scholarly journals Rotating Stall Induced Non-Synchronous Blade Vibration Analysis for an Unshrouded Industrial Centrifugal Compressor

Sensors ◽  
2019 ◽  
Vol 19 (22) ◽  
pp. 4995 ◽  
Author(s):  
Xinwei Zhao ◽  
Qiang Zhou ◽  
Shuhua Yang ◽  
Hongkun Li
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Wave ◽  
Pressure Sensors ◽  
Load Condition ◽  
Rotating Stall ◽  
Aerodynamic Load ◽  
Blade Vibration ◽  
Impeller Blade ◽  
Time Space ◽  
Stall Cells

Rotating stall limits the operating range and stability of the centrifugal compressor and has a significant impact on the lifetime of the impeller blade. This paper investigates the relationship between stall pressure wave and its induced non-synchronous blade vibration, which will be meaningful for stall resonance avoidance at the early design phase. A rotating disc under a time-space varying load condition is first modeled to understand the physics behind stall-induced vibration. Then, experimental work is conducted to verify the model and reveal the mechanism of stall cells evolution process within flow passage and how blade vibrates when suffering such aerodynamic load. The casing mounted pressure sensors are used to capture the low-frequency pressure wave. Strain gauges and tip timing sensors are utilized to monitor the blade vibration. Based on circumferentially distributed pressure sensors and stall parameters identification method, a five stall cells mode is found in this compressor test rig and successfully correlates with the blade non-synchronous vibration. Furthermore, with the help of tip timing measurement, all blades vibration is also evaluated under different operating mass flow rate. Analysis results verify that the proposed model can show the blade forced vibration under stall flow condition. The overall approach presented in this paper is also important for stall vibration and resonance free design with effective experimental verification.

Experimental Investigation for Enhanced Control of Rotating Unsteady Flow Instabilities in an Unshrouded Centrifugal Compressor Impeller

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
B. Mischo ◽  
P. Jenny ◽  
Y. Bidaut ◽  
N. Fonzi ◽  
D. Hermann ◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
Leading Edge ◽  
Fem Analysis ◽  
Rotating Stall ◽  
Test Rig ◽  
Blade Vibration ◽  
Impeller Blade ◽  
Compressor Impeller ◽  
Frequency Interaction ◽  
Computational Fluid Dynamics Cfd

Abstract Unshrouded industrial centrifugal compressor impellers operate at high rotational speeds and volume flow rates. Under such conditions, impeller blade excitation is dominated by high frequency interaction with stationary parts, i.e., vaned diffusers or inlet guide vanes. In a previous study conducted on two full compression units of the original equipment manufacturer (OEM), the authors identified, characterized, and quantified resonant blade vibration caused by the interaction of the impeller blades with rotating stall cells during severe off-design conditions. This caused significant dynamic stress in the blades. In a follow-up study, this phenomenon was reproduced successfully experimentally under representative off-design conditions in a downscaled test rig and numerically with unsteady computational fluid dynamics (CFD) and structural mechanical finite element method (FEM) analysis. The gained knowledge was translated into a new diffuser design philosophy, based on sectorwise circumferential variation of the leading edge angle. This paper presents the patented philosophy, which is experimentally verified on the same test rig configuration in terms of flow path geometry and measurement equipment that was used in the mentioned prior study to assess resonant blade interaction. The results confirm the design aims: rotating stall onset was delayed without affecting the aerodynamic performance of the stage. Resonant blade interaction with rotating stall observed in the baseline diffuser could not be avoided with the two new diffuser designs. However, with the two new diffusers, the induced mechanical stresses in the impeller and the excitability were reduced by up to 12%.

Experimental Investigation for Enhanced Control of Rotating Unsteady Flow Instabilities in an Unshrouded Centrifugal Compressor Impeller

2019 ◽  
Author(s):  
B. Mischo ◽  
P. Jenny ◽  
Y. Bidaut ◽  
N. Fonzi ◽  
D. Hermann ◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
Leading Edge ◽  
Fem Analysis ◽  
Rotating Stall ◽  
Test Rig ◽  
Blade Vibration ◽  
Impeller Blade ◽  
Compressor Impeller ◽  
Frequency Interaction ◽  
Computational Fluid Dynamics Cfd

