Application of SLIPI-Based Techniques for Droplet Size, Concentration, and Liquid Volume Fraction Mapping in Sprays

Abstract

Structured laser illumination planar imaging (SLIPI)-based techniques have been employed during the past decade for addressing multiple light scattering issues in spray imaging. In this article, SLIPI droplet sizing based on the intensity ratio of laser-induced fluorescence (LIF) over Mie scattering (SLIPI-LIF/Mie) and SLIPI-Scan for extinction-coefficient (µ e ) mapping are applied simultaneously. In addition, phase Doppler anemometry (PDA) and numerical calculations based on the Lorenz-Mie theory are also employed in order to extract the droplets Sauter mean diameter (SMD), the droplets number density (N), and the liquid volume fraction (LVF) in a steady asymmetric hollow cone water spray. The SLIPI-LIF/Mie ratio is converted to droplets SMD by means of a calibration procedure based on PDA measurements. The droplet SMD for the investigated spray varies from 20 µm to 60 µm, the N values range from 5 to 60 droplets per mm 3 , and the LVF varies between 0.05 × 10 −4 and 5.5 × 10 −4 within the probed region of the spray. To generate a series of two-dimensional images at different planes, the spray scanning procedure is operated in a "bread slicing" manner by moving the spray perpendicularly to the light sheet axis. From the resulting series of images, the procedure described here shows the possibility of obtaining three-dimensional reconstructions of each scalar quantity, allowing a more complete characterization of droplet clouds forming the spray region.

Application of FRAME for Simultaneous LIF and LII Imaging in Sooting Flames Using a Single Camera

“…To generate high fidelity LSI measurement data, a precise subtraction of stray light (background) from the signal of interest is required. To that end, for more than a decade, SLIPI (Structured Laser Illumination Planar Imaging) has been used to suppress background signals and multiple light scattering in non-combusting optically dense sprays [ 28 , 29 , 30 ], and in flames with distinct background and stray light [ 26 , 27 ]. For example, using SLIPI, optically dense diesel sprays [ 31 ] and ethanol sprays were characterized in terms of spray structures and spray quantities [ 29 ].…”

“…To that end, for more than a decade, SLIPI (Structured Laser Illumination Planar Imaging) has been used to suppress background signals and multiple light scattering in non-combusting optically dense sprays [ 28 , 29 , 30 ], and in flames with distinct background and stray light [ 26 , 27 ]. For example, using SLIPI, optically dense diesel sprays [ 31 ] and ethanol sprays were characterized in terms of spray structures and spray quantities [ 29 ]. The averaged SLIPI [ 26 ] and single-shot SLIPI techniques [ 27 ] were employed in combination with Rayleigh thermometry in a high background scattering environment for full-field temperature measurement in methane/air flames.…”

Study of spray structure under flash boiling conditions using 2phase-SLIPI

“…It does not disable the ability to resolve the hollow structures existing in the collapsed spray, which is the main target of this work. In future work, to obtain more quantitative measurements, extinction correction can be done by using dual-SLIPI (Kristensson et al, 2011a), combined side-scattering detection and transmission measurement (Wellander et al, 2011;Mishra et al, 2020),or 3D Tomo-SLITI(structured laser illumination transmission imaging) (Kristensson et al, 2012).…”

Using structured laser illumination planar imaging (SLIPI) as a new technique to monitor the degradation of biodegradable oils in electrical power transformers

“…In this article, an alternative technique called SLIPI (Structured Laser Illumination Planar Imaging) [6][7][8] was used as a diagnostic tool to monitor the aging of biodegradable oils (natural esters and synthetic esters). This technique has already proven its effectiveness in classifying the quality of mineral oils, according to Regnima et al [9].…”