Anomalous Heat Transfer Enhancement in a Limited Package of Inclined Grooves on a Heated Section of a Plate in a Turbulent Air Flow

Abstract

The abnormal intensification of a separated flow and heat transfer in limited packages of inclined grooves on a heated isothermal section of a plate in a uniform air flow at Re = 3 × 10⁴ are numerically and physically modeled. The numerical predictions obtained on the basis of solutions of the Reynolds-averaged Navier–Stokes equations when closed by a model of shear stress transport and the energy equation are validated by comparing them with heat measurement data using the gradient heatmetry method of heat flux measurements in a package of four inclined grooves on a special thermophysical setup at St. Petersburg Polytechnic University (SPbPU). The influence of the number of grooves in limited packages on the intensification of the separated flow and heat transfer on a structured plate is analyzed on a previously created thermophysical setup for studying heat transfer in a single groove with the angle of inclination varying from 0° to 90°. It is shown that with an increase in the number of grooves, there is an increase in the relative heat transfer coefficients in them, caused by an increase in extraordinary pressure drops in the grooves as they move away from the leading edge of the plate, accompanied by an intensification of recirculating and swirling flows. A fundamental difference in the distribution of the relative heat transfer coefficient in the end part for the first and subsequent grooves in limited packages is established. As the number of grooves increases, heat transfer in the end sections intensifies.