Abstract Unshrouded industrial centrifugal compressor impellers operate at high rotational speeds and volume flow rates. Under such conditions impeller blade excitation is dominated by high frequency interaction with stationary parts, i.e. vaned diffusers or inlet guide vanes. In a previous study conducted on two full compression units of the original equipment manufacturer (OEM), the authors also identified, characterized and quantified resonant blade vibration caused by the interaction of the impeller blades with sub-synchronous rotating stall cells during severe off-design conditions. The resonant impeller excitation lead to significant dynamic stress in the blades. In a follow-up study the authors have reproduced this phenomenon under representative off-design conditions in a downscaled test rig and successfully reproduced the phenomenon with unsteady Computational Fluid Dynamics (CFD) and structural mechanical Finite Element Method (FEM) analysis. The gained knowledge of these studies was translated into a new diffuser design philosophy, based on a sectorwise circumferential variation of the leading edge angle. In this paper, the patented philosophy by the OEM is presented and verified experimentally on the same test rig configuration in terms of flow path geometry and measurement equipment that was used in the mentioned prior study to assess resonant blade interaction. The results confirm the design aims: rotating stall onset was delayed without affecting the aerodynamic performance of the stage. Resonant blade interaction with rotating stall observed in the baseline diffuser could not be avoided with the two new diffuser designs. However, with the two new diffusers, the induced mechanical stresses in the impeller and the excitability were reduced by up to 12%.

scholarly journals Rotating Stall Flow and Dangerous Blade Excitation of Centrifugal Compressor Impeller: Part 1 — Phenomenon of Large-Number Stall Cells

1991 ◽  
Author(s):  
U. Seidel ◽  
J. Chen ◽  
U. Haupt ◽  
H. Hasemann ◽  
D. Jin ◽  
...  
Keyword(s):  
Phase Analysis ◽  
Centrifugal Compressor ◽  
High Performance ◽  
Fast Response ◽  
Rotating Stall ◽  
Blade Vibration ◽  
Response Dynamic ◽  
Compressor Impeller ◽  
Stall Cells ◽  
High Level

A new structure of rotating stall with unusual large-number stall cells (up to 7) has been detected experimentally in a high performance single stage centrifugal compressor system with backswept impeller and vaned diffusers. The number of stall cells is firstly identified by a phase analysis of pressure signals obtained from fast response dynamic transducers located at different circumferential positions on the shroud wall, and then verified by comparing the resulting frequencies of blade vibration with that measured from blade mounted strain gages. Up to 6 transducers in one radial position have been used for more certainty of the phase analysis. For the case of intermittent stall patterns, the frequency analysis of pressure and blade vibration signals is performed separately for sections with different characters of oscillation to avoid the smearing effect if signals of the whole pattern are averaged. As a result, the large-number stall cells, numbered 4–7, were determined in the speed range of 12000–14000 rpm, and in the higher speeds of 15000–16000 rpm right after the occurrence of normal stall cells of 2, when the flow rate is slightly reduced along the constant speed line. For the large-number stall cell case, the measured blade vibration strain has reached such a high level that is already beyond the tolerance of blade material. Moreover, frequencies of blade excitation are always in the vincinity of resonance. These two features, which are not observed for the normal stall cell case and for the excitation of broadband character, show a particular danger of this phenomenon to the compressor operation.

scholarly journals Rotating Stall in Centrifugal Compressor Vaneless Diffuser: Experimental Analysis of Geometrical Parameters Influence on Phenomenon Evolution

2004 ◽  
Vol 10 (6) ◽  
pp. 433-442 ◽  
Author(s):  
Giovanni Ferrara ◽  
Lorenzo Ferrari ◽  
Leonardo Baldassarre
Keyword(s):  
Centrifugal Compressor ◽  
Dynamic Pressure ◽  
Pressure Sensors ◽  
Experimental Tests ◽  
Fast Response ◽  
Rotating Stall ◽  
Geometrical Parameters ◽  
Vaneless Diffuser ◽  
Response Dynamic ◽  
Frequency Domains

The rotating stall is a key problem for achieving a good working range of a centrifugal compressor and a detailed understanding of the phenomenon is very important to anticipate and avoid it. Many experimental tests have been planned by the authors to investigate the influence on stall behavior of different geometrical configurations. A stage with a backward channel upstream, a 2-D impeller with a vaneless diffuser and a constant cross-section volute downstream, constitute the basic configuration. Several diffuser types with different widths, pinch shapes, and diffusion ratios were tested. The stage was instrumented with many fast response dynamic pressure sensors so as to characterize inception and evolution of the rotating stall. This kind of analysis was carried out both in time and in frequency domains. The methodology used and the results on phenomenon evolution will be presented and discussed in this article.

