Friction and Heat Transfer Characteristics in Turbulent Swirl Flow Subjected to Large Transverse Temperature Gradients

Abstract

Friction and heat transfer characteristics of turbulent air flowing through tubes with twisted strip swirl promoters were studied experimentally and analytically. Data were obtained for pitch-to-diameter ratios as low as 3.15 and for Reynolds numbers up to 100,000. Both heating and cooling tests were run for tube wall to fluid bulk temperature ratios from 0.6 to 1.9 (degR/degR) to evaluate compressibility and buoyancy effects. Both temperature-varying properties and the centrifugal force field imposed on the compressible fluid by the twisted strips cause considerable deviations from the incompressible heat transfer predictions. Experimental results are presented as deviations to the incompressible predictions and can be correlated by f=fo(Tˆw/Tˆb)−0.1(HeatingandCooling)Nu=Nuo(Tˆw/Tˆb)−0.32(1+0.25Gr/Re)(Heating)Nu=1.07Nuo(Tˆw/Tˆb)−0.1(1−0.25Gr/Re)(Cooling) where the subscript “o” refers to the incompressible analytical solution. The analysis presented is more direct and complete than the previous development by Smithberg and Landis [3]2 by also accounting for curvature effects and the significant tape distortions encountered with tightly twisted strips.

Heat Transfer to Dispersed Swirl Flow of High-Pressure Water With Low Wall Superheat

“…The heat transfer coefficient between the vapor and wall was adopted from the single-phase work of Thorsen and Landis [4]. The correlation equation [4] was chosen because its database had high wall superheat, as did the swirl flow data of [17].…”

“…This work introduced the importance of both convect: ve and body force effect on heat transfer. Subsequent flow analyses [3,4] defined important swirl flow parameters, including the equivalent swirl velocity, and formed the basis for the development of heat transfer coefficient correlations. These efforts were followed by further development [5] of correlation equations for both pressure drop and heat transfer for turbulent single-phase swirl flow in tubes.…”

A combined approach to predict friction coefficients and convective heat transfer characteristics in A tube with twisted tape inserts for a wide range of Re and Pr

“…Their theory is compared with their own experimental results related to friction coefficients. Further refinement of their theory is undertaken by Thorsen and Landis [3] for the situation of swirl flow subjected to large transverse temperature gradients. Very recently Sarma et al [4] visualized the swirl flow as a convective flow in a tube with modified eddy diffusivity equation of van [5,6] dealt with heat transfer and pressure drop correlations for twisted tape inserts in two parts for laminar and turbulent flows with transition.…”

Turbulent convection in round tube equipped with propeller type swirl generators

“…Blum and Oliver [12] determined the local heat transfer coefficients for air and carbon dioxide in an electrically heated tube, and in their work an initial vortex generator with four square slots was used to inject the gas tangentially into the tube. Thorsen and Landis [13] investigated the heat transfer in swirling flow theoretically. They developed a mathematical model for turbulent heat transfer and friction factor in swirling flow at relatively high temperatures.…”