Education of the republic of uzbekistan tashkent state technical university named after islam karimov

№3/2021 year. 
Technical science and innovation
218 
ultrasonic action for intensifying processes in gaseous media drops to almost zero. The 
possibility of forming vibrations of such intensity is provided due to the use of flexural-
vibrational disk radiators as emitters [5]. To generate ultrasonic frequency vibrations in gaseous 
media, the disk transducer for a given size of the ultrasonic vibrational system is excited in the 
odd (fifth, seventh, ninth, etc.) mode of the main resonant frequency of bending vibrations of the 
disk. ... To ensure high energy characteristics, a multi-package arrangement of pairs of 
piezoelectric elements is used in the design of the transducer. Such a design scheme allows to 
combine parallel stacks of piezoelectric elements, improving heat removal from each of the 
stacks by increasing the mass of the working radiating region of the transducer, and providing an 
increase in energy consumption even compared to the simple addition of individual transducers. 
Emitters of this type are distinguished by a high quality factor, multifrequency, and if the 
conditions for frequency matching and the presence of harmonics in the supply voltage are not 
met, they have a high probability of excitation at a parasitic harmonic. 
When creating electronic generators, it is necessary to take into account that the wave 
resistance of gaseous media is orders of magnitude less than, for example, liquids. This requires 
a more powerful "rocking" of the ultrasonic oscillatory system by an electronic generator. 
In addition, the low coefficient of output of acoustic energy from the emitter into the 
gaseous environment (less than 0.01 of the energy stored by the emitter) and the use of titanium 
alloy for the manufacture of the emitter increases the Q-factor of the ultrasonic vibrating system. 
up to 1000 and more, which leads to increased requirements for the quality of the system of 
phase automatic frequency control (PLL) of the electronic generator, which maintains the 
resonant mode of operation of the ultrasonic emitter and generator. 
The stability of the wave resistance of gaseous media to the ultrasonic effect of a wide 
range of powers (up to 140 dB and more) ensures a consistent mode of energy transfer in the 
"generator - emitter - processed medium" system. 
However, the low heat transfer coefficient of gaseous media causes significant heating of 
ultrasonic emitters (up to 100 ° C and more), which leads to a shift of the resonant frequency of 
ultrasonic emitters to lower frequencies (for example, the resonant frequency of the emitter can 
decrease from 20 to 18 kHz when the temperature changes from 20 to 100 ° C). 
The considered design and functional features of the oscillating systems used impose 
certain requirements on electronic ultrasonic generators, which must be implemented when 
creating ultrasonic equipment for intensifying processes in gaseous media. 
In fig. In fig. 1 shows the design of an electronic generator designed to power ultrasonic 
vibrating systems designed to influence gaseous media during the intensification of various 
processes.