Excitation of Blade Vibration due to Surge of Centrifugal Compressors

1992 ◽  
Author(s):  
D. Jin ◽  
U. Haupt ◽  
H. Hasemann ◽  
M. Rautenberg
Keyword(s):  
Centrifugal Compressor ◽  
Rotational Speed ◽  
High Performance ◽  
Dynamic Pressure ◽  
Rotating Stall ◽  
Blade Vibration ◽  
High Rotational Speed ◽  
Blade Thickness ◽  
Periodic Pressure ◽  
Compressor Surge

Centrifugal compressor surge at high rotational speed and reduced blade thickness can produce dangerous excitation effects which have numerous resulted in problems in the past. This paper presents an investigation of blade excitation during surge in a high performance single stage centrifugal compressor with various impeller and diffuser geometry. The blade vibration was measured using blade mounted strain gages. The flow characteristics during surge as the cause of blade excitation were simultaneously determined by fast response dynamic pressure transducers. The experiments have been performed using a radial and a backswept impeller, as well as a vanless and vaned diffusers. The rotational speed of the compressor was varied from 5,000 to 14,500 rpm. The characteristics of unsteady flow during surge, such as, the flow pattern of rotating stall and the non-periodic pressure fluctuation during surge were studied in detail. The experimental results demonstrated that, in addition to the excitation of rotating stall during surge, strong non-periodic pressure fluctuations at the beginning and the end of the surge induced dangerous blade excitations in all compressor configurations. The maximum strain values of blade vibration for all compressor versions at different rotational speeds of the compressor were measured to estimate the danger of blade excitation during surge. The results showed that the blade excitation during compressor surge with vaned diffusers is stronger than the excitation with a vanless diffuser and that the blade excitation with a radial impeller is stronger than the excitation with a backswept impeller.

Geometric considerations in the capture of localized flow reversal in centrifugal compressor vaneless diffusers using steady state simulations

2016 ◽  
Vol 231 (21) ◽  
pp. 3959-3973
Author(s):  
Chris Clarke ◽  
Russell Marechale ◽  
Abraham Engeda ◽  
Michael Cave
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Centrifugal Compressor ◽  
Flow Characteristics ◽  
Rotating Stall ◽  
Flow Reversal ◽  
Contour Plot ◽  
Vaneless Diffuser ◽  
Impeller Blade ◽  
Steady State Simulation

A steady state simulation procedure is proposed to capture localized flow reversal inside of a centrifugal compressor vaneless diffuser. The procedure was performed on 12 compressor stages of varying geometry for speed lines of 13,100, 19,240, and 21,870 r/min. The simulations were run for all points from choke to surge including the experimentally determined rotating stall onset point. The experimental data and geometry were provided by Solar Turbines Inc. San Diego, CA. It was found possible to capture localized flow reversal inside of a vaneless diffuser using a steady state simulation. The results showed that using a geometric parameter, comparing the diffuser width, b4, to the impeller blade pitch distance, dpitch, it could be determined whether or not a steady state simulation could capture localized flow reversal. For values of b4/dpitch beneath 0.152 flow reversal could not be captured. But, for values of b4/dpitch above 0.177 localized flow reversal was captured. For values between 0.152 and 0.177, no conclusions could be drawn. Where possible, experimental data were compared against the diffuser inlet and outlet numerical profiles and the meridional contour plot. These comparisons served to validate the approach used in this article. These validations showed that the procedure defined herein is accurate and trustworthy within a specific range of geometric and flow characteristics. There are two other conclusions. First, the b4/dpitch parameter helps to define the type of flow breakdown. For b4/dpitch below 0.152, the flow breaks down in the circumferential direction, but for values of b4/dpitch above 0.177, the flow breaks down in the span-wise direction. Second, the simulations were able to capture instances of localized flow reversal before rotating stall onset. This concludes that localized flow reversal is not the determining factor in rotating stall onset as has been suggested by other investigators.

Correlation Analysis of Multiple Sensors for Industrial Gas Turbine Compressor Blade Health Monitoring

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Brian Kestner ◽  
Tim Lieuwen ◽  
Chris Hill ◽  
Leonard Angello ◽  
Josh Barron ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Acoustic Pressure ◽  
Dynamic Pressure ◽  
Pressure Sensors ◽  
Rotating Stall ◽  
Compressor Blade ◽  
Blade Vibration ◽  
Multiple Sensors ◽  
Dynamic Pressure Measurements ◽  
Industrial Gas Turbine

This paper summarizes an analysis of data obtained from an instrumented compressor of an operational, heavy duty industrial gas turbine; the goal of the aforementioned analysis is to understand some of the fundamental drivers, which may lead to compressor blade vibration. Methodologies are needed to (1) understand the fundamental drivers of compressor blade vibration, (2) quantify the severity of “events,” which accelerate the likelihood of failure and reduce the remaining life of the blade, and (3) proactively detect when these issues are occurring so that the operator can take corrective action. The motivation for this analysis lies in understanding the correlations between different sensors, which may be used to measure the fundamental drivers and blade vibrations. In this study, a variety of dynamic data was acquired from an operating engine, including acoustic pressure, bearing vibration, tip timing, and traditional gas path measurements. The acoustic pressure sensors were installed on the first four compressor stages, while the tip timing was installed on the first stage only. These data show the presence of rotating stall instabilities in the front stages of the compressor, occurring during every startup and shutdown, and manifesting itself as increased amplitude oscillations in the dynamic pressure measurements, which are manifested in blade and bearing vibrations. The data that lead to these observations were acquired during several startup and shutdown events, and clearly show that the amplitude of these instabilities and the rpm at which they occur can vary substantially.

