喷雾中液滴粒径，浓度，和温度分布检测方案(激光粒度仪)

Structured laser illumination planar imaging (SLIPI) is a technique capable ofsuppressing multiple light scattering effects in optically dense sprays, resulting inspray images without blurs and with enhanced contrast. The novelty of the workpresented in this thesis concerns the applications of a variety of SLIPI-basedtechniques for the measurement of droplet size, droplet concentration, and liquidtemperature in atomizing sprays. Two types of spray systems are investigatedhere: 1) Steady hollow-cone water sprays using temporally averaged imaging.2) Transient Direct-Injection spark ignition (DISI) biofuel sprays usinginstantaneous imaging.The temporally averaged measurements are performed using three-phase SLIPI(3p-SLIPI) with liquid injection pressures in the range of 20–50 bar and at ambientconditions. Droplet sizing is obtained by combining SLIPI with the laser-inducedfluorescence (LIF)/Mie ratio approach, where the droplet Sauter mean diameter isdeduced after calibration with phase Doppler anemometry measurements. Thedroplet concentration and liquid volume fraction are obtained by combining theSLIPI-LIF/Mie method with light transmission measurements. This is performedusing a laser sheet scanning approach, which provides three-dimensionalquantitative reconstructions. Finally, the spray temperature is obtained bycombining SLIPI with two-color LIF ratio thermometry for a liquid temperatureranging from 25–55°C. It is found that multiple light scattering inducesmeasurement errors even for sprays having singly scattered photons in majority.This finding, therefore, strongly supports the application of SLIPI for quantitativespray measurements, even for optically dilute sprays. The 3p-SLIPI approach isbased on recording a minimum of three modulated sub-images successively, eachhaving a different spatial phase; therefore, it has been primarily used fortemporally averaged imaging.To circumvent this limitation, two novel instantaneous imaging approaches, 2p-SLIPI and 1p-SLIPI (corresponding to two-phase and one-phase, respectively),have been developed. In the 2p-SLIPI optical setup, the “lines structure” isoptically shifted by exploiting the birefringence property of a calcite crystal. Thisnovel optical approach is used to image spray dynamics in ethanol and butanolDISI sprays at liquid fuel injection pressures of 80 and 160 bar, where the spraychamber is operated at 2-bar air pressure. Finally, the results from instantaneous2p-SLIPI and 1p-SLIPI imaging have been compared, showing promisingapplications for the study of spray dynamics.