Session: 38-05 Gas Turbine Engine Transition Ducts and Flow Interactions II

Paper Number: 82526

82526 - Unsteady Investigation of the Effect of Purge Air on the Flow Field Inside a Turbine Vane Frame Using Particle Image Velocimetry 

High fossil fuel expenses and the need to reduce green-house gas emission motivate manufacturers to design more efficient civil aircraft engines. In the case of directly driven jet engines, this is possible through the increased by-pass ratios for high propulsive efficiencies. This trend implies a change of the operating condition of the low-pressure turbine (LPT) towards lower rotational speeds at larger diameters. Turbine vane frames (TVFs) constitute a new generation of inter-turbine ducts that guide the flow from the high-pressure turbine (HPT) to the LPT in radial and circumferential direction. The TVF setup integrates turning vanes and thus removes the need for a separate vane blade-row in the first LPT stage. Consequently, the TVF offers benefits for overall engine weight and length, resulting in overall efficiency gains. This paper offers new insight into the complex three-dimensional flow field in a TVF duct. 

Experimental measurements have been conducted at the two-spool test rig at the Graz University of Technology in a test vehicle consisting of a single-stage HPT, the TVF, and the first LPT rotor. Engine-relevant flow conditions are achieved at the TVF inlet, including HPT tip clearance and purge air effects. Particle Image Velocimetry (PIV) was used to capture the flow field in-between two struts of the TVF. Splitter vanes are located inside each strutted segment along the second half of the TVF axial length. This paper presents new optical results for a TVF, based on measurements from a PIV test section located upstream of the splitter vanes in the first half of the TVF duct. The test section captures flow data in the area of strong unsteady interactions between the HPT and the TVF, one of the key mechanisms governing TVF aerodynamic performance. There is very limited PIV data for inter-turbine ducts such as a TVF available in the public domain, in particular for high-speed rotating rig setups, due to the complex setup and execution to obtain high-quality data with this approach. 

To resolve the unsteady behavior of the fluid, the flow field has been recorded at six subsequent stator-rotor positions. Moreover, two data sets of varying HPT purge flows were obtained and discussed to characterize the effect of purge air inside the measurement domain. 

Presenting Author: Malte Schien Graz University of Technology - Institute of Thermal Turbomachinery and Machine Dynamics

Presenting Author Biography: The present author grew up in Frankfurt am Main, Germany where Malte Schien finished High Shool in year 2013. Subsequently, Mr. Schien began to study Mechanical Engineering at the Technical University Brunswick. During the study his interest into tubomachinery and fluid flow emerged thanks to the lectures and academic support provided by the local Institute of Jet Propulsion and Turbomachinery. Malte Schien finalized his studies in the year 2021 in cooperation with the Institute of Thermal Turbomachinery and Machine Dynamics at Graz University of Technology. In the following he began to work as a Ph.D. student at the latter institute.

Authors:

Malte Schien Graz University of Technology
Asim Hafizovic Graz University of Technology
Filippo Merli Graz University of Technology
Florian Planck Graz University of Technology
Jakob Woisetschläger Graz University of Technology
Emil Goettlich Graz University of Technology