Combustion and exhaust emission characteristics of low swirl injector

Deng, Yangbo; Wu, Hongwei; Su, Fengmin

doi:10.1016/j.applthermaleng.2016.08.169

Cited by 17 publications

(3 citation statements)

References 21 publications

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“…The associated flow field and emission characteristics have been reported for various gaseous fuels, including natural gas, hydrogen, syngas and liquid fuels 21 – 23 . Reacting flow field of the LSI is characterized by the absence of the CRZ which helps to reduce NOx production by shortening the reactants residence time 24 , 25 . The non-reacting flow field of the LSI is relatively uniform, without or with a suspended weak CRZ.…”

Section: Introductionmentioning

confidence: 99%

Central recirculation zone induced by the DBD plasma actuation

Jiang

Lei

et al. 2020

Sci Rep

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Central recirculation zone (CRZ) is commonly formed in the near field of the injector exit by the vane swirler and used to stabilize the flame. In our experiment, a CRZ induced by the DBD plasma actuation was observed in the low swirl burner configuration for the first time, which clearly demonstrated that the mechanism of the combustion control by the plasma swirler is mainly through the aerodynamic effect. Three dielectric barrier discharge (DBD) actuators are placed in a circular array around the axis to generate ionic wind in the circumferential direction of the injector. Characteristics of the flow field have been measured using Laser Doppler Anemometry. It is found that a central recirculation zone with the shape of an ellipsoid is formed in the non-reacting flow field with the plasma actuation. The position of the upstream stagnation point was determined by the strength of the actuation. Although the CRZ disappears in the reacting flow field as the result of combustion heat release, the influence of the discharge on the flame lift-off height is noticeable. The results demonstrate that swirl enhancement by the plasma swirler is feasible, flexible and effective as a non-intrusive measure for flow control.

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Section: Introductionmentioning

confidence: 99%

Central recirculation zone induced by the DBD plasma actuation

Jiang

Lei

et al. 2020

Sci Rep

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“…The lobed swirl injector we developed has demonstrated the advantages of low swirl injector (LSI), which was initially developed almost three decades ago. 9,10 Since then, the low swirl stabilized lifted flame has been gaining continuous interest, including fundamental studies for in-depth understandings and improved designs, such as the optimal design of the LSI including parametric studies of vane shape, 11 swirl number, 12 the distribution of holes on the perforated plate, 13,14 the premixed section length, 15 the shape of the injector outlet sleeve, 16 etc. It was found that the low swirl design is able to weaken the recirculation zones and reduce the residence time of hot combustion products, thus resulting in a decrease in NOx emissions.…”

Section: Introductionmentioning

confidence: 99%

“…It was found that the low swirl design is able to weaken the recirculation zones and reduce the residence time of hot combustion products, thus resulting in a decrease in NOx emissions. It was observed that different swirl numbers led to different types of flame, 12 while flow vortices were affected by the Damköhler number 17 that relates the chemical reaction timescale to the transport phenomena rate occurring in the combustion system. However, very few studies have been carried out in terms of the application of lobed swirl injector in combustion control.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of non-premixed and partially premixed methane lifted flames established on a lobed swirl injector

Jiang

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part A:

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A lobed swirl injector was tested to examine its potential in combustion control for non-premixed and partially premixed flames. It was found in the experiment that the flame derived from the injector changed between attached and detached flames at different conditions, demonstrating a promising way to control combustion. When air is supplied through the external channel of the lobed swirl injector and fuel passes through the internal channel, a stable lifted flame that is partially premixed was established above the injector exit. With the increase of airflow rate, the flame lift-off height decreases gradually until it is reattached to the injector, forming a diffusion flame. When increasing the fuel flow rate, the lift-off height increases gradually until the flame is blown out. Flow fields of the partially premixed lifted flames were investigated using stereoscopic particle image velocimetry. Streamlines located in the near field of the injector exit do not expand but bend inward, which is quite different from the expansion motion at the exit of the traditional vane swirler. The trough structure on the lobed swirler leads to the outer air flowing inward. Although the crest structure should make the inside gas flow outward, the strong entrainment of the surrounding air would restrain the radial outward motion of the inner gas, thus causing a contracted motion. After the streamline develops to an axial position further away from the injector exit, the swirling jet begins to expand under effects of both the centrifugal force and the development of shear layer to form turbulence. This flow pattern affects both the flame stabilization position and the neighboring reaction zone structure significantly. The measurements also show that the lobed swirl injector is very capable of entraining the ambient air that is sucked into the mainstream from the downward direction.

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