General Electric later this year plans to begin performance testing of blade designs at a wide range of speeds to enable a comprehensive record of blade data to identify the optimal design for blades featured in the counterrotating stages of the open rotor engine.
In late 2009 GE began a series of blade tests on a GE-NASA test rig used in the 1980s to test the GE36 unducted fan. Among those tests are wind-tunnel evaluations of multiple configurations of sub-scale blades.
GE says to determine that current test data was consistent with data collected in the 1980s, the initial tests were conducted on one-fifth-scale versions of F31/A31 blades identical to those featured on the GE36.
Continuing acoustic tests have involved more complex blade configurations to reflect design gains made since the 1980s including inter-blade spacing, blade sweep angle and cord length and other features derived from 3-D aerodynamic design, says GE.