Blade Excitation by Broad-Band Pressure Fluctuations in a Centrifugal Compressor

1988 ◽  
Vol 110 (1) ◽  
pp. 129-137 ◽  
Author(s):  
U. Haupt ◽  
M. Rautenberg ◽  
A. N. Abdel-Hamid
Keyword(s):  
Centrifugal Compressor ◽  
Reverse Flow ◽  
Pressure Ratio ◽  
Pressure Fluctuations ◽  
Broad Band ◽  
Rotating Stall ◽  
High Mass ◽  
Blade Vibration ◽  
Flow Angle ◽  
Unsteady Pressure

The mechanism of blade excitation during the operation of a high-mass-flow, high-pressure-ratio centrifugal compressor has been investigated. This was carried out in the compressor operating range below 60 percent of design speed and in the zone of unsteady flow occurrence, where considerable blade vibration has been measured but no periodic unsteady pressure pattern such as rotating stall could be identified. Experiments conducted to study the mechanism of interactions between flow and blades were accomplished using several measuring methods simultaneously, such as measurements of blade vibration, flow angle at impeller inlet, unsteady pressure at different meridional and peripheral locations, as well as flow visualization by means of oil pattern. Analysis of the measurements showed typical broad-band characteristics of the unsteady pressure field and also for the blade vibration behavior. Results of flow angle investigations at the impeller inlet together with the analysis of oil pattern show that the broad-band pressure fluctuations and blade excitation can be attributed to a strong reverse flow near the suction side of the radial blade in the shroud zone. This reverse flow has its source downstream of the impeller and is extending back up to a location ahead of the impeller inlet. Similar results were obtained when the compressor was operated with vaneless and vaned diffuser configurations.

Numerical Study on the Influence of Tip Clearance on Rotating Stall in an Unshrouded Centrifugal Compressor

2017 ◽  
Author(s):  
Wenying Ju ◽  
Shengli Xu ◽  
Xiaofang Wang ◽  
Xudong Chen ◽  
Shuhua Yang ◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
Numerical Study ◽  
Leading Edge ◽  
Rotating Stall ◽  
Tip Clearance ◽  
Forming Process ◽  
Impeller Blade ◽  
Tip Clearance Flow ◽  
Rotating Speed ◽  
Operation Conditions

Whole annulus unsteady simulations are performed by CFD with the whole flow passage model from inlet guide vanes to volute of an unshrouded centrifugal compressor. Characteristics and development mechanism of rotating stall are analyzed including the flow field and the impeller blade load in time and frequency domain. Rotating stall with three cells is observed in both two actual operation conditions but the cell rotating speed and the forming process is different. Leading edge tip clearance leakage is a criterion to predict the formation of a spike stall in centrifugal compressors. Tip clearance flow also plays an important role in the moving of rotating instabilities and the propagation of stall cells. It can effectively slow down the stall forming and decrease the pressure load on blade by reduced the tip clearance size at the leading edge.

The Analysis of Aerodynamic Load for High Speed Centrifugal Compressor Blade

2013 ◽  
Vol 675 ◽  
pp. 103-106
Author(s):  
Gui Hua Zhu ◽  
Tuan Hui Qiu ◽  
Min Xie
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
High Speed ◽  
Fluid Model ◽  
Pressure Ratio ◽  
Design Flow ◽  
Aerodynamic Load ◽  
Impeller Blade ◽  
Rate Condition ◽  
Rotating Speed

With the ANSYS Workbench software,the 3D fluid model of the impeller for the centrifugal compressor is set up,whose design flow is 3.2kg/s,rotating speed is 32473r/min,pressure ratio is 3.8,and then with the method of CFD,the k-ε two equations model is selected as the turbulence model,in the condition of design speed,the fluid region of the impeller is simulated under eight different flow rate,the aerodynamic load of the impeller blade and its distribution is acquired under different flow rate,the results showed that the location of the largest aerodynamic load is in the blade that near the outlet of impeller,under the design flow rate condition,the largest aerodynamic load is 0.1969MPa,the aerodynamic load increases with the flow rate decreases.

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