CFD Analysis of Swirling Flow Fields Inaxisymmentric Gas Turbine Combuster

Author(s):  
Mr. G Satheesh Kumar ◽  
Mr. Harish Mugutkar ◽  
Mrs. D Swetha ◽  
Author(s):  
H. Ek ◽  
I. Chterev ◽  
N. Rock ◽  
B. Emerson ◽  
J. Seitzman ◽  
...  

This paper presents measurements of the simultaneous fuel distribution, flame position and flow velocity in a high pressure, liquid fueled combustor. Its objective is to develop methods to process, display and compare large quantities of instantaneous data with computations. However, time-averaged flow fields rarely represent the instantaneous, dynamical flow fields in combustion systems. It is therefore important to develop methods that can algorithmically extract dynamical flow features and be directly compared between measurements and computations. While a number of data-driven approaches have been previously presented in the literature, the purpose of this paper is to propose several approaches that are based on understanding of key physical features of the flow — for this reacting swirl flow, these include the annular jet, the swirling flow which may be precessing, the recirculating flow between the annular jets, and the helical flow structures in the shear layers. This paper demonstrates nonlinear averaging of axial and azimuthal velocity profiles, which provide insights into the structure of the recirculation zone and degree of flow precession. It also presents probability fields for the location of vortex cores that enables a convenient method for comparison of their trajectory and phasing with computations. Taken together, these methods illustrate the structure and relative locations of the annular fluid jet, recirculating flow zone, spray location, flame location, and trajectory of the helical vortices.


Author(s):  
Tao Ren ◽  
Michael F. Modest ◽  
Somesh Roy

Radiative heat transfer is studied numerically for reacting swirling flow in an industrial gas turbine burner operating at a pressure of 15 bar. The reacting field characteristics are computed by Reynolds-averaged Navier-Stokes (RANS) equations using the k-ε model with the partially stirred reactor (PaSR) combustion model. The GRI-Mech 2.11 mechanism, which includes nitrogen chemistry, is used to demonstrate the the ability of reducing NOx emissions of the combustion system. A Photon Monte Carlo (PMC) method coupled with a line-by-line spectral model is employed to accurately account for the radiation effects. CO2, H2O and CO are assumed to be the only radiatively participating species and wall radiation is considered as well. Optically thin and PMC-gray models are also employed to show the differences between the simplest radiative calculation models and the most accurate radiative calculation model, i.e., PMC-LBL, for the gas turbine burner. It was found that radiation does not significantly alter the temperature level as well as CO2 and H2O concentrations. However, it has significant impacts on the NOx levels at downstream locations.


Author(s):  
Matthew E. Thomas ◽  
Mark J. Ostrander ◽  
Andy D. Leonard ◽  
Mel Noble ◽  
Colin Etheridge

CFD analysis methods were successfully implemented and verified with ongoing industrial gas turbine engine lean premix combustion system development. Selected aspects of diffusion and lean premix combustion modeling, predictions, observations and validated CFD results associated with the Solar Turbines Mars™ SoLoNOx combustor are presented. CO and NOx emission formation modeling details applicable to parametric CFD analysis in an industrial design environment are discussed. This effort culminated in identifying phenomena and methods of potentially further reducing NOx and CO emissions while improving engine operability in the Mars™ SoLoNOx combustion system. A potential explanation for the abrupt rise in CO formation observed in many gas turbine lean premix combustion systems is presented.


Author(s):  
Leilei Ji ◽  
Wei Li ◽  
Weidong Shi ◽  
Ramesh Agarwal

This paper investigates the influence of different tip clearances on the transient characteristics of mixed-flow pump under stall condition. The instantaneous internal flow fields of mixed-flow pump with four tip clearances (0.2 mm, 0.5 mm, 0.8 mm and 1.1 mm) are explored by conducting unsteady time accurate simulations. Reynolds-averaged Navier-Stokes (RANS) equations are employed in the simulations and the results of computations are compared with experimental data. The results show that the pump head decreases by 22.1% and the pump efficiency drops by 13.9% at design flow condition when the impeller tip clearance increases from 0.2 mm to 1.1 mm. The swirling flow occurs in the inlet pipe of the mixed-flow pump with different tip clearances under stall condition, and the initial starting point of the swirling flow gets further away from the impeller inlet with increase in tip clearance because of increase in circumferential velocity and change in momentum of the tip leakage flow (TLF). The high turbulent eddy dissipation (TED) regions in the flow are attributed to the TLF, swirling flow, back flow and stall vortex, and their intensity are affected by the change in tip clearance. The oscillating trend of time domain distribution of TED enhances first and then decreases with increase in tip clearance and it exhibits a propagation feature under the effect of stall vortex, while most of the energy in the frequency domain remains concentrated in the low frequency part under stall condition.


Author(s):  
V. Vassiliev ◽  
S. Irmisch ◽  
S. Florjancic

The key aspects for the reliable CFD modelling of exhaust diffusers are addressed in this paper. In order to identify adequate turbulence models a number of 2D diffuser configurations have been simulated using different turbulence models and results have been compared with measurements. An automated procedure for a time- and resource-efficient and accurate prediction of complex diffuser configuration is presented. The adequate definitions of boundary conditions for the diffuser simulation using this procedure are discussed. In the second part of this paper, the CFD procedure is being applied to investigate the role of secondary flow on axial diffusers. Prediction results are discussed and compared with available measurement data.


Author(s):  
Jörg Schlüter ◽  
Thilo Schönfeld ◽  
Thierry Poinsot ◽  
Werner Krebs ◽  
Stefan Hoffmann

Since the flame of high intense low NOx gas turbine combustion systems is stabilized by swirl, the analysis of the swirl flow is very crucial to the design and optimization of such combustion systems. Although a huge amount of publications have been provided on this field just a few have used Large Eddy Simulation due to limits in computer resources. Using Large Eddy Simulation the large vortical structure of the flow is resolved leading to a much better insight of the flow features. Hence, in this paper the Large Eddy Simulation has been applied to investigate the non reacting confined swirling flow downstream of a gas turbine burner. A high accuracy of the prediction of the full three dimensional simulation could be pointed out by comparison of the computational results to measurements. Further the large vortical structure and the dynamic behavior of the flow has been analyzed. The formation of a precessing vortex core is visualized. Due to the precessing motion of the central recirculation zone an alternate vortex shedding at the edges of the burner nozzle is induced. From LES Strouhal numbers for the vortex shedding process are calculated which are confirmed by hot wire measurements.


2012 ◽  
Vol 622-623 ◽  
pp. 1119-1124 ◽  
Author(s):  
Cheng Tung Chong ◽  
Simone Hochgreb

The flow field of a lab-scale model gas turbine swirl burner was characterised using particle imaging velocimetry (PIV) at atmospheric condition. The swirl burner consists of an axial swirler, a twin-fluid atomizer and a quartz tube as combustor wall. The main non-reacting swirling air flow without spray was compared to swirl flow with spray under unconfined and enclosed conditions. The introduction of liquid fuel spray changes the flow field of the main swirling air flow at the burner outlet where the radial velocity components are enhanced. Under reacting conditions, the enclosure generates a corner recirculation zone that intensifies the strength of the radial velocity. Comparison of the flow fields with a spray flame using diesel and palm biodiesel shows very similar flow fields. The flow field data can be used as validation target for swirl flame modelling.


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