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Effects Of Ribs On Internal Blade-Tip Cooling

In English

Författare

Summary, in English

This work concerns an experimental study of pressure drop and heat transfer for turbulent flow inside a U-duct with relevance for tip cooling of gas turbine blades. The U-duct models the internal blade cooling flow passages. Both friction factors and convective heat transfer coefficients were measured along the bend (turn) part of the U-duct for three different rib configuration cases, namely (a) single rib at three different rib positions, i.e., inlet, middle and outlet, (b) two ribs with three different configurations, i.e., at the inlet and middle, at the middle and outlet as well as at the inlet and outlet, and (c) three ribs. The rib height-to-hydraulic diameter ratio, e/Dh, was 0.1 and the pitch ratios were 10 and 20. The Reynolds number was varied from 8,000 to 20,000. The test rig has been built in such a way that various experimental setups can be handled as the bend (turn) part of the U-duct can easily be removed and the rib configurations can be changed. The surface temperature was measured by using a high-resolution measurement technique based on narrow band thermochromic liquid crystals (TLC R35C5W) and a CCD camera placed facing the bend (turn) part of the U-duct. The calibration of the TLC is based on the hue-based color decomposition system using an in-house designed calibration box. Both the friction factor and heat transfer coefficient were affected by the position and configuration of the ribs along the bend wall. The highest friction factor was found for two ribs placed at the middle and outlet positions of the bend wall, respectively. The highest heat transfer coefficient was found for two ribs placed at the inlet and middle positions of the bend wall, respectively. The uncertainties in the experiments were estimated to be 3% and 6% for the Nusselt number and friction factor, respectively.

Avdelning/ar

Publiceringsår

2012

Språk

Engelska

Sidor

1033-1041

Publikation/Tidskrift/Serie

ASME Conference Proceedings

Dokumenttyp

Konferensbidrag

Förlag

American Society Of Mechanical Engineers (ASME)

Ämne

  • Energy Engineering

Conference name

ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition

Conference date

2011-06-06 - 2011-06-10

Conference place

Vancouver, Canada

Status

Published

Forskningsgrupp

  • heat transfer

ISBN/ISSN/Övrigt

  • ISBN: 978-0-7918-5465-5
  • Paper no. GT2011-45118