The Tip Clearance Flow Resonance Behind Axial Compressor Nonsynchronous Vibration

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Jean Thomassin ◽  
Huu Duc Vo ◽  
Njuki W. Mureithi
Keyword(s):  
Shear Layer ◽  
Rotor Blade ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Tip Clearance ◽  
Tip Clearance Flow ◽  
Experimental Apparatus ◽  
Clearance Flow ◽  
Blade Tip ◽  
Blade Tip Clearance

Nonsynchronous vibration (NSV) is a particular type of aero-elastic phenomenon, where the rotor blades vibrate at nonintegral multiples of the shaft rotational frequencies. NSV behavior appears similar to off-design stall flutter but with a particular blade tip flow evolution. This paper demonstrates the link between NSV and the resonance induced by the tip clearance flow based on a proposed hypothesis and experimental confirmation. At off-design operating conditions, the rotor blade tip clearance shear layer flow can evolve tangentially. It is proposed that this tangential flow becomes a support for an acoustic feedback wave that settles between rotor blades. The feedback wave is driven by the blade vibratory motion and synchronizes the shear layer vortical structures with the blade vibration frequency. Depending on the blade tip local temperature, and when the feedback wavelength matches within one or two blade pitches, the system becomes resonant and very high vibrations can occur on the blade. An axial stage compressor test rig is set-up to look into the underlying mechanism behind NSV through targeted measurements using both static and rotating instrumentation. The experimental apparatus consists of the first stage of a high pressure compressor driven by an electric motor. The test-section is built to minimize the effects of the adjacent stator blade rows in order to isolate the role of rotor blade tip clearance flow on NSV. Sensitivity studies are carried out to assess and demonstrate the effects of the rotor blade tip clearance and inlet temperature on NSV and validate the predicted resonance for NSV occurrence under various conditions. Vibrations and surface pressure data from adjacent blades are collected to demonstrate the predicted interactions between neighboring rotor blades. Finally, evidence of the staging phenomenon, inherent to the proposed NSV mechanism, is experimentally obtained. All the data obtained are consistent with and thus in support of the proposed mechanism for NSV.

Experimental Demonstration of the Tip Clearance Flow Resonance Behind Compressor Non-Synchronous Vibration

2008 ◽  
Author(s):  
Jean Thomassin ◽  
Huu Duc Vo ◽  
Njuki W. Mureithi
Keyword(s):  
Shear Layer ◽  
Rotor Blade ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Tip Clearance ◽  
Tip Clearance Flow ◽  
Experimental Apparatus ◽  
Clearance Flow ◽  
Blade Tip ◽  
Blade Tip Clearance

Non-Synchronous Vibration (NSV) is a particular type of aero-elastic phenomenon where the rotor blades vibrate at non-integral multiples of the shaft rotational frequencies. NSV behaviour appears similar to off-design stall flutter but with a particular blade tip flow evolution. This paper demonstrates the link between NSV and the resonance induced by the tip clearance flow, based on a proposed hypothesis. At off-design operating conditions, the rotor blade tip clearance shear layer flow can evolve tangentially. It is proposed that this tangential flow becomes a support for an acoustic feedback wave that settles between rotor blades. The feedback wave is driven by the blade vibratory motion. This forms a closed loop system where the feedback wave synchronizes the shear layer vortical structures with the blade vibration frequency. Depending on the blade tip local temperature, and when the feedback wavelength matches within one or two blade pitches, the system becomes resonant and very high vibrations can occur on the blade. An axial stage compressor test rig is used to look into the underlying mechanism behind NSV. The experimental apparatus consists of the first stage of a High Pressure Compressor (HPC) driven by an electric motor. The test section is built to minimize the effects of the adjacent stator blade rows to isolate the role of rotor blade tip clearance flow on NSV. Sensitivity studies are carried out to assess the effects of the rotor blade tip clearance and inlet temperature on NSV. Finally, evidence of the staging phenomena, inherent to the proposed NSV mechanism, is experimentally obtained.

