High Momentum Jet Flames at Elevated Pressure: A — Experimental and Numerical Investigation for Different Fuels

Author(s):  
Oliver Lammel ◽  
Michael Severin ◽  
Holger Ax ◽  
Rainer Lückerath ◽  
Andrea Tomasello ◽  
...  

In this work, results of comprehensive high-pressure tests and numerical simulations of high momentum jet flames in an optically accessible combustion chamber are presented. A generic single nozzle burner was designed as a full-scale representation of one duct of a high temperature FLOX® gas turbine combustor with a model pilot burner supporting the main nozzle. As an advanced step of the FLOX® gas turbine combustor development process, tests and simulations of the entire burner system (consisting of a multi nozzle main stage plus a pilot stage) are complemented with this work on an unscaled single nozzle combustor, thus supporting the development and testing of sub concepts and components like the mixing section and dual-fuel injectors. These injectors incorporate a gaseous fuel stage and a spray atomizer for liquid fuels, both separately exchangeable for testing of different fuel placement concepts. The combustor was successfully operated at gas turbine relevant conditions with natural gas including a variation of the Wobbe index, and with light heating oil with and without water admixture. The presented work is the first of two contributions and covers the description of the experimental setup, an overview of the numerical methods, high-pressure test results for different fuels and variations of the operating conditions including exhaust gas measurements and basic optical diagnostic methods, together with CFD results for several cases. The other part will present detailed and focused investigations of few conditions by complex and extensive optical and laser combustion diagnostics.

Author(s):  
Yeoung Min Han ◽  
Min Soo Yoon ◽  
Woo Seok Seol ◽  
Dae Sung Lee ◽  
Victor I. Yagodkin ◽  
...  

An experimental investigation is carried out on modeling of fuel atomization for the purpose of simulating the idle regime of a gas turbine combustor through atmospheric testing. If the simulation is successfully applied, it will significantly reduce the cost of testing. The simulation must sustain nearly the same fuel spray characteristics and the same aerodynamics at the exit of the frontal device. Air assisting through the main stage of a dual orifice fuel nozzle is employed to match the fuel spray characteristics. Optical diagnostic methods including flow visualization and Adaptive Phase/Doppler Velocimetry are used for the investigation of spray characteristics. Once the fuel spray characteristics are matched by air assisting, the combustor characteristics may then be matched by maintaining the loading parameter constant. The possibility of modeling with air assisting is shown and appropriate conditions for air assisting are found.


Author(s):  
Holger Ax ◽  
Oliver Lammel ◽  
Rainer Lückerath ◽  
Michael Severin

Abstract A detailed investigation on flame structures and stabilization mechanisms of confined high momentum jet flames by one-dimensional (1D)-laser Raman measurements is presented. The flames were operated with natural gas (NG) at gas turbine relevant conditions in an optically accessible high-pressure test rig. The generic burner represents a full scale single nozzle of a high temperature FLOX® gas turbine combustor including a pilot stage. 1D-laser Raman measurements were performed on both an unpiloted and a piloted flame and evaluated on a single shot basis revealing the thermochemical states from unburned inflow conditions to burned hot gas in terms of average and statistical values of the major species concentrations, the mixture fraction and the temperature. The results show a distinct difference in the flame stabilization mechanism between the unpiloted and the piloted case. The former is apparently driven by strong mixing of fresh unburned gas and recirculated hot burned gas that eventually causes autoignition. The piloted flame is stabilized by the pilot stage followed by turbulent flame propagation. The findings help to understand the underlying combustion mechanisms and to further develop gas turbine burners following the FLOX concept.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Lei Sun ◽  
Yong Huang ◽  
Zhilin Liu ◽  
Shaolin Wang ◽  
Xiaobo Guo

Abstract The lean blowout (LBO) limit is crucial for gas turbine combustor in the aero engine. The effect of atomization of liquid fuels on the LBO limit is needed to be further studied. On the other hand, the effects of atomization on the LBO limit can be neglected if gas fuels are utilized in a combustor. Thus, the comparative experiment between liquid fuel and gas fuel can be utilized to study the effects of atomization performance of liquid fuels on the LBO limit. In this paper, the LBO limit for a gas turbine combustor utilizing methane is studied experimentally. Seven kinds of combustor configurations are chosen for the experimental test. The LBO limits are obtained for all the chosen combustors. The variation of the LBO limit with the combustor configuration for both methane and aviation kerosene exhibits the similar tendency, i.e., the LBO limits utilizing methane are slightly larger than those utilizing aviation kerosene for the same combustor. Further, the atomization performance has little effects on the LBO limits for the present combustor configurations at the present operating conditions where the SMD for the fuel atomizer utilizing aviation kerosene is about 10 μm.


Author(s):  
Bertram Janus ◽  
Andreas Dreizler ◽  
Johannes Janicka

This study reports on measurements in a generic non-premixed gas turbine combustor segment. Flow and scalar field were characterized using advanced laser diagnostic methods. The optically accessible burning chamber allowed for measurement of inflow conditions close-by the nozzle important for comparisons with numerical simulations. The generic nozzle design is sufficiently simplified to be precisely reproduced by block structured computational grids but shows typical features of gas turbine applications. To expose the influence of heat release on the flow field properties both isothermal and combusting conditions were investigated. Striking features of the present configuration are a detached flame, multiple recirculation zones, and complex coherent flow structures.


Author(s):  
Dominik Schäfer ◽  
James D. Gounder ◽  
Oliver Lammel ◽  
Holger Ax ◽  
Rainer Lückerath ◽  
...  

