Experimental Investigation of Spatial and Temporal Aspects of the Liquid Fuel Placement in a Swirl Cup at Elevated Pressure

Becker, Julian; Hassa, Christoph

doi:10.1115/gt2004-53524

Cited by 9 publications

(3 citation statements)

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“…Wang et al 5 studied the hardware design of the flow field structure and found that the flare influenced the size of the recirculation zone and droplet dispersion. Becker and Hassa 6 and Shanmugadas et al 7 studied the fuel placement and droplet size inside the swirl cup using PDI and PLIF. They highlighted that swirl shear layers should be considered in fuel injector designs for improving atomization and interactions between fuel and the air shear layer.…”

Section: Introductionmentioning

confidence: 99%

Predicting the Sauter Mean Diameter of Swirl Cup Airblast Fuel Injector Based on Backpropagation (BP) Neural Network Model

Fang,

Liu,

Yang

et al. 2023

ACS Omega

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This study was dedicated to introducing a new method for predicting the Sauter mean diameter (SMD) buildup in the swirl cup airblast fuel injector. There have been considerable difficulties with predicting SMD mainly because of complicated flow characteristics in a spray. Therefore, the backpropagation (BP) neural network-based machine learning was applied for the prediction of SMD as a function of geometry, condition parameters, and axial distance such as primary swirl number, secondary swirl number, venturi angle, mass flow rate of fuel, and relative air pressure. SMD was measured by a phase Doppler particle analyzer (PDPA). The results show that the prediction accuracy of the trained BP neural network was excellent with a coefficient of determination (R 2 ) score of 0.9599, root mean square error (RMSE) score of 1.4613, and overall relative error within 20%. Through sensitivity analysis, the relative air pressure drop and primary swirl number were the largest and smallest factors affecting the value of SMD, respectively. Finally, the prediction accuracy of the BP neural network model is far greater than the current prediction correlations. Moreover, for the predicting target in the present study, the BP neural network shows the advantages of a simple structure and short running time compared with PSO-BP and GRNN. All these prove that the BP neural network is a novel and effective way to predict the SMD of droplets generated by a swirl cup airblast fuel injector.

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Section: Introductionmentioning

confidence: 99%

Predicting the Sauter Mean Diameter of Swirl Cup Airblast Fuel Injector Based on Backpropagation (BP) Neural Network Model

Fang,

Liu,

Yang

et al. 2023

ACS Omega

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“…The effect of ambient pressure and temperature on the spray structure of the pressure swirl and airblast sprays has been investigated in several previous studies [5][6][7][8][9][10][11][12]. In most of these investigations, the external spray structure and drop size variation are captured at various operating conditions.…”

Section: Introductionmentioning

confidence: 99%

Effect of Ambient Pressure on the Internal Atomization Processes of a Gas-Turbine Fuel Injector

Shanmugadas

Chakravarthy

2021

ICLASS

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The present work investigates the internal atomization characteristics of a gas-turbine fuel injector under elevated ambient pressure conditions. The injector is a piloted prefilming type airblast atomizer in which a dual orifice nozzle is used as the pilot nozzle. The injector assembly involves primary and secondary swirlers which are separated by a curved prefilmer called venturi. The fuel placement and droplet size at the injector exit depends on the flow evolution within the atomizer geometry which is influenced by the individual hardware components and ambient conditions. The injector geometry is split into different modules such as pilot nozzle, primary swirler, venturi, secondary swirler etc. and the modules are combined together forming different stages such that spray formation can be tracked as the flow evolves through it. High-speed imaging and laser induced fluorescence (planar and volumetric) imaging are performed to capture the internal flow field and phase Doppler interferometry measurements are conducted to obtain droplet size and axial velocity variation at every stage. Experiments are conducted up to 7 bar ambient pressure at constant fuel air ratio (FAR) with each stage configurations. The increase in ambient pressure lead to the collapse of the primary spray from the dual orifice nozzle which resulted in a narrow cone angle and in the formation of bigger droplets. Further, the ambient pressure influenced the wall filming process forming thick liquid films and rims at the prefilmer tip. The counter-rotating shear layer formed at the secondary swirler exit limited the influence of ambient pressure at the secondary exit and overall, the average droplet size increased at the injector exit. The effect of spray cone collapse of the pilot nozzle spray is not visible at the injector exit. This suggests that the wall filming on the venturi surface and the shear layers at the secondary exit, are the major contributing parameters in the drop formation and fuel placement at the injector exit at elevated pressure operating conditions.

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“…The pilot stage of the lean-burn injector is a typical swirl cup design which uses a pressure swirl atomizer with two coaxial, counter-rotating swirlers to atomize the fuel. The spray of swirl cup have been studied by many researchers, [10][11][12][13][14] most of the works center on flow structure. Indeed, only few experiments are preformed to characterize the spray.…”

Section: Introductionmentioning

confidence: 99%

Improvement on ignition and lean blowout performances of a piloted lean-burn combustor

Liu

Yang

et al. 2016

Proceedings of the Institution of Mechanical Engineers, Part A:

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This work focuses on optimizing the flame stability by matching the primary spray with swirling air streams in swirl cup which is used as pilot stage of a lean-burn fuel injector. Two configures of pressure-swirl atomizer for pilot spray have been investigated for their ignition and lean blowout (LBO) performances, the new designed pilot atomizer decrease fuel-air ratio (f/a) of the ignition limit by about 35%, and capability of LBO is greatly improved with decreasing fuel-air ratio from 0.015 to 0.005. Furthermore, in order to relate the pilot spray characteristics with the combustion performances, the performances of pilot pressure-swirl atomizer working both single and together with swirlers are carried out by optical spray diagnostics in a quiescent open air environment. Fuel planar laser induced fluorescence method for fuel distribution, particle image velocimetry method for velocity of droplets, and Fraunhofer diffraction technique for line-ofsight measurement of D 32 are used to visualize the spray. The interactions between pilot spray and pilot, main swirling air streams are analyzed. The relative pressure loss of swirling air streams larger than 3% is recommended for this type of spray facility to make sure high quality of atomization at ignition and near LBO conditions. Improvements of ignition and LBO performances by optimizing the pilot spray illustrate that matching pilot spray with swirling air streams is an effective method to improve capability of stable combustion in fuel-staged multi-injection combustors.

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Experimental Investigation of Spatial and Temporal Aspects of the Liquid Fuel Placement in a Swirl Cup at Elevated Pressure

Cited by 9 publications

References 0 publications

Predicting the Sauter Mean Diameter of Swirl Cup Airblast Fuel Injector Based on Backpropagation (BP) Neural Network Model

Predicting the Sauter Mean Diameter of Swirl Cup Airblast Fuel Injector Based on Backpropagation (BP) Neural Network Model

Effect of Ambient Pressure on the Internal Atomization Processes of a Gas-Turbine Fuel Injector

Improvement on ignition and lean blowout performances of a piloted lean-burn combustor

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