Abstract
Purpose This paper investigates experimentally the aerodynamic performance and forced response characteristics of two
rotors (baseline and optimized design) under the influence of frequency mistuning effects.
Method The optimized rotor blade was obtained by a multidisciplinary optimization framework, in which the aerodynamic
performance and vibration characteristics were improved numerically. From steady-state aerodynamic measurements, the
total pressure ratios at different operating conditions of the baseline and optimized blade were measured and validated. The
optimized blade demonstrated a 0.5% improvement in total pressure ratio and a consistent shift of the performance curve
towards higher mass flow rates. Ten modified cylinders were uniformly installed circumferentially in front of the rotor to
serve as the excitation source, so the forced response of both baseline and optimized blade during the acceleration process
was observed and measured by using the blade tip-timing technique.
Results Blade tip-timing data analysis revealed that the rotor blades exhibited relatively strong responses at engine order
(EO) 10 and 12, which was caused by the coupling effect of the upstream cylinder and downstream outlet stator. A detailed
analysis and evaluation were required because they were found to be close to the design speed. Compared with the baseline
blade, the maximum vibration amplitude decreased by 7.3% for EO = 10, and the amplitude magnification factor reduced
from 1.56 to 1.47, approximately 5.7%. Similarly, for EO = 12, the maximum amplitude and amplitude magnification factor
of optimized blade also decreased by 18% and 3.5% respectively. Furthermore, an improved fundamental mistuning model
(FMM) was employed to predict the vibration amplitudes of all blades. The average predicted vibration amplitudes exhibited
good agreement with the measured values in the deterministic analysis. Especially for the case of EO = 12, the relative error
of the averaged amplitude was less than 1%. However, accurately predicting the maximum amplitude remains challenging
due to the complex structural and aerodynamic coupling. The maximum relative error exceeded 16%.
Conclusion Even so, both experimental and numerical results indicated that the amplitude magnification factor of optimized
blade was smaller than that of the baseline.
rotors (baseline and optimized design) under the influence of frequency mistuning effects.
Method The optimized rotor blade was obtained by a multidisciplinary optimization framework, in which the aerodynamic
performance and vibration characteristics were improved numerically. From steady-state aerodynamic measurements, the
total pressure ratios at different operating conditions of the baseline and optimized blade were measured and validated. The
optimized blade demonstrated a 0.5% improvement in total pressure ratio and a consistent shift of the performance curve
towards higher mass flow rates. Ten modified cylinders were uniformly installed circumferentially in front of the rotor to
serve as the excitation source, so the forced response of both baseline and optimized blade during the acceleration process
was observed and measured by using the blade tip-timing technique.
Results Blade tip-timing data analysis revealed that the rotor blades exhibited relatively strong responses at engine order
(EO) 10 and 12, which was caused by the coupling effect of the upstream cylinder and downstream outlet stator. A detailed
analysis and evaluation were required because they were found to be close to the design speed. Compared with the baseline
blade, the maximum vibration amplitude decreased by 7.3% for EO = 10, and the amplitude magnification factor reduced
from 1.56 to 1.47, approximately 5.7%. Similarly, for EO = 12, the maximum amplitude and amplitude magnification factor
of optimized blade also decreased by 18% and 3.5% respectively. Furthermore, an improved fundamental mistuning model
(FMM) was employed to predict the vibration amplitudes of all blades. The average predicted vibration amplitudes exhibited
good agreement with the measured values in the deterministic analysis. Especially for the case of EO = 12, the relative error
of the averaged amplitude was less than 1%. However, accurately predicting the maximum amplitude remains challenging
due to the complex structural and aerodynamic coupling. The maximum relative error exceeded 16%.
Conclusion Even so, both experimental and numerical results indicated that the amplitude magnification factor of optimized
blade was smaller than that of the baseline.
Original language | English |
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Journal | Journal of Vibration Engineering and Technologies |
Volume | 13 |
Issue number | 75 |
DOIs | |
Publication status | Published - 12 Jan 2025 |
Keywords
- Axial compressor
- Forced response
- Blade tip-timing
- Mistuning
- Amplitude magnification