ISBN 9783843900164

978-3-8439-0016-4, Reihe Thermodynamik

Florian Höfler
Experimental Investigations of Wall Integrated Impingement Cooling Configurations for Thermally Highly Loaded Gas Turbine Blades

157 Seiten, Dissertation Universität Stuttgart (2011), Softcover, A5

Zusammenfassung / Abstract

In this work, a new gas turbine blade cooling concept was experimentally investigated in terms of internal heat transfer characteristics. The investigated geometry is related to a passage in the mid-chord section of the blade. It features a combination of wall- integrated impingement jets with local flow extraction. The jets are directed toward the pressure and suction sides of the blade. Starting from a baseline geometry, several geometry variations and their influence on the heat transfer were investigated. This included film cooling holes on the pressure side, ribs on the impingement target surfaces, varied jet-to-jet spacing, and conically tapered impingement holes.

A new test rig made of plexi glass was designed and manufactured during the present study. It meets the requirements for the desired flow conditions and the optical heat transfer measurements. The basic measurement technique was a transient Thermochromic Liquid Crystal (TLC) method. With this method, spatially resolved heat transfer distributions of all channel walls were gained. Additionally, surface thermocouples, heat flux sensors, and a steady-state TLC method were used in complementary measurements.

A thorough uncertainty analysis is presented for all measurement techniques. It is shown that the uncertainties for the transient TLC experiments mainly depend on the measured heat transfer coefficients and hence on the measurement location. The highest uncertainties occur in the jet stagnation regions and are calculated to ±13%.