Characterization of the Transient Spray from a High Pressure Swirl Injector

Evers, Lawrence W.

doi:10.4271/940188

Cited by 23 publications

(7 citation statements)

References 3 publications

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“…The injection time is 3 ms and the injection frequency is 20 Hz. Drop size distributions obtained either by a diffraction technique [3,10,12] or by a light diffusion technique [3,5,7,8] show that the largest drops of the spray are mainly contained in the pre-spray. The liquid¯ow issuing from the nozzle is lit from the back by a stroboscope with a maximum working frequency of 1000 Hz and a¯ash duration of the order of 2 ms. A diffusion screen is positioned between the light source of the liquid in order to homogenize the background of the image.…”

Section: Results Under Transient Working Conditionsmentioning

confidence: 99%

Investigation on the Drop Size Distribution of SpraysProduced by a High-Pressure Swirl Injector. Measurementsand Application of the Maximum Entropy Formalism

Boyaval¹,

Dumouchel²

2001

Part. Part. Syst. Charact.

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This paper reports an investigation on the volume‐based drop size distribution of sprays produced by swirl atomizers dedicated to direct‐injection spark‐ignited engines. Because of the use of high injection pressures to reduce the atomization time, the spatial density of the spray is high and prevents from classical measurements of spray drop size distribution. This problem is overcome by combining an experimental approach to the application of the maximum entropy formalism (M.E.F.). Based on the determination of correction factor series to correct the measurements from multiple light scattering, the experimental procedure allows obtaining some distribution characteristic features. According to a previous study, two of these characteristics are used as information in a M.E.F. procedure to derive the spray volume‐based drop size distribution. This characteristic is of paramount importance for evaluating the large drop population with accuracy. The overall procedure is presented in detail and discussed. It was applied to a series of four swirl atomizers in order to study the influence of the nozzle geometry and of the injection pressure on the injector performances. Conducted under both stationary and transient working conditions, this study allows a more precise understanding of the performances of GDI injectors as far as the spray drop size distributions are concerned.

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Section: Results Under Transient Working Conditionsmentioning

confidence: 99%

Investigation on the Drop Size Distribution of SpraysProduced by a High-Pressure Swirl Injector. Measurementsand Application of the Maximum Entropy Formalism

Boyaval¹,

Dumouchel²

2001

Part. Part. Syst. Charact.

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“…The ®ltered liquid is kept in a closed reservoir (4) pressurized by nitrogen (1). The liquid¯ow-rate and the issuing jet mean velocity are controlled by two successive pressure regulators (2) and (3). The injection pressure used as reference is measured with the manometer positioned upstream of the injector (5).…”

Section: Particle Sizing Methodsmentioning

confidence: 99%

Droplet Size Distribution and Sphericity Measurements of Low-Density Sprays Through Image Analysis

Malot

Blaisot²

2000

Part. Part. Syst. Charact.

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An image analysis technique has been developed in order to determine the drop size distributions of sprays produced by low‐velocity plain cylindrical jets. The particle sizing method is based on incoherent backlight images. Each drop is analyzed individually in the image. The two‐dimensional image resulting from the projection of the three‐dimensional object shape (the drop) on a screen (the video sensor surface) is modeled. The model, based on the point spread function formulation, has been developed to derive a relation between contrast and relative width of individual drops. This relation is used to extend the domain of validity of drop size in terms of size range, out of focus and image resolution. The shape parameter is determined for each drop image through morphological analysis. Spherical and non‐spherical droplets are then sorted on the basis of this parameter. Non‐spherical drops are regarded as non‐fully atomized liquid bulks or coalesced drops. Finally, the droplet size distribution of true spherical droplets is established for a low‐velocity plain cylindrical liquid jet.

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“…In other words, the atomization in two-phase flows is most effectively achieved by generating a high relative velocity between the liquid jet and the surrounding air resulting from higher momentum by the mutual interactions between working fluids. Much of what is known about important parameter affecting the mixing process has been obtained from experiments with air-to-liquid mass flow ratio (ALR) and geometric configuration of the nozzle [2]. The progressive understanding of disintegration process has been achieved in experimental approaches of the swirling turbulent velocity, and improved results were obtained [3,4].…”

Section: Introductionmentioning

confidence: 99%

Effects of ALR and configuration ratio on turbulent structures in swirling flows

Lee

2008

J Mech Sci Technol

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To assess the significant physics associated with the increase of ALR and configuration ratio of the nozzle tip in pneumatic swirling flows, comprehensive observations using a 3-D PDPA system were experimentally carried out. Profiles of mean velocities, turbulence intensities, SMD variations, and correlations between droplet size and turbulence components were quantitatively acquired. As discussed in a previous literature, axisymmetric swirl angle of 30 o is selected for this investigation because of its strong turbulence levels in the flowfield and finer droplet disintegrations. Various ALRs (Air-to-Liquid Mass Ratio) as well as the length-to-diameter ratios of nozzle tip as parameters were chosen. Due to the complex interactions in swirling flows under these variables, this experimental observation will be of fundamental importance to the understanding of turbulence structures. From the observations, it indicated that increasing the ALR causes the spray development to be positively fluctuated on the atomization in both axial and tangential RMS velocities. Also, it can be concluded that the SMD decreases continuously with increase of ALR, substantiating the fact that the fluctuations are inversely proportional to the SMD variation. Meanwhile, the spray behavior is characteristic with a reduction of length-to-diameter ratio; smaller the configuration ratio, the higher the turbulence intensities and smaller SMD variations in the flowfield.

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Characterization of the Transient Spray from a High Pressure Swirl Injector

Cited by 23 publications

References 3 publications

Investigation on the Drop Size Distribution of SpraysProduced by a High-Pressure Swirl Injector. Measurementsand Application of the Maximum Entropy Formalism

Investigation on the Drop Size Distribution of SpraysProduced by a High-Pressure Swirl Injector. Measurementsand Application of the Maximum Entropy Formalism

Droplet Size Distribution and Sphericity Measurements of Low-Density Sprays Through Image Analysis

Effects of ALR and configuration ratio on turbulent structures in swirling flows

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