Turbulent Flow Heat Transfer and Friction in a Rectangular Channel With Varying Numbers of Ribbed Walls

Abstract

An experimental study of wall heat transfer and friction characteristics of a fully developed turbulent air flow in a rectangular channel with transverse ribs on one, two, and four walls is reported. Tests were performed for Reynolds numbers ranging from 10,000 to 80,000. The pitch-to-rib height ratio, P/e, was kept at 8 and rib height-to-channel hydraulic diameter ratio, e/D h , was kept at 0.0625. The channel length-to-hydraulic diameter ratio, L/D h , was 15. The heat transfer coefficient and friction factor values were enhanced with the increase in the number of ribbed walls. The friction roughness function, R(e + ), was almost constant over the entire range of tests performed and was within comparable limits of the previously published data. The heat transfer roughness function, G(e + ), decreased with additional ribbed walls and compared well with previous work in this area. Friction data obtained experimentally for the case with four ribbed walls compared well with the values predicted by the assumed theoretical relationship used in the present study and past publications. Results of this investigation could be used in various applications of internal channel turbulent flows involving different numbers of roughened walls.

Numerical Simulations of a Rectangular Channel with Symmetric and Non-symmetric Wedge-shaped Turbulators

“…Chandra et al [19,20] later generalized the approach for channels with various numbers of rib turbulated walls.…”

Effect of rib spacing on heat transfer and friction in a rotating two-pass square channel with asymmetrical 90-deg rib turbulators

“…Han and Zhang (1992) [10], Ekkad and Han (1996) [11] presented more detailed heat transfer distributions in a square channel with 90-deg ribs, 60-deg parallel or V ribs. On the other hand, Chandra et al (1997Chandra et al ( , 2003 [12,13], Rau et al (1998) [14], and Ahn et al (2008) [15] focused the number of ribbed walls (one to four) on heat transfer. They found that both the heat transfer coefficient and the friction factor increase with an increasing number of ribbed walls, but the relative increase in heat transfer is lower than the increase in friction factor.…”

“…Refs [10]. and refs [12]. measured regional averaged heat transfer in straight ribbed channel using thermocouples and heater plates, and refs [11].…”

An Investigation of Coolant Within Serpentine Passages of a High-Pressure Axial Gas Turbine Blade

“…(14). The work of Chandra et al [7] on similar but stationary walls provides approximate values for f =f 1 for each channel. Liou et al [8] explore correlations for friction factor for smooth channels as a function of Reynolds and rotation numbers and show that the channel-average friction factor is increased by 10-20% due to rotation numbers on the order of those seen in this experiment.…”