On Effect of the Flare Angle on the Behaviour of the Flow Field of Twin-Radial Swirlers/High Shear Injector

2019 ◽  
Author(s):  
Sonu Kumar ◽  
Swetaprovo Chaudhuri ◽  
Saptarshi Basu
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
High Speed ◽  
Recirculation Zone ◽  
Swirl Flow ◽  
High Shear ◽  
Gas Turbine Combustor ◽  
Flow Topology ◽  
Mean Velocity ◽  
And Performance

Abstract The swirl flow in gas turbine combustor plays a major role in flame stabilisation and performance of engine. Since the swirl flow is very complex and boundary sensitive phenomena, it is difficult to interpret it properly. High shear injector is being used now a days in modern gas turbine combustor to generate the swirl flow and achieve better fuel atomisation in the combustion chamber. High shear injector accommodates a series of swirlers (primary and secondary) with a diverging flare at the exit and fuel nozzle mounted at the centre of the swirler. In the present study it is tried to understand the influence of the flare angle on the non-reactive flow behaviour of the swirling spray flow-field generated through counter-rotating high shear injector. To perceive the influence of flare angle on the flow topology of the spray flow-field generated by a high shear injector, seven different flare half angles (β): 40°, 45°, 50°, 55°, 60°, 65° and 70° respectively were selected as a geometrical parameter to conduct the experiments. High-Speed Particle Image Velocimetry (HSPIV) technique was employed to perceive the topological structure of the spray flow field, mean and instantaneous behaviour of the velocity fields respectively. For all the cases mass flow of air and liquid (water) were kept constant. It was observed that with change in flare angle the size of the CTRZ, mean velocity and turbulent behaviour were also changing. Here the size of CTRZ is represented in terms of nondimensional radial width (W/Df) and height (H/Df) of the recirculation zone. The experiment was conducted without flare, initially and then subsequently with flares. It was found that both the radial width and the height of the recirculation zone were smallest for without flare case. With increase in flare angle the radial width and height of the CTRZ increases initially up to 60° flare angle and afterward decreased. The experiments made clear that flare angle has strong effect on the spray flow-field.

Resolving Large- and Small-Scale Structures in the Swirl Flow of a Typical Land-Based Gas Turbine Combustor Single Nozzle Rig

2014 ◽  
Author(s):  
R. K. R. Katreddy ◽  
S. R. Chakravarthy
Keyword(s):  
Velocity Field ◽  
Gas Turbine ◽  
Large Scale ◽  
Recirculation Zone ◽  
Laser Diagnostics ◽  
Swirl Flow ◽  
Sudden Expansion ◽  
Small Scale ◽  
Gas Turbine Combustor ◽  
Scale Structures

The present study focuses on identifying and resolving large-scale energy containing structures and turbulent eddies in a typical gas turbine combustor single nozzle rig, using particle image velocimetry in cold flow. A generic fuel-air nozzle through a swirler is integrated with a sudden expansion square duct with optical access to perform laser diagnostics. Experiments are conducted to analyze the swirl flow field under starting and operating flow conditions. Three-component velocities are obtained in cross-sectional planes of Z/D = 0, 1.25, and 2.5 (normalized by the nozzle diameter), and two-component velocities are obtained in the mid-plane along the longitudinal (Z-) axis from Z/D = 0 to 2.5D. Velocity splitting is performed using spatial Gaussian smoothing with a kernel with filter width equal to integral scale is performed over the velocity fields to resolve the field of large-scale energy containing eddies. Proper orthogonal decomposition is performed over the large-scale velocity field, and the modes obtained indicate the existence of the precessing vortex core (PVC), formation of small scales Kelvin-Helmholtz (K-H) vortices for Z/D < 1.25D, and large-scale growing K-H structures in 1.25D < Z/D < 2.5D. Turbulent kinetic energy (TKE) is obtained from the turbulent velocity fluctuations below the integral length scale and is observed to be higher at the interface of the corner recirculation zone (CRZ) and central toroidal recirculation zone (CTRZ). Resolving the swirl velocity field obtained in the above manner into large-scale structures formed by the PVC, CTRZ, K-H vortices, CRZ, and small-scale turbulence field, indicates the clear distinction in rapid mixing zones and unsteady convective zones. The length-scales and zones of these structures within the swirl combustor are identified.

