Research Papers: Gas Turbines: Combustion, Fuels, and Emissions

Influence of the Primary Jets and Fuel Injection on the Aerodynamics of a Prototype Annular Gas Turbine Combustor Sector

[+] Author and Article Information
Bassam Mohammad, San-Mou Jeng

Department of Aerospace Engineering, University of Cincinnati, Cincinnati, OH 45221

M. Gurhan Andac

 General Electric Aviation, Evendale, OH 45215

J. Eng. Gas Turbines Power 133(1), 011505 (Sep 24, 2010) (8 pages) doi:10.1115/1.4002004 History: Received April 07, 2010; Revised April 08, 2010; Published September 24, 2010; Online September 24, 2010

Transverse dilution jets are widely used in combustion systems. The current research provides a detailed study of the primary jets of a realistic annular combustion chamber sector. The combustor sector comprises an aerodynamic diffuser, inlet cowl, combustion dome, primary dilution jets, secondary dilution jets, and cooling strips to provide convective cooling to the liner. The chamber contracts toward the end to fit the turbine nozzle ring. 2D PIV is employed at an atmospheric pressure drop of 4% (isothermal) to delineate the flow field characteristics. The laser is introduced to the sector through the exit flange. The interaction between the primary jets and the swirling flow as well as the sensitivity of the primary jets to perturbations is discussed. The perturbation study includes: effect of partially blocking the jets, one at a time, the effect of blocking the convective cooling holes, placed underneath the primary jets and shooting perpendicular to it. In addition, the effect of reducing the size of the primary jets as well as off-centering the primary jets is explained. Moreover, PIV is employed to study the flow field with and without fuel injection at four different fuel flow rates. The results show that the flow field is very sensitive to perturbations. The cooling air interacts with the primary jet and influences the flow field although the momentum ratio has a 100:1 order of magnitude. The results also show that the big primary jets dictate the flow field in the primary zone as well as the secondary zone. However, relatively smaller jets mainly influence the primary combustion zone because most of the jet is recirculated back to the CRZ. Also, the jet penetration is reduced with 25% and 11.5% corresponding to a 77% and 62% reduction of the jet’s area, respectively. The study indicates the presence of a critical jet diameter beyond which the dilution jets have minimum impact on the secondary region. The jet off-centering shows significant effect on the flow field though it is in the order of 0.4 mm. The fuel injection is also shown to influence the flow field as well as the primary jets angle. High fuel flow rate is shown to have very strong impact on the flow field and thus results in a strong distortion of both the primary and secondary zones. The results provide useful methods to be used in the flow field structure control. Most of the effects shown are attributed to the difference in jet opposition. Hence, the results are applicable to reacting flow.

Copyright © 2011 by American Society of Mechanical Engineers
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Figure 1

Typical swirl cup arrangement with counter rotating radial swirlers

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Figure 2

Swirl cup exit configuration and coordinate system illustration

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Figure 3

Schematic of the experimental facility

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Figure 4

Illustration of the primary jets partial blocking

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Figure 5

The effect of partially blocking the primary dilution jets on the flow field

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Figure 6

Illustration of primary jets and cooling jets interaction

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Figure 7

The effect of blocking the cooling strip underneath the primary jets

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Figure 8

Illustration of primary jet holes off centering

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Figure 9

The effect of off-centering the primary jets on the SAC flow field

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Figure 10

The effect of primary jet size on the flow field

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Figure 11

Profiles of F/A ratio by mass at fuel flow rate of 25 pphr at different axial stations

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Figure 12

Normalized equivalence ratio contours imposed on velocity vectors at fuel flow rate of 25 pphr

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Figure 13

Velocity vectors and streamlines with and without fuel injection (fuel flow rate of 25 pphr)

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Figure 14

Difference in velocity magnitudes with and without fuel injection at fuel flow rate of 25 pphr

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Figure 15

Fuel injection effect on the flow field structure at fuel flow rate of 55 pphr

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Figure 16

Effect of the fuel injection on the edges of the CRZ and jets wake regions



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