The direct deposition of multiple hot film sensors onto a turbine NGV using thin film processing techniques
Abstract
Multiple hot film sensors were directly deposited, as thin films, onto research turbine Nozzle Guide Vanes (NGV) to monitor the state of the vane boundary layers under low Reynolds number conditions. The sensors were fabricated using thin film processing techniques, including coating the vanes with an organic insulator, vacuum deposition of metals, and ceramic and photolithography. A method of depositing a thin film of polyimide directly onto the entire surface area of a component was perfected. The nominal thickness is 3 micrometers and this acts as a thermal and electrical insulator. By employing suitable vacuum deposition techniques a thin film construction of sensors and lead out tracks can then be produced within a thickness of a further 2 micrometers. The direct fabrication of hot film sensors onto the vanes represents a very significant advance, since complex three dimensional recesses do not need to be machined into the vane surface. The instrumented vanes were built into an annular cascade and run in a cold flow turbine test facility. The hot film sensors exhibited excellent characteristics, and selected turbine rig test results are included to show the quality of the data obtained.
- Publication:
-
NASA STI/Recon Technical Report N
- Pub Date:
- September 1991
- Bibcode:
- 1991STIN...9221450C
- Keywords:
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- Boundary Layer Flow;
- Guide Vanes;
- Hot-Film Anemometers;
- Photolithography;
- Thin Films;
- Turbine Exhaust Nozzles;
- Vacuum Deposition;
- Air Flow;
- Flow Measurement;
- Polyimides;
- Fluid Mechanics and Heat Transfer