Objective The purpose is to investigate both experimentally and theoretically the tip clearance effects in advanced axial flow compressors. This investigation aims to produce adequate theoretical models, which will be incorporated in future industrial design systems, thus leading to higher compressor efficiency.Firstly, a four-stage low-speed research compressor (LSRC) has been comprehensively instrumented with conventional pressure taps and probes. Laser two focus (L2F) has been used as well to get detailed pressure and velocity maps of a tip-clearance vortex developing in a multi-stage environment. Two sizes of tip gap have been completed and analysed: comprehensive and accurate sets of data extremely close to both hub and casing have been successfully obtained, and interesting features of the flow are revealed. The demonstration of the three-dimensional anemometer has been unsuccessful in the time available after problems in the areas of probe alignment and signal processing. Successful use of this instrument is only just beginning on bench tests, but its employment in a turbomachine is recognized as having high relative risk. Therefore an alternative has been identified from a laser manufacturer to obtain detailed three-dimensional measurements for validations of three-dimensional theoretical approach. To conclude on experimental studies, a simple experimental high-speed cascade rig (HSCR) has been partially prepared to understand the basic tip-clearance leakage behaviour; the inlet scroll which delivers the upstream yaw angle has been designed and manufactured, a rotating hub arrangement which simulates the relative motion between casing and rotating blade rows has been studied and designed (detailed drawings have been achieved). Finally a draft blade has been designed and will be finalised with respect to the inlet scroll performances. Also, a database has been built after a literature study. As anticipated, only a few experimental cases have been found interesting since many parameters are lacking, which underlines the need to do the above experiments. This database not only provides a new means of communication between partners but it has been used to validate the theoretical model. Secondly, a simple two-dimensional model based on a throughflow approach and a solid-body rotation of the tip-leakage vortex has been achieved and tested against a selection of the database experimental test cases. The model does not predict the tip leakage underturning to an acceptable level of accuracy and overestimates the spanwide extent of the leakage vortex effects: a great deal of effort is required to improve its accuracy and reduce its CPU time consumption for industrial purposes. A three-dimensional Navier-Stokes pressure-corrected solver has been modified to account for actual tip clearance geometry and therefore improve its numerical prediction accuracy. Four geometries have been tested: their results helped to visualize the complex flow patterns in the clearance area; some of them are compared to those of the first-level model. Work has also be done to reduce the CPU time consumption which is now of the order of 1 ms/node/iteration. Improvement in turbulence modelling as well as in grid orthogonality are mandatory.A database will be constructed using both existing open literature experimental results and those produced during the present project work. The intended experiments will use 2-dimensional and 3-dimensional laser anemometry, first in an existing low speed multi-stage axial compressor, then in an annular cascade rig developed specifically for the project. The influence of several parameters will be investigated. A first theoretical model will be produced , compatible with the existing circumferentially averaged through-flow industrial codes. A second one will be dedicated to 3-dimensional codes solving Reynolds-averaged Navier-Stokes equations in a multi-stage environment. To ensure the current project can be completed in 2 years, an appropriate subset of the work has been selected: Development of the first theoretical model and validation. Development of stage one of the second theoretical model. Completion of a first series of experiments on the existing compressor. Design of the specific annular cascade rig. Construction of a major part of the database. Fields of science natural sciencescomputer and information sciencesdatabasesengineering and technologyelectrical engineering, electronic engineering, information engineeringelectronic engineeringcomputer hardwarecomputer processorshumanitieslanguages and literatureliterature studiesengineering and technologyelectrical engineering, electronic engineering, information engineeringelectronic engineeringsignal processingnatural sciencesphysical sciencesclassical mechanicsfluid mechanicsfluid dynamics Programme(s) FP2-AERO 0C - Specific research and technological development programme (EEC) in the field of industrial manufacturing technologies and advanced materials applications (BRITE/EURAM) - Specific activities relating to aeronautics -, 1989-1992 Topic(s) Data not available Call for proposal Data not available Funding Scheme CSC - Cost-sharing contracts Coordinator Société Nationale d'Études et de Construction de Moteurs d'Aviation (SNECMA) EU contribution No data Address 2 boulevard du Général Martial Valin 75724 Paris France See on map Total cost No data Participants (4) Sort alphabetically Sort by EU Contribution Expand all Collapse all CRANFIELD UNIVERSITY United Kingdom EU contribution No data Address Road Wharley End MK43 0AL CRANFIELD,BEDFORD See on map Links Website Opens in new window Total cost No data NATIONAL TECHNICAL UNIVERSITY OF ATHENS Greece EU contribution No data Address Iroon Polytechnioy 5 15780 ATHENS See on map Total cost No data ROLLS-ROYCE PLC United Kingdom EU contribution No data Address 65 BUCKINGHAM GATE SW1E 6AT LONDON See on map Total cost No data TURBOMECA SA France EU contribution No data Address Avenue du President Szydlowski BORDES See on map Links Website Opens in new window Total cost No data
