Experimental study on flow and heat transfer enhancement by elastic instability in swirling flow

Elastic turbulence has shown great potential to improve mixing and heat transfer performance. Most of the studies, however, are focused on the mixing behaviour, heat transfer characteristics induced by elastic turbulence are still not well established. This work investigates systematically the flow and heat transfer performance by elastic turbulence in a swirling flow region. The heat transfer enhancements in the bulk fluid and between the fluid and the wall are characterized by the effective thermal conductivity and the Nusselt number, respectively. The variations of statistical properties, such as probability distribution functions and spectra profiles are analysed for the characterization of elastic turbulence. The results indicate that viscoelastic fluid intensifies the heat transfer performance with gradually increasing swirling velocity, and a 3.5 times enhancement comparing to the Newtonian fluid at the fully develop elastic turbulence regime is obtained. Particularly, the power spectra show a power-law decay over decades with exponent of −3.9.