Heat Transfer in Two-Pass Rotating Rectangular Channels (AR=1:2 and AR=1:4) With 45° Angled Rib Turbulators

Abstract

This paper reports the heat transfer coefficients in two-pass rotating rectangular channels (AR=1:2 and AR=1:4) with rib roughened walls. Rib turbulators are placed on the leading and trailing walls of the two-pass channel at an angle of 45° to the flow direction. Four Reynolds numbers are considered from 5000 to 40000. The rotation numbers vary from 0.0 to 0.3. The ribs have a 1.59 by 1.59 mm square cross section. The rib height-to-hydraulic diameter ratios (e/Dh) are 0.094 and 0.078 for AR=1:2 and AR=1:4, respectively. The rib pitch-to-height ratio (P/e) is 10 for both cases, and the inlet coolant-to-wall density ratio (Δρ/ρ) is maintained around 0.115. For each channel, two channel orientation are studied, 90° and 45° with respect to the plane of rotation. The results show that the rotation effect increased the heat transfer on trailing wall in the first pass, but reduced the heat transfer on the leading wall. For AR=1:4, the minimum heat transfer coefficient was 25% of the stationary value. However, the rotation effect reduced the heat transfer difference between the leading and trailing walls in the second pass.

Effect of rib height on heat transfer in a two pass rectangular channel (AR=1:4) with a sharp entrance at high rotation numbers

“…The results from Azad et al [13] and Al-Hadhrami et al [14] confirmed the results of Wagner et al [10,11] and Taslim et al [12]. Fu et al [15] performed experiments in ribbed channels with narrow aspect ratios. The rotation number in their study ranged from 0.0 to 0.3.…”

“…The entrance condition for that study was a sharp bend. This entrance geometry resulted in high heat transfer in the channel first pass compared to a fully developed case of Fu et al [15]. The sharp entrance condition also reduced the effect of rotation in the first passage.…”

Enhanced Internal Heat Transfer on the Tip-Wall in a Rectangular Two-Pass Channel (AR = 1:2) by Pin-Fin Arrays

“…Taking the advantage of impinging and turning effects, the tip can be cooled to a certain extent. During recent years, several studies have concerned turbulent heat transfer in various two-pass channels [7][8][9][10][11][12][13][14][15][16][17][18]. For example, Ekkad et al [7] measured the detailed heat transfer distributions inside straight and tapered two-pass channels with and without rib turbulators.…”

Effects of inlet velocity profile on flow and heat transfer in the entrance region of a ribbed channel

“…Park et al [2] focused on the effects of the rib pitch, rib height, and inclined angles on the thermal performance factor. Fu et al [3] considered the effects of the channel aspect ratio on the heat transfer coefficient in a two-pass ribbed channel. Fu et al [4] and Han et al [5] investigated the effect of rotation number and density ratio on the friction factor.…”