Research objectives and content
The proposed research project aims to the measurement of three-dimensional flows in turbomachinery components operating in high speed flow. The investigation shall be carried out in the Annular Cascade Facility and in the Compressor Test Rig of the Laboratory of Thermal Turbomachines (LTT). The 3-D Laser Doppler Anemometer (LDA) system, already in operation at LTT, shall be used for these studies.
The objectives of the proposed work are twofold:
- to obtain quantitative flowfield data in the annular cascade facility, aiming to the parametric investigation of tip clearance flow, which falls within the framework of ongoing research on this subject - to improve the measurement technique for the three-dimensional LDA system, in order to reduce the acquisition time for the measurement of turbulence quantities with a sufficiently low uncertainty. For this purpose, the capabilities of the existing data acquisition hardware devoted to the LDA system shall have to be exploited, and improved methods of signal handling shall have to be established.
It is expected that, by the completion of the project, improvements in the laser-based measurement technique shall be achieved, providing greater measurement flexibility and improved data accuracy. At the same time, measurements in the annular cascade are expected to shed more light to the ongoing research on tip clearance flow phenomena
Training content (objective, benefit and expected impact)
Further training in laser-based non-intrusive flow diagnostic techniques and optical signal processing; extension of candidate's experience in external high speed flow aerodynamics to internal flow turbomachinery aerodynamics. Mutual benefit for candidate and host institution expected in both technical and European cooperation terms. Enhancement of experimental capabilities at LTT/NTUA and possible continuation of contact between candidate/host lab and the European Space Agency.
Links with industry: the annular cascade facility has been developed within the framework of two Brite projects ("Tip clearance effects in advanced axial flow compressors", Contract No. AERO 0021-C(CD), and "Advanced civil core compressor aerodynamics", Contract No. AERO CT92-0039); the facility has been partially financed by SNECMA and Turbomeca of France and BMW-Rolls-Royce of Germany. Industrial relevance: tip clearance effects are of great importance to gas turbine manufacturers; extensive investigations are underway by numerous groups worldwide.