a flare igniter to optimize its design. A computational model of a torch igniter for a gas turbine engine of a serial gas-turbine engine in a software package for numerical three-dimensional thermodynamic simulation of AN-SYS FLUENT has been developed. To reduce the calculation time and the size of the finite element model, recommendations on the adaptation of the geometric model of the igniter for numerical modeling are proposed. The mod-els of flow turbulence and combustion, as well as initial and boundary conditions, are selected and substantiated. Verification of the calculation results obtained by comparison of numerical simulation with the data of tests on a specialized test bench was performed. It is shown that the developed computational model makes it possible to simulate the working process in the torch igniters of the GTE combustion chambers of the investigated design with a high degree of confidence. The scientific novelty of the work consists in substantiating the choice of the combustion model, the turbulence model, as well as the initial and boundary conditions that provide adequate results to the full-scale experiment on a special test bench. The developed method of modeling the combustion process in gas turbine torch igniters can be effectively used to optimize the design of igniters based on GTE operation conditions, as well as combustion initialization devices to expand the range of stable operation of the combustion chamber. 


Author(s):  
Jinghe Lu ◽  
Xiao Liu ◽  
Shuying Li ◽  
Enhui Liu ◽  
Zhihao Zhang ◽  
...  

Abstract With the development of high performance gas turbine engines, the temperature before turbine is rising and it presents a serious challenge to existing thermal management. It is very attractive to use fuel as the cooling medium for gas turbine engines. For this purpose, the effects of fuel temperature on combustion characteristics are urgently needed to be understood. In this work, the characteristics of lean direct injection (LDI) combustor is simulated by changing the physical properties of fuel with different temperatures. The predictions of gas phase and droplet velocity, droplet diameter are compared well with the experiment data. The numerical results show that as fuel temperature rises, the droplet evaporation rate and mixing efficiency of fuel and air in non-reacting case is improved significantly, the spray angle, concentration and distribution profile of fuel in reacting case are enlarged as well. When fuel temperature is raised from 350K to 550K, the peak value of droplet evaporation rate at the vicinity of nozzle is increased by 26.7 times, the uniformity index downstream of the primary recirculation zone (PRZ) is increased by 2.57%, the axial length and maximum negative axial velocity of PRZ are reduced by 13% and 21%. The average temperature and NO emission at combustor outlet are increased by 1.99% and 48.15%, the mass fraction of CO is decreased by 5.45%. Besides, the number, diameter, and distribution space of droplets are decreased sharply. The formation of premixed flame and propagation of high-temperature region are promoted, the flame front is changed from a conical shape to a recessed shape. The combustion efficiency can be improved by increasing fuel temperature. The present study is expected to provide insightful information for understanding characteristics of LDI combustor with elevated fuel temperatures.


Author(s):  
Chao Zhang ◽  
Aldo Abate ◽  
John Crockett ◽  
Eric Ho

High pressure compressor (HPC) stator vanes of small gas turbine engines frequently have high circumferential variation of vibratory stress. This is very important for vibratory stress measurement by strain gauge tests and structural high cyclic fatigue characterization. The current paper presents experimental results of studying the effects of HPC stator angular positions in gas turbine engines on the circumferential distribution pattern of vibratory stress. Strain gauge tests were done on a stator with cantilevered vanes. Each vane had a strain gauge deployed at the same location. The stator was installed in gas turbine engines at two different angular positions during strain gauge tests. The experimental results show that more than one resonant peak occurred for a given vibratory mode and engine order resonance. The frequencies of resonant peaks were close to one another. The circumferential distribution of maximum vibratory stress (i.e., the maximum magnitude of these resonant peaks) with respect to the stator itself has a similar pattern at the two different angular positions. This clearly indicates the distribution pattern does not follow the gas-path aerodynamic pressure, but follows the stator angular positions. The frequency of the maximum vibratory stress was found to vary from sector to sector instead of from vane to vane; the vanes in each sector have a same frequency. Mistuning analysis was performed on the HPC stator to illustrate a number of resonant peaks and the sector-to-sector frequency variation of the maximum vibratory stress. The approach of “subset of nominal system modes” (SNM) [1, 2] was employed for mistuning analysis and the frequency distributions of stator vanes obtained by bench frequency response tests were used as input data. At the end, one might conclude that the high circumferential variation of vibratory stress be related to mistuning effects due to small variations in vane properties.


Author(s):  
Hsi-Wu Wong ◽  
Zhenhong Yu ◽  
Michael T. Timko ◽  
Scott C. Herndon ◽  
Elena de la Rosa Blanco ◽  
...  

The experimental data and numerical modeling were utilized to investigate the effects of exhaust sampling parameters on the measurements of particulate matter (PM) emitted at the exit plane of gas-turbine engines. The results provide guidance for sampling system design and operation. Engine power level is the most critical factor that influences the size and quantity of black carbon soot particles emitted from gas-turbine engines and must be considered in sampling system design. The results of this investigation indicate that the available soot surface area significantly affects the amount of volatile gases that can condense onto soot particles. During exhaust particle measurements, a dilution gas is typically added to the sampled exhaust stream to suppress volatile particle formation in the sampling line. Modeling results indicate that the dilution gas should be introduced upstream before a critical location in the sampling line that corresponds to the onset of particle formation microphysics. Also, the dilution gas should be dry for maximum nucleation suppression. In most aircraft PM emissions measurements, the probe-rake systems are water cooled and the sampling line may be heated. Modeling results suggest that the water cooling of the probe tip should be limited to avoid overcooling the sampling line wall temperature and, thus, minimize additional particle formation in the sampling line. The experimental data show that heating the sampling lines will decrease black carbon and sulfate PM mass and increase organic PM mass reaching the instruments. Sampling line transmission losses may prevent some of the particles emitted at the engine exit plane from reaching the instruments, especially particles that are smaller in size. Modeling results suggest that homogeneous nucleation can occur in the engine exit plane sampling line. If newly nucleated particles, typically smaller than 10 nm, are indeed formed in the sampling line, sampling line particle losses provide a possible explanation, in addition to the application of dry diluent, that they are generally not observed in the PM emissions measurements.


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