Ultrasonic Atomiser Assembly with Dual Sonotrodes
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Solution Overview
Problem
Ultrasonic standing wave atomisers face challenges in efficiently atomizing fluids without contaminating the reflector, particularly when dealing with viscous fluids or high viscosity suspensions, due to direct contact issues and inefficient energy distribution.
Innovation Solution
An atomiser assembly with a channel device and energy generator configuration that establishes a standing wave within the channel by adjusting the displacement between the energy generator and channel outlet to a multiple of n(λ/4), where n is an odd number, creating a pressure node for effective fluid atomization, and optionally using a tapered channel outlet to enhance the jet effect for spray coating or minimizing it for spray drying applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rigid reflector is used to create a standing wave in ultrasonic atomisers, then the standing wave is established effectively, but the atomised product contaminates the reflector
Solution Approach 1:
The invention removes the rigid reflector from the system entirely. Instead of using a reflector to create the standing wave, the patent employs two sonotrodes facing each other, each generating ultrasonic waves that interfere to form a standing wave pattern in the fluid between them. This extraction of the reflector eliminates the contamination problem while maintaining the standing wave functionality.
Solution Approach 2:
The invention introduces the fluid itself as an intermediary medium between the two sonotrodes. The fluid acts as the medium through which ultrasonic waves propagate and interfere to create the standing wave pattern. This eliminates the need for a solid reflector that would be contaminated, as the standing wave is now established in the fluid volume rather than requiring a solid boundary.
2Object-generated harmful factors
If the distance between sonotrodes is increased to reduce reflector contamination, then contamination is reduced, but the standing wave production efficiency decreases
Solution Approach 1:
By removing the reflector entirely and using two active sonotrodes instead, the system eliminates the trade-off between contamination and efficiency. The two sonotrodes can be positioned at optimal distances to create strong standing waves without the contamination issues inherent in reflector-based systems.
Solution Approach 2:
The invention changes the operational parameters by using two sonotrodes operating at similar frequencies rather than one sonotrode and one reflector. This allows for flexible adjustment of the distance between sonotrodes while maintaining effective standing wave production, as both elements are active ultrasonic sources rather than one being a passive reflector.
3Productivity
If ultrasonic energy is increased to improve atomization of viscous fluids, then atomization efficacy improves, but energy consumption increases
Solution Approach 1:
The invention uses mechanical vibration at ultrasonic frequencies from two sonotrodes to create a standing wave pattern that intensely agitates the fluid. This mechanical vibration approach is more efficient for atomizing viscous fluids than increasing simple ultrasonic power, as the standing wave creates regions of high velocity and pressure variation that effectively break up the fluid into droplets.
Solution Approach 2:
The standing wave creates periodic regions of high and low pressure that cyclically act on the fluid, enhancing atomization efficiency. This periodic action allows for effective atomization of viscous fluids through repeated cycles of compression and rarefaction, rather than requiring continuously high ultrasonic power levels.
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 achieves high-efficacy and efficient atomization of fluids, reducing contamination risks and optimizing particle dispersion, with adjustable settings for various fluid viscosities and applications, such as spray coating and spray drying.
Implementation Method 1
a standing wave is established within the channel
Implementation Method 2
the reflected acoustic energy to be in phase with that radiated
Implementation Method 3
ultrasonic waves generated by an ultrasonic transducer
Implementation Method 4
Points with high acoustic energy levels are formed at the standing wave pressure nodes and, with sufficient incident ultrasonic energy, liquids introduced into these areas will be broken up into droplets
Data Source
AI summary
A compact apparatus for atomisation of fluid samples comprises a sonotrode (11), placed so that an ultrasonic wave emitted by the sonotrode is directed through a channel (25) in a separate channel device (21) and reflected by from the interface (26) in a high-low impedance transition zone (Tz), so that a standing wave is formed within the channel. A positive air flow through the channel, driven by a pressure differential at each end of the channel, interacts with the working fluid or slurry being delivered by a fluid delivery device (30) to atomise it. The speed of the air flow and the dispersal, homogeneity, and size of particles in the slurry sample can be controlled by varying the shape of the channel outlet.