Self-Excited Blade Vibration Experimentally Investigated in Transonic Compressors: Acoustic Resonance

2015 ◽  
Vol 138 (4) ◽  
Author(s):  
F. Holzinger ◽  
F. Wartzek ◽  
H.-P. Schiffer ◽  
S. Leichtfuss ◽  
M. Nestle
Keyword(s):  
Rotor Blade ◽  
Guide Vane ◽  
Separated Flow ◽  
Acoustic Resonance ◽  
Rotating Stall ◽  
Rotor Blades ◽  
Inlet Guide Vane ◽  
Blade Vibration ◽  
Excited Vibration ◽  
Experimental Findings

This paper investigates the acoustically induced rotor blade vibration that occurred in a state-of-the-art 1.5-stage transonic research compressor. The compressor was designed with the unconventional goal to encounter self-excited blade vibration within its regular operating domain. Despite the design target to have the rotor blades reach negative aerodamping in the near stall region for high speeds and open inlet guide vane, no vibration occurred in that area prior to the onset of rotating stall. Self-excited vibrations were finally initiated when the compressor was operated at part speed with fully open inlet guide vane along nominal and low operating line. The mechanism of the fluid–structure interaction behind the self-excited vibration is identified by means of unsteady compressor instrumentation data. Experimental findings point toward an acoustic resonance originating from separated flow in the variable inlet guide vanes (VIGV). A detailed investigation based on highly resolved wall-pressure data confirms this conclusion. This paper documents the spread in aerodynamic damping calculated by various partners with their respective aeroelastic tools for a single geometry and speed line. This significant spread proves the need for calibration of aeroelastic tools to reliably predict blade vibration. This paper contains a concise categorization of flow-induced blade vibration and defines criteria to quickly distinguish the different types of blade vibration. It further gives a detailed description of a novel test compressor and thoroughly investigates the encountered rotor blade vibration.

Self-Excited Blade Vibration Experimentally Investigated in Transonic Compressors: Acoustic Resonance

2015 ◽  
Author(s):  
F. Holzinger ◽  
F. Wartzek ◽  
M. Nestle ◽  
H.-P. Schiffer ◽  
S. Leichtfuß
Keyword(s):  
Rotor Blade ◽  
Guide Vane ◽  
Separated Flow ◽  
Acoustic Resonance ◽  
Rotating Stall ◽  
Rotor Blades ◽  
Inlet Guide Vane ◽  
Blade Vibration ◽  
Excited Vibration ◽  
Experimental Findings

This paper investigates the acoustically induced rotor blade vibration that occurred in a state-of-the-art 1.5-stage transonic research compressor. The compressor was designed with the unconventional goal to encounter self-excited blade vibration within its regular operating domain. Despite the design target to have the rotor blades reach negative aerodamping in the near stall region for high speeds and open inlet guide vane, no vibration occurred in that area prior to the onset of rotating stall. Self-excited vibrations were finally initiated when the compressor was operated at part speed with fully open inlet guide vane along nominal and low operating line. The mechanism of the fluid-structure-interaction behind the self-excited vibration is identified by means of unsteady compressor instrumentation data. Experimental findings point towards an acoustic resonance originating from separated flow in the variable inlet guide vanes. A detailed investigation based on highly resolved wall pressure data confirms this conclusion. The paper documents the spread in aerodynamic damping calculated by various partners with their respective aeroelastic tools for a single geometry and speed line. This significant spread proves the need for calibration of aeroelastic tools to reliably predict blade vibration. The paper contains a concise categorization of flow induced blade vibration and defines criteria to quickly distinguish the different types of blade vibration. It further gives a detailed description of a novel test compressor and thoroughly investigates the encountered rotor blade vibration.

