Periodic Reporting for period 3 - FloCoTec (FLOw COntrol TEChniques Enabling Increased Pressure Ratios in Aero Engine Core Compressors for Ultra-High Propulsive Efficiency Engine Architectures)
Reporting period: 2021-02-01 to 2022-03-31
To overcome the detrimental effects arising from pronounced rotor tip leakage flows, casing treatments (CT) are commonly applied. However, while CTs are known to strengthen the flow in the rotor tip region, they typically cause a radial re-balancing of the flow and weaken the downstream compressor flow at lower span heights. This phenomenon will be particularly pronounced within the compact rear stages of future high-pressure ratio HPCs with small blade heights, and considerably increases the risk of a premature compressor stall due to weaker flows at lower span regions.
To tackle these aerodynamic challenges, GEDE investigates innovative HPC technologies including an advanced 3D blade design for HPC rear stages within CS2 Joint Undertaking. TUM aims to contribute to the research of GEDE through:
OB 1. The development of compressor flow treatment technologies that strengthen the flow across the entire span, enhance the stability in a multi-stage compressor environment, and maximise the potential of the CT-technology. The aim is to deliver an efficiency-neutral HPC rear stage design with an increase of compressor stall margin by ≥ 5%.
OB 2. The provision of a compressor rig test facility that allows for a validation of the HPC rear stage technologies developed by GEDE and TUM, including a detailed quantification of the HPC performance and operability, under engine representative conditions.
OB 3. The development and application of advanced unsteady pressure and temperature measurements that allow for a time-accurate entropy estimation and thus provide a detailed understanding of the flow physics and aerodynamic loss mechanisms within the developed HPC rear stage concept.
The numerical reaearch activities provided a novel flow treatment concept, which counteracts the radial rebalancing effect caused by the CT. The novel FT concept of CT plus blowing type FT lead to an efficiency neutral HPC rear stage concept with a stability increase of more than 10%. Thus, objective OB1 could be fulfilled and the expectations were exceeded. The experimental work provided a compressor test rig HPC rear stage technologies developed by GEDE. With the aid of the rig, the HPC concept's performance and operability, under engine representative conditions could be quantified and OB2 was fulfiled. The applied advanced unsteady pressure (FRAP) and temperature (hot wire) measurement probes allowed for a time-accurate entropy estimation and the fulfillment of OB3. Hence, all objective of the projects were met.
To exploit the research activities in an optimum way, TUM plans to further mature the developed FT concept and to reconsider this in future HPC designs. Furthermore, the gained expertise with regards to high frequency measurements will help TUM and GEDE for future compressor tests in HSRC rig. In that context, TUM and GEDE plan to leverage the novel measurement techniques and support EU researchers by sharing their knowledge base via consultations, publications, etc.
The dissemination of FloCoTec was mainly conducted via three international conference publications and one journal publication. Furthermore, various student theses and jobs helped to disseminate and the progress of the project. Finally, two PhD theses are currently being developed. Hereby, one thesis will focus on the numerical and one on the experimental aspects of FloCoTec.