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

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 [1], 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 [2]. 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.

Heat Transfer Augmentation Technologies for Internal Cooling of Turbine Components of Gas Turbine Engines

“…Several other experimental investigations of heat transfer and flow behavior in rotating channels consider effects of channel shape and orientation [169,[248][249][250][251], pin fins [169,251,252], impingement cooling [253], dimpled surfaces [254], arrays of spherical protrusions [255], trailing edge cooling [256][257][258], and rib turbulators [148,149,166,169,259,260]. For example, Tse and Steubner [98] measure different velocity components in a serpentine channel with 45 ∘ ribs.…”

Formation of vertex flow in the rotating channel and influence of operation factors on its intensity

“…Ученый использовал тестовые модели, которые точно повторяют геометрию расчетных моделей в [6]. Целью его работы стало определе-ние опытным путем структур основного потока [5] и структуры вторичного течения [1]. Замер скорости осуществлялся с помощью метода цифровой трас-серной визуализации (Particle Image Velocimetry) на специализированном экспериментальном стенде.…”

“…Замер скорости осуществлялся с помощью метода цифровой трас-серной визуализации (Particle Image Velocimetry) на специализированном экспериментальном стенде. Результаты опытных исследований, проведенных в [1,5], подтвердили корректность результатов чис-ленного моделирования в [6].…”

Formation of vertex flow in the rotating channel and influence of geometric factors on its intensity

“…ASME Turbo Expo, June 6-10, 2011, Vancouver, British Columbia, Canada Paper GT2011-45926. [6] Schroll M., Lange L., Elfert M. Investigation of the effect of rotation on the flow in a two-pass cooling system with smooth and ribbed walls using PIV. ASME Turbo Expo, June 6-10, 2011, Vancouver, British Columbia, Canada, Paper GT2011-46427.…”