RECENT ADVANCES IN HEAT TRANSFER APPLICATIONS USING SWEEPING JET FLUIDIC OSCILLATORS

Abstract

The passive sweeping jet fluidic oscillators are a promising potential candidate in heat transfer applications such as gas turbine cooling, electronic components cooling, and heat exchanger enhancement component. This review presents a detailed discussion, summary, and comparison of the heat transfer studies on the sweeping jets. Sweeping jets can be created by two different fluidic oscillators types (i.e., wall-attachment type and jet interaction type). Those passive fluidic oscillators do not need a moving part nor active control to create sweeping jets. In the wall-attachment type, the fluid enters the fluidic oscillator, fills the cavity (mixing chamber and two feedback tubes), and a power jet is formed. Due to the inherent infinitesimal disturbances in the primary flow, when the flow enters the chamber, Coanda effect pushes the flow to one side, introducing two asymmetric vortices in the mixing chamber. The asymmetric flow pattern is amplified through two feedback tubes, causing one vortex to grow bigger and pushing the jet flow to the opposite wall. This behavior of vortex-jet interaction is repeated interchangeably between the two vortices, resulting in a sweeping jet. However, for the jet interaction type, two or more primary jets enter the confined geometry (interaction or mixing chamber) and collide with each other. Counter-rotating vortices are formed inside the interaction chamber. These vortical patterns create and drive the sweeping motion. The review starts with an introduction of the fluid dynamic theory of production of sweeping jets through the passive fluidic oscillators, followed by introducing different types and designs of various fluidic oscillators and their applications in fluid mechanics and heat transfer. The review of heat transfer using sweeping jets is divided into three sections including film cooling, impingement cooling, and other heat transfer schemes in heat exchangers and thermal actuations. A brief review of heat transfer in pulsating jets created by fluidic oscillators is also included.