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Investigation of the Effect of Rotation on the Flow in a Two-Pass Cooling System with Smooth and Ribbed Walls using PIV

Schroll, Michael and Elfert, Martin and Lange, Lena (2011) Investigation of the Effect of Rotation on the Flow in a Two-Pass Cooling System with Smooth and Ribbed Walls using PIV. In: Proceedings of the ASME TURBO EXPO 2011, June 06-10, 2011, Vancouver, British Columbia, Canada. ASME Turbo Expo 2011, 06-10 June 2011, Vancouver, Canada.

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Official URL: http://www.asmeconferences.org/TE2011/

Abstract

A rotating cooling system with a 180 deg turn is investigated experimentally using the 2C PIV technique to measure the flow inside. This cooling configuration consists of two ducts of arbitrary cross-sections representing a two-pass front part of an idealized but nevertheless engine relevant turbine blade cooling design. The system has been investigated with ribbed walls in both passages for cooling enhancement as well as with smooth walls as a reference version in order to identify the effects induced by ribs. The rib orientation on the walls is 45 deg. With a rib height of 0.1 of hydraulic duct diameter and a pitch of 10 times rib height, a representative well-established rib lay-out was selected. This paper presents measurements of the axial flow during rotation of this two-pass system for rotation numbers up to 0.1. Together with previously obtained stationary results, this data completes the investigation of the secondary flow field with rotational results acquired with a two-component PIV measuring technique with improved sequencer technique. The Two-Pass Cooling System was analyzed on the rotating test rig using two-component Particle Image Velocimetry (2C PIV) a non-intrusive optical planar measurement technique. PIV is capable of obtaining complete flow maps of the instantaneous as well as averaged flow field even at high turbulence levels, which are typical for the narrow serpentine-shaped ribbed cooling systems. An in-house developed synchronization device enables very accurate control of the laser flashes and image acquisition with regard to the angular position of the measurement plane (light sheet) and thereby very accurately stabilizes the position of the channel within the image during PIV recording which then leads to very accurate mean velocities. The presented investigations were conducted in stationary and rotating mode. The results demonstrate the combined interaction of different vortices induced by several effects such as the inclination of ribs, Coriolis forces due to rotation and inertial forces within the bend. Additionally, a flow separation was observed at the divider wall downstream of the bend (in the second pass) that has a strong impact on the flow field depending on the rotational speed. The axial flow maps presented in this paper in combination with the secondary flow maps published previously are of sufficient high quality and spatial resolution to serve as a benchmark test case for the validation of flow solvers. The turbulent channel flow was investigated at a Reynolds number of 50,000 and at rotation numbers of 0.0 and 0.1.

Document Type:Conference or Workshop Item (Speech, Paper)
Title:Investigation of the Effect of Rotation on the Flow in a Two-Pass Cooling System with Smooth and Ribbed Walls using PIV
Authors:
AuthorsInstitution or Email of Authors
Schroll, MichaelAT-TM
Elfert, MartinAT-TU
Lange, LenaAT-TM
Date:9 June 2011
Journal or Publication Title:Proceedings of the ASME TURBO EXPO 2011, June 06-10, 2011, Vancouver, British Columbia, Canada
Refereed publication:Yes
In ISI Web of Science:No
Status:Published
Keywords:turbine blade, blade cooling, rotational effects, Coriolis force, Dean vortex, U-turn, two-pass cooling system, ribs, flow measurements, particle image velocimetry, PIV, flow field diagnostics, CFD validation
Event Title:ASME Turbo Expo 2011
Event Location:Vancouver, Canada
Event Type:international Conference
Event Dates:06-10 June 2011
Organizer:ASME International Gas Turbine Institute
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Aeronautics
HGF - Program Themes:Propulsion Systems
DLR - Research area:Aeronautics
DLR - Program:L ER - Engine Research
DLR - Research theme (Project):L - Virtual Engine and Validation Methods
Location: Köln-Porz , Göttingen
Institutes and Institutions:Institute of Propulsion Technology > Turbine
Institute of Propulsion Technology > Engine Measurement Systems
Deposited By: Dr. Michael Schroll
Deposited On:22 Jun 2011 10:56
Last Modified:22 Jun 2011 10:56

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