Heat Transfer in a Rotating Twin-Pass Trapezoidal-Sectioned Passage Roughened by Skewed Ribs on Two Opposite Walls

Heat transfer in rotating scale-roughened trapezoidal duct at high rotation numbers

“…The Re impact on rotational heat transfer is similar to that of forced convection in the static channel featured by the Re n relationship in Eqs. (3) and (4) that agrees with our previous heat transfer results in the rotating channels with smooth-walls and rig-roughened surfaces [14,22,29,30,34]. 3.…”

“…This buoyancy number can physically reflect the relative strength of rotating buoyancy force and is derived from the momentum equation based on the Boussinesq approximation [22]. Methods of heat transfer augmentation for rotating channels involve surface ribs [10,[18][19][20][21][22][23][24]30], array of longitudinal humps [25], pin-fins [26], dimples [27] and impingement [28,29]. In our previous study [31], the characteristics of heat transfer and pressure drop in a static narrow rectangular channel roughened by deepened scales were examined.…”

“…A large amount of laboratory-scale heat transfer experiments using simplified models of the real blade cooling geometry that examine their heat transfer performances in the rotating channels with various enhancement techniques is well documented. The geometries of enhanced rotating channels relevant to their cooling performances such as the type of surface enhancements, channel orientation, wall heating condition, channel cross-sectional shapes and multi-pass connections have been examined at various test conditions [10,[18][19][20][21][22][23][24][25][26][27][28][29][30] but only a few of these studies emulate the real engine conditions by operating the high pressure tests [10,19,22,29,30]. These experimental studies [10,[18][19][20][21][22][23][24][25][26][27][28][29][30] have agreed that the Reynolds (Re) and rotation (Ro) numbers characterize the forced convection and the Coriolis forces in their own rights with the buoyancy impact to be indexed by density ratio (Dq/q).…”

Heat transfer of rotating rectangular duct with compound scaled roughness and V-ribs at high rotation numbers

“…Taken into the account of increased cooling area by these deepened scales from the flat surface, this type of HTE mechanisms elevate the turbulent heat transfer in a non-rotating narrow channel to the levels about 3-4.5 times of Nu ∞ values for the backward and forward lows respectively [23]. In the past, considerable amounts of laboratory-scale heat transfer experiments using simplified models of the real blade cooling geometry with various HTE measures are well documented but only a few of these studies emulate the real engine conditions by operating the tests at high pressures [2,11,12]. The typical HTE effectiveness in terms of Nu/Nu ∞ ratio as exemplified in Fig.…”

“…These pursuits call for a variety of passive HTE methods to be tested refers to centerline of rotating leading wall T refers to centerline of rotating trailing wall 0 refers to non-rotating situation moderated due to the interdependent effects of Coriolis forces and rotating buoyancy. Here, these rotation induced heat transfer impacts vary with the shape and orientation of the rotating channel, the configurations of surface roughness, the connecting turns and the heating conditions [1][2][3][4][5][6][7][8][9][10][11][12][13]; while the mechanisms for HTE performances due to ribs, dimples or pin-fins are generally retained as those in the non-rotating channels. A variety of surface ribs [14][15][16][17][18], dimples [19,20], pin-fins [21,22] and the scaled roughness [23] has been initially devised to enhance heat transfer rates in non-rotating ducts.…”