Study of the Cold Flow Field of a Multi-Injection Combustor

2009 ◽  
Author(s):  
F. Wang ◽  
Y. Huang ◽  
T. Deng
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Gas Turbine ◽  
Recirculation Zone ◽  
Turbulent Model ◽  
Gas Turbine Combustor ◽  
Cold Flow ◽  
Basic Work ◽  
Lining Structure ◽  
Recirculation Zones

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.

scholarly journals Development of Micro Gas Turbine Combustor with a Recirculation Zone Induced by an Upward Swirl

2008 ◽  
Vol 3 (1) ◽  
pp. 204-215
Author(s):  
Kousaku YOTORIYAMA ◽  
Shunsuke AMANO ◽  
Hidetomo FUJIWARA ◽  
Tomohiko FURUHATA ◽  
Masataka ARAI
Keyword(s):  
Gas Turbine ◽  
Recirculation Zone ◽  
Gas Turbine Combustor ◽  
Micro Gas Turbine

scholarly journals The Dynamics of Suspended Solid Particles in a Two Stage Gas Turbine

1986 ◽  
Author(s):  
W. Tabakoff ◽  
A. Hamed
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Suspended Solid ◽  
Solid Particles ◽  
Two Stage ◽  
Particle Momentum ◽  
Performance Deterioration ◽  
And Performance

Gas turbine engines operating in dusty environments are exposed to erosion and performance deterioration. In order to provide the basis for calculating the erosion and performance deterioration of turbines using pulverized coal, an investigation is undertaken to determine the three dimensional particle trajectories in a two stage turbine. The solution takes into account the influence of the variation in the three dimensional flow field. The change in particle momentum due to their collision with the turbine blades and casings is modeled using empirical equations derived from experimental Laser Doppler Velocimetry (LDV) measurements. The results show the three dimensional trajectory characteristics of the solid particles relative to the turbine blades. The results also show that the particle distribution in the flow field are determined by particle-blade impacts. The results obtained from this study indicate the turbine blade locations which are subjected to more blade impacts and hence more erosion damage.

scholarly journals Visualisation and performance evaluation of biodiesel/methane co-combustion in a swirl-stabilised gas turbine combustor

Fuel ◽  
2020 ◽  
Vol 277 ◽  
pp. 118172 ◽  
Author(s):  
Ogbonnaya Agwu ◽  
Jon Runyon ◽  
Burak Goktepe ◽  
Cheng Tung Chong ◽  
Jo-Han Ng ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Gas Turbine ◽  
Gas Turbine Combustor ◽  
And Performance

Flow Field of a Model Gas Turbine Swirl Burner

2012 ◽  
Vol 622-623 ◽  
pp. 1119-1124 ◽  
Author(s):  
Cheng Tung Chong ◽  
Simone Hochgreb
Keyword(s):  
Flow Field ◽  
Radial Velocity ◽  
Gas Turbine ◽  
Air Flow ◽  
Atmospheric Condition ◽  
Flow Fields ◽  
Swirl Flow ◽  
Scale Model ◽  
Swirl Burner ◽  
Swirling Air Flow

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.

803 Study of a Micro-Gas turbine Combustor with a Recirculation Zone Induced by an Upward Swirl

2005 ◽  
Vol 2005.3 (0) ◽  
pp. 5-6
Author(s):  
Kousaku YOTORIYAMA ◽  
Shunsuke AMANO ◽  
Hidetomo FUJIWARA ◽  
Tomohiko FURUHATA ◽  
Masataka ARAI
Keyword(s):  
Gas Turbine ◽  
Recirculation Zone ◽  
Gas Turbine Combustor ◽  
Micro Gas Turbine

Study of Flame Stability in a Step Swirl Combustor

1996 ◽  
Vol 118 (2) ◽  
pp. 308-315 ◽  
Author(s):  
M. D. Durbin ◽  
M. D. Vangsness ◽  
D. R. Ballal ◽  
V. R. Katta
Keyword(s):  
Gas Turbine ◽  
Recirculation Zone ◽  
Swirling Flow ◽  
Tangential Velocity ◽  
Combustion Stability ◽  
Combustion Model ◽  
Fuel Injector ◽  
Gas Turbine Combustor ◽  
Swirl Combustor ◽  
Radial Profiles

A prime requirement in the design of a modern gas turbine combustor is good combustion stability, especially near lean blowout (LBO), to ensure an adequate stability margin. For an aeroengine, combustor blow-off limits are encountered during low engine speeds at high altitudes over a range of flight Mach numbers. For an industrial combustor, requirements of ultralow NOx emissions coupled with high combustion efficiency demand operation at or close to LBO. In this investigation, a step swirl combustor (SSC) was designed to reproduce the swirling flow pattern present in the vicinity of the fuel injector located in the primary zone of a gas turbine combustor. Different flame shapes, structure, and location were observed and detailed experimental measurements and numerical computations were performed. It was found that certain combinations of outer and inner swirling air flows produce multiple attached flames, aflame with a single attached structure just above the fuel injection tube, and finally for higher inner swirl velocity, the flame lifts from the fuel tube and is stabilized by the inner recirculation zone. The observed difference in LBO between co- and counterswirl configurations is primarily a function of how the flame stabilizes, i.e., attached versus lifted. A turbulent combustion model correctly predicts the attached flame location(s), development of inner recirculation zone, a dimple-shaped flame structure, the flame lift-off height, and radial profiles of mean temperature, axial velocity, and tangential velocity at different axial locations. Finally, the significance and applications of anchored and lifted flames to combustor stability and LBO in practical gas turbine combustors are discussed.

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