Rotor Blade Unsteady Aerodynamic Gust Response to Inlet Guide Vane Wakes

1993 ◽  
Vol 115 (1) ◽  
pp. 197-206 ◽  
Author(s):  
S. R. Manwaring ◽  
S. Fleeter
Keyword(s):  
Rotor Blade ◽  
Guide Vane ◽  
Axial Flow ◽  
Unsteady Aerodynamics ◽  
Rotor Blades ◽  
Inlet Guide Vane ◽  
Unsteady Aerodynamic ◽  
Forcing Function ◽  
Reduced Frequency ◽  
Flow Compressor

A series of experiments is performed in an extensively instrumented axial flow research compressor to investigate the fundamental flow physics of wake-generated periodic rotor blade row unsteady aerodynamics at realistic values of the reduced frequency. Unique unsteady data are obtained that describe the fundamental unsteady aerodynamic gust interaction phenomena on the first-stage rotor blades of a research axial flow compressor generated by the wakes from the inlet guide vanes. In these experiments, the effects of steady blade aerodynamic loading and the aerodynamic forcing function, including both the transverse and chordwise gust components, and the amplitude of the gusts, are investigated and quantified.

Rotor Blade Unsteady Aerodynamic Gust Response to Inlet Guide Vane Wakes

1991 ◽  
Author(s):  
Steven R. Manwaring ◽  
Sanford Fleeter
Keyword(s):  
Rotor Blade ◽  
Guide Vane ◽  
Axial Flow ◽  
Unsteady Aerodynamics ◽  
Rotor Blades ◽  
Inlet Guide Vane ◽  
Unsteady Aerodynamic ◽  
Forcing Function ◽  
Reduced Frequency ◽  
Flow Compressor

A series of experiments are performed in an extensively instrumented axial flow research compressor to investigate the fundamental flow physics of wake generated periodic rotor blade row unsteady aerodynamics at realistic values of the reduced frequency. Unique unsteady data are obtained which describe the fundamental unsteady aerodynamic gust interaction phenomena on the first stage rotor blades of a research axial flow compressor generated by the wakes from the Inlet Guide Vanes. In these experiments, the effects of steady blade aerodynamic loading and the aerodynamic forcing function, including both the transverse and chordwise gust components, and the amplitude of the gusts, are investigated and quantified.

Quick Start of an Industrial Gas Turbine Engine Through the Development of “Silent Start” VGV Schedule

2020 ◽  
Author(s):  
Senthil Krishnababu ◽  
Vili Panov ◽  
Simon Jackson ◽  
Andrew Dawson
Keyword(s):  
Guide Vane ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Rotating Stall ◽  
Rotor Blades ◽  
Start Time ◽  
Turbine Engine ◽  
High Pressure Ratio ◽  
Compressor Map ◽  
Industrial Gas Turbine

Abstract In this paper, research that was carried out to optimise an initial variable guide vane schedule of a high-pressure ratio, multistage axial compressor is reported. The research was carried out on an extensively instrumented scaled compressor rig. The compressor rig tests carried out employing the initial schedule identified regions in the low speed area of the compressor map that developed rotating stall. Rotating stall regions that caused undesirable non-synchronous vibration of rotor blades were identified. The variable guide vane schedule optimisation carried out balancing the aerodynamic, aero-mechanical and blade dynamic characteristics gave the ‘Silent Start’ variable guide vane schedule, that prevented the development of rotating stall in the start regime and removed the non-synchronous vibration. Aerodynamic performance and aero-mechanical characteristics of the compressor when operated with the initial schedule and the optimised ‘Silent Start’ schedule are compared. The compressor with the ‘Silent Start’ variable guide vane schedule when used on a twin shaft engine reduced the start time to minimum load by a factor of four and significantly improved the operability of the engine compared to when the initial schedule was used.

A Resonance Tracking Algorithm for the Prediction of Turbine Forced Response With Friction Dampers

2000 ◽  
Author(s):  
C. Bréard ◽  
J. S. Green ◽  
M. Vahdati ◽  
M. Imregun
Keyword(s):  
Rotor Blade ◽  
Turbine Blades ◽  
Turbine Rotor ◽  
Forced Response ◽  
Rotor Blades ◽  
Test Case ◽  
Friction Damper ◽  
Blade Vibration ◽  
Frequency Shifts ◽  
Friction Dampers

