Self-Excited Counterflow Disturbance and Heat Transfer Characteristics of Al2O3–Water Nanofluids

Abstract

A numerical study of the heat transfer and flow resistance performance of Al 2 O 3 -water nanofluids in selfoscillating hot runners with different chamber lengths was performed. The control volume method based on the Semi-Implicit Method for Pressure Linked Equations (SIMPLE) algorithm was used to numerically solve the governing equations of the two-dimensional computational domain. The inlet flow rate was determined according to the Reynolds number (10;000 < Re < 50;000), and the uniform temperature was applied to the wall of the hot runner. The effects of chamber length and volume fraction on the heat transfer performance of nanofluids vortex pulsation were described by temperature, thermal boundary-layer thickness, pulsation frequency, Nusselt number, pressure drop, and heat transfer performance evaluation index. The simulation outcomes indicated that the counterflow vortex can reduce the thermal boundary-layer thickness and increase the mixing degree between the central mainstream region and the wall. It was also observed that the heat transfer performance increases with the increase of the chamber length. When L∕d 1 5.6, the heat transfer performance is the highest, and the main frequency (f 398.01 HZ) at the center of the chamber corresponds to the pressure pulsation amplitude of 35,982.6 Pa.