Abstract
The combined effects of rotation and jet impingement on local heat transfer in a two-pass rotating rectangular channel is studied. The results of an experimental investigation on the surface heat transfer coefficients under a perforated plate of multiple, staggered array, round impinging air jets are presented. The jet rotation number (Ro) is varied from 0.0 to 0.0226, and the jet Reynolds number (Rej) is varied from 2,500 to 12,500. The isolated effects of Rej, and rotating speed (D = 0, 400, and 800 rpm), are measured. The pressure distributions in the channel are recorded before and after impingement. The experimental results show that the Nusselt number increases with an increase in jet Reynolds number and decreases slightly with an increase in cross flow for both radially outward and inward flow. The Nusselt number is high on the trailing wall (radially outward) and on the leading wall (radially inward) for forward rotation. The channel average Nusselt numbers show reasonable agreement when compared with previously reported correlations. The pressure distributions show that the major effect on heat transfer is the jet impingement in the beginning of the channel and the cross flow at the end of the channel. The results also show that heat transfer at high rotation numbers increases up to 10-15% for the forward rotation, and decreases by 10-18% for the reverse rotation when compared with stationary results. This is due to the secondary flow induced in the channel by rotation (Coriolis and centrifugal forces). This study was performed to determine the influence of jet impingement on the cooling of turbine blades under rotating conditions. These results can be applied to cooling design of gas turbine blades.
Zhang, Yuming (1996). Jet impingement heat transfer in two-pass rotating rectangular channels. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1996 -THESIS -Z438.