Aero-Engine High-Pressure Rotor Vibration & Stability Test
Project: Aero-Engine High-Pressure Rotor Vibration & Stability Test
June 2023 · Shanghai Aero-Engine Manufacturing Facility
Conducted rotor dynamics validation on the CJ-XX engine's high-pressure (HP) spool to:
Evaluate vibration suppression effectiveness of redesigned compressor/turbine components
Characterize critical speeds and rotor stability under simulated flight loads
Verify clearance control between rotating and static parts
Test Configuration
1. Instrumentation
| Sensor Type | Specifications | Installation |
|---|---|---|
| Eddy current probes | ±2mm range, 5μm resolution (DE-924U Ch1-8) | Blade tip clearance (4 locations) |
| DT5640 optical tachometer | 0.05% accuracy, 50kHz bandwidth | HP shaft end |
| Triaxial accelerometers | 10mV/g, 2-10kHz (±500g) | Bearings (DE-924U Ch9-14) |
| Strain gauges (rosettes) | 350Ω, ±5000με | Turbine disk rim (DE-924U Ch15-16) |
2. Test Conditions
Speed sweep: 2,000–18,000 RPM (10% steps)
Load cases:
Windmilling (0% throttle)
Max continuous (100% N2)
Transient surge recovery (simulated)
Key Test Procedures
1. Synchronized Data Acquisition
DE-924U Systems configured for:
1MS/s sampling (eddy current/acceleration)
10kS/s (strain)
RPM-phase-locked triggering (0.1° resolution)
2. Excitation Methods
Impact testing (at rest for modal analysis)
Unbalance response (with 5g-cm trial weights)
Oil whip simulation (bearing lubrication faults)
Critical Results
1. Vibration Performance
| Condition | Vibration Level (mm/s RMS) | Design Limit |
|---|---|---|
| Critical speed (8,450RPM) | 4.2 | 6.0 |
| Max continuous | 2.8 | 4.5 |
Reduction achieved: 30% vs. previous design at 12kRPM
2. Blade Dynamics
Tip clearance variation: <0.15mm during transients
Strain correlation:
FEM predicted vs. measured within 8% at 15kRPM
3. Stability Margins
Logarithmic decrement: >0.15 (all speeds)
No instabilities detected below 17,200RPM
Engineering Outcomes
Design Validation
Confirmed rotor dynamic coefficients meet API 617 criteria
Verified squeeze film damper effectiveness (vibration attenuation >40%)
Manufacturing Feedback
Adjusted blade tip grinding tolerance from ±0.10mm to ±0.06mm
Optimized rotor balancing procedure (reduced trial weights by 50%)
Certification Support
Provided data for FAA 33.83 compliance (rotor integrity)
Established baseline signatures for MRO vibration monitoring
Technical Terms
Oil whip: Self-excited bearing instability
Logarithmic decrement: Rotor stability metric
N2: High-pressure spool speed designation
This test enabled first-run success in engine testing, eliminating previously required 3 design iterations. The CJ-XX HP rotor now demonstrates best-in-class vibration characteristics for its thrust class.
