CROSS-REFERENCE TO RELATED APPLICATION

This application is a non-provisional of U.S. Provisional Application Ser. No. 62/685,104, filed Jun. 14, 2018, entitled “ADVANCED PROCESSING FOR SPRAY FLUX MEASUREMENTS USING PHASE-DOPPLER INTERFEROMETRY,” the contents of which are expressly incorporated herein by reference in their entirety, including any references therein.

AREA OF THE INVENTION

The present disclosure generally relates to systems and methods for measuring sprays based upon individual measurements taken of individual droplets and thereafter performing analysis on an ensemble of such individual measurements of the droplets that pass through a measurement region of a measurement system. More particularly, the present disclosure relates to a measurement system where at least a droplet dimension (e.g. diameter) is determined for individual droplets passing through a measurement volume.

BACKGROUND OF THE INVENTION

Spray flux is a spatially-dependent vector characteristic of a flow field representing the net time-averaged or ensemble-averaged volumetric transport of the liquid phase per unit area per unit time. Spray flux may be expressed in terms of ccliquid/(cm2s).

Φ=1T⁢∑i⁢π⁢⁢di36⁢1Ai⁢v^i(1)
Where T is the total sampling time. For the i-th droplet, d is the diameter, v is the unit velocity vector, and A is the projected area of the measurement volume, normal to v.

Spray flux is difficult to measure in practice. Mechanical patternation such as sampling rakes and grids may be used but these are intrusive measurements. If used without isokinetic sampling, they may not accurately measure the liquid volume carried by small droplets. Unless some external knowledge of droplet velocities exists, only instruments that can determine a liquid mass-velocity relationship on a per-droplet-basis or ensemble basis can be used to determine spray flux. The candidates for flux-measurement-capable, non-intrusive sprays diagnostics are reduced to magnetic resonance imaging, double-pulse techniques (e.g. planar image velocimetry), and phase-Doppler interferometry (PDI, PDA, PDPA). Phase-Doppler has spatial, temporal, and/or droplet number density advantages over the other two techniques.

Spray flux is computed from an ensemble of individual droplet measurements assumed to be members of a stationary system. Spray flux is rendered from a vector sum of all droplets in a data set acquired by a measuring system that is thereafter: (1) divided by an effective sampling area of the measurement volume normal to the droplet velocity, and (2) divided by a total sampling time in an ensemble-average or time-average sense.

Determining spray flux using a phase-Doppler interferometer and state of the art instrumentation software is predicated on an assumption that a substantial majority of spray flux droplet trajectories are aligned parallel to a primary (sizing) velocity component (SeeFIG.1, V1) of a spray flux data acquisition instrument. This assumption is not generally met by acquiring raw data for determining the spray flux by traversing a measurement point through a plane of a spray pattern. Rotating the spray nozzle above the measurement point such that the spray flux droplet velocity vectors align with V1yields good agreement between calculated spray flux values and a spray flux determined by a sampling tube data. However, mechanical requirements of a sensing harness used to meet the above-described ideal measurement condition are onerous. Furthermore, not all spray flows have a strong orientation to the flux vector—for example, the recirculation zone of a hollow-cone atomizer does not exhibit strong orientation.

SUMMARY OF THE INVENTION

A system and method are described herein for rendering a characteristic for a set of particles passing through a measurement volume of a particle optical measurement system. Notably, the disclosed system and method address a difficulty in accurately determining, for example, a spray flux from phase-Doppler measurements due to an inability to accurately characterize an effective sampling area of the measurement volume through which individual particles pass during measurement. The effective sampling area of the measurement volume is a function of at least: (1) a particle trajectory into the measurement volume; and (2) a second primary particle mark (e.g. diameter). Other embodiments compensate for measurement errors that may result in a reduction of the effective sampling volume for a given droplet such as detector saturation or intensity validation.

As will be explained by reference to the illustrative examples provided herein, a system and method are described for rendering a characteristic for a set of particles passing through a measurement volume of a particle optical measurement system. The method includes acquiring raw particle data for the particles passing through the measurement volume. The raw particle data comprises a set of raw particle records. Each particle record comprises at least: a trajectory of at least one particle, and a second primary mark of the at least one particle whose value influences an effective sampling area corresponding to the measurement volume. The method includes generating and storing an effective sampling area based upon: the trajectory of the at least one particle, and the second primary mark. Thereafter, an ensemble characteristic is rendered for the set of particles by performing an operation on the sampling area-corrected set of particle records.