Numerical Investigation of Tip Clearance Flow Induced Flutter in an Axial Research Compressor

2016 ◽  
Author(s):  
Daniel Möller ◽  
Maximilian Jüngst ◽  
Felix Holzinger ◽  
Christoph Brandstetter ◽  
Heinz-Peter Schiffer ◽  
...  
Keyword(s):  
Early Stage ◽  
Rotor Blades ◽  
Tip Clearance ◽  
Blade Vibration ◽  
Tip Clearance Flow ◽  
Transonic Compressor ◽  
Clearance Flow ◽  
Fluctuation Pattern ◽  
Blade Tip ◽  
Pass Through

A flutter phenomenon was observed in a 1.5-stage configuration at the Darmstadt transonic compressor. This phenomenon is investigated numerically for different compressor speeds. The flutter occurs for the second eigenmode of the rotor blades and is caused by tip clearance flow which is able to pass through multiple rotor gaps at highly throttled operating points. The vibration pattern during flutter is accompanied by a pressure fluctuation pattern of the tip clearance flow which is interacting with the blade motion causing the aeroelastic instability. The velocity of the tip clearance flow fluctuation is about 50% of the blade tip speed for simulation and experiment and also matches the mean convective velocity inside the rotor gap. This is consistent for all compressor speeds. From this investigations, general guidelines are drawn which can be applied at an early stage during compressor design to evaluate the susceptibility to this kind of blade vibration.

Blade Tip Clearance Flow and Compressor NSV: The Jet Core Feedback Theory as the Coupling Mechanism

2007 ◽  
Author(s):  
Jean Thomassin ◽  
Huu Duc Vo ◽  
Njuki W. Mureithi
Keyword(s):  
High Speed ◽  
Feedback Mechanism ◽  
Rotor Blades ◽  
Tip Clearance ◽  
Coupling Mechanism ◽  
Blade Vibration ◽  
Potential Core ◽  
Tip Clearance Flow ◽  
Clearance Flow ◽  
Blade Tip

This paper investigates the role of tip clearance flow in the occurrence of non-synchronous vibrations (NSV) observed in the first axial rotor of a high-speed high-pressure compressor (HPC) in an aero-engine. NSV is an aero-elastic phenomenon where the rotor blades vibrate at non-integral multiples of the shaft rotational frequencies in operating regimes where classical flutter is not known to occur. A physical mechanism to explain the NSV phenomenon is proposed based on the blade tip trailing edge impinging jet like flow, and a novel theory based on the acoustic feedback in the jet potential core. The theory suggests that the critical jet velocity, which brings a jet impinging on a rigid structure to resonance, is reduced to the velocities observed in the blade tip secondary flow when the jet impinges on a flexible structure. The feedback mechanism is then an acoustic wave traveling backward in the jet potential core, and this is experimentally demonstrated. A model is proposed to predict the critical tip speed at which NSV can occur. The model also addresses several unexplained phenomena, or missing links, which are essential to connect tip clearance flow unsteadiness to NSV. These are the pressure level, the pitch-based reduced frequency, and the observed step changes in blade vibration and mode shape. The model is verified using two different rotors that exhibited NSV.

Parametric Study of Blade Tip Clearance, Flow Rate, and Impeller Speed on Blood Damage in Rotary Blood Pump

2009 ◽  
Vol 33 (6) ◽  
pp. 468-474 ◽  
Author(s):  
Nahn Ju Kim ◽  
Chenguang Diao ◽  
Kyung Hyun Ahn ◽  
Seung Jong Lee ◽  
Marina V. Kameneva ◽  
...  
Keyword(s):  
Flow Rate ◽  
Parametric Study ◽  
Tip Clearance ◽  
Blood Pump ◽  
Rotary Blood Pump ◽  
Tip Clearance Flow ◽  
Blood Damage ◽  
Clearance Flow ◽  
Blade Tip ◽  
Blade Tip Clearance

Experimental Off-Design Investigation of Unsteady Secondary Flow Phenomena in a Three-Stage Axial Compressor at 68% Nominal Speed

2004 ◽  
Author(s):  
Andreas Bohne ◽  
Reinhard Niehuis
Keyword(s):  
Dynamic Pressure ◽  
Axial Compressor ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Tip Clearance ◽  
Tip Clearance Flow ◽  
Pressure Transducers ◽  
Surge Margin ◽  
Clearance Flow ◽  
Flow Phenomena

This paper deals with unsteady measurements in a highspeed three-stage axial compressor with inlet guide vanes (IGV) and controlled diffusion airfoils (CDA) at off-design conditions. The compressor under consideration exhibits design features of real industrial compressors. The main emphasis is put on the experimental investigation of two operating points at 68% nominal speed where a significant mismatching of the stages occurs. The first operating point is the last stable one near the surge margin whereas the second one represents choke. Probe traverses with a high resolution both in space and time show the significant potential upstream influence of the rotor blades. This effect and the disturbances caused by the convected wakes do strongly influence the unsteady boundary layer behaviour of the stator blades which are detected by glue-on hot-film sensors at different spanwise positions. Dynamic pressure transducers on the casing show that the structure of the rotor tip clearance flow strongly depends on the operating conditions of the compressor. Conclusions can be drawn concerning the consideration of the discussed unsteady effects within the design process of multistage axial compressors with respect to the presented results.

