Flow Field and Structure of Swirl Stabilized Non-Premixed Natural Gas Flames at Elevated Pressure

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):  
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.


2006 ◽  
Vol 129 (3) ◽  
pp. 680-687 ◽  
Author(s):  
Klaus Peter Geigle ◽  
Wolfgang Meier ◽  
Manfred Aigner ◽  
Chris Willert ◽  
Marc Jarius ◽  
...  

A technical gas turbine combustor has been studied in detail with optical diagnostics for validation of large-eddy simulations (LES). OH* chemiluminescence, OH laser-induced fluorescence (LIF) and particle image velocimetry (PIV) have been applied to stable and pulsating flames up to 8 bar. The combination of all results yielded good insight into the combustion process with this type of burner and forms a database that was used for the validation of complex numerical combustion simulations. LES, including radiation, convective cooling, and air cooling, were combined with a reduced chemical scheme that predicts NOx emissions. Good agreement of the calculated flame position and shape with experimental data was found.


Author(s):  
F. Wang ◽  
Y. Huang ◽  
T. Deng

Multi-injection combustor (MIC) could extend the steady working range of the whole combustor and reduce emissions therefore, so it is one of the Gas Turbine Combustor (GTC) design direction of future. The cold flow character of MIC is the basic work for MIC designers. Because of the low cost nowadays, the CFD method is a very suitable tool for it. Thus, firstly realizable k-epsilon turbulent model (RKE) and Reynolds stress turbulent model (RSM) were used to simulate the downstream flow field of a double radial swirl-cup amongst a simple tube, and the prediction results are compared with the experimental data which are gained by another researcher in Beihang University. The comparison between the experimental data and the CFD prediction results are shown that in most regions, the prediction results quite agree with the experimental data, and the max error of RKE model and RSM model is about 5% and 3% respectively. So the RKE model can be used for swirl-cup combustor simulation for its low computing cost. Then the RKE model is applied in a single swirl-cup gas turbine combustor and two kinds of multi-injection GTC flow field simulation. In the comparison between one single swirl-cup and nine arranged swirl-cups which all are in the same lining structure, each swirl-cup in MIC has a recirculation zone after its exit. Gradually, the recirculation zones mixed and united together in the downstream region. Finally, the recirculation zones structure turns to be similar to the structure in the single swirl-cup GTC after the primary combustion holes. In the other comparison between two kinds of lining structures which all are fixed with the same multi-injection head, the primary combustion holes affect flow field obviously. All the recirculation zones finished before the former primary combustion holes of the MIC without the primary combustion holes, and the separated recirculation zones form a new recirculation zone close to the primary holes for the MIC with primary holes. So the MIC design should combine with the real combustor lining structure to make a high performance for the whole combustor.


2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Andreas Schwärzle ◽  
Thomas O. Monz ◽  
Andreas Huber ◽  
Manfred Aigner

Jet-stabilized combustion is a promising technology for fuel flexible, reliable, highly efficient combustion systems. The aim of this work is a reduction of NOx emissions of a previously published two-stage micro gas turbine (MGT) combustor (Zanger et al., 2015, “Experimental Investigation of the Combustion Characteristics of a Double-Staged FLOX-Based Combustor on an Atmospheric and a Micro Gas Turbine Test Rig,” ASME Paper No. GT2015-42313 and Schwärzle et al., 2016, “Detailed Examination of Two-Stage Micro Gas Turbine Combustor,” ASME Paper No. GT2016-57730), where the pilot stage (PS) of the combustor was identified as the main contributor to NOx emissions. The geometry optimization was carried out regarding the shape of the pilot dome and the interface between PS and main stage (MS) in order to prevent the formation of high-temperature recirculation zones. Both stages have been run separately to allow a detailed understanding of the flame stabilization within the combustor, its range of stable combustion, the interaction between both stages, and the influence of the modified geometry. All experiments were conducted at atmospheric pressure and an air preheat temperature of 650  °C. The flame was analyzed in terms of shape, length, and lift-off height, using OH* chemiluminescence (OH-CL) images. Emission measurements for NOx, CO, and unburned hydrocarbons (UHC) emissions were carried out. At a global air number of λ = 2, a fuel split variation was carried out from 0 (only PS) to 1 (only MS). The modification of the geometry leads to a decrease in NOx and CO emissions throughout the fuel split variation in comparison with the previous design. Regarding CO emissions, the PS operations are beneficial for a fuel split above 0.8. The local maximum in NOx emissions observed for the previous combustor design at a fuel split of 0.78 was not apparent for the modified design. NOx emissions were increasing, when the local air number of the PS was below the global air number. In order to evaluate the influence of the modified design on the flow field and identify the origin of the emission reduction compared to the previous design, unsteady Reynolds-averaged Navier–Stokes simulations were carried out for both geometries at fuel splits of 0.93 and 0.78, respectively, using the DLR (German Aerospace Center) in-house code turbulent heat release extension of the tau code (theta) with the k–ω shear stress transport turbulence model and the DRM22 (Kazakov and Frenklach, 1995, “DRM22,” University of California at Berkeley, Berkeley, CA, accessed Sept. 21, 2017, http://www.me.berkeley.edu/drm/) detailed reaction mechanism. The numerical results showed a strong influence of the recirculation zones on the PS reaction zone.


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.


2012 ◽  
Vol 510 ◽  
pp. 545-548
Author(s):  
Liang Yu ◽  
Shu Sheng Yuan ◽  
Zhi Bing Pang ◽  
Yun Liang Wang

RNG (Renormalization Group) k-ε turbulent model was applied to the numerical simulation of turbulent mixing processes in the RQL gas turbine combustor, and SIMPLE algorithm was used to solve the finite difference equations. The calculated conclusions were used to analyze temperature distribution of the mixed flow field and near-wall region of the flow field, and then discuss the NOx emissions. The results show that the effect of the injector zone geometry and the jet to crossflow momentum flux ratios on the NOx emissions is obvious. The reasonable control of jet is beneficial to reduce the local high temperature area and is able to improve the distribution of the exit temperature. And then achieve the goal of reducing the environmental pollution.


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