Mean drop sizes from pressure-swirl nozzles

Lefebvre, A. H.; Wang, X. F.

doi:10.2514/3.22946

Cited by 134 publications

(35 citation statements)

References 7 publications

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“…), a comparison of the nozzle types reveals that the pressure‐swirl nozzles are capable to produce smaller SMD s than the twin‐fluid nozzles for a constant energy input at investigated conditions. This statement is valid for both viscosities of µ = 0.001 Pa s and µ = 0.014 Pa s. A possible explanation for this effect is provided by Lefebvre and Wang (): For both nozzle types, the relative velocity between the liquid and the surrounding gas has a profound effect on atomization. However, another important factor for disintegration is the contribution of the instabilities created within the liquid itself.…”

Section: Resultsmentioning

confidence: 83%

“…The air core is continued through the exit orifice of the nozzle thereby reducing the characteristic length of the liquid compared to the diameter of the exit itself. The annular liquid lamella disintegrates due to internal instabilities as well as due to instabilities which originate from the interplay with the surrounding air (Lefebvre and Wang 1987).…”

Section: Introductionmentioning

confidence: 99%

“…The pressure-swirl nozzle is suitable to atomize low viscous liquids very effectively (Lefebvre and Wang 1987). With an increase in viscosity the swirl intensity decreases due to enhanced friction.…”

Section: Introductionmentioning

confidence: 99%

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Performance and Efficiency of Pressure‐Swirl and Twin‐Fluid Nozzles Spraying Food Liquids with Varying Viscosity

Stähle

Schuchmann

Gaukel

2015

J Food Process Engineering

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We investigated two different sized pressure‐swirl nozzles and two twin‐fluid nozzles (external and internal mixing) spraying food liquids with different viscosities (0.001 Pa s ≤ µ ≤ 0.308 Pa s). Liquid pressures in the range of 0.2 MPa ≤ pL ≤ 30 MPa and gas‐to‐liquid ratios of 0.01 ≤ GLR ≤ 2.92 were applied. To compare the nozzles, we used two energy based approaches: The spraying efficiency e and the energy density EV. The spraying efficiency of all investigated nozzles was within reported ranges from literature. When described as a function of EV, the Sauter mean diameter (SMD) of the spray drops showed a power‐law dependency. Further, the SMD was independent of the size of the pressure‐swirl nozzles and the location (internal or external) of mixing in twin‐fluid nozzles. The pressure‐swirl nozzles were superior over the twin‐fluid nozzles when low viscous fluids were sprayed. However, only the twin‐fluid nozzles were able to spray viscosities of µ ≥ 0.143 Pa s satisfactorily. Overall, the EV concept showed to be an appropriate method for the prediction of SMD in dependency of energy relevant process parameters. Practical Application In spray‐drying of foodstuffs, the spray drop size is a crucial parameter. It depends on the physical properties of the liquid, on the type of nozzle and on the chosen process parameters. The nozzle comparison by means of the energy density EV enables the operator to quickly choose the needed energy, i.e. the process parameters, which has to be supplied to the nozzle at a specific viscosity and liquid volume flow rate to obtain the desired mean spray drop size. This facilitates the operation of spray dryers and the scale up of spraying nozzles.

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Section: Resultsmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

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Performance and Efficiency of Pressure‐Swirl and Twin‐Fluid Nozzles Spraying Food Liquids with Varying Viscosity

Stähle

Schuchmann

Gaukel

2015

J Food Process Engineering

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“…4 One is the duplex atomizer, which has two tangential ports in the swirl chamber. One port is used for low flow rates.…”

Section: Summary Of Spray Generation Principlesmentioning

confidence: 99%

A novel spray generator for low-energy oil burners

Etzold

Han

Durst

2016

International Journal of Spray and Combustion Dynamics

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Outcomes of development work that resulted in a spray generator which yields spray droplets of small Sauter diameters at very low flow rates through the spray-generating nozzle are reported. This nozzle produces a liquid jet that operates in two modes to switch on or switch off the spray production. To achieve this, a liquid jet impinging on a flat surface is employed. The jet is operated at Ohnesorge-Reynolds numbers that do not yield a spray. The conditions for this state of operation are given. The spray production is, in a second mode of operation, initiated by triggering the Rayleigh instability of this jet so that the impingement on the flat plate occurs in the form of drops. As the drops are initiated, an intermittent spray is produced by the flat surface, that is, each droplet results in a spray leaving the flat surface. This is demonstrated experimentally and measurement results are presented to show that droplets of small Sauter mean diameters are produced in this way. The influence of the jet-generating nozzle diameter on the Sauter diameter is also reported. Comparisons of the droplet-generated sprays are carried out for various other forms of spray generators, keeping the nozzle diameter and the flow rate the same as those for the droplet sprays.

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“…To quickly create smaller fuel droplets, multiple-nozzle LDI concepts (where many small fuel/air mixers replace one conventional nozzle) have been envisioned [7,[9][10][11]. These concepts take advantage of results showing that geometrically similar but smaller fuel nozzles produce a fuel spray with lower mean diameter droplets [12][13][14]. These multipoint lean direct injection (MLDI) arrays exhibit an additional benefit in the reduction of recirculation zone volume.…”

mentioning

confidence: 99%

Experimental Study of a Multinozzle Combustor at Elevated Pressures

Villalva¹,

Dolan²,

Munday³

et al. 2015

AIAA Journal

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Emissions measurements and OH chemiluminescence imaging were performed on a novel multipoint lean direct injection combustor designed for low-NOx emissions and with the flexibility to operate at both high-and low-power settings. The combustor has five rows of fuel nozzles that can be staged in three independent circuits as required. The fuel nozzle stages are not identical; instead, they are optimized for different power settings. NOx, CO, and unburned hydrocarbons were measured for a variety of settings, including lean blowout, idle, intermediate power, and simulated full power. Effects of pressure, inlet temperature, equivalence ratio, and fuel flow distribution were studied. OH chemiluminescence was used to observe flame structure and interpret emissions trends. The local equivalence ratio, calculated with the fuel and air flow rates particular to each combustor stage, was a useful parameter for interpreting emissions. The combustor demonstrated the ability to operate at a wide range of conditions, from an overall equivalence ratio of 0.55 to lean blowout at 0.079. Low-NOx operation was achieved at high power by using all fuel stages and controlling fuel flow to obtain an even distribution among the nozzles and reduce peak temperatures while using staging to provide good stability at low power.

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Mean drop sizes from pressure-swirl nozzles

Cited by 134 publications

References 7 publications

Performance and Efficiency of Pressure‐Swirl and Twin‐Fluid Nozzles Spraying Food Liquids with Varying Viscosity

Performance and Efficiency of Pressure‐Swirl and Twin‐Fluid Nozzles Spraying Food Liquids with Varying Viscosity

A novel spray generator for low-energy oil burners

Experimental Study of a Multinozzle Combustor at Elevated Pressures

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