Abstract
This paper reports a study of the thermoacoustic phenomena in steam-generating channels of the cooling system of heat-loaded devices. The examined cooling modes are characterized by surface boiling of the heat carrier, which occurs due to high heat flows at the cooled surface and large underheating of the flow core to the saturation temperature. Under such conditions, high-frequency pulsations of acoustic pressure may occur in cooling channels. It has been established that the emergence of thermoacoustic oscillations could lead to the formation of a standing wave in the channel, one of the conditions for whose formation is the presence of a wave reflection boundary. We have proposed a mathematical model describing the generation of thermoacoustic vibrations in a cooling channel. It was assumed that fluctuations with a high amplitude arise due to the resonance observed when the frequency of forced vibrations of steam bubbles coincides with the vapor-liquid column's natural frequency of vibrations or their harmonics. To calculate the amplitude of pressure fluctuations in the channel, the dependence has been derived, which takes into consideration the viscous dissipation of energy and energy losses at the ends of the channel. It has been shown that when approaching the resonance, the contribution of volumetric viscosity to the viscosity absorption factor increases. It has been established that for the examined conditions the losses of energy on the walls of the channel and losses in the boundary layer could be neglected. We have calculated the amplitude of thermoacoustic pressure fluctuations for conditions corresponding to actual processes in surface-boiling cooling channels. The reported procedure is proposed to be used in the design of liquid cooling systems for heat-loaded devices for which cooling modes imply a significant underheating of the heat carrier to a saturation temperature, as well as surface boiling
Highlights
The development of powerful electrical devices requires complete information about operational stability of the thermal mode control system
Application of such a technique makes it possible to obtain high energy flow densities, and at low temperature heads [3]. Heat exchange under such conditions is often accompanied by stable high-frequency pressure pulsations in the channel, which are self-oscillatory in character. It could be considered an established fact that the occurrence of thermoacoustic vibrations could lead to the formation of a standing wave in the channel, one of the conditions for whose formation is the wave reflection boundaries
The principal mechanisms of energy losses in a sound wave are associated with viscous dissipation and thermal conductivity, losses at the inlet and outlet of the channel and the scattering of sound on steam bubbles
Summary
The development of powerful electrical devices requires complete information about operational stability of the thermal mode control system. One of the most effective ways to cool a heating surface is to divert heat under a bubble boiling mode of the subcooled liquid [1, 2]. Application of such a technique makes it possible to obtain high energy flow densities, and at low temperature heads [3]. Heat exchange under such conditions is often accompanied by stable high-frequency pressure pulsations in the channel, which are self-oscillatory in character. The boiling of an subcooled liquid at the forced convection in pipes and channels has been given much attention, which is associated with a possibility of the emergence of a high level of acoustic pressure
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