Abstract A promising alternative to modern swirl combustors for gas turbines are high momentum jet stabilized combustors. This gas turbine burner concept consists of circular arranged jet nozzles through which partially premixed high momentum jets enter the combustion chamber in axial direction. Furthermore, it features fuel flexibility, load flexibility and low pollutant emissions. The investigated generic combustor consists of an eccentric single nozzle in a square chamber. This nozzle represents a full-scale segment of a concentrically arranged multi-nozzle configuration. All measurements were carried out at the high pressure combustion test rig (HBK-S) at the German Aerospace Center (DLR) in Stuttgart. The generic single nozzle model combustor has been operated in a high-pressure test rig with large optical access in order to gain a detailed understanding of fuel distribution, droplet distribution, fuel air mixing and high temperature regions through various sections of the combustion chamber. For this purpose, different laser based measurement techniques have been applied simultaneously under gas turbine relevant conditions on liquid fuels (oil and oil/water). Other measurements in this combustor on gaseous fuels were presented in preceding (parts A and B) and current publications (part C). Mie scattering was used to visualize the liquid phase of oil and water downstream of the nozzle. In order to gain knowledge about the droplet velocity, a Nd:YAG double pulse laser at 532 nm was used for Particle Image Velocimetry (PIV). Additionally the gaseous and liquid phases of oil have been visualized through Planar Laser Induced Fluorescence (PLIF) by excitation of poly-cyclic aromatic hydrocarbons (PAHs) with a laser wavelength of 266 nm. To observe high temperature regions, OH and PAH PLIF was also performed with a low bandwidth at 283 nm from a Nd:YAG pumped dye laser. It was possible to separate the low-intensity OH signal of the hot gas regions from the PAH signal by collecting the different LIF signals simultaneously through a dual camera setup. Instantaneous PAH LIF images of the liquid and gaseous phase were compared with Mie scattering images for a qualitative impression of the evaporation. For this a structural comparison between the liquid phases of both images has been carried out. Results indicate, that the evaporation of most of the liquid fuel takes place near the hot gas region, as a large proportion of droplets are carried far downstream of the nozzle by the high momentum jet.


Author(s):  
Masato Hiramatsu ◽  
Yoshifumi Nakashima ◽  
Sadamasa Adachi ◽  
Yudai Yamasaki ◽  
Shigehiko Kaneko

One approach to achieving 99% combustion efficiency (C.E.) and 10 ppmV or lower NOx (at 15%O2) in a micro gas turbine (MGT) combustor fueled by biomass gas at a variety of operating conditions is with the use of flameless combustion (FLC). This paper compares experimentally obtained results and CHEMKIN analysis conducted for the developed combustor. As a result, increase the number of stage of FLC combustion enlarges the MGT operation range with low-NOx emissions and high-C.E. The composition of fuel has a small effect on the characteristics of ignition in FLC. In addition, NOx in the engine exhaust is reduced by higher levels of CO2 in the fuel.


Author(s):  
S. James ◽  
M. S. Anand ◽  
B. Sekar

The paper presents an assessment of large eddy simulation (LES) and conventional Reynolds averaged methods (RANS) for predicting aero-engine gas turbine combustor performance. The performance characteristic that is examined in detail is the radial burner outlet temperature (BOT) or fuel-air ratio profile. Several different combustor configurations, with variations in airflows, geometries, hole patterns and operating conditions are analyzed with both LES and RANS methods. It is seen that LES consistently produces a better match to radial profile as compared to RANS. To assess the predictive capability of LES as a design tool, pretest predictions of radial profile for a combustor configuration are also presented. Overall, the work presented indicates that LES is a more accurate tool and can be used with confidence to guide combustor design. This work is the first systematic assessment of LES versus RANS on industry-relevant aero-engine gas turbine combustors.


Author(s):  
George Rocha ◽  
Simon Reynolds ◽  
Theresa Brown

Solar Turbines Incorporated has combined proven technology and product experience to develop the new Taurus 65 gas turbine for industrial power generation applications. The single-shaft engine is designed to produce 6.3 megawatts of electrical power with a 33% thermal efficiency at ISO operating conditions. Selection of the final engine operating cycle was based on extensive aerodynamic-cycle studies to achieve optimum output performance with increased exhaust heat capacity for combined heat and power installations. The basic engine configuration features an enhanced version of the robust Centaur®50 air compressor coupled to a newly designed three-stage turbine similar to the Taurus 70 turbine design. Advanced cooling technology and materials are used in the dry, lean-premix annular combustor, consistent with Solar’s proven SoLoNOx™ combustion technology, capable of reducing pollutant emissions while operating on standard natural gas or diesel liquid fuels. Like the Titan™ 130 and Taurus 70 products, a traditional design philosophy has been applied in development of the Taurus 65 gas turbine by utilizing existing components, common technology and product experience to minimize risk, lower cost and maximize durability. A comprehensive factory test plan and extended field evaluation program was used to validate the design integrity and demonstrate product durability prior to full market introduction.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Vedant Dwivedi ◽  
Srikanth Hari ◽  
S. M. Kumaran ◽  
B. V. S. S. S. Prasad ◽  
Vasudevan Raghavan

Abstract Experimental and numerical study of flame and emission characteristics in a tubular micro gas turbine combustor is reported. Micro gas turbines are used for distributed power (DP) generation using alternative fuels in rural areas. The combustion and emission characteristics from the combustor have to be studied for proper design using different fuel types. In this study methane, representing fossil natural gas, and biogas, a renewable fuel that is a mixture of methane and carbon-dioxide, are used. Primary air flow (with swirl component) and secondary aeration have been varied. Experiments have been conducted to measure the exit temperatures. Turbulent reactive flow model is used to simulate the methane and biogas flames. Numerical results are validated against the experimental data. Parametric studies to reveal the effects of primary flow, secondary flow and swirl have been conducted and results are systematically presented. An analysis of nitric-oxides emission for different fuels and operating conditions has been presented subsequently.


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