ENDWALL HEAT TRANSFER AT THE TURN SECTION IN A TWO-PASS SQUARE CHANNEL WITH AND WITHOUT RIBS

Summary, in English

The endwall heat transfer characteristics at the turn section in a two-pass square channel have been examined experimentally using a liquid crystal thermal imaging technique. The effects of periodic ribs on the endwall heat transfer are also discussed. Results indicate that the heat transfer at the turn section in the absence of ribs is dominated by the flow impingement. Close to the impingement region, the Nusselt number is scaled by Re-0.56; further downstream, the scaling factor changes to Re-0.62. The heat transfer distribution on the endwall is not monotonic and a local minimum region is observed. It is believed that the local minimum region is associated with the transition between two regimes with distinct turbulence levels. In the presence of ribs, the heat transfer patterns are significantly altered. Due to the increased turbulence levels induced by the protrusion of ribs, the local minimum Nu region cannot be detected. In addition, thermal performance is evaluated based on the constant flow rate and pumping power criteria. It is found that the highest heat transfer enhancement factor is obtained at a rib pitch ratio of 12.

• Author: Lei Wang; Zahra Ghorbani-Tari; Chenglong Wang; Zan Wu; Bengt Sundén
• Department/s: Heat Transfer
• Publishing year: 2013
• Language: English
• Pages: 321-332
• Publication/Series: Journal of Enhanced Heat Transfer
• Volume: 20
• Issue: 4
• Links: http://dx.doi.org/10.1615/JEnhHeatTransf.2014010077
• Document type: Journal article
• Publisher: Begell House
• Topic: Energy Engineering
• Keywords: rough surface; structured ribs; single-phase flow; gas turbine; liquid; crystal method
• Status: Published
• ISBN/ISSN/Other: ISSN: 1563-5074