Aerothermal Experimental Investigation of LPT-OGVs

Doctoral thesis, 2017

This thesis presents the design, commissioning, and experimental data of a newly built turbine facility at Chalmers University of Technology for investigating the ow in the engine exit structure (EES). The EES is the structure located downstream of the lowpressure turbine (LPT) in a jet engine. Flow through this structure is highly complex since non-uniformities generated at the LPT interact with the outlet guide vanes (OGVs) located inside this structure. Due to the ow complexity, a facility that can reproduce engine conditions including realistic cavities is required to validate numerical methods. To generate realistic inlet boundary conditions for the EES, an LPT stage is located upstream of the EES. The facility is a large-scale low-speed annular cascade, and the ow Reynolds number based on the channel height of the LPT turbine stage is 465,000, which is representative for large turbofan engines. This facility follows classical low-speed wind tunnel conceptual design. Experimental correlations obtained from data collected in a previous rig and from previous studies in low-speed wind tunnels are used to compute and optimize pressure losses. CFD tools are used to evaluate the nal design of the facility. A nite-element analysis of the LPT rotor and structure is performed, and a short overview of this analysis is included in the thesis. Aero measurements were performed at several operation points of the rig for commissioning purposes. Flow periodicity and uniformity in the test section inlet are studied, and these measurements showed that the ow quality requirements are successfully fullled. Furthermore, experimental investigation of the EES aerodynamics and performance is performed. Data from multi-hole probe measurements and static pressure taps on two instrumented OGVs is used for this purpose. A complete set of hardware and software are developed, as well as experimental routines for high-quality aero measurements. The results from these tests show the capability of Chalmers LPT-OGV facility to reproduce LPT ow and provide high-quality data for CFD validation. CFD calculations are performed for several operational points and compared with the obtained experimental data. Good agreement between experimental and numerical time-averaged ow quantities is achieved. The eect of the inlet boundary conditions into the EES is studied showing associated changes in the ow and performance. Analysis of the ow structures is performed based on the obtained measurement data. Finally, the results of this thesis provide a new experimental tool for evaluating novel EES designs under representative engine conditions and open-up the potential of the new facility for future research of LPT-OGV ows for the aerospace industry.