This paper presents an iterative method for determining the resonant speed shift when non-linear friction dampers are included in turbine blade roots. Such a need arises when conducting response calculations for turbine blades where the unsteady aerodynamic excitation must be computed at the exact resonant speed of interest. The inclusion of friction dampers is known to raise the resonant frequencies by up to 20% from the standard assembly frequencies. The iterative procedure uses a viscous, time-accurate flow representation for determining the aerodynamic forcing, a look-up table for evaluating the aerodynamic boundary conditions at any speed, and a time-domain friction damping module for resonance tracking. The methodology was applied to an HP turbine rotor test case where the resonances of interest were due to the 1T and 2F blade modes under 40 engine-order excitation. The forced response computations were conducted using a multi-stage approach in order to avoid errors associated with “linking” single stage computations since the spacing between the two bladerows was relatively small. Three friction damper elements were used for each rotor blade. To improve the computational efficiency, the number of rotor blades was decreased by 2 to 90 in order to obtain a stator/rotor blade ratio of 4/9. However, the blade geometry was skewed in order to match the capacity (mass flow rate) of the components and the condition being analysed. Frequency shifts of 3.2% and 20.0% were predicted for the 1T/40EO and 2F/40EO resonances in about 3 iterations. The predicted frequency shifts and the dynamic behaviour of the friction dampers were found to be within the expected range. Furthermore, the measured and predicted blade vibration amplitudes showed a good agreement, indicating that the methodology can be applied to industrial problems.

Numerical and Experimental Investigation on the Influence of Blades Gap Flow on Axial Blood Pump Performance

2019 ◽  
Author(s):  
Guangmao Liu ◽  
Donghai Jin ◽  
Mengyu Wang ◽  
Xingmin Gui
Keyword(s):  
Rotor Blade ◽  
Guide Vane ◽  
Flow Characteristics ◽  
Pressure Rise ◽  
Blood Pump ◽  
Inlet Guide Vane ◽  
Pump Efficiency ◽  
Blade Root ◽  
Gap Flow ◽  
Blade Tip

Abstract The axial blood pump body primarily contains the Inlet Guide Vane (IGV), Rotor Impeller (RI), Outlet Guide Vane (OGV) and pump casing. There must be gaps between rotor blade tip and pump casing or between OGV blade root and rotor hub for the impeller rotating in the pump. The flow characteristics inside an axial blood pump with different blade gaps were numerically simulated and analyzed. Hydraulics experiments were conducted to verify the numerical results. The results show that the pump efficiency decreased slowly when the OGV blade gap increased from 0.1 mm to 0.3 mm, but quickly when the rotor blade gap increased from 0.1 mm to 0.3 mm. The hydraulics characteristic results indicate that the pressure rise and efficiency are mainly influenced by the rotor blade gap. The OGV blade root gaps have little influence on the decrease of pressure rise and efficiency. The novel configuration with uneven blade gaps inside the pump result in improved hydraulics and hemolytic performance compared with the similarly sized configuration with even blade gaps.

scholarly journals Investigation on the Flow Field Entropy Structure of Non-Synchronous Blade Vibration in an Axial Turbocompressor

Entropy ◽  
2020 ◽  
Vol 22 (12) ◽  
pp. 1372
Author(s):  
Mingming Zhang ◽  
Anping Hou
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Guide Vane ◽  
Leading Edge ◽  
Inlet Guide Vane ◽  
Tip Leakage Flow ◽  
Good Correspondence ◽  
Blade Vibration ◽  
Tip Leakage ◽  
Spiral Vortex

In order to explore the inducing factors and mechanism of the non-synchronous vibration, the flow field structure and its formation mechanism in the non-synchronous vibration state of a high speed turbocompressor are discussed in this paper, based on the fluid–structure interaction method. The predicted frequencies fBV (4.4EO), fAR (9.6EO) in the field have a good correspondence with the experimental data, which verify the reliability and accuracy of the numerical method. The results indicate that, under a deviation in the adjustment of inlet guide vane (IGV), the disturbances of pressure in the tip diffuse upstream and downstream, and maintain the corresponding relationship with the non-synchronous vibration frequency of the blade. An instability flow that developed at the tip region of 90% span emerged due to interactions among the incoming main flow, the axial separation backflow, and the tip leakage vortices. The separation vortices in the blade passage mixed up with the tip leakage flow reverse at the trailing edge of blade tip, presenting a spiral vortex structure which flows upstream to the leading edge of the adjacent blade. The disturbances of the spiral vortexes emerge to rotate at 54.5% of the rotor speed in the same rotating direction as a modal oscillation. The blade vibration in the turbocompressor is found to be related to the unsteadiness of the tip flow. The large pressure oscillation caused by the movement of the spiral vortex is regarded as the one of the main drivers for the non-synchronous vibration for the present turbocompressor, besides the deviation in the adjustment of IGV.

