Spray Device With Differentiated Orifices For Droplet Uniformity
Solution Overview
Problem
Existing spray devices struggle to maintain a uniform spray pattern with a narrow droplet size distribution, especially when miniaturized, due to coalescence of jets and droplets caused by air streams and uneven orifice spacing.
Innovation Solution
The spray device features a membrane layer with first and second orifices of different sizes, where the first orifices are smaller and more densely packed in the central region, and the second orifices are larger and less densely packed in the peripheral region, to control coalescence and maintain a narrow droplet size distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the spray device is miniaturized with smaller orifices, then the droplet size is reduced, but the distance between orifices decreases causing jet coalescence and broadened droplet size distribution
Solution Approach 1:
The patent applies local quality by differentiating orifice characteristics across different spatial regions. The front wall contains both first orifices (smaller diameter, higher density) in a central region and second orifices (larger diameter, lower density) in a peripheral region. This local differentiation compensates for the coalescence effect in densely packed central orifices while maintaining efficient spray coverage in peripheral regions, thereby achieving uniform droplet size distribution across the entire spray pattern despite miniaturization.
2Productivity
If orifices are densely packed to increase spray coverage, then the productivity is improved, but jet coalescence increases causing broadened droplet size distribution
Solution Approach 1:
The patent implements local quality by creating distinct orifice groups with different characteristics: first orifices with smaller diameter and higher density in the central region for controlled spray patterns, and second orifices with larger diameter and lower density in the peripheral region for broader coverage. This spatial differentiation allows the system to achieve both high productivity through increased total orifice count and narrow droplet size distribution by optimizing each region's orifice characteristics to prevent coalescence.
3Ease of manufacture
If all orifices are of the same size, then the manufacturing is simplified, but the droplet size distribution becomes broadened due to coalescence effects
Solution Approach 1:
The patent applies local quality by specifying different orifice diameters for different regions: first orifices with a first diameter in the central region and second orifices with a second diameter in the peripheral region. While this requires more complex manufacturing than uniform orifices, it precisely controls droplet size distribution by compensating for coalescence effects in the central high-density region, achieving the desired narrow droplet size distribution that uniform orifices cannot provide.
4Speed
If the membrane layer is made thinner to improve spray response, then the spray speed is improved, but the structural integrity decreases leading to deformation
Solution Approach 1:
The patent employs a thin membrane layer as the front wall structure that provides both rapid spray response and sufficient structural integrity. The membrane is designed with optimal thickness to allow quick deformation in response to pressure changes for fast spray actuation, while maintaining enough strength to support the differentiated orifice structure and prevent unwanted deformation. This thin film approach enables the system to achieve improved spray response time without sacrificing the structural integrity needed to maintain precise orifice geometry.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration results in a more uniform spray pattern with a narrower droplet size distribution, as the smaller central orifices compensate for increased coalescence by producing droplets that are already larger, matching the final droplet size of the larger peripheral orifices.
Implementation Method 1
each jet will initially breakup into a mono disperse primary droplet train according to the so-called Rayleigh breakup mechanism
Implementation Method 2
The front wall of this known device is relatively thin and elastically deformable for adopting an overall curved profile once exposed to the pressure of said pressurized fluid
Data Source
AI summary
The present invention provides a spray device that generates a fluidic micro-jet spray and that allows and retains a relatively narrow droplet size distribution, of micro-jets and droplets obtained via the Rayleigh breakup mechanism, under a well-defined control of coalescence. To tint end a spray device is characterized in that a spray nozzle unit is formed by a nozzle body (1), comprising a support body (2) with at least one cavity (3) spanned by a membrane layer (4) having a nozzle orifice throughout a thickness of said membrane layer at an area of said cavity (3) in fluid communication with that cavity (3). The nozzle orifice may be part of a first relatively dense group of first orifices (5a) or of a less dense second group of second nozzle orifices (5b) in the membrane layer. A mean diameter of the nozzle orifices (5a) located in the first group substantially differs from the mean diameter of the nozzle orifices (5b) in the second group to obtain a uniform droplet size distribution in the spray.