Two-Dimensional Heat Transfer Distribution of a Rotating Ribbed Channel at Different Reynolds Numbers

The convective heat transfer distribution in a rib-roughened rotating internal cooling channel was measured for different rotation and Reynolds numbers, representative of engine operating conditions. The test section consisted of a channel of aspect ratio equal to 0.9 with one wall equipped with eight ribs perpendicular to the main flow direction. The pitch to rib height ratio was 10 and the rib blockage was 10%. The test rig was designed to provide a uniform heat flux boundary condition over the ribbed wall, minimizing the heat transfer losses and allowing temperature measurements at significant rotation rates. Steady-state liquid crystal thermography (LCT) was employed to quantify a detailed 2D distribution of the wall temperature, allowing the determination of the convective heat transfer coefficient along the area between the sixth and eighth rib. The channel and all the required instrumentation were mounted on a large rotating disk, providing the same spatial resolution and measurement accuracy as in a stationary rig. The assembly was able to rotate both in clockwise and counterclockwise directions, so that the investigated wall was acting either as leading or trailing side, respectively. The tested Reynolds number values (based on the hydraulic diameter of the channel) were 15,000, 20,000, 30,000, and 40,000. The maximum rotation number values were ranging between 0.12 (Re = 40,000) and 0.30 (Re = 15,000). Turbulence profiles and secondary flows modified by rotation have shown their impact not only on the average value of the heat transfer coefficient but also on its distribution. On the trailing side, the heat transfer distribution flattens as the rotation number increases, while its averaged value increases due to the turbulence enhancement and secondary flows induced by the rotation. On the leading side, the secondary flows counteract the turbulence reduction and the overall heat transfer coefficient exhibits a limited decrease. In the latter case, the secondary flows are responsible for high heat transfer gradients on the investigated area.

[1]  Jack L. Kerrebrock,et al.  1998 Heat Transfer Committee Best Paper Award: Complementary Velocity and Heat Transfer Measurements in a Rotating Cooling Passage With Smooth Walls , 1999 .

[2]  T. H. Lee,et al.  Thermal performance of developing flow in a radially rotating parallelogram channel with 45° ribs , 2012 .

[3]  Giovanni Maria Carlomagno,et al.  Heat transfer measurements in a rotating two-pass square channel , 2007 .

[4]  J. H. Wagner,et al.  Effects of Rotation on Coolant Passage Heat Transfer , 1991 .

[5]  Mohammad E. Taslim,et al.  An Experimental Investigation of Heat Transfer Coefficients in a Spanwise Rotating Channel With Two Opposite Rib-Roughened Walls , 1991 .

[6]  Je-Chin Han,et al.  High performance heat transfer ducts with parallel broken and V-shaped broken ribs , 1992 .

[7]  A. Murata,et al.  Aiding and opposing contributions of centrifugal buoyancy on turbulent heat transfer in a two-pass transverse- or angled-rib-roughened channel with sharp 180° turns , 2004 .

[8]  B. Launder,et al.  Flow and heat transfer in a rotating U bend with 45 degree ribs. , 2001 .

[9]  T. Arts,et al.  Color theory perception of steady wide band liquid crystal thermometry , 2012 .

[10]  P. Ligrani,et al.  Heat Transfer Augmentation Technologies for Internal Cooling of Turbine Components of Gas Turbine Engines , 2013 .

[11]  B. Facchini,et al.  Heat transfer in internal channel of a blade: Effects of rotation in a trailing edge cooling system , 2012 .

[12]  Ahmad K. Sleiti,et al.  Effect of Coriolis and centrifugal forces on turbulence and transport at high rotation and density ratios in a rib-roughened channel , 2008 .

[13]  James P. Johnston,et al.  Effects of System Rotation on Turbulence Structure:A Review Relevant to Turbomachinery Flows , 1998 .

[14]  Je-Chin Han,et al.  Computation of heat transfer in rotating two-pass square channels by a second-moment closure model , 2000 .

[15]  Je-Chin Han,et al.  Uneven Wall Temperature Effect on Local Heat Transfer in a Rotating Two-Pass Square Channel With Smooth Walls , 1993 .

[16]  Arun K. Saha,et al.  Unsteady RANS Simulation of Turbulent Flow and Heat Transfer in Ribbed Coolant Passages of Different Aspect Ratios , 2005 .

[17]  T. Arts,et al.  Flow field investigation in rotating rib-roughened channel by means of particle image velocimetry , 2012 .

[18]  R. Theunissen,et al.  A new facility for time-resolved PIV measurements in rotating channels , 2008 .

[19]  Srinath V. Ekkad,et al.  Gas Turbine Heat Transfer and Cooling Technology , 2012 .

[20]  Jack L. Kerrebrock,et al.  Complementary Velocity and Heat Transfer Measurements in a Rotating Cooling Passage With Smooth Walls , 1998 .

[21]  S. J. Kline,et al.  Describing Uncertainties in Single-Sample Experiments , 1953 .

[22]  A. Murata,et al.  Large eddy simulation with a dynamic subgrid-scale model of turbulent heat transfer in an orthogonally rotating rectangular duct with transverse rib turbulators , 2000 .

[23]  Danesh K. Tafti,et al.  Large Eddy Simulation of Flow and Heat Transfer in the Developing Flow Region of a Rotating Gas Turbine Blade Internal Cooling Duct With Coriolis and Buoyancy Forces , 2008 .

[24]  Tony Arts,et al.  The Effect of Periodic Ribs on the Local Aerodynamic and Heat Transfer Performance of a Straight Cooling Channel , 1996 .