ACOUSTIC DRYING METHOD USING SOUND OUTLET CHANNEL
A method for drying a material using an acoustic wave drying including an acoustic resonant chamber that imparts acoustic energy to transiting air received from an airflow source. The acoustic resonant chamber includes a primary air channel having side surfaces connecting an air inlet and an air outlet, the primary air channel having a primary air channel length between the air inlet and the air outlet. A closed-end resonant chamber is formed into a first side surface of the primary air channel, the closed-end resonant chamber having a resonant chamber length. The acoustic resonant chamber also includes a sound air channel having a sound air channel inlet on a second side surface of the primary air channel opposite to the closed-end resonant chamber and a sound air channel outlet for directing an air impingement airstream containing acoustic energy onto the material.
1 . A method for drying a material, comprising:
receiving air from an airflow source into an air inlet of an acoustic resonant chamber;
directing a first fraction of the received air out of the acoustic resonant chamber through an air outlet;
wherein the acoustic resonant chamber includes:
a primary air channel having side surfaces connecting the air inlet and the air outlet, the primary air channel having a primary air channel length between the air inlet and the air outlet;
a closed-end resonant chamber formed into a first side surface of the primary air channel, the closed-end resonant chamber having side surfaces and a resonant chamber length; and
a sound air channel having a sound air channel inlet on a second side surface of the primary air channel opposite to the closed-end resonant chamber and a sound air channel outlet for directing a second fraction of the received air onto the material as an air impingement airstream containing acoustic energy, the material being spaced apart from the sound air channel outlet by a gap distance, the sound air channel having a sound air channel length between the sound air channel inlet and the sound air channel outlet.
2 . The method of claim 1 wherein the second fraction is no more than 50%.
3 . The method of claim 1 wherein the primary air channel length, the resonant chamber length and the sound air channel length are selected such that the acoustic energy in the air impingement airstream provides an acoustic pressure at a surface of the material of at least 125 dB-SPL, and the air impingement airstream impinges on the surface of the material with an air velocity of no more than 40 m/s.
4 . The method of claim 1 wherein the primary air channel length, the resonant chamber length and the sound air channel length are selected such that more than 70% of the acoustic energy is imparted in a single main resonant mode.
5 . The method of claim 1 further including one or more secondary closed-end resonant chambers formed into a side surface of the closed-end resonant chamber, the secondary closed-end resonant chambers having secondary resonant chamber lengths.
6 . The method of claim 5 further including one or more tertiary closed-end resonant chambers formed into a side surface of the secondary closed-end resonant chambers, the tertiary closed-end resonant chambers having tertiary resonant chamber lengths.
7 . The method of claim 1 wherein the gap distance is adjusted to position the material substantially at a displacement node of a main resonant mode.
8 . The method of claim 7 wherein the gap distance is adjusted during the operation of the acoustic wave drying system by:
using a microphone system to measure an acoustic frequency of the main resonant mode in the air directed onto the material;
determining a position of the displacement node of the main resonant mode responsive to the measured acoustic frequency; and
adjusting the gap distance so that the material is substantially positioned at the displacement node.
9 . The method of claim 8 wherein the gap distance is adjusted by adjusting a position of the material or by adjusting a position of the acoustic resonant chamber.
10 . The method of claim 1 wherein a jet edge having an acute jet edge angle is formed where the closed-end resonant chamber joins with the primary air channel.
11 . The method of claim 10 wherein the jet edge angle is selected to maximize the amount of acoustic energy imparted in a main resonant mode.
12 . The method of claim 1 wherein the acoustic energy is generated passively by the movement of the transiting air through the acoustic resonant chamber.
13 . The method of claim 1 further including an active acoustic transducer positioned within the acoustic resonant chamber controlled to stimulate resonance at a specified acoustic frequency.
14 . The method of claim 1 wherein the material is an ink receiver medium having an image-wise ink deposit or a web medium coated with a liquid coating.
15 . The method of claim 1 wherein the air provided airflow source is heated using a heat source.