3-D digitizers target turbine blade inspection

OCTOBER 16, 2008--Turbine blades are primarily designed by using computational fluid dynamics (CFD) to simulate the flow of gases over the blades. Simulation lets engineers evaluate the performance of different blade designs using virtual prototypes. However, before a CFD model can evaluate blade geometry it must be validated by running a physical test with an identical blade to ensure the simulation matches the test results. The complexity of turbine blades has made it impossible to capture the geometry with standard coordinate measuring machines (CMMs), laser scanners, or white light scanners. Turbine blade manufacturers have addressed this problem by working with NVision, which uses the MAXOS system that uses concentrated light rather than a touch probe. The system eliminates the inaccuracies inherent in contact probe measurement on small radii or sharp edges, caused by ball-offset geometry. The MAXOS can measure radii down to 0.004 in.without the need to spray the material with a matte coating. The accuracy of the system is +/-0.0004 in. on polished and machined services and the resolution between the measured points down to 0.0001 in. For more information, go to http://www.nvision3d.com/news.html.