Water Film Formation on an Axial Flow Compressor Rotor Blade

2008 ◽  
Author(s):  
Theoklis Nikolaidis ◽  
Periclis Pilidis ◽  
J. A. Teixeira ◽  
V. Pachidis
Keyword(s):  
Rotor Blade ◽  
Guide Vane ◽  
Axial Flow ◽  
Water Film ◽  
Inlet Guide Vane ◽  
Computational Domain ◽  
Axial Flow Compressor ◽  
Water Ingestion ◽  
Compressor Rotor ◽  
Flow Compressor

A numerical approach was used to evaluate the liquid water film thickness and its motion on an axial flow compressor rotor blade under water ingestion conditions. By post-processing blading data and using computer programs to create the blades and their computational grid, the global computational domain of the first stage of an axial flow compressor was built. The flow field within the domain was solved by CFX-Tascflow, which is a commercial CFD code commonly used in turbomachinery. The computational domain consists of an extended inlet, an inlet guide vane, a rotor and a stator blade. Having solved the flow field at Design Point, the inlet guide vane blade was re-positioned to account for changes in idle speed. At that speed, the effects of water ingestion are expected to be more significant on gas turbine engine performance. Several cases with water ingestion were studied, changing parameters like water mass and compressor rotational speed. A FORTRAN computer program was created to calculate the water film height and speed. The extra torque needed by the compressor to keep running at the same rotational speed, was also calculated. The considerable increase in torque was confirmed by experimental observations according to which water ingestion had a detrimental effect on gas turbine operation.

Noise generation in vane axial fans due to rotating stall and surge

2001 ◽  
Vol 215 (1) ◽  
pp. 57-64 ◽  
Author(s):  
M Čudina
Keyword(s):  
Rotor Blade ◽  
Guide Vane ◽  
Axial Flow ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Noise Generation ◽  
Total Noise ◽  
Operating Stability ◽  
Partial Load ◽  
Axial Fans

A characteristic of axial flow fans is instabilities in their performance and noise in partial load operation. These instabilities are a consequence of rotating stall created in the rotor blade and/or in the guide vane cascade. At some operating conditions the rotating stall caused the appearance of a surge representing the lowest region of fan operating stability. The rotating stall and especially surge caused a steep increase in the emitted noise and lowered the performance of the fan. The present paper highlights the rotating stall generation phenomenon and its influence on the emitted total noise level and noise spectra for axial flow fans with inlet and outlet guide vanes.

Influence of Hot Streak Circumferential Length-Scale in Transonic Turbine Stage

2004 ◽  
Author(s):  
L. He ◽  
V. Menshikova ◽  
B. R. Haller
Keyword(s):  
Heat Transfer ◽  
Computational Study ◽  
Guide Vane ◽  
Strong Dependence ◽  
Rotor Blades ◽  
Inlet Temperature ◽  
Turbine Stage ◽  
Blade Vibration ◽  
Nozzle Guide ◽  
Hot Streak

A computational study is carried out on the influence of turbine inlet temperature distortion (hot streak). The hot streak effects are examined from both aeromechanical (forced blade vibration) and aero-thermal (heat transfer) points of view. Computations are firstly carried out for a transonic HP turbine stage, and the steady and unsteady surface pressure results are compared with the corresponding experimental data. Subsequent analysis is carried out for hot-streaks with variable circumferential wavelength, corresponding to different numbers of combustion burners. The results show that the circumferential wavelength of the temperature distortion can significantly change unsteady forcing as well as the heat-transfer to rotor blades. In particular, when the hot-streak wavelength is the same as the nozzle guide vane (NGV) blade pitch, there is a strong dependence of the preferential heating characteristics on the relative clocking position between hot-streak and NGV blade. However, this clocking dependence is shown to be qualitatively weakened for the cases with fewer hot streaks with longer circumferential wavelengths.

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