Combustor Dilution Hole Placement and Its Effect on the Turbine Inlet Flowfield

Leonetti, Michael; Lynch, Stephen P.; O’Connor, Jacqueline; Bradshaw, Sean D.

doi:10.2514/1.b36308

Cited by 7 publications

(3 citation statements)

References 31 publications

(44 reference statements)

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“…The parameters values are set such that the momentum ratio of the port-jets to the axial bulk cross-flow is representative of primary jets in an Rich-Quench-Lean type combustor (see section 4.1 in [1]). In terms of flow physics, the momentum ratio is an important parameter as it determines the jet characteristics (shape and penetration) [2]. The working fluid in the experimental rig is water at 25 • C with kinematic viscosity ν = 8.917 × 10 −7 m 2 /s.…”

Section: B Combustor Port Flowmentioning

confidence: 99%

Comparison of Finite-Volume and Spectral/hp Methods for Large-Eddy Simulation of Combustor Port Flow

2022

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High-order accurate methods provide significant accuracy/cost benefits for well-resolved and geometrically simple scale-resolving turbulent flow simulations. However, the benefit on under-resolved unstructured grids for complex industrial geometries is unclear. The purpose of this work is to contribute to understanding of the benefit of high-order schemes for Large- Eddy Simulations (LES) in practical applications. A crucial requirement is a high-order solver that supports hybrid unstructured grids. In this context, accuracy and cost of a highorder spectral/hp Nektar++ solver and a standard second-order finite-volume OpenFoam solver are systematically compared for performing LES (with sub-grid scale treatments) on two configurations. The first configuration is Taylor-Green vortex, which shows that the accuracy benefit of fifth-order LES depends upon the mesh type and the level of under-resolution. The second configuration is geometrically more complex and represents the dilution port flows of gas turbine combustors. Specifically, the flow consists of cross-flow radial jets impinging onto each other, providing a rich variety of features and thus, making the case challenging. It is found that for a given cost, fifth-order LES reproduces the unsteady flow features significantly better and offers moderate improvements in the mean quantities. Moreover, results from a finer 5× more costly OpenFoam simulation suggest that for a similar accuracy, fifth-order LES could be 3-8× cheaper.

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Section: B Combustor Port Flowmentioning

confidence: 99%

Comparison of Finite-Volume and Spectral/hp Methods for Large-Eddy Simulation of Combustor Port Flow

2022

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“…Experimental results show that the location of the primary dilution holes not only has an effect on lean blowout stability but also has a significant effect on combustion efficiency. Michael 17 investigates the effect of combustor dilution holes placement on the turbine inlet flow field for aviation gas turbines. This study shows that a nonuniform velocity profile due to a high-momentum dilution jet can have a more significant effect on the turbine than previously thought.…”

Section: Introductionmentioning

confidence: 99%

Cooling characteristics of dilution holes in can-type combustor of micro gas turbine

Wang

Liu

Wang

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part A:

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For the purpose of studying the effect of structural changes in the dilution zone on the main performance evaluation parameters of the combustor, a can-type combustor of a micro gas turbine containing 16 dilution holes was used as the original structure. Seven optimization cases were designed by adjusting the number of dilution holes and the area of single hole in the range of hole numbers from 8 to 28 while keeping the total area of dilution holes. The main conclusions obtained by the numerical simulation study are as follows. The total flow of the dilution zone decreases with the number of holes reduce but due to the increase of single hole flow with the area, the airflow rigidity is significantly enhanced, so the entire airflow is disturbed more strongly and the dilution effect is strengthened. In general, the total pressure loss of the combustor presented an increasing trend with the decrease in the number of holes, and the pressure loss reaches a minimum value of 3400 Pa when the number of holes is 14. The combustion efficiency decreased as the number of holes increased, when the hole numbers increased to 20, the combustion efficiency dropped abruptly below 95%. The variation tendency of outlet temperature distribution factor (OTDF) is generally consistent with the combustion efficiency, and the minimum OTDF is 0.29 for the number of holes of 28. In summary, compared with the original structure with 16 holes, the OTDF decreases by 7.69%, the NOx concentration decreases by 16.67%, and the combustion efficiency increases by 3.1% when the number of holes is 8. Although the total pressure loss is increased by 8%, it is still within a reasonable range. Therefore the combustor with 8 holes can be considered a better optimized case.

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“…Practical gas turbines featuring swirl stabilised flame burners further include dilution (side) jets to affect downstream reactant mixing with cooler dilution air thereby helping to control combustion temperature and limit pollutant emissions (particularly oxides of nitrogen). [6][7][8][9] Whilst earlier works have looked into either BB jets [10][11][12] or dilution jets in crossflow regimes, 8,[13][14][15][16] no attempt has been made to study the influence of side dilution jets on the flow field and turbulent mixing of non-swirling and swirling BB stabilised jets in geometries similar to those in industrial combustors. With the above in mind, the present study numerically investigates the impact of side dilution jets on the flow features, turbulence field, and mixing of BB jets, both non-swirling and swirling confined flows.…”

Section: Introductionmentioning

confidence: 99%

Effect of side dilution jets on the velocity field and mixing in swirl and bluff-body stabilised annular confined flows

Gillani

Al-Abdeli

Tian

2022

Proceedings of the Institution of Mechanical Engineers, Part A:

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Stationary and mobile power generation systems, as well as those for aero propulsion, continue to rely heavily on gas turbines. Operational envelopes which critically depends on (flame) jet stabilisation mechanisms, such as swirl, are also affected by considerations for emissions control. In this context, the evolving swirling flow domains feature injection of side (peripheral) dilution air. Despite this, the role of side dilution jets on modifying the flow, turbulence, and mixing fields of turbulent bluff-body (BB) stabilised (swirling) annular flows has not been investigated. This study uses three-dimensional simulations, supported with experimental data to establish boundary conditions, to investigate the interaction of side dilution jets (Red = 18,000) with both non-swirling (S = 0) and swirling (S = 0.3) turbulent BB stabilised annular flows (Res = 35,500). Constant Temperature Anemometry (CTA) measurements are conducted to resolve inlet boundary conditions. The Reynolds Stress Model (RSM) and species transport model (isothermal) are used with validations against benchmark datasets. Results show that the introduction of side dilution jets into a confined domain, whether swirling or not, induces (asymmetrical) Peripheral Recirculation Zones (PRZ). However, the strength, length, and location of PRZ varies with swirl and the downstream positioning of side dilution jets (H = 2.6D, 6.6D). Additionally, side dilution jets increase centreline velocity decay for both, non-swirling and swirling BB flows. In terms of turbulence characteristics, addition of side dilution jets leads to significant gains in shear layer turbulence with an increase of 72% and 35% in turbulent kinetic energy for non-swirling and swirling BB flows, respectively. Analysis of the mixing characteristics shows negligible impact of side dilution jets in the upstream region, however, from x/D > 3 considerable improvement in central jet (fuel) mixing is observed.

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Combustor Dilution Hole Placement and Its Effect on the Turbine Inlet Flowfield

Cited by 7 publications

References 31 publications

Comparison of Finite-Volume and Spectral/hp Methods for Large-Eddy Simulation of Combustor Port Flow

Comparison of Finite-Volume and Spectral/hp Methods for Large-Eddy Simulation of Combustor Port Flow

Cooling characteristics of dilution holes in can-type combustor of micro gas turbine

Effect of side dilution jets on the velocity field and mixing in swirl and bluff-body stabilised annular confined flows

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