scholarly journals Experimental Investigation of a Forced-Response Condition in a Multistage Compressor

2015 ◽  
Vol 31 (5) ◽  
pp. 1320-1329 ◽  
Author(s):  
William L. Murray ◽  
Nicole L. Key
Keyword(s):  
Experimental Investigation ◽  
Forced Response ◽  
Response Condition ◽  
Multistage Compressor

scholarly journals Experimental Investigation and Modeling of Surge in a Multistage Compressor

2017 ◽  
Vol 105 ◽  
pp. 1751-1756 ◽  
Author(s):  
Enrico Munari ◽  
Mirko Morini ◽  
Michele Pinelli ◽  
Pier Ruggero Spina
Keyword(s):  
Experimental Investigation ◽  
Multistage Compressor

Experimental Investigation of Mode Localization and Forced Response Amplitude Magnification for a Mistuned Bladed Disk

2000 ◽  
Author(s):  
John Judge ◽  
Christophe Pierre ◽  
Oral Mehmed
Keyword(s):  
Experimental Investigation ◽  
Traveling Wave ◽  
Forced Response ◽  
Response Amplitude ◽  
Mode Shapes ◽  
Bladed Disks ◽  
Element Analysis ◽  
Mode Localization ◽  
Bladed Disk ◽  
Out Of Plane

The results of an experimental investigation on the effects of random blade mistuning on the forced dynamic response of bladed disks are reported. The primary aim of the experiment is to gain understanding of the phenomena of mode localization and forced response blade amplitude magnification in bladed disks. A stationary, nominally periodic, twelve-bladed disk with simple geometry is subjected to a traveling-wave, out-of-plane, “engine order” excitation delivered via phase-shifted control signals sent to piezo-electric actuators mounted on the blades. The bladed disk is then mistuned by the addition of small, unequal weights to the blade tips, and it is again subjected to a traveling wave excitation. The experimental data is used to verify analytical predictions about the occurrence of localized mode shapes, increases in forced response amplitude, and changes in resonant frequency due to the presence of mistuning. Very good agreement between experimental measurements and finite element analysis is obtained. The out-of-plane response is compared and contrasted with the previously reported in-plane mode localization behavior of the same test specimen. This work also represents an important extension of previous experimental study by investigating a frequency regime in which modal density is lower but disk-blade interaction is significantly greater.

scholarly journals An Experimental Investigation of Vibration Localization in Bladed Disks: Part II — Forced Response

1997 ◽  
Author(s):  
Marlin J. Kruse ◽  
Christophe Pierre
Keyword(s):  
Experimental Investigation ◽  
Forced Response ◽  
Mode Shapes ◽  
Bladed Disks ◽  
Structural Coupling ◽  
Vibration Localization ◽  
Bladed Disk ◽  
Engine Order ◽  
Localized Mode ◽  
The Impact

The results of an experimental investigation on the effects of random blade mistuning on the forced dynamic response of bladed disks are reported. Two experimental specimens are considered: a nominally periodic twelve-bladed disk with equal blade lengths, and the corresponding mistuned bladed disk, which features slightly different blades of random lengths. Both specimens are subject to traveling-wave excitations delivered by piezo-electric actuators. The primary aim of the experiment is to demonstrate the occurrence of an increase in forced response blade amplitudes due to mistuning, and to verify analytical predictions about the magnitude of these increases. In particular, the impact of localized mode shapes, engine order excitation, and disk structural coupling on the sensitivity of forced response amplitudes to blade mistuning is reported. This work reports one of the first systematic experiments carried out to demonstrate and quantify the effect of mistuning on the forced response of bladed disks.

Mistuned Forced Response Predictions of an Embedded Rotor in a Multistage Compressor

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Fanny M. Besem ◽  
Robert E. Kielb ◽  
Paul Galpin ◽  
Laith Zori ◽  
Nicole L. Key
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Aerodynamic Performance ◽  
Forced Response ◽  
Response Analysis ◽  
Data Set ◽  
Multistage Compressor ◽  
The Individual ◽  
Decoupled Method ◽  
Tremendous Impact

This paper covers a comprehensive forced response analysis conducted on a multistage compressor and compared with the largest forced response experimental data set ever obtained in the field. The steady-state aerodynamic performance and stator wake predictions compare well with the experimental data, although losses are underestimated. Coupled and uncoupled unsteady simulations are conducted on the stator–rotor configuration. It is shown that the use of a decoupled method for forced response cannot yield accurate results for cases with strong inter-row interactions. The individual and combined contributions of the upstream and downstream stators are also assessed. The downstream stator is found to have a tremendous impact on the forced response predictions due to the constructive interactions of the two stator rows. Finally, predicted mistuned blade amplitudes are compared to mistuned experimental data. The average amplitudes match the experiments very well, while the maximum response amplitude is underestimated.

scholarly journals Age-related increases in reaction time result from slower preparation, not delayed initiation

2021 ◽  
Author(s):  
Robert M Hardwick ◽  
Alexander D Forrence ◽  
Maria Gabriela Costello ◽  
Kathy Zachowski ◽  
Adrian M Haith
Keyword(s):  
Reaction Time ◽  
Reaction Times ◽  
Forced Response ◽  
Movement Preparation ◽  
Response Condition ◽  
Time Condition ◽  
Age Related ◽  
Brain Structure And Function ◽  
Time Required ◽  
Reaction Time Condition

Recent work indicates that healthy younger adults can prepare accurate responses faster than their voluntary reaction times indicate, leaving a seemingly unnecessary delay of 80-100ms before responding. Here we examined how the preparation of movements, initiation of movements, and the delay between them are affected by age. Participants made planar reaching movements in two conditions. The "Free Reaction Time" condition assessed the voluntary reaction times at which participants responded to the appearance of a stimulus. The "Forced Reaction Time" condition assessed the minimum time actually needed to prepare accurate movements by controlling the time allowed for movement preparation. The time taken to both initiate movements in the Free Reaction Time and to prepare movements in the Forced Response condition increased with age. Notably, the time required to prepare accurate movements was significantly shorter than participants' self-selected initiation times; however, the delay between movement preparation and initiation remained consistent across the lifespan (~90ms). These results indicate that the slower reaction times of healthy older adults are not due to an increased hesitancy to respond, but can instead be attributed to changes in their ability to process stimuli and prepare movements accordingly, consistent with age-related changes in brain structure and function.

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