Empirical Flutter Prediction Method.
Final rept. Sep 84-Sep 87,
GE AIRCRAFT ENGINES CINCINNATI OH ADVANCED TECHNOLOGY OPERATION
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Design of advanced technology engines is often limited by compressor blade instability or flutter. Test points from the annular cascade data base were analyzed, to predict from aeromechanical data which of 14 types of stability or instability would result. The basic approach was to identify for each pair of stability regions, linear combinations hyperplanes of the aeromechanical variables, whose numerical value would be above a critical level for all test points in one stability region and would be below the critical level for test points in the other stability region. It was found that 76 of the pairs of stability regions allowed a hyperplane to discriminate between the two regions, but for 24 a curved surface or nonlinear combination variables would be needed. Review of 85 of the 891 test points used to construct the hyperplanes revealed that the hyperplanes correctly identify the stability condition of 59 of the points in a literal sense, but are correct in a broader practical sense for 79 of the points. When the hyperplanes were applied to 51 validation test points taken from several actual enginerig test data, they gave virtually no correct results. This result is not immediately explainable. Keywords Stall Choke Discriminant Cluster. edc
- Fluid Mechanics
- Jet and Gas Turbine Engines