Just an update on how the GE9X is progressing
At the end of that article there is a link to a video, https://p.widencdn.net/c9nl5y/GE9X_BlockTest_v3
of "Block Testing", can someone give some details what that entails? And what it the large "ball" that is attached?
The ball keeps vortices from forming that occur in no velocity near ground operation of an engine at high throttle. A moving aircraft breaks the vortex. If the ball isn't there, asymmetrical flow disturbs the test results and results in data worse than in service.
I do not know the particulars of GEs block test. In general there is a run at maximum thrust for maximum allowed time, as the link notes, followed by the engine then doing a maximum continuous thrust climb setting. There are thrust transients, for example, flight idle to maximum thrust (aborted landing).
As the compressor linkages had issues before, the thrust settings will be varied to excercise the compressor stators. So reduced thrust takeoffs, reduced thrust climb, thrust reverse, anything that might impact the engine.
It is a rather expensive, multi day test.
Many engines fail the test. Compressor stator mapping is found to be wrong (insufficient compressor stall margin on one side or poor engine efficiency on the other side, this is a science that appears to be an art to those who don't know how the optimizations work on compressor stator mapping). Note: my knowledge is on old airfoil shapes, so it takes an informed team to do this programing and to plan the test.
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