Numerical Simulation of a Transonic Centrifugal Compressor Blades Tip Clearance Flow of Vehicle Turbocharger

2008 ◽  
Author(s):  
Gongda Guo ◽  
Yangjun Zhang ◽  
Jianzhong Xu ◽  
Xinqian Zheng ◽  
Weilin Zhuge
Keyword(s):  
Shock Waves ◽  
Centrifugal Compressor ◽  
Tip Clearance ◽  
Tip Leakage Flow ◽  
Tip Clearance Flow ◽  
Tip Leakage ◽  
Transonic Centrifugal Compressor ◽  
Clearance Flow ◽  
Blade Tip ◽  
Blade Tip Clearance

Flow induced by blade tip clearance is important for centrifugal compressor, especially for the high charging ratio transonic centrifugal compressor of the vehicle. Based on three-dimensional CFD method, the evolution and mechanism of tip clearance flow for the high charging ratio transonic centrifugal compressor are investigated. It is verified that shock waves have important effect on blade tip clearance flow. The original position and strength of leakage vortices depend on the position and intensity of shock waves. The tip leakage vortex (TLV) evolution is influenced by the evolution of passage vortex (PV), corner vortex (CV) and separated vortex (SV). Shock wave, adverse pressure gradient and casing boundary layer accelerate the leakage vortices breakdown. Leakage vortex loss is the most important factor of impeller loss. The research on the blades tip leakage flow of transonic centrifugal compressor for vehicle lays a foundation for transonic centrifugal compressor flow control.

Study on Effect of Rotor Vibration on Tip Clearance Variation and Fast Active Control of Tip Clearance

2010 ◽  
Vol 139-141 ◽  
pp. 2469-2472 ◽  
Author(s):  
Bing Hui Jia ◽  
Xiao Dong Zhang
Keyword(s):  
Tip Clearance ◽  
Operating Efficiency ◽  
Rotor Vibration ◽  
Tip Clearance Flow ◽  
Clearance Flow ◽  
Blade Tip ◽  
Flight Loads ◽  
Variation Mechanism ◽  
Clearance Control ◽  
Blade Tip Clearance

The tip clearance flow of axial turbomachines is important for their aerodynamic and maneuver performance. And the tip clearance gap leakage flow is of continuing concern in reducing efficiency losses that occur within turbines. In order to gain significant reductions in emissions and specific fuel consumption as well as dramatic improvements in operating efficiency and increased service life of aero-engine, variation mechanism of blade tip clearance was analyzed and the equation of dynamic clearance was shown firstly, then the effect of rotor vibration in clearance variation which include flight loads and engine loads was studied in this paper; based on the dynamic measurements of blade tip clearance, a method that ensure tip clearance at optimal state in given mission profile through active rotor vibration control and active tip clearance control was presented. Besides, fuzzy control theory was used to solve the high nonlinear variation of tip clearance. The analysis result shows that this technique is useful.

Plasma Actuator Blade Tip Clearance Flow Control in a Linear Turbine Cascade

2012 ◽  
Vol 28 (3) ◽  
pp. 504-516 ◽  
Author(s):  
Daniel K. Van Ness ◽  
Thomas C. Corke ◽  
Scott C. Morris
Keyword(s):  
Flow Control ◽  
Plasma Actuator ◽  
Tip Clearance ◽  
Turbine Cascade ◽  
Tip Clearance Flow ◽  
Clearance Flow ◽  
Blade Tip ◽  
Blade Tip Clearance

scholarly journals Flow Field Investigation in the Exit Region of a Radial Inflow Turbine Using LDV

1994 ◽  
Author(s):  
D. Muthuvel Murugan ◽  
Widen Tabakoff ◽  
Awatef Hamed
Keyword(s):  
Flow Field ◽  
Field Investigation ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Complex Flow ◽  
Tip Clearance Flow ◽  
Exit Region ◽  
Flow Investigation ◽  
Clearance Flow ◽  
Radial Inflow Turbine

Detailed flow investigation in the downstream region of a radial inflow turbine has been performed using a three component Laser Doppler Velocimetry. The flow velocities are measured in the exit region of the turbine at off-design operating conditions. The results are presented as contour and vector plots of mean velocities, flow angles and turbulent stresses. The measured parameters are correlated to the rotor blade rotation to observe any periodic nature of the flow. The measurements reveal a complex flow pattern near the tip region at the rotor exit due to the interaction of the tip clearance flow. The degree of swirl of the flow near the tip region at the rotor exit is observed to be high due to the gross under turning of the flow near the tip region. The effect of the rotor on the exit flow field is observed in the proximity of the